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engine smokes, has good compression


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05-17-08, 12:57 PM   #1  
engine smokes, has good compression

I bought an early 70's cub cadet, not running. K301 12hp engine. Replaced the points and spark plug and changed oil.. It will start and runs smoothly but smokes terribly. Ran it for about 20 minutes and smoke did not go away. Compression is a little over 120 lbs which leds me to belive it may not be the rings. Any ideas on what I should look for now and how to test it. It is very loud, needs a new muffler so I am worried that I might not be able to hear if it is knocking.

Ron

 
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05-17-08, 04:01 PM   #2  
Do this put a teaspoon of oil in the spark plug hole,check the compression again,if compression goes up then the rings are bad,if no change the the valve guides are bad.Hope this helps.

Jerry

 
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05-17-08, 09:56 PM   #3  
thanks Jerry

will try the oil in the cylinder frist thing tomorrow. If it is valve guides will I have to disassemble the engine to replace them?

Ron

 
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05-18-08, 12:04 AM   #4  
Yep.... If it's smoking that badly, I'd think the oil ring is stuck, worn, or damaged.


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

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05-18-08, 01:41 PM   #5  
compression check after adding oil

made about 3 lbs higher after adding oil. Also found oil level was pretty high over the full mark, so that may have been the smoking problem. Will get back here after I let it run for a while.

Ron

 
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05-20-08, 12:46 AM   #6  
smoke improves

ran it about 10 minutes and smoking problem definitely improved, although it still smokes a little. now having problems with it running. will run about 10 minutes then dies and doesn't want to start again. will run with starter fluid prime. dies as soon as you stop priming. like it is not getting fuel through the carb. might be the fuel line, since I didn't replace it, or could be the shut-off valve at the tank. will check that next and let you know what I find.

 
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05-20-08, 12:56 AM   #7  
It possiblty you got some debries in the fuel tank and got the valve clogged somehow some engines do have inline filter and it can be clogged as well.

Now for the oil level get some of the oil out if you are over the full mark and let it stay below full level mark.

Useally most gas aircooled engine genrally use the straght 30 Wt oil in summer time unless specifed by manufacter.

If you used the 10W30 oil or 5W30 oil then it is too thin for summertime [ unless it reqired by the engine manufacter ] that what i am thinking on that part.

Merci,Marc

 
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05-20-08, 06:20 PM   #8  
One can give an engine a good valve job, and it will have
good compression, even though it is totally worn out.

It will run, and have good compression, but burn oil badly.

Pull the head and look at the piston/cyl.

Fish

 
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05-20-08, 07:01 PM   #9  
In your first post, you mentioned that you changed the oil, but later you mentioned the oil was over full. I can't help but wonder if your carb float is sticking allowing fuel to run thru the carb when the engine is off, drip down into the crankcase causing the over full condition. Gas mixed with oil is a BAD lubricant, and can cause engine damage. Does your oil smell "gassy"? Then change the oil right away, and fix the carb and maybe even install a fuel shut off in the fuel line.

 
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05-23-08, 05:31 PM   #10  
oil problem not all my worries

Thanks for the answers and advice, everyone. No gas in oil, checked it. Unfortunatly I can't keep it runnig long enough now to really check the oil problem. First thing I did when I got this thing was pull the gas tank out and really clean it inside and out. It sit several years before I got it and the gas had dried out in the tank, it was full of gummy stuff and trash. Shut off valve was stopped up and wouldn't work so pulled it out of the tank to clean it. Got all that working and then put an in line fuel filter in the line. pulled the carb and cleaned it thoroughly and replaced all the gaskets. Stared it up and it problaly ran for a total of about 30 minutes. Then it quit working, would run with starter fluid. Pulled the carb and found the bowl full of black powdery stuff. Appears that I made a mistake when I didn't change the old fuel lines and trash came from the line on the engine side from the fuel filter I installed. So cleaned the carb very thoughly again, but now I can't get it running again. It will run but keeps missing and popping and won't smooth out. If you hold your hand a few inches away from the throat of the carb you can feel gas spraying out. Some drop about 1/2 the size of a BB. I believe it is getting too much gas and choking out and that is the reason I can't get it u to speed. Since it worked fine until dirt got in the carb I believe this is a carb problem, not an engine problem. Anybody got any ideas what is wrong with the carb that would cause to spray gas out the throat.

Ron

 
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05-23-08, 09:22 PM   #11  
For air to be pushing out the throat, I would suspect the intake valve is stuck open. There should not be much movement of air in that direction through the carb.


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05-24-08, 01:47 PM   #12  
still good compression

I don't know cheese. he still gets about 125 lbs compression. It's really hard to see in there but the gas being sprayed out seems to be coming out of the tiny holes in the middle of the hi speed needle. a brass pin that is in the center of the throat behind the choke plate. this needle has several tiny holes in it at the bottom, the top and the middle. and appears to be hollow inside so that all of the holes are connected. It doesn't seem like much air is begin pushed out of the carb, it's more like the gas is being shot out of a water gun.

Ron

 
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05-24-08, 09:47 PM   #13  
Ok, that makes me wonder if the float isn't floating, and the fuel pump is pumping gas into the carb, forcing it out the venturi nozzle. Is the spark plug wet?


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05-25-08, 03:08 AM   #14  
Smoking engine

Gas in the oil is probably caused by the float out of adjustment or dirt in the port holes. Clean carbaruetor, put new spark plug in, adjust the float, dirt may be in the needle valve causing it to stay open. Also, coil needs to be checked if it is dying after 10 minutes.

DaveZ

 
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05-29-08, 04:17 PM   #15  
carb problem

OK, sorry it took so long to get back to this. I found another carb, i think it is for a k241 engine instead of a k301. Anyway put it on and engine would start athough I never could get it to smooth out and run properly, but at least it would run. still spit just a tiny bit of gas out the throat. so I took the old carb apart again and put in new valve seat and float valve, think it was not cutting off the gas flow when It was full. found after that I can get it to run pretty smoot at idle speed but still won't run at high speed, and it dies at low speed after a few minutes of running. I think it may still be a problem with the float not shutting off all the time when it should. conclusion is I guess the carb is bad some way but I am lost about how to fix it. Wonder about the tiny little spring that sets under the float that I saw somewhere in a picture somewhere on line, I think it is supposed to prevent the float from bouncing. I found a place on line that sells replacement seats and high speed needles. however there are about 10 different sizes and I don't know how to figure out which one I need and don't really know it that will fix it anyway. Any advice would be welcome.

 
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05-29-08, 09:23 PM   #16  
Take apart the original carb, and clean it, replace the needle (use your engine numbers and carb info to determine what needle you need), and replace the gaskets. It might just take a good cleaning to get it working again.


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05-31-08, 01:21 PM   #17  
new carb

I ordered a new carb and shouild get it here by monday or tuesday. If that solves the problem, then I will try repairing the old one. I have two cub cadets with the same engine so having a spare carb could turn out to be a good thing.

 
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06-02-08, 02:09 PM   #18  
humm

ok, got the new carb in and on. starts fine and idles fine. A little before you get it up to 1/2 speed, it starts cutting out and can't smooth it out with high speed jet adjustment. crank up the speed a little more and he dies. I put in new points and the gap may be off some. Don't know it that could cause this problem or not. Had to quit for today because of wet weather. Is there an actual timing adjustment on the kohler or is it set by a mark on the cam gear and crank that is not adjustable like most B&S engines.

 
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06-02-08, 09:41 PM   #19  
The valve timing is set by a mark on the cam and crank and is non-adjustable, but tha'ts true for most all engines. The ignition timing is seperate, and is adjustable. Set the points at .020" with the points at their most-open position. If the points are not correctly set, or have moisture/condensation on them, it would cause the break-up during high speed like you described. Maybe it was partly from the wet weather?


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06-03-08, 06:46 PM   #20  
points!!!

OK, set the points to .020 and he ran like a top for about 15 minutes, then just quit and would not start again. After some more trouble shooting revealed no spark, I found the condenser was hooked up to the wrong side of the coil. I put in new points when I first started working on this rig but never thought to check the wiring on the coil. An ohm meter reads open even when the points are closed so guess the new ones are burned up already. Will get a new set of points tomorrow and try again. Had no idea that having the condenser on the wrong side of the coil could burn up the points so fast. I noticed the points were sparking a lot when I started him up, but just assumed that must be normal. Guess Not On futher thought I think that is the point of the condenser, to arrest the spark on the points.

Ron

 
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