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I have read several accounts of oil leaking from the fuel pump, but many posts stop and the post originator never mentions what the issue was. I am experiencing that problem with my John Deere LA125 with 145 hours. I do not smell oil in the fuel, and have not yet tested the compression. Does anyone have any insights from past experience? Perhaps a similar model with similar engine (Briggs and Stratton 21 HP)? I guess the leading causes are either clogged breather, or rings going bad? I hope the latter is a long shot given the engine has only 145 hours on it.

Now I read a bit more regarding a possible cause is a head gasket. Is there a way to tell by looking wether or not it's a head gasket issue? Man, how can you have these issue with only 145 hours???

There is no way of telling unless you have a leakdown tester tool... But regardless it is a relatively easy job to change the head gasket anyway. 145 hours is not uncommon to blow one.....
I would suggest that the cylinder head is checked to ensure it is flat (fine grit sandpaper on a sheet of glass or mirror) and do the head bolts up a little more than spec on reassembly....this will prevent reoccurance

Will do if the test indicates it for sure. Thank you. I will do a compression test in the AM before I go further. What is a good compression reading? And what would figure is the more common occurrence, head gasket leak or clogged breather reed?

talley2191 said:

Will do if the test indicates it for sure. Thank you. I will do a compression test in the AM before I go further. What is a good compression reading? And what would figure is the more common occurrence, head gasket leak or clogged breather reed?

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Doing a compression test on Briggs is no good as they do not release figures for it.
A leakdown test is used to check the sealing capabilities of compression related components (valves, gaskets, rings) using a set air pressure which goes through special test equipment from Briggs.
I read alot about compression tests on small engines and always wonder why?
Iv never had to do one in 8-9 years of working on small engines.

It does sound like a bad head gasket. Compression test may or may not tell you for sure. Only an experienced tech will get it right more than 75% of the time. I do a lot of compression tests but they only tell me that the cylinder is leaking, not where. The compression for a Briggs engine cold should be about 110-125 psi, after four good pulls. A leak down tester will tell the tech where the leak is. Problem, compression tester =$25 leakage tester = $175. Great tool but not for the average Joe. I would pull the head and clean everything I can and install a new head gasket. Overall this is the cheapest and easiest thing to do. Good luck.. Just thought of this. Have you pulled the valve cover and checked to see if the breather is stuck. Clean it with carb cleaner and shake it. You should hear it rattle.

Thank you. Looks like a $7.55 part if I'm looking at the correct part number. I'll be sure to post follow up after the compression test in the morning.

So compression test was normal and other signs (appears to have exhaust coming back through dipstick)seem to indicate head gasket does in fact need to be replaced. Only 145 hours....very disappointed in Briggs and Stratton. I'll follow up once the work is done. Thank you

Not that unusual to replace. Make sure that you check and clean the cooling fins. Overheating is a cause of head gasket failure. As long as you have the head off clean out the carbon.

Final post on the issue. Head gasket and a new spark plug and the mower is again running perfect. No smoke or oil coming from the oil pump. Thanks for the help and perhaps this thread will help someone else.

talley2191 said:

Final post on the issue. Head gasket and a new spark plug and the mower is again running perfect. No smoke or oil coming from the oil pump. Thanks for the help and perhaps this thread will help someone else.

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Your post just did help someone else I thought it might be a flywheel seal but noticed oil was just under fuel pump this John Deere has about same hours on it owner had problem with mice in the shed nest caused over heating and then head gasket caused oil leak. thanks guys big help just saved customer a lot of money.

talley2191 said:

I have read several accounts of oil leaking from the fuel pump, but many posts stop and the post originator never mentions what the issue was. I am experiencing that problem with my John Deere LA125 with 145 hours. I do not smell oil in the fuel, and have not yet tested the compression. Does anyone have any insights from past experience? Perhaps a similar model with similar engine (Briggs and Stratton 21 HP)? I guess the leading causes are either clogged breather, or rings going bad? I hope the latter is a long shot given the engine has only 145 hours on it.

Click to expand...

think i am having similar problem with 19.5 B&S engine. oil comes out the small brass filter on the fuel pump. i've tried replacing the fuel pump but that is not the fix. there is a rubber hose that goes from the fuel pump to the oil filler tube. i believe pressure in the oil chamber is causing oil to move through that hose. many say its to much oil in the oil resevoir chamber. i've tried running very low oil (32cc instead of the called for 48cc) and still get the oil in the fuel pump. others say its a head gasket but that is not likely since the engine runs excellently, no smoking or stutter. some say the exhaust muffler is plugged with oil, again no problem with engine running or starting, which if the outlet were plugged or restricted one could expect difficulty with the engine running, not to mention these engines dont run on oil gas mix so exhaust is not really filled with oil residue. i dont think a plugged exhaust is the problem, but i do believe that a plugged or restricted muffler could create some problems with back pressure to the oil chamber.
and lastly, some say bad rings or cracked ring or some such thing, but if one has that kind of internal engine problem you're going to experience more trouble then just oil into the fuel pump.

that fuel pump is a diaphragm actuated pump. oil is on the diaphragm side not the fuel side, so oil is not getting into the fuel pump side feeding the carburator. if it were oil would quickly cause the carb to fail. now after all that, i disconnected that hose and ran the engine for an hour without problems. but i had a big oil mess so i put the line back on and now i get oil in the fuel pump again.

so not really knowing the exact problem, i'm going to disconnect the line on the oil filler tube and plug the nipple. then if there is some place that i can access vacuum i am going to put the line on it. if not then im going to leave it alone. if the engine begins to show symptoms i'll just reconnect and try cleaning out the muffler. other than that i dont think any has proposed what the actual problem is, and the correct fix for it.

hope this helps. gerald