1986 Marathon low compression. Here are my options. What do you recommend?

[BBuford]

1986 Marathon. I am measuring compression at 60 to 70lbs.

Starts up and runs easily.

I am noticing gas/oil leaking around the cylinder and out the exhaust manifold.

Option 1 - I have purchased a new gasket set for $16. I can clean up and install new gaskets to better seal the motor.

Will this help my compression possibly?

Option 2 - Or should I buy the upper cylinder kit with new jug, piston, ring, and seals for $200ish and go that route since I have to take the cylinder apart to just put fresh gaskets on?

[Govnah69]

It could just be the gaskets, but if you are gonna have it opened up anyways, why not just rebuild it since it will all be apart any how. If you reach down and grab the clutch area can you feel any movement in the shaft? If so you probably wanna opt for a total rebuild. I'd check that first and go from there. But I'd definitely do the whole top end if I was gonna pull it apart. You'll be happier in the end.

[Govnah69]

And to answer your question regarding if the gaskets would cause low compression. It's yes they can cause it, but if they are bad, good chance you have worn parts inside that would love a sprucing up

[BBuford]

Just to make sure I understand what you are saying . . .

I need to reach in and grab the shaft of the motor that goes to the Drive Clutch. If I can pull up or push down on it and it wiggles or if the shaft has play left or right, I need to think about replacing the crankshaft as well?

[Govnah69]

Correct, if you have play In that shaft your bearings or crankshaft is shot ... Or both are. Rebuild kits have all these parts Included

[Dabble Inn]

I have an 85 Marathon I just did a complete rebuild on because the crankshaft bearings were shot, It still had 115lbs compression and ran fine too. But for the price ($337) and since I had to completely tear it down anyway I went ahead and did it all including a new crankshaft.

Keep in mind how old it is and what other possible broken parts you might find, I sure did on mine. You'll sleep better knowing it's all new...

Here's a link to my thread on what I found. Good Luck....

http://www.buggiesgonewild.com/gas-e...e-rebuild.html

[BBuford]

Sounds good. I will have to check it all out. I am sure I would have to find a shop to press in the bearings if I go to replace crankshaft?

[kyerik]

You will need to make a puller to pull the crank case halves apart. Here's how i did it on a 3PG engine: http://www.buggiesgonewild.com/gas-e...se-halves.html


You might just need to get a loaner bearing puller from an auto parts store to get the old bearings off the crankshaft. They might stick to the crank case halves- then you can tap them out carefully. I used a hammer to carefully tap the new bearings on. If you haven't ever done anything like it before, you might want to have a shop install the new bearings.

[BBuford]

Originally Posted by Govnah69

Correct, if you have play In that shaft your bearings or crankshaft is shot ... Or both are. Rebuild kits have all these parts Included

Okay, I reached in and tried to wiggle the clutch and shaft. I definitely have some play in the crankshaft or bearings.

So I am looking for a rebuild kit.

[Govnah69]

Bad news, ya gotta rebuild it...
Good news you'll have a sweet piece when you are done that will last another 30 years

Originally Posted by BBuford

Okay, I reached in and tried to wiggle the clutch and shaft. I definitely have some play in the crankshaft or bearings.

So I am looking for a rebuild kit.