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B&S 15.5HP 28N707 dead???


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10-30-05, 05:26 PM   #1  
B&s 15.5hp 28n707 Rip???

Hi all,
I'm new here. This looks like a great forum!

Quick facts: 9 year old Sears Lawn tractor (new 11/96), B&S 15.5HP OHV 28N707-0173, auto trans (Hydrostatic drive), well maintained (regular oil changes/air filters/spark plugs) used for lawn care and with snow blade for winter snow plowing. Never any problems starting or running. All original exept battery and a couple of starter relays (solenoids).

About 3 years ago it started smoking (blue) after I changed the oil. The oil level was correct per dipstick. It was lightly smoking and stopped over time as - I was to figure out - the oil level dropped. So over the last few years I needed to put less than a full crankcase of oil in at an oil change or the engine would smoke so badly that I could not use the tractor. I also would find a lot of oil in the air filter housing so I knew that there was blowby and the crackcase oil was being forced into the intake tract via the breather. I went to speak with someone at a local small engine place and when I told the guy what engine it was and how old, all he said was that it lasted twice what most people get out of them and I should be thankful. The last year I knew I was right on the edge of keeping the crankcase full enough for lubrication/cooling but low enough to control smoking.

Well yesterday I was doing my fall cleanup and after about 2 hours of continuous running I was going along and there was a slight screeching sound and the engine just died. It cranked a bit when I tried to restart then it would not even crank. When it cooled down I checked the crankcase oil level with the dipstick and (surprise, duh) no oil. I can barely turn the crankshaft with a breaker bar and 5/8" socket on the lower crank (pulley) bolt. No difference with the sparkplug in or out. Honestly the last couple of weeks have been hectic and I did not keep track of the oil level so I know its my own fault if the oil level ran down.

So I'm assuming its seized/FUBAR. I'm assuming the worst but is there anythink else I should look at that could be seized other than the main guts (crank, rod, piston) such as the starter drive or ignition coil that possibly could be binding? I've removed the drive and mower deck belts from the pulley so I know its definetaly in the engine somewhere. I just want to be sure I did not overlook something simple.

I'm ready to fork up the $450 for a new engine. I looked at new tractors (today) and for about the same $1300 I spent in '96 I can get about the same tractor (even with a 18 or 19HP B&S engine), but I think I'll just replace this engine as the rest of the tractor is in very good shape and I'm not 100% sure (and nobody at Sears can tell me) if my grass catcher and plow will fit a new model.

Thank you for reading this long post. All advice, opinions, (condolences?), welcome.

Paul
ps. I have the Briggs and Stratton 'Single Cylinder OHV Repair Manual' (2002 ed). Does anyone else think this is the most disorganized and practically useless service manual they have ever owned?


Last edited by Paul78zephyr; 10-30-05 at 05:48 PM.
 
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10-30-05, 07:18 PM   #2  
Hi again,
OK its about 1-1/2 hours +/- since my post above. Wife and son (2-1/2) are asleep so I'm trying not to make a racket downstairs in the garage.

I removed the plastic starter gear cover (two sheet metal screws), the upper dipstick tup mounting screw, the top blower screen (round part, 4 screws), and the sheet metal blower housing (red on my engine, 4 bolts). First thing I notice is that the small gear on the top of the starter is engaged with the flywheel ring gear. With the spark plug out I tried to turn the engine by hand using my hand alone on the flywheel/plastic fan. Using two hands I can just get it to turn a bit. Then I try a breaker bar with a 15/16" socket on the large bolt on the top (that holds the flywheel on?). At first it was a bit stiff to turn but eventually is loosened up a bit. I also took a socket wrench and lightly tapped on the top of the small starter drive gear and got it to drop down and dissengage the ring gear. I also removed the dipstick and its outer tube completely from the crankcase. Although as I mentioned in the above post that after it quit, and I let it cool, the dipstick showed no oil on it, looking down directly into the crankcase (where the dipstick tube mounted) I could see that there was some oil in the engine crankcase. I decided to try to crank the engine with the starter (with the spark plug removed and its wire grounded) and to my utter suprise the engine cranked over 'real nice'. No bad noises, etc, although the starter gear again hung up and would not dissengage from the ring gear. After tapping it down again so it was out of engagement and cranking it a few more times it would crank and the gear eventually would dissengage. But I think that little spring/clutch mechanism is shot. I did a compression test (cold engine) and repeatedly got 100+ psi. So now I'm really confused as to what is wrong (or not with this engine). It still maybe fried internally. I will try to start it tomorrow as I do not want to wake my wife and son (and the rest of my neighbors) now. I will let you all know what happens.

Paul

 
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10-30-05, 07:48 PM   #3  
It probably siezed due to lack of lubrication, and your working it with the prybar got it loose again. It will probably run again, but they usually don't last long after siezure. The starter gear won't always drop back away from the flywheel unless the engine starts up. Then, the engine rotation spins the gear back down the starter drive.


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10-30-05, 08:33 PM   #4  
was this a I/C......anyway if it was, they will come back to life after a seizure if the connecting rod wasn't broken...... but it sounds like you kept the oil too low, they have to be in operating range on the stick. also when they start to using oil like that, switching over to a xw-40 weight or straight 40 in the summer will sometimes slow it down alot......you also said from the breather tube, it was spewing oil into the carb? may have just been a simple bad breather. and i bet the guy that told you, you were lucky to get that many years out of it, has either seen to many run low on oil, or with poor maintenence, or just dislikes briggs engines. though if it runs.....run it till it does go. but just make sure to keep the oil up in it...... i mean you don't know where the piston and or connecting rod will go, when it may break from improper lubrication again.

 
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10-30-05, 10:16 PM   #5  
rake60
I just rebuilt a B&S 15.5HP OHV 28N707-0173 in May.
Same issue the owner had run it low on oil and it seized.
It IS an I/C engine with a cast iron sleeve in the cylinder.
All it took was a little light honing and a new set of rings.
Runs great, no smoke. It also had starter drive issues.
I replaced the plastic ring gear on the flywheel with an aluminum ring
gear that is available from Briggs. You just drill the rivets out of the
flywheel that hold the plastic ring gear on, and bolt the aluminum
gear on.

 
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10-31-05, 09:34 AM   #6  
Hi all,
Thanks to those that replied already.
Well first thing this AM I put some oil in it (straight 30W) but did not fill it all the way. I cranked the engine a bit with the spark plug out and it sounded OK. Put the blower cover, starter cover, and blower screen back on. I put the spark plug back in and it started right up - didn't even need any choke. I let it run for about 40 minutes at normal throttle setting just sitting in my driveway. No smoke or 'bad' noises I can detect. I did engage the mower drive for a minute or two to put it under some load and all seems OK.

While it was running I took the dipstick out and put my hand over the top of the dipstick tube and I can definately feel a slight vacuum. I always thought that my rings and/or valves were going bad and I was getting blowby and that is why I had oil going up the breather tube into the air filter housing and causing the engine to 'burn oil' and smoke. But now I'm confused as to exactly why oil is being drawn into the breather tube, especially when I fill the crankcase to the recommended level. I understand the crankcase needs to be under a slight vacuum to 'purge' it of and blowby/fumes, but what exactly controls how much oil can be sucked up into the air filter housing via the breather tube? Can anyone explain this?

I did remove the breather valve assembly (B&S 495735) and tested it according to the B&S OHV repair manual which says be sure the fiber disc valve is not stuck or binding which mine is not. But I've never replaced it.

So I guess I'll run it until it dies/seizes again. I'm not sure it was not mortally wounded in the last episode. All opinions, thoughts, advise welcome.
Thanks, Paul

 
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10-31-05, 12:33 PM   #7  
like i said, switching it over to a heavier weight oil will help decrease consumption. like say 15w-40, or straight 40 weight.

was this a i/c? well anyway, if it sounds fine, it should be alright for a while longer. just keep the oil to the full mark, may use more, but its safer then keeping it low. the engine you have most likely has a oil slinger, just throws oil everywhere inside. it needs that oil up at the right level. the breather's little valve in it may look alright, but they can wear out, letting too much oil out while it purges the air out of the crankcase.....it lets the internal pressure out. though a loose or leaking dipstick gasket can affect it as well. don't run it till it seizes again, i mean you really don't want the connecting rod and piston to fly where it chooses, may even end up grenading the engine, this is if you keep the oil really low, keep it full and check it often. use a heavier wieght to keep consumption down as well. you may be able to find a used or new engine for a good price on e bay, or somewhere like that

 
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10-31-05, 06:33 PM   #8  
Yes it is an I/C 'Platinum'. What does I/C stand for? I did not mean to imply that I will run it without maintenance until it dies, just that I will keep the oil level as full as possible - without smoke - and just see how long it lasts before I buy a new engine.

I'm still confused about the breather valve operation. I've also read about oil consumption if the dipstick seals are leaking and not sure how this would play into it. Maybe someone knows exactly how this who breather/crankcase vacuum system works on these engines. I understand auto engine PCV systems but this system seems different.

The best price I've seen for a brand new 28N707 on the internet is $449.95 including UPS ground shipping.

Paul

 
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10-31-05, 08:09 PM   #9  
I/C stands for industrial commercial engine....... a intek would be a step up, though the i/c is a great engine. bronze bearings, cast iron cylinder sleeve. i've seen these babies seized two or three times in a row before they blew. don't try though, but do keep the oil up, its just something i stress. but the breather is there for what its name implies, has that little fiber disk, acts as a valve, when it wears out, gets crudded up inside. it'll let more and more oil pass through, though it lets internal crankcase pressure out into the carb leaving a negative pressure inside

 
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10-31-05, 10:32 PM   #10  
The breather is just a check valve. It lets air out of the crankcase, but not back in. If yours isn't stuck, it's probably ok. They don't go bad often.

Common problems creating blowby on that engine are bad rings or a blown head gasket.


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11-01-05, 06:04 AM   #11  
See next post,
Sorry
Paul


Last edited by Paul78zephyr; 11-01-05 at 06:38 PM.
 
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11-01-05, 06:14 AM   #12  
Cheese,
I really didn't think my breather was bad but for 8 bucks I figured I would replace and see if it helped. I knoiw blowby is caused by bad rings, valves or head gasket. But if I had one of these problems and had blowby wouldnt my crankcase be under positive pressure? When I tested it yesterday, after I got it running again, I put my hand over the dipstick tube (with the dipstick removed) and there was definately a vacuum. So how could I have blowby?

I always defined an engine that 'burns oil' as an engine that is allowing oil to travel directly from the crankcase into the combustion chamber - either up the cylinder wall past worn rings, or down the valve stems via worn valave guides/seals. I truly believe that my B&S 'burns oil' because it is getting to the airfilet hosing via the breather hose and then sucked in thru the carb.

I really see the engine 'burning oil' (smoking) when I fill the crankcase to the full mark on the dipstick. Say about 2/3 full and it does not smoke (or very slightly). Also it may not smoke badly with a nearly full crankcase just running with nothing engaged. But when I engage the mower deck and put it under load, or mow slightly uphill it will smoke badly. Also if it is smoking and I shut it off and remove the air filter the entire black plastic filter housing (thats the filter attaches to) is all full of oil. So if its not some problem with the breather, and assuming by the crankcase vacuum that I do not have blowby, WHAT is going on???

Thanks,
Paul

 
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11-01-05, 09:05 PM   #13  
With the dipstick off, you'll feel vacuum pulses each time the piston moves toward TDC. The blowby occurrs just after this moment. The blowby doesn't necessarily cause the engine crankcase pressure to be positive. Blowby is combustion gasses getting past the rings, but it may not be enough entering to overcome the negative pressure in the engine. What it does, though, is cause a small amount of air to be pushed out the breather every time the piston moves towards BDC. This air takes oil with it. If the drainback hole in the bottom of the breather is clogged, it will push a lot of oil out of it, but if running at 2/3 oil level greatly reduces this, then that's probably not the problem. The low oil level keeps some of the oil out of the cylinder, and the bad oil rings don't have to control so much oil, so it doesn't burn so much. I believe your rings are bad. It could possibly be a bad head gasket as well, but I'm leaning towards rings because you can run it low and slow the smoking down.

The rings control oil in the cylinder AND blowby. Pull the rubber hose from the breather to the air filter housing and start the engine while holding your finger near the end of the hose. I'll bet you feel a fair amount of air coming out that hose, probably some oil, and smoke. If you see smoke there, it's blowby.


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11-02-05, 07:12 PM   #14  
Cheese,
Thanks for the reply and advise. You may be right about the blowby and bad rings. I did what you said and there is definately positive pressure and airflow from the end of the hose that goes from the breather to the air filter housing. I never really though about the drainback hole in the breather. Essentially the breather also 'traps' oil vapors and seperates it back into liquid oil to drain back into the crankcase, correct? (there seems to be some type of 'mesh' inside the breather housing that must coagulate the oil mist).

Well anyway I just replaced the breather (8 bucks) and the dipstick/filler tube upper and lower seals (2 bucks ea) as -according to the B&S OHV manual - these parts will cause addition oil consumption if worn and they were cheap. The guy at the place where I bought the parts said that sometimes these engines consume alot of oil when they blow the head gasket. But wouldn't I see other running problems? And as I posted earlier the engine checked out with 100psi compression using a high quality compression guage.

So at this point I guess what ever oil consumption and smoking there is...there will be. I'll still try to minimize this by reducing the crackcase oil volume a bit if i havve to, but I will not let myself get into a very low oil situation again which probably triggered the siezing episode. Unfortunately, as fun a project as a re-ring/rebuild would be, I just don't have time for stuff like that anymore (my home garage already has TWO small block Ford engines in states of disassembly). I'll do my best to keep it running but if it gets real bad and/or seizes again I'll spend the $450 on a new engine and hope to get another 9 years out of the tractor.

Paul

 
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11-02-05, 10:15 PM   #15  
The head gasket will cause oil consumption, and you won't always have a noticeable change in performance or compression reading. The gasket can blow between the cylinder and the chamber that the pushrods travel through, blowing compression and combustion gasses into the crankcase and out the breather. I still think you have bad rings, but the head gasket is easy to change, and cheap.

The breather has the mesh material to catch the oil and allow only vapor to escape, as you suspected.

A rebuild on this engine doesn't take much time...3 or 4 hours if you're at ease with a wrench in your hand and take the time to check things good while you're doing it, clean out the oil pan, etc... That's from removal to reinstallation with air tools.


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11-03-05, 05:55 AM   #16  
Cheese,
Is there a definitive test for the blown head gasket as you decribe? I work on older cars as ahobby and have rebuilt car engines, transmissions, etc so the wrenching is no issue. What is involved with changing the head gasket? What must come off and what can stay? Can you elaborate? If I go for entire rebuild and my rings are bad, what about the cylinder? Must it be overbored?

Thanks,
Paul

 
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11-03-05, 07:56 AM   #17  
rake60
If you have a compressor a Leakdown Test would tell you if you have a
head gasket or rings issue. Here's a link to a page that shows how to
build an inexpensive simple tester. That information is at the lower half
of the page.

http://www.perr.com/tip15.html

 
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11-06-05, 06:53 AM   #18  
Hi,
I'd like to try to do the leakdown test. I have an air compressor with a regulator on the output that I can accurately adjust the air pressure from 0-100 psi. What is the easiest (but safe) way to hold the crankshaft from turning? Can I hold it by the upper flywheel-to-crqankshaft bolt with a socket/breaker bar or this this too dangerous? Or maybe the flywheel itself can be wedged somehow? How much pressure should I use to check for leaks (the link above said 30-40 psi)?

Thanks,
Paul

 
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11-06-05, 05:36 PM   #19  
rake60
The Briggs tool to hold the crankshaft is a split plate with a keyway in it, that clamps onto the crankshaft. It has a 1/2" square hole in it that you use a 1/2" breaker bar to hold it. I find 30PSI is enough. Your basically just listening for leaks, and you will hear some. No engine is air tight. Your listening for bad leaks. If it's leaking bad from both the carb and muffler, your piston is top dead center on the intake stroke. Rotate it until the piston comes to top dead center again, and it will be on the compression stroke. If the engine has a compression release you need to be approx. 1/4" past top dead center or the compression release will be holding the exhaust valve slightly open, giving a false indication of a leaking exhaust valve.
Make sure you have a good hold on your engine locking tool. Even 30PSI can make a breaker bar swing with enough force to break a finger.

 
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11-06-05, 07:30 PM   #20  
Thank you! I will let you know how I make out.

Paul

 
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11-06-05, 10:41 PM   #21  
The leakdown test is a pretty good way to check, but I usually just pull the head and change the gasket when I suspect it's the problem. It gives you a view of the cylinder too, which helps determine the engine's condition. Sometimes you can see the ring gap on the first compression ring too, which gives you an idea of the condition of the rings.

You probably won't have to bore it. Check the ridge on the cylinder wall. If it's bad, I'd go with another engine. You could get a new set of rings, position a ring in the cylinder, and check the end gap to see if the cylinder will be good to go again.

You don't have to pull much of anything to remove the head. Not even the engine shroud. Just the 2 bolts in the front of the shroud, remove the muffler, take out the 2 intake screws, and the head bolts. Pop the head off and have a look....nothing like seeing it for yourself.


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11-07-05, 05:51 PM   #22  
llamaman11
Dame Engine - very different problem

I inherited a Craftsman lawn tractor from my wife's grandmother. Her granddad had taken the enigne apart to work on it and passed away before finishing. Our Gran asked me to take the mower after it sat for 3 years. The parts that grandad had removed (air filter, filter cover, engine & fan covers) were all gone. Lost. i have replaced these, and fixed a sheared shaftpin. I set teh valves, filled it with oil and fuel and cranked it up. VROOM! Went like mad for 30 seconds then stalled and backfired. Cranked it and same thing for the next 10 tries. I parked it for the evening.
This evening I go into the shed and the fuel smell was so bad I nearly got sick! The fuel tank had drained completly into the engine! Now there is oil & gas leaking out of the valve gaskets and the seat of the oil fill tube!
What in gods name has caused this?

Thanks! - llamaman

 
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11-07-05, 06:52 PM   #23  
sounds like the governor isn't set right, not knowing hp or brand of engine, the carb is the fault for the gas, check the float for heaviness or sloshing of gas, if its full of gas, it'll sink to the bottom of the fuel bowl, leaving the inlet needle open, letting gas flow, most of the time through the breather. other things would be a sticking float, or it needs a new needle and seat kit. needle or seat, either of the two may be worn, letting fuel by.
and forgot to add, but i'm sure you will, change the oil, then to make sure, after a little while, change the oil again.

 
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11-07-05, 07:20 PM   #24  
Meanwhile, back at the ranch...

OK the B&S failed the leakdown test today pretty bad. I removed the blower screen for access to the upper crank/flywheel bolt (15/16"), air filter, spark plug, and dipstick. I rotated it to compression TDC and introduced air at 20psi (I figured I start low) to the sparkplug hole. Well it blew the air out from the top of the dipstick tube 'real good'. If I put my hand over the dipstick tube then the air would blow out from the breather hose at the air filter. No air at the carb or muffler so the valves are OK. Funny, I did not even have to hold the crank to keep the engine from spinning - so either the air pressure was too low, or I'm getting so much blowby that there is not enough pressure building up in front of the piston to force it down!

So I guess I got bad rings bigtime. Well it still runs (thought it was dead last week after it seized) and after 9 years I guess thats all I can expect. Maybe I'll pull the head as you suggested Cheese, as I can now see thats a very simple job. But other than a head gasket this engine is going to run out its life as is. I'll spend the $450 for a new engine as I just don't have time (even a few hours) to tear this one down and fix it right. I just have too many other unfinished projects...from my cars to the house to...and I take care of my 2-1/2 year old son during the day!

*****Thanks to everyone for all the help!!!!*****

 
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11-08-05, 12:05 AM   #25  
Yep, you've narrowed it down. It's either the head gasket or the rings.


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11-08-05, 08:42 AM   #26  
Cheese,
So what you are saying is it still could be a head gasket, even from the results of my test. Is there no other way to determine between head gasket and rings?
OK, if I do the head gasket must I remove the carb/intake elbow and muffler from the head? I see by my B&S exploded illustration that there are dowels btween the head and block so the head must move staight off a bit even with the 8 (?) head bolts removed. It looks like the carb/elbow would clear but perhaps the muuffler would hang up. Also, do I need to remove the valve cover? Will the pushrods stay in the block or will they come out with the head. Im just trying to see if I can save any time.

Thanks,
Paul

 
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11-08-05, 11:43 PM   #27  
You'll need to remove the valve cover (only 4 bolts), remove the muffler at least enough to pull the head by it, and remove the intake bolts, but leave it attatched to the engine. The head will slip by it. The push rods will fall out...no problem though. Inspection is pretty much the only real way to know what the problem is. When you get the head off, look at the thin part of the gasket between the cylinder and the area that the pushrods pass through. This is where the problem would be, if the head gasket is the problem. It may be obviously blown, or just a bit darker and sooty/oily looking at that area.


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11-10-05, 07:30 PM   #28  
OK Cheese,

Even though there are a billion other things I should be doing instead...off with it's head!

After removing the blower screen, starter cover, and main shrould, I cleaned off as much dirt/crud form the outside of the head and the head/block area as I could with an air blow gun. I ended up removing the muffler. After the 2 bolts that hold it to the head were off, and one for a support bracket, it was loose but still kinda in the way. To really remove it I needed to remove a 'cow catcher' type piece (one bolt each sude) that is attached to the tractor forward frame just under the muffer. Then I could remove the muffer. I removed the 2 bolts at the intake elbow-to-head and just left the entire elbow/carb/air filter/linkage assembly hang of the side of the engine. There was also this sheet metal 'U' shaped piece that wrapped around the side and bottom of the finned area of the block and head. There was one small screw with a black wire on it on the side under the carb (I assume some kind of ground connection - I havent had a chance to re-look at the schematics) and another one that was directly under the block between the block and the tractor frame. Hardly could get my fingers in there. Good thing I had a 5/16" ratcheting box wrench (I'm a tool hound). Next the valve cover and finally thr the 8 head bolts. A little tap from a small rubber mallet (probably wasn't even necessary) and the head cam right off.

Ok, get to the point...
The head gasket was definately hurting in the thin area that you mentioned and Im sure it was allowing stuff (like oil) to go in and out there where it should not have. I will try to have some pix next week (I dont have a digital camera, so I need to get the roll of film finished, developed, and get the pix on a CD) of the head, block showing the head gasket, piston, cylinder wall, and combusion chamber conditions. Basically the combustion chamber and top of the piston are fairly caked with kinda hardish black sooty stuff. Im not sure how, or even if, I should clean this stuff off. The cylinder walls are...well Ive seen better and worse. Some areas you can still see the original cross hatching but at several points around the cylinder you can see wear marks in the dircition of the piston travel. Just looking at them I would guess they may be at the ring end gap areas, but I could be wrong. Obviously at least one wear area should be the piston thrust side. After removing a bit of the sooty black ring at the top of the cylinder I could discern no noticeble ridge in the actual metal cylinder wall (would not catch my finger nail).

It is still possible that I have a blown head gasket AND bad rings but this engine is coming apart no further! I have my replacement head, head to elbow, and valve cover gaskets (~$19). The place I got them did not have the head to muffler gasket but the original one looks reusable. I'll post more when I get the pix back but in the meantime please comment - especially on what I should (or should not) do about the deposits in the combustion chamber and piston top.

Thanks again,
Paul

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http://www.cardomain.com/ride/773108/1

 
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11-10-05, 07:49 PM   #29  
Sounds like you have found part, if not all, of the problem. As for the black soot, you can clean it off if you like. A wire brush, or a scraper, just about anything short of a grinder will do. It's not a sensitive area. After cleaning it, use your blower on the air compressor to blow out the debris and the area between the piston and cylinder just to avoid scratching the cylinder walls.

The lines you see running the length of the cylinder may be from the ring gaps as you suspect, if there are only 3 and they are around 1/8" or so wide and appear to be slightly raised or level with the cylinder surface. They also could be indication of improper oiling in the cylinder if they are more like scratches or scrapes.

You'll know if that fixed it soon enough! I forgot to mention the cylinder shroud (the U shaped metal shield) and the ground wire for the carb solenoid. I guess you had the type of muffler that goes down and exits under the mower frame through a big rectangular muffler can. Those are a bit in the way as you found out.


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11-14-05, 12:14 PM   #30  
OK Cheese,
I ended up taking about an hour or so to clean up the combustion chamber and mating head/block surfaces. When I removed the head gasket from the block (it was stuck on just a bit) I could see that the gasket was breached on both the block as well as head side and there was soot on the block right at the thin area between the cylinder and pushrod chamber. I used a drill with a circular wire brush with fairly soft brisles which cleaned fairkly well and did no damage to any of the aluminum surfaces. Where there were heavy soot deposits I needed to scrape a bit with a small screwdriver then buff with the wire brush. Finally I used a soft scotchbrite pad on the flat mating surfaces and buffed them up to a nice polish. Still visible were the tiny 'nick' marks left in both the head and block surfaces by the 'texture' of the head gasket. As I had said in the previous post the combustion chamber was pretty bad so between the scraper and the wire wheel I got it about 85% clean which is like 1000% better than it was! I got a whole roll of 'before and after' pics, now if I ever get them developed I can post them (or at least some of them - Im not sure of the pic policy here).

My only questions at this point is what do you recommend about the head bolt threads. The B&S manual says to apply Valve Guide Lubricant (pn 93963) to the threads. Im not sure really what this stuff is. Can I use anti-sieze compound (the silver gooey paste type), or maybe just some oil - or maybe they should just be installed dry??? They did not seem to have anything on them when I took them out, but then again theyve been 'cookin' for 9 years, but they looked brand new, no discoloration and I had no trouble getting them out. Also the manual recommends torquing the head bolts in sequence (there is a diagram) 75 in-lb, 150 in-lb, 220 in-lb final (I'll have to convert these numbers to ft-lbs as all I have is an old Craftman beam style torque wrench). Do you agree with this (the torque values)?

Thanks again,
Paul

 
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11-15-05, 12:37 AM   #31  
Yes, follow the torque sequence and values. If you do anything to the head bolt threads at all, use some very light oil like 3in1 oil sparingly (a couple of drops maybe).


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11-16-05, 10:36 AM   #32  
Stu
Hi everybody,
I'm a first time user of this site.
One thing I should point out, that seems to be overlooked, is with the original siezure issue. In alot of cases, with an engine siezure, the siezure is on the big end (conrod), and yes, it will free up, when the engine has cooled.
The problem is, that now that everything has expanded (with heat) and contracted (cooled down), the conrod bolts can come loose. Although your engine might go now, the question is for how long, and what sort of engine are you going to be left with to repair? My advice, would be to strip the engine and make sure.

 
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11-17-05, 06:46 PM   #33  
Hi all,
Well its all back together with a new head gasket and cleaned combustion chamber/piston top (see previous post). A fresh full 3 pints of 30W oil and a new Autolite 3924 spark plug. I cranked it for about a minute with the spark plug out to allow the splash lubrication system to splash. In went the plug and it started right up at the first turn of the key. I let it run for 15 minutes at full operating throttle and then took my 2-1/2 year old son for a ride around the house a few times for about another 15 minutes before shutting it down. Basically it runs and sounds great. And even with a full crankcase of oil I could not detect any smoking or oil burning (thats a first in 3 years!). But it was late in the day when I finished so I will need to follow up with a leakdown test and look more closely for oil consumption/burning - probably this weekend. But so far so good.

I agree (and this was discussed earlier) that there may be some permanent damage to the bottom end from the original siezing incedent (that started this thread) but the head gasket job is a far as I'm going with this engine. If the bottom end lets go down the road I'll replace the engine.

G*d I hate that B&S manual! Try finding the correct torque for the intake elbow-to-head bolts. That is one of the worst organized manuals I've ever seen.

Thanks again to all (especially Cheese!) for your input. Ill try to post pics if this site allows.

Paul

 
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11-18-05, 01:16 AM   #34  
Great! I'm glad to hear that it's not smoking! If you'd like to post pics, the site doesn't allow much space. You pretty much have to post the pics on a host site and link to them to get them to appear on this forum.

I hope your engine will hold up for a good long time. I have un-stuck a few siezed engines and let em go and some lasted quite a long time before giving up the ghost.


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11-18-05, 10:58 AM   #35  
Ok all,
Here is the link to my cardomain website with the pics of the head gasket job (Cheese, I bet you've seen this a hundred times!). Let me know what you think or any comments/questions welcome.

Thanks again to all,
Paul

http://www.cardomain.com/ride/773108/2

ps Dont let the website name throw you. It is my cardomain website for my 78 Mercury Zephyr 'sleeper'. If you want to see it just go to page 1.


Last edited by Paul78zephyr; 11-18-05 at 11:11 AM.
 
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11-18-05, 11:46 AM   #36  
as long as you don't start to hear a knock, it should last you a bit longer....nice job cleaning it up! bore doesn't look bad either.... goes to actually show, briggs makes some good ones.

 
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11-19-05, 01:33 AM   #37  
That gasket was definitely blown, huh?! Good job with it, and thanks for keeping us posted through the process. Looks like you did a nice job with the car too!


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07-26-12, 04:42 PM   #38  
I see that you have rebuilt your briggs and statton engine. i have a model 28n707-1026 and i was wondering if you could help me to rebuild mine. Did you buy a book? I have never done this before and i can't afford to take it to a shop to get it fixed. i have been all over the internet trying to find step by step instructions but i have came up empty. so when i seen your post i was hoping that maybe you might be able to help me.
Thank You,
Richard

 
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07-26-12, 08:29 PM   #39  
Hello richard307,

This thread is 7 years old, so I doubt the original poster is even still around here. Start a new thread on the topic and ask whatever you need to know. The pros here are glad to help.


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