1998 Big Bear 350 Possible Blown Engine

1518 Views 5 Replies 2 Participants Last post by ryan313, Feb 7, 2018

ryan313

Discussion Starter · Feb 1, 2018

Yesterday I picked up a 98 Big Bear 350, I am not gonna lie it is a bit of a roach. I got it for $150, knowing that it had an engine problem. I got it from a buddy, he never messed with it, but said he thinks it dropped a valve. Somebody has messed with it before, the jug bolts are only in a few threads, the valve cover bolts are loose, the recoil cover is missing. I figured for $150, I would take a gamble and see if I can get it running.

I put a socket on the crank, it turns about half a revolution, and just stops. I put a screwdriver in the plug hole, the piston is moving up and down. I pulled the valve covers, I can see the lobe inside moving, but it does not hit the valves in the current position. Any ideas what I can check? I know I will probably have to finish taking off the head, but it looks like whoever took the bolts out didn't finish removing it. I didn't have much time to mess with it, before it got dark out. I wanted to ask the experts (reading up and researching before I post, it seems like you guys are) so I have a game plan for tomorrow. Thanks!!

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dezz

· #2 · Feb 1, 2018

This could be one of many things wrong and locking it up.
You first need to pull the cylinder head and go from there.
I do not know why someone would pull the cylinder mounting bolts before removing the timing chain. The timing chain/cam gear must be removed first.

If your going to be digging this deep into this machine, if you haven't got a service manual, get one. It's less than $20 off tradebit.com.

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ryan313

Discussion Starter · #3 · Feb 2, 2018

The timing cover screws are loose, so they took that off too. The chain and gear is still on though. I will get the manual and dig into it more. Thanks!!

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ryan313

Discussion Starter · #4 · Feb 5, 2018

Would It be easier to pull the engine out to try and figure out the issue? Any Expert opinions??

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dezz

· #5 · Feb 5, 2018

Pull the cylinder first. That's easy. If the problem is in the bottom end, then and only then will you need to pull the engine.

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ryan313

Discussion Starter · #6 · Feb 7, 2018

I spent only a few minutes trying to figure out how to take the head off, I watched several videos and it looks pretty simple. In the machine, it looks like there isn;t enough room, I cant even get the head bolts to clear the frame to remove them.

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