18.5 briggs motor

S2710 · Oct 28, 2015

Hi all first time on the garden tractor site. I just bought a cub cadet at a auction and it started good and seemed to run fine. I got it home and changed oil in it and tried it out and it ran good and then all of a sudden it belched out a lot of blue smoke and then was fine few seconds later it did it again. I drove it up by the shop and it ran fine but you could see it was burning oil. Can these motors be overhauled or should I look for a different motor. Thank You

Bob

jeffcat · Oct 28, 2015

Hold on a second. Blue can be oil and also when a big slug of raw gas goes through. What did it smell like? Did your oil level stay the same? When the big cloud of smoke came did the engine stay the same or did it struggle? Could your engine be so worn that it is blowing oil up through the breather hose right into the carb system. Cause bad rings. You could also have a messed up carb. Many of those engines have Niki carbs and when they work correctly they are great. When they are messed up they are a true pain! Many lawn mower places would sell you a used one for not too much off of a junker. Get the carb and the manifold all in one piece. Don't disturb things too much. Just a stupid question. You should used like one leader of oil. A little over a quart. I know people who got distracted and put in too much oil. They never even looked at the dip stick. Trying to think of everything here. Also check your air filter. Good luck and get back to us.

T.R.K. · Oct 28, 2015

Any chance the oil was over full? What weight oil? Should be 30wt. The thin car stuff can sometimes cause problems.

You don't say which engine. If it was a Briggs overhead valve single, I would pull the head and replace the head gasket. chances are its blown into the pushrod galley and putting combustion pressure in the crankcase. This could also happen to a Briggs twin, just more common on the singles.

It could be a bad crankcase breather, but its not that common.

lastly, it could be rings.

S2710 · Oct 29, 2015

The motor is a single cyl. briggs 18.5 ELS 500 OHV full pressure lube system with a spin on oil filter.

When it let the big puff of blue smoke the motor shuttered and it had a oil smell. When I bought the mower the crank case was over filled, but when I changed it I put the correct amount of 10 W 30 in it. That little bit that I ran it it smoked real bad and it is down to the add line now.

I would think if I took a compression check on it, it would be low if the head gasket was blown, and if it was rings it would be low also. If I took a second test and put a couple of squirts of oil in the cylinder, if the compression came up it would that mean the head gasket is OK and the rings are bad?

Thank You
Bob

David G · Nov 1, 2015

I think that the engine might have had really thick oil in it before and a lot of blowby.

18.5 briggs motor

S2710

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jeffcat

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T.R.K.

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S2710

Well-known Member

David G

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