Exhaust Leak - Now What?

I have a 1971 Johnson 9.5 that I am pretty sure has an exhaust leak. It had little power and from reading various posts, a decarb was recommended. The motor has not been run for years. I cleaned the carb, and found the high speed jet severly restricted from varnish. After the cleaning it ran only marginally better - that's when I did the decarb. With the cover off, spraying Seafoam down the carb, I noticed exhaust gas coming from somewhere below the heads. Also, the motor would hesitate, and die periodically. I noticed the hestiation and killing stopped with the cover removed. Does this suggest a leak, and if so, how big a job is replacing the seal? I have a service manual, but have never torn one apart.

Re: Exhaust Leak - Now What?

Anyone have any experience changing the exhaust seal on a 71 Johnson 9.5? I don't know what I am in for if this is the cause of this leak.

Re: Exhaust Leak - Now What?

The 9.5 is a bit tricky to disassemble. Your best bet is to get a copy of the factory service manual, which will detail the process, with photos.

Fortunately, you can order it right here at iboats.com:

http://www.iboats.com/Johnson_9_5_h...5454155--**********.220838006--view_id.440154

Re: Exhaust Leak - Now What?

It's probably leaking form the powerhead - where it mounts the leg. I have a 35hp with a similar problem. A couple of the mounting bolts worked loose and blew the gasket. Now, fumese merge from the joint. It still runs OK as the exhaust gasses just get sucked back into the engine. To fix it I have to remove the powerhead and I anticipate bastard bolts that break, plus two that are very tricky to get at topside, which are a designer's mistake I think.