Engine John Deere GT235 Pushing Oil into air cleaner

BiLLyGT235

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Hi guys. Sorry, this is an old subject and I've read all of the old threads here and elsewhere on other user's similar problems, but still have found no resolution. Now it is happening to mine and the problem is crippling.

John Deere GT235 (2001 / 2002). It has the Briggs & Stratton 18 HP V-Twin engine on it. This engine does have a screw-on oil filter, and is pressure lubricated. It is a model 350777.

Start fresh with properly gapped clean spark plugs, oil level right in the middle of the "Full" and "Add" hash marks (which seems to be the sweet spot for these Briggs V-Twins for some reason), fresh clean air filter, new foam ring, clean fuel filter, and of course new oil filter. After running it for 15 minutes, the oil filter and foam ring are saturated with oil. It pushed so much oil in 15 minutes, that the difference was VERY noticeable on the dip stick. When I took the air cleaner cover and clamping horn off and set it on the floor of my garage, a large puddle seeped out of it.

When I blow into the crank case vent tube, there is good firm resistance, and I can suck freely air from it. Where I the little check valve / flapper located on my crank case? There are no noticeable oil leaks around my valve cover gaskets. There is no O-ring present on my dip stick nor up in the cap. I don't ever recall there being one. The dip stick cap has a narrow deep groove around it that nests over top of the top of my dip stick and the top of the dip stick is cut flat - I'm guessing that is all there ever was for a seal, so I can't imagine that's the problem.

Any help diagnosing this problem is greatly appreciated. I will try all suggestions and report back my findings. When reading a bunch of other posts (not just here but in other similar user forums), it's disappointing seeing how many people (such as yourselves) try to help giving advice to never hear back or never find out if any suggestions helped. I won't leave you hanging. I need to get this resolved quickly. We mow about 2-3 acres and it's up to my knees now. I may have to break out my scythe. :(

Thanking you all in advance.

-BiLLy
 

bertsmobile1

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Well Billy, I do hope you are better at fixing the mower than you are searching our problem.

Most likely cause is a blow head gasket between the cylinder and the push rod tunnel.
Quick & dirty test is to remove the dip stick tube a minute or so after the engine is turned off.
If it blows smoke signals then the gasket is gone.

Confirm by doing a leak down test or just cranking by hand in a quiet room with the dip stick out.
Usually you can hear the gas hissing.
Another indication is a bit of a roar and a puff of white smoke when the throttle opens wide like when you engage the blades or tromp the motion lever / pedal.
 

BiLLyGT235

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Thank you Bertsmobile1. Who woulda thought the first reply comes from half way around the world?!?! I will try that right now and report back. I did check my dipstick and it most certainly does NOT have any kind of gasket under the cap or on the tube. There is a tight groove around the inside of the cap that looks like it would tightly fit around the tube that the cap screws onto. I cannot imagine that little bit of air seepage could push as much oil as I'm losing. The little bit of mowing we did yesterday (15 minutes), lowered the level on the tube from mid point to the ADD mark on the dip stick. We have no noticeable power loss at all and it goes to WOT without hesitation early on, but as the air cleaner loads up with oil, power drops. I adjusted the valves yesterday - first time that has been done in 17 years. They were at around 0.012 to 0.015. Set them all at 0.004-0.006. To see if the dipstick O-ring thing has any merit, I will put a plastic bag over the fill tube and tightly secure it with heavy rubber bands. I will run it for a few minutes and remove the bag and see what I see. Thanks for the suggestions. I'll share my results here. -BiLLy
 

BiLLyGT235

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Okay, I refilled the crankcase to midway on the dipstick. I put a plastic sandwich bag around the dipstick fill tube and secured it with rubber bands. I reinstalled the clean air cleaner, bullhorn and shroud. I started it up and let it run for two minutes. It started fine but ran like absolute crap - barely kept running and was smoking almost immediately. The bag on the dipstick was puffing in and out extremely fast showing fluctuating crankcase pressure. I would have thought it would be more balanced with the engine being a V-Twin, with one piston going up as one is coming down, but that was just a guess.

I let it run two minutes and then shut it off and removed the bag from the dip stick and white smoke wafted up out of the engine oil fill tube. So,.......I guess blown head gasket it is. :( Any tricks as to determine which head gasket it is?

Thanks for the help.

-BiLLy
 

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bertsmobile1

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Quick and filthy method is to pull off both rocker covers and start or crank the engine.
The one that is leaking will be obvious as you should see, hear & feel the gas passing into the push rod tube.
If cranked you are listening. if run you can see but it will throw oil everywhere
 
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