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Tecumseh OHV engine


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10-29-03, 04:01 PM   #1  
Tecumseh OHV engine

I've been working on a Sears 143.640022 (Tecumseh ?) engine
in a lawn tractor/snow blower belonging to my neighbor. I believe that the piece of equipment has been sitting for at least a year without running. There were a few carb problems that I solved right away with a repair kit but there is a second problem that seems a bit more puzzling. The engine will now start and run just fine until you get the speed up to about 2100 rpm. At that point the engine looses power and blows gas back out the carb throat. That says to me that the intake valve is hanging up. I've removed the valve cover and rocker arms and have been pushing sideways on the intake and exhaust valve trying to determine if the valve guides may be worn out. The intake valve moves side to side quite a bit more than the exhaust valve does. A couple of years back I rebuilt a Chevy engine in my pickup and some where I read that you could check the valve guides in a Chevy engine by putting a dial indicator on the valve stem and move the valve back & forth and the max deflection you should see was about 0.002. In any event I could easily check the valve guides if I could figure out how to remove the head. There is a single head bolt under the valve cover that has to be removed but you can't remove the valve cover box without removing the valves. You can't seem to remove the valves without removing the head ! The traditional valve spring compression tools I have for Briggs engines just won't fit with the mechanical restrictions on the Tecumseh engine. I'm sure that the service manual will tell me how to solve the puzzle but I just ordered one for the engine but don't yet have it. Has anyone played with a Tecumseh engine like this one? I've also seen indications that there may be a compression release system on this engine to aid in starting that could be malfuntioning and causing the problem. The valve train all seems to be free and unrestricted so I don't think the problem is an obvious sticking valve.

 
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10-29-03, 04:41 PM   #2  
Fisher
Could easily be a valve clearence problem.
Fish

 
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10-29-03, 05:06 PM   #3  
I checked the valve lash with a feeler gauge at about 0.008. Since I don't have a manual I don't know if that is normal or not. A large Cat diesel engine would have more like 0.020 clearance between rocker arm and the intake valve stem, but I don't know what to expect on a small engine.

 
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10-30-03, 04:01 AM   #4  
mikejmerritt
Hello jughead, this engine is in the Tecumseh HH line of cast iron engines and does have a mechanical compression release cam. I believe it to be a 12HP. IF its an HH120 the intake setting is .010 and exhaust .020.

Go here http://www3.sears.com/intro.shtml and type your engine model and you will get a choice of a parts list or exploded view of the engine. This should help with the valve removal problem...Mike

 
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10-30-03, 11:00 PM   #5  
Hello Jughead!

I agree, it does sound like a valve problem. This sounds like the 12hp that mike mentioned. I have a spring compressor that will compress these valve springs, but I can't remember where I got it. If you pull the head on this engine, there is a lot of stuff to keep track of, and some "O" rings that must be replaced. I don't see any reason to remove the head from your description though. Set the valve lash and see what happens. If the compression release is stuck, it may free up with a little bit of running. If not, it is on the camshaft and you will have to remove the sump cover to access it. Let us know how it goes!


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10-31-03, 01:18 PM   #6  
I'm working 12 hour days 7 days a week right now until Nov 11th so I won't get back to the project until then. In the mean time I will probably get the manual and be able to confirm a cross ref between craftsman & tecumseh. I find it interesting that the valve doesn't seem to hang up until the engine gets to 2100 rpm and promptly goes away at lower speeds. I've rebuilt many Briggs engines in the past and I know that they just have a different cam that holds the intake valve open a bit longer than normal. My tecumseh tech manual for 3 to 11 HP L-head engines shows that tecumseh does their compression release by holding open the exhaust valve. If I had the head off and could examine the intake valve and it's seat I'm sure that it would reveal if the intake valve is somehow hanging up before it can close. I've replaced worn valve guides in Briggs engines before but don't recall that they had problems like what I'm seeing here. I just can't think of another logical reason other than valve lash for the problem. The fact that I've got at least 0.008 with a nominal 0.01 spec seems to rule out valve lash as the problem unless the spec is much more critical than normal. I can't wait to get the bottom of this problem & let you know what I've found, it should prove interesting !

 
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11-01-03, 09:40 PM   #7  
The cam with compression release has a flywheight that holds a pin that protrudes above the cam lobe surface to keep the valve from closing all the way until the engine starts. Then centrifugal force makes the flyweight pull the pin back down below the cam lobe surface so that the lifter can ride on the cam lobe and close the valve. This mechanism can stick, and can get worn and cause problems. We'll look forward to hearing what you find!


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11-02-03, 02:01 AM   #8  
I read the short description of the compression release mechanism in one of my Tecumseh manuals. I also read that the mechanism actuated the exhaust valve. Consider what would likely happen if the mechanism WAS on the intake valve, perhaps because this is an OLDER engine, and the mechanism WAS sticking. The compression would tend to be released and would only be restored to normal at a HIGHER than normal speeds. What I'm seeing is exactly the opposite. There is blow back through the carb at a speed moderately higher than idle EVERY time the engine speeds up and the blow back goes away EVERY time engine speed is reduced. I now surmise that somehow the intake valve is partly binding in the valve guide because of a weaker than normal spring or because of excessive clearance of the guide itself. I've pushed down on the top of the intake valve stem after removing the rocker arm and the spring seems to react about the same as the exhaust valve. I don't recall ever seeing a spec on the force necessary to produce a certain spring compression and thus yielding a spring constant for either a Briggs or Tecumseh engine. Specs like that are well known for chevy engines and are important because a spring that is too strong would tend to wear the cam shaft and cause higher friction forces. A spring that is too weak would cause overshoot on the back side of the cam lob and would delay valve closure. This delay would be proportional to engine speed. Perhaps this is what I'm seeing here. I've never heard of springs getting stronger but springs getting weaker with age and use is common. The engine HASN'T been run for at least a year and perhaps it stopped with the intake valve spring in the compressed position for that year. I only wish that I had a calibrated finger to tell for sure. Maybe I'll see the service manual next week and be able to make further progress. I can't wait.

 
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11-02-03, 09:35 PM   #9  
I don't think you have a spring problem, but you never know. It does sound like symptoms of a floating valve. After reading your last post, I think there's a pretty good chance you have an exhaust restriction. Either way, I believe the problem is valve or exhaust related.


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11-02-03, 11:05 PM   #10  
I've since learned from my neighbor that the machine has been sitting for about 3 years. It was outside but covered up with a pickup truck topper when I dug it out & got it started. I think that a plugged exhaust system would cause the engine to bog down at higher speeds and there would be a big loss of power but wouldn't have any effect on the operation of the valves at all. The machine will move OK on it's own power and the snow blower attachment will turn OK without a load as long as I keep the engine speed low.

I guess I could imagine that a partly restricted exhaust system would cause a complete loss of power eventually and since the air fuel mixture couldn't get out the exhaust port fast enough there would be a much higher pressure than normal remaining in the chamber when the intake valve finally opens at the end of the exhaust cycle and cause the blow back thru the carb. This could happen with a perfectly good valve train. At lower speeds the blow down period is long enough and the pressure is low enough when the intake valve opens for the engine to operate normally.

A large spider condo construction project could have been taking place inside the muffler during the three years the machine sat idle. I might be able to quickly confirm this because the exhaust system can be easily disconnected. I also believe it might be wise to try it before I jerk the head.

Stay tuned!

 
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11-04-03, 12:58 AM   #11  
Sounds like you got the idea! I hope you find your problem there, and you won't have to worry with internal engine repairs.


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11-06-03, 07:30 PM   #12  
The correct manual came in the mail the other day. There is a cross ref from craftsman to tecumseh that reveals that I am working on an OH160 engine. The valves would come out real easy if I had a 670237A valve spring compressor. I can see how they compress the spring with this tool and remove the keeper from the top of the valve stem. Perhaps Cheese is correct and the trouble is a restricted exhaust system. It would save a lot of time if I don't have to do any internal work to the engine.

On the Briggs engines I've worked on I was always able to get a part number by downloading & printing a diagram from the B & S web site. Anyone know how to get the same info on Tecumseh engines? There seems to be a lot of complaining about the price of parts you have to pay when you order directly from craftman. They give you a parts list, but of course, they have their craftsman numbers on the diagram and you get to pay their prices. It would be nice to use the regular tecumseh numbers and the pay the regular tecumseh prices.

 
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11-06-03, 11:17 PM   #13  
If you type in the craftsman model # of the engine at www.sears.com/partsdirect the part numbers you get should be actual tecumseh numbers.


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11-07-03, 08:16 PM   #14  
Cool ! I knew about the web page you cited, Cheese, but I didn't know that the part numbers were the real tecumseh ones. Guess I figured that Craftsman would change all the numbers so you would have to buy from them. In all fairness, I did some on line shopping and didn't find a huge difference in the price for a typical oversized piston between Craftsman and some of the other pervayers of small engine parts. There did seem to be a big difference between an after market carb kit and one sold by Tecumseh. The carb kit is probably made by Walbro anyway then sold to Tecumseh then to the dealer and finally to you. Lots of hands in there taking a piece of every dollar you spend. Maybe I'll try some of the after market carb kits and see if they really are the bargin they seem to be.

Will let you know soon about the OH160 engine as I'll be off for a couple of weeks starting on the 11th.

 
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11-12-03, 07:12 AM   #15  
I got back into the garage last evening and checked out the exhaust system on the engine. While the muffler is going bad, there isn't any obstructions of the exhaust flow. I completely removed the muffler & fired the engine up and still have the same problem. It still blows back through the carb over a certain engine speed. The blue exhaust flame was cool but I'm still going to have to get into the engine to fix the problem. At least I have the manual now and know how to get the valves out. I will let you know what I've found relative to the valve train. It will have to be excessive wear of the valve guides or some kind of wierd problem with the compression release system.

 
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11-12-03, 04:21 PM   #16  
Fisher
OK!

It is time......

Check your flywheel key.....

Fish

 
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11-12-03, 04:52 PM   #17  
Neat idea about the flywheel key, but I don't get it. If the
key was completely sheered the engine wouldn't run. A partly
sheered key would effect the ignition timing but wouldn't do
anything to the valves. Never the less, it would be easy to
check since the flywheel cover is off anyway. I've seen a partly
sheered key on a B & S before but I don't remember it being
a serious problem. Perhaps only a partial loss of power.
I'll let you know.

 
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11-12-03, 05:38 PM   #18  
Fisher
Just sounds like a good possibility.

 
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11-12-03, 08:51 PM   #19  
Agreed.

Fish always thinks of that before I do, lol . It is a good possibility that the key is partially sheared. A sheared key is not very common on lawn tractors, but can happen...especially if someone had the flywheel off for some reason and didn't tighten the flywheel nut good enough during re-installation.


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11-15-03, 08:24 AM   #20  
A visual inspection of the flywheel keyway was made and revealed
that no slipage of the flywheel on the crankshaft has occured.
I tried to remove the crankshaft with the pullers
that I already own with negative results. Tecumseh shows
a number for their flywheel puller which I now have on order.
I also ordered the (cheap) valve spring removal tool. I did buy
a valve spring compression tool that works from the top of
the engine that will compress the valve spring but I still am
unable to remove the keepers from the top of the valve stem.
The only way for that to happen is for the valve to be supported
from below. Tecumseh advises to put the cylinder on TDC which
was done, but I believe that I may not be able to compress
the valve spring sufficiently to bottom the valve out on the top of the piston.

I am now starting to believe that the crux of the problem may
be with the compression release mechanism. Perhaps it was
assembled incorrectly or has failed in such a manner that
centrifugal force does exactly the opposite of what it should and
opens the intake valve on an increase in speed.

A complete gasket set was ordered as I am now expecting to
be inside the engine inspecting the camshaft when I receive
the necessary tools to complete the tear down. With my wierd
work schedule this could take another month unless I receive
what I need before the end of next week.

I'm sure that this adventure will not be soon forgotten and maybe everyone will learn something from the 'fix' if/and/or when it occurs.

 
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11-16-03, 04:47 PM   #21  
This is a little off topic, but it has to do with this engine and design.
I understand there are problems with OHV engines as far as reliability goes. Can anyone comment on this?

 
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11-19-03, 09:41 AM   #22  
I got the pullers & valve removal tools and within minutes I had the engine apart. It sure pays to have the proper tools for the job! The intake valve & valve margin look good under a microscope so I don't think the valve has been hanging up. Also confirmed is the fact that the keyway & flywheel is OK. What I did find that I don't like is the fact that the intake valve guide is loose in the head. On these Tecumseh engines you are supposed to put the head in hot oil and the valve guides in the freezer before installation. It is supposed to be a tight fit and that is exactly what I see with the exhaust valve guide. Presently the intake guide is free to go in & out and will easily bottom on the spring clip. The guide could have a tendency to slip up as the valve closes. It could also have the same effect as a worn out valve guide inside diameter. What isn't known is if the slipping is keeping the valve from properly closing at higher engine speeds. There seems to be no evidence of improper closing on the valve margin or the valve seats. Both seem to be good & smooth with no ridges visable even under a 30X microscope. My reason for believing that the problem MAY still be inside with the compression release mech is my initial compression test way back before I even knew there was any kind of trouble at all. My routine compression measurement yielded a satisfactory 125 psi with a short burst from the starter. I would think that the compression release wouldn't allow such a good reading at low cranking speeds, but I have only limited knowledge of what to expect with Tecumseh engines. Maybe someone out there has tried this experiment and knows what to expect on a routine compression check. B & S advises that you can't really get a good compression indication with an engine installed with their compression release mech and they advise to just spin the engine over backwards and look for a good 'bounce' as the piston goes on compression from the back side. I'm thinking that I could use some epoxy to secure the valve guide in the head and re-assemble the engine. At the moment nothing could be lost by trying this as IF this is the root of my trouble I'll be buying a new head & guides anyway. Should the experiment fail and I still have a problem I would want the guide secure so I don't cause any further wear on the head or outer valve guide surface. A win-win situation either way. At the moment I just want to find the root cause of the problem.

 
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11-19-03, 02:35 PM   #23  
Wow, all the nice info. Cheese like it better when people give lots of info like you just did. It allows him to help people better! He will be replying to your message soon. Sounds like you have a interesting problem.

 
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11-19-03, 07:09 PM   #24  
I did use some epoxy to secure the intake valve guide into the head. My main fear here is that the epoxy will not hold up to the high temperatures. I've used some rather expensive epoxy material at work that, if I remember correctly, will work upwards to about 500 degrees F. What I used here was some cheap off the shelf stuff with an unknown temperature characteristic. It should suffice, though, for a short experiment. If you think this is an interesting one, I've got another; a Honda Elite with a 5HP motor that is difficult to start. I've been going head to head with this one at the same time but did mention it here until now.

 
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11-19-03, 10:44 PM   #25  
Jughead...JB weld would work well to secure the guide, or red locktite should hold up well enough too. Since there was play in the valve guide, I would think you need to lap the valve now, since the guide is in fixed position now. It may have slightly altered the position in which the valve seats. With the symptoms you described, I would lap the valve anyway.


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11-19-03, 11:16 PM   #26  
Yea, I was going to lap the valves while I was at it. Before I used the epoxy on the valve guide I was careful to hold the valve onto the seat while the epoxy was setting up. I just used some wood blocks & clamps to hold everything in place. That way the valve will be aligned with the seats and I won't have to do any grinding. The intake valve stem shows some wear that you can feel with your fingers. I didn't mic it yet but will do so soon. The exhaust valve seems to be OK. I'll bet the guide was jumping up & down in the head as the engine was running. Any bets as to if this is the cause of the main problem??

 
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11-19-03, 11:47 PM   #27  
Good chance that was it...guess you'll know soon enough!


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11-20-03, 08:49 PM   #28  
Well, the jury is still out on the intake valve guide problem. I completely reassembled the engine and it started right up. It did seem to be better, but the problem was still there. After a short run I again examined the intake valve guide only to find it loose in the head. This evening I got some JB weld and will try once more to confirm the cause of the difficulty. I selected the produce because it DID have a 600 deg F max operating temperature. All the other products I looked at typically worked only to 250 deg F. That's a huge difference and was probably the cause of the failure in the first experiment. I'm sure that the head hit 250 deg within seconds and I didn't get the engine stabilized quick enough before the guide gave way and started moving in the head. I'm sure that the product I was using wasn't up to the task but I was worth a try. I'll try again tomorrow and let you know.

 
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11-21-03, 12:52 PM   #29  
I used the JB weld last evening and this morning I reassembled the engine and test ran it again. The problem still persists, with a twist. First let me say that I first fired up the engine, got everything stabilized then I was "go for throttle up." There was still lots of spitting of fuel out the carb as the engine attempted to pass thru 2100 rpm. Needless to say there was a lot of ruff running at higher speeds. Idle, as always, remained perfect and I'm happy with it. Following the first short run I inspected the intake valve guide and confirmed that the JB weld had held and the guide was still firmly attached to the head. That was good news. I quickly reassembled the engine an ran it some more just for kicks. It seemed to getting a lot better after a couple of minutes of running. That was even better news. About then I happened to notice a C clip that I forgot to reinstall on the intake rocker arm. I shut the engine down, opened up the valve cover, and reinstalled the C clip. It was then that I noticed a very LARGE valve lash on both the intake and exhaust valves. I know that I tightened up the screws that hold the valve housing to the head but it must have gotten loose because I only used a nut driver for that task. I retightened the box with socket wrench and, of course, that again changed the valve lash to normal. There is another twist here as well. My Tecumseh manual clearly states that the valve lash should be 0.010 on the intake valve and 0.020 on the exhaust valve in the third line of chapter 4. One of the pictures in chapter 4 calls for 0.005 on the intake valve and 0.010 on the exhaust valve, as does the specifications in the back. Another twist, I can't find in the specifications a valve stem diameter. They make reference to that in chapter 4 but there only seems to be a diameter for the valve guide. My neighbor states that he installed oversized valves in this engine many years back. My measurement of 0.3405 on the intake valve and 0.3390 on the exhaust valve stem seems to bear that out because my only specification for the valve guides is 0.312 and the manual states that the oversized valves are 1/32 inch larger which yields 0.312 + 0.0312 = 0.343. The bad news is that while readjusting the valve lash after finding the valve housing loose I broke the adjusting screw on the exhaust valve. It will have to be replaced before anymore 'playing around' is attempted.

So what is 'moral' of this whole sad tale??

1. The intake valve has a noticable ridge on the stem and while I can't confirm that it is worn too small will need to be replaced because it can be moved quite a bit in the guide and is most likely not closing all the way at higher speeds.

2. JB weld seems to work in securing the guide to the head where other products did not. This product can take the heat and can 'stay in the kitchen.'

3. My neighbor says that his son in Chicago has an identical machine that has been sitting for quite some time and would be available for parts.

4. At this point I wouldn't be opposed to just tearing down the whole engine for a quick inspection of the cam shaft/compression release mech.

I was in the repair business for 20 plus years and I know that it would be hard for a small engine shop to make a profit with these kinds of problems and even harder for an owner to justify spending hours & hours working on it. It's a good thing I'm only doing this for 'kicks.'

 
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11-22-03, 12:56 AM   #30  
You can correct for valve stem and guide wear by having the guides knurled at a machine shop if you believe it is bad enough to be causing your problem. Are you satisfied that your carb settings are correct?

Wierd things happen to these engines sometimes, but it's not rocket science. Have you checked exactly how much play is in the valve?


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11-22-03, 07:03 AM   #31  
It's always difficult to measure accurately the internal diameter of anything without a plug gauge. I've got one for B & S valve guides but that won't help here. I wouldn't expect to see any more than about 0.001 difference between the valve stem and the valve guide anyway. Besides, the intake valve stem has a ridge you can feel (and see) and indicates that something bad is happening here. If this was a large engine you would have plenty of black smoke and excessive oil consumption from the oil getting into the cylinder from a worn valve stem like this. That's why they have to use valve stem seals on large engines. Just why you can get along without them on a small engine is a mystery to me. Perhaps you just don't have the volume of oil because there is no pressure lubrication system. The fact the you can actually see gas spitting OUT of the carb along with a strong burst of COLD air (in other words, NOT a backfire) for sure indicates that the intake valve isn't closing for some reason. My only question has been is the problem caused by the valve itself or from the compresson release equipment on the cam shaft. It would have been nice to confirm that the problem was with the loose valve guide but that didn't happen. The valve, valve guides, and head will have to be replaced and I'm hoping this will be the ultimate (if not expensive) fix. Hopfully I'll be getting another engine just like it so some parts interchanging will greatly simplify getting to the bottom of this mystery. In any event I'm about to go back to working twelve hour days (tonight) for the next 16 days and won't get back to the project until Dec 9th. I'll be able to see any posts here but until then won't have time to do much engine work in the garage.

 
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11-22-03, 10:56 AM   #32  
I did measure the valves & valve guides before cleaning up the shop. The measurements are as follows:

Top of intake valve stem (un worn portion) 0.341
Bottom of intake valve stem (worn portion) 0.3405
Intake valve guide internal diameter 0.346

Exhaust valve stem 0.339
Exhaust valve guide internal diameter 0.341

The exhaust valve & guide are about what I would expect but the figures indicate that the intake valve & guide are worn out. Since I don't have a nominal value for either the guide or the valve stem it's hard to tell just how much the wear is. The intake valve guide diameter also has a taper as it's bigger by about 0.001 to 0.002 at the top of than near the bottom. It's unknown if the wear is enough to keep the valve from properly seating at higher speeds. I should be able to accumulate the necessary parts to fix the known problems while I working the next two weeks then get a fresh start in December. Cheers until then.

 
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12-10-03, 04:29 PM   #33  
I'm back at the 16HP tecumseh overhead valve engine this afternoon. While I was working the last 15 days new parts came in for the engine. I received new valves and a head. There were a few differences between the old head and the new. The new head had inserts in the valve guides. My neighbor informed me that he had installed oversized valves a few years back and that was confirmed by my measurments this afternoon. The new standard sized intake valve stem measures 0.3095 and the new exhaust valve stem measures 0.3085. The valve guides measure 0.311. It looks like the new head can accomidate worn valve guides by just replacing the inserts. To me there was a little confusion over the term "oversized" valves. If you are dealing with "large" engines that term implies that the valve HEAD is larger allowing additional flow and you also need a different cylinder head and larger valve seats. Tecumseh means that just the valve STEM is larger, the heads on the standard and oversized valves are exactly the same size. Clearly an oversized valve can be used when your valve guides are worn out (and your guides don't have inserts) and you just introduce a reamer to the old guides and replace the valve with an oversized one. I think my neighbor was confused by the term as well because he stated that he could never see a performance difference when he went "oversized" a few year back. Now I know why.

Hopefully I will be able to get the tecumseh back together in the morning and report a solution to the mystery of the carburator blowback on this engine.

 
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12-11-03, 10:27 PM   #34  
The new head & valves didn't solve the problem. I've removed the engine from the tractor and am trying to remove the pulley on the PTO end. It's rusted badly and I'm sure that it will have to be cut off as I've be unable to move it with the pullers that I have. The blades come out tomorrow and hopefully I'll post what I've found inside as that is about the only place the trouble can be now.

 
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12-12-03, 09:24 PM   #35  
I was able to get the engine apart after removing the PTO belt drive pulley on the crankshaft. The pulley was difficult to remove because the set screws were rusted and stuck. Both set screws were drilled out. Next I tried the normal gear puller without success. What did work, finally, was to drill & tap three holes so that the standard tecumseh flywheel puller could be applied to the pulley. The puller screw was pulled up quite tight and the end of the large screw pushing on the end of the crankshaft was hit with a hammer a couple of times before tightening up on it some more. In this manner the pulley was slowly worked off the shaft. Since the pulley will have to be replaced anyway drilling on it wasn't any concern at all. The PTO end shaft was rusty and that's why the pulley wasn't coming off so easy. All compression release parts were inspected. All seemed to be in good order but at this time I don't see how any of these parts (compression release mechanism) can contact any part of the intake valve tappet. I didn't spend much time on that today as the engine was very dirty and needed to be degreased and the old gaskets scraped off. The cylinder cooling fins were in many cases completely impacted with dirt, grass, and grease and badly needed to be cleaned. I'll return to the possible valve lift problems tomorrow before reassembling the engine. I've been looking at the Tecumseh manual this evening and I believe there is a problem with the way the compression release is working but I'll have to wait till tomorrow to confirm this.

 
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12-14-03, 01:31 AM   #36  
The compression release mechanism was inspected and found to be in good order. I see now how the thing works and checked to see if the pin was stuck. Everything was free and moving OK. The only thing I noticed upon disassembly of the engine was the POSSIBLE out of phase position of the cam gear in relation to the crank shaft. I was looking for something like this to happen but the way the tecumseh engine comes apart I could see that it's possible for the cam gear to move a notch or two while the case halves are split. If the cam was out of time by one gear tooth I could see how you could get some wierd things happening. Since I didn't find anything wrong with the compression release mechanism or anything else for that matter, I'm assuming that there was a timing problem.

There was another small problem when reassembling this engine. This engine is equipped with two rotating counterweights that must be phased properly while reassembling. Tecumseh provides two holes so you can insert pins to hold the gears in place while reassembling the engine case halves. The holes have standard pipe plugs installed with a square head. Unfortuately, the plugs are in a recessed holes. There is no way to get an adjustable wrench on them. It's also difficult to buy the proper socket for the 9/32 square plug. I ended up getting a whole set of sockets from Sears designed to remove stripped nuts. There was a socket in the set that I could pound into the plug so I could get them out. Sometimes the simple things like removing or installing a part can stall the job for hours.

Due to the enountered delay above I didn't get the engine reassembled in time to test run it today and now it will be the last half of next week before I can get back to the project. I'm anxious to know if the problem is solved.

 
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12-14-03, 08:15 PM   #37  
Me too. Are you suggesting that the cam gear got out of time when the engine was put together? If that is the case, it would have never run well at all...ever since it was assembled. Is that the case? I didn't realize it never ran well previous to your taking on this project. If the gears were out of time, it would definitely cause a symptom like yours, or not run at all. The gears cannot really get out of time on their own (not without causing a good bit of damage and probably never running again), so it would have had to have happened one time when the engine was apart. Thing is, on this engine, the engine case doesn't have to be opened for valve replacement or guide reaming.


"Who is John Galt?" - Ayn Rand (Atlas Shrugged)

God bless!

 
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12-15-03, 04:02 AM   #38  
Yes I agree with your statements about the valve & valve guides. I don't know if the engine ever ran properly or not. This is an older engine and has been around since the 70's. The only thing I was told about the engine was that the governor never worked right. I could believe that because I couldn't ever get the engine to run over 2100 rpm. Check out the picture of the top of the piston. Either something got into the cylinder through the spark plug hole or the valves have been hitting the top of the cylinder. The problem I have with the valves hitting the cylinder is the location of the pits. They seem to be outside of the locations where the valves can possibly come down. On the other hand, if something got into the cylinder through the spark plug hole I would expect to see a more random pattern across the cylinder head. I would expect to see some damage to the valve heads if there was contact with the piston, which is another thing I DIDN'T see. I'm making the assumption that the engine was disassembled at one time or another and reassembled incorrectly with the cam shaft timing off by one gear tooth. Keep in mind that the Tecumseh gears have more teeth than the B & S gears do so that a one tooth error has a smaller effect on this engine.

What can be learned from this whole 'soap opera' ?

Choose your assumptions carefully.
Expect the final solution to be the last thing you try.
Some things in life are and will forever remain a mystery.

I was previously self employed in an electronics repair business for 20 plus years. Sometimes I would get a strange case like this that just didn't make sense. Usually this was due to someone who had been working on the same piece of equipment that could never solve all the problems before giving up. You will never get the complete truth because of forgetfullness and/or embarassment so don't bother to ask too many questions. Cheese, I'm sure you've been there & done that !

Stay tuned until Wednesday and I'll let you know if the problems are solved.

 
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12-15-03, 04:16 AM   #39  
After reading the FAQ's I see that I will be unable to post the picture in an attachment because the IMG code is off for me.

 
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12-15-03, 10:21 PM   #40  
I have not yet posted any pics on here, but it can be done. Here's a way for you to see how it is done. Go to the thread about V8 chainsaws. DennisG is the member who posted the pic. Click on his profile at the bottom of his post. At the top of his profile page, you can click on "search for all posts by this user". Click that and scroll down to the one with the IMG code in it. This is how he posted the pic. The pic must be hosted elsewhere on the net, and this site will draw the pic from the site it is on.


"Who is John Galt?" - Ayn Rand (Atlas Shrugged)

God bless!

 
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