'85 Marathon Gas Runs Erratic - full bore or nada

[van the man]

Im no expert but i just recently went through an engine and would say that if there was a lot of gunk around the crankshaft area then those seals are bad and good thinking on replacing them. The flywheel is no fun. Im intrested in what you find. My 86 has a kinda similar problem suddenly.

[CPOdaddyduke]

Originally Posted by van the man

Im no expert but i just recently went through an engine and would say that if there was a lot of gunk around the crankshaft area then those seals are bad and good thinking on replacing them. The flywheel is no fun. Im intrested in what you find. My 86 has a kinda similar problem suddenly.

I have ordered the seals, maybe a week to get (I live way out in the country so everything is mail-order). I will try to remember to take a few pics tomorrow and post so y'all can see what I see. (I agree that whenever you see lots of grease/oil/grime caked up around something, it's usually indicative of at least some seepage in the area - seals are suspect. I did check all the bolts that hold the crankcase and cylinder jug together and they are all good-n-tight. I have not yet removed the drive clutch, so can't see that seal up close yet. I have a puller that should get the flywheel off, but I will be machining a tool for extracting the drive clutch (it's really stuck on there).

[cart around]

Here is a home made puller. http://www.buggiesgonewild.com/gas-e...-gas-cart.html

[CPOdaddyduke]

Below are a couple of pics of the output shaft of the engine sitting on the bench. I can't tell much until I clean it up a little, but I am still a little suspicious. I don't know exactly what it is supposed to look like, but I am not sure about this one..

As far as the clutch puller is concerned, $35 for the store-bought is a bit rich for my blood, especially since I have the resources and equipment to make one for almost nothing. I am making one out of a piece of 3/4-16 threaded rod that was lying around the shop, grinding a couple of flats on one end to turn with a big cresent wrench, and turning down an appropriate length on the other end to contact/push against the crankshaft. It will look a little like the store-bought one except I won't go to the trouble to fashion a hex head on it, just something good enough to get a solid grip with a wrench to turn it. I might even just weld a bar on the end to turn with. Or, if I get in a lazy streak and don't feel like chucking it up on the lathe, I'll just make it work like the one in the post with a piece of spacer rod. Remind me in a few days and I will send a pic of it when I get it done.

[cart around]

That second picture looks like the seal is part way out.

[CPOdaddyduke]

Originally Posted by cart around

That second picture looks like the seal is part way out.

That was my initial take on it as well; and if you look very closely, it looks a little like the seal housing is a little beat up and a bit warped. I have tried to find some pics online of what a good clean engine should look like - only found one of a rebuilt engine for sale on ebay that showed a small portion of that seal. In that pic, the seal looked flush with the case (hopefully attached).??? but then, the shape of the casting and seal body also don't look exactly the same to me.???

It will probably be Thursday before I get to cleaning it up and studying it further (just too busy with life at the moment). But right now, I have high expectation that that seal is a large contributor to my problem.

I will keep the forum posted.

[clr.R4tch3t]

Sorry, these pictures aren't great. The lighting wasn't the best..

[CPOdaddyduke]

Originally Posted by clr.R4tch3t

Sorry, these pictures aren't great. The lighting wasn't the best..

Actually, I think your pics are great; thanks. Now I really know what it is supposed to look like.

[CPOdaddyduke]

I do have some news and a diagnosis.

If interested, check out the pics of the clutch puller I made. It may be a bit of an overkill for likely a one-time use, but it grows out of the use of scrap and spare parts and things just seem to keep adding to it. But it worked great.

Anyway, I removed the clutch, and the first thing I did was to grab the output shaft with my hand and turn it, and I immediately felt puffs of air blowing out of the shaft seal onto my hand as I rocked the shaft back & forth. I then noticed a fairly defined paper-thin gap around the shaft where it [is supposed to] contacts the seal. Well, I think, there you have it.

New seals ordered should be arriving in a couple of days. I'll replace both. Now, I am fairly confident that that was the main problem all along.

[clr.R4tch3t]

How is the up and down movement of the crank? My seals were beyond toast due to lack of maintenance and my crank bearings were also smoked, adding to the seal wear. I found splitting the cases and replacing the bearings to be a fairly painless endeavor.