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Hello all,
I recently purchased a LB 10515 with the F Engine via Craigslist. After cutting the grass for about an hour I noticed a sizable amount of gas/oil leaking onto the front of the mower (see picture). I assume it has a failed engine seal but not sure where. The engine has OK compression (around 90 cold) and runs fine. I have had several Duraforce mowers but this is my first F engine so not sure what the issue is and if the seal is an easy fix. Can anyone provide any guidance as to whether or not this is a common issue and how challenging it is to resolve. I want to determine if I should just use it as is and let it take its course or if I should attempt fix or just get rid of it. Thanks for any feedback.

Looks like the upper main seal......

Thanks for the information. Do you know if there is a part number for this? I have been looking at ereplacementparts.com and cannot find it. Also, any thoughts on how big of a job this would be?

I wouldn't be so quick to assume a main seal. If a main seal is leaking to that extent on one of these 2 strokes it will really effect performance, and I'm not hearing you say it's lacking in performance. I think I would clean the mower up really well and crank it up and carefully look for the source of the leak. If it's coming out of the carb then it's probably just the needle and seat not sealing well. Those particular tanks are prone to leaking as well, so look it over good. If you do indeed find that one of the main seals is faulty then here is the link below to the parts breakdown for a 1993 model 10515. Item #1 part number 611396 for both the top and bottom crank seals. On a pusher F series the seals can be replaced fairly easily and quickly, but since this one is a self-propel and the pulley will have to be removed for the bottom seal then you can probably double the labor time.


http://www.partstree.com/parts/lawn...00001-3999999/engine-assembly-self-propelled/

Below is a link to the parts breakdown showing the pulley, for some reason they left that pulley off the breakdown for the 10515, so you may have to refer to another model number like this 10518 instead. Item #33 is pulley F 609976 and held in place with a setscrew item #32 setscrew 610345. Those 2 parts are often ruined coming off, so be aware.

http://www.partstree.com/parts/lawn...0001-7999999/engine-fuel-tank-blade-assembly/

If a main seal is leaking to that extent on one of these 2 strokes it will really effect performance...

Click to expand...

Specifically, it would be running very lean... to the point of extinction.

Thanks again for the information. Engine compression is at about 90 PSI cold. From the research I have done this is the lower end of the acceptable range for these motors. It runs fine, if it wasn't for the oil leaking all over the front I would not know that there was an issue.

Pull the carb and check the reeds. If they are bent, damaged, or if a blade of grass, or any debris is stuck in the sealing surface not allowing the reeds to fully close it will tend to blow some oil out.