J70elcnb, exhaust manifold gasket question

[laurentide]

Greetings, I think this is my first post in the outboard forums, and I have a question about a leaking exhaust manifold gasket on an '82 70hp. I've done a few things to address the more common issues I've had...rebuilt the carbs, replaced the head gasket, gear oil, impeller...and the only real issue that this engine has is this leak. I haven't addressed it because I'm a little bit worried/confused about trying to get the bolts out.

My first question is: should I even worry about it? I only know it's leaking because there's some burnt oil residue around the center bolt on the housing. It seems persistent, but not catastrophic at this point.

The follow up question is: If I should replace these gaskets, can I do it myself? It's been a freshwater engine its whole life, and none of the head gasket bolts had any issues. Is it hard to drop the lower cowling? I'm a backyard hobbyist, not a mechanic, so my skills are somewhat limited.

Thanks!

 

[boobie]

Re: J70elcnb, exhaust manifold gasket question

The side cover gaskets on that mtr had a habit of leaking. What you could try is to remove the bolt, put some 3M 847 sealer around it and retorque it. Check the rest of the bolts while you're retorqueing. If you have the proper tools, you don't have to remove the lower cowl.

 

[laurentide]

Re: J70elcnb, exhaust manifold gasket question

^^^Thanks, boobie. I'll try some of that sealer...that's kind of what I was getting at, I guess. I'll post back here if I need to replace the seals...thanks again.

 

[F_R]

Re: J70elcnb, exhaust manifold gasket question

Just so you know, the leak around the bolt may be the least of your worries. The cause may be a warped inner exhaust cover plate. They had a problem with that happening. When it warps, the gasket leaks and squirts water into the cylinders through the exhaust ports. That results in complete destruction of the powerhead. You won't know it is happening till it is too late.

 

[durban]

Re: J70elcnb, exhaust manifold gasket question

just hope its not the 2 bottom bolts that are leaking , if thats the case you have no option but to remove the tray ,save your self trouble remove the tray & replace all gaskets , do the job properly & save your self headace,s later my personal opinion

 

[laurentide]

Re: J70elcnb, exhaust manifold gasket question

Thanks, guys. I think I'll order the gaskets and check that inner cover plate. Would there be any visual evidence of warping on that part once the manifold is apart?

 

[F_R]

Re: J70elcnb, exhaust manifold gasket question

The warpage occurs right around the exhaust port where the plate is thin and no nearby supporting bolts or metal structure on the opposite side of the plate. If it is leaking, there probably will be visual evidence. In any case, you need to check the whole area with a good straightedge.

EDIT: This picture isn't your exact model, but it shows what you are looking for.

 

[Home Cookin']

Re: J70elcnb, exhaust manifold gasket question

Scary. Any symptoms before? I'm on my second mid-80's 70 and the first one, I didn't get a precise diagnosis, but it was water in the exhaust ports, possibly a baffle failing? Same thing maybe? Before then it was hard to start, even to restart when hot, and hard to hold idle.

Just wondering--and learning! Thanks

 

[laurentide]

Re: J70elcnb, exhaust manifold gasket question

Scary. Any symptoms before? I'm on my second mid-80's 70 and the first one, I didn't get a precise diagnosis, but it was water in the exhaust ports, possibly a baffle failing? Same thing maybe? Before then it was hard to start, even to restart when hot, and hard to hold idle.

Just wondering--and learning! Thanks

I don't have any symptoms other than the leak on the outer cover. It starts, runs and idles fine. Hopefully that part checks out OK...it's a pretty expensive piece of molded metal.

Thanks for the info, gentlemen. This is a fantastic resource to have.

EDIT: just adding that I have no evidence of water in any of the cylinders. Plugs all look like they should when pulled. That may mean nothing...I have no idea. Also, since this is an old, beater engine, I may just drill access holes to get those two lower bolts out and install stoppers.

 

[boobie]

Re: J70elcnb, exhaust manifold gasket question

As long as you have no water in the cyl's now and it still runs good, I'd try the 3M 847 trick first and see what happens. Been there.

 

[laurentide]

Re: J70elcnb, exhaust manifold gasket question

As long as you have no water in the cyl's now and it still runs good, I'd try the 3M 847 trick first and see what happens. Been there.

I must admit that this is my favorite option...as they say, if it ain't broke...thanks.