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Briggs 8hp Burning Oil - A Lot!


IDoIt's Avatar
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05-03-06, 05:22 PM   #1  
Briggs 8hp Burning Oil - A Lot!

I just acquired a Sears front tyne tiller with 8hp briggs 190402 engine. Thing's pretty old but I thought I could use it a little. I got it running and used it for the first time today. It ran Ok but stalled during idle after I finished using it. It ran well for about 30 minutes prior to stalling. I pulled the plug and it was covered in burnt oil. Checking the crankcase it was down about 1/2 Qt. Did a compression check and got 90psi hot. Not sure what the correct compression should be. No oil is being sucked into the carb from the crankcase vent and there did not seem to be excess by-pass from the vent tube. I used 30 wt oil and made sure it was not over filled. With the amount of oil burning I'm leaning toward a head gasket but wanted some feedback first. Are head gaskets a problem with these engines? I think for that much oil to be used in such a short time it could not be from the valve stem. As well this seems to be an "L" head where the valves are opened from the bottom of the combustion chamber so the oil would have to travel up hill. You really have to look for the blue smoke coming from the exhaust but it does puff quite a bit more momentarily when I go from idle to full throttle. I'm willing to replace the head gasket but not do a valve and ring job. Anyone with a little experience in this would be appeciated.

 
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05-03-06, 07:40 PM   #2  
If this is a L head engine (flathead, side valve) its not the head gasket... oil burning can come from valve stems, but those tend to leak when its off, and it burns just a little at startup and its fine. Or a bad breather (but you say you don't see oil coming up and out of it?) this would lead to maybe a stuck or worn out oil ring. With 90 psi, the compression rings are good. Btw, make sure its not overheating, this will tend to break the oil down more.... thin it out etc by making sure all the cooling fins are clean and clear.

 
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05-03-06, 11:36 PM   #3  
Definitely sounds like rings to me too.


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05-04-06, 03:55 AM   #4  
Thanks for the feedback. The first thing I did was clean up the engine. There was some dirt lodged in the cooling fins. Well if 90psi would indicate an oil ring is there a possibility it could just be cruded up and running it with fresh oil will clean it out and improve it? Sounds like wishful thinking.

 
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05-04-06, 04:24 AM   #5  
That is an aweful lot of oil in the time you ran it. Are you sure the oil drain plug/cap is tight? Is it possible that the unit is so filthy that you wouldn't notice a leak at either the drain or even the base/sump gasket?

 
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05-04-06, 05:37 AM   #6  
I'm absolutely sure this is not a leak. I completely solvent and hot water washed this engine before I ran it. There are no external leaks. It's all going through the combustion chamber. Which is why I'm a little perplexed because it is difficult to see any smoke from the exhaust until I throttle up from idle to full speed. But the plug is not lying, I run it for 15-20 minutes and the plug is caked with oil deposits and the level is down. I tried a leakdown test but had no way to lock the engine from turning so all I did was a hot engine compression test. I used a little Marvel Mystery Oil in the crankcase and gas to try and lossen up any deposits as usually these old engines suffer from neglect and poor owner service. I'm thinking of trying a 50wt oil to see if that slows things down. Thanks for the continued feedback.

 
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05-04-06, 09:06 AM   #7  
I too tend to think like cheese and v8.Even thow 90 psi is a good compression reading,sounds like the oil ring is not quite right.And the scrapper (middle) ring is not in too good of shape eghter.since the engine oil is getting up to the spark plug.

When/if you tare it down to check,take an extra look at the ring groves on the pistion too.sounds like the rings are moving just too much.

 
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05-04-06, 09:57 AM   #8  
I've already decided to sell it - with full disclosure. I bought it for $50 just to do one area of my yard that needed leveling. Couldn't really rent one of this size for that. I think for someone who needs a tiller and can invest in a little engine work it will be good. The transmission seems ok, I even sharpened the tynes. These things don't really run much. I think someone will be able to nurse it through a few more seasons even with the oil burning. I ran it on idle for a while today and the oil burning isn't getting any better so I shut it down and put an ad in my wife's work Shop-n-Swap. Free ad, never failed before. Trying to get $100 which would break me about even. Thanks for all the feedback and info.

 
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