Exhaust air from exhaust housing cover...normal????

[mrecho76]

Hello all,

I have a 1996 Johnson 115 that's always been a bit of a hassle to start, even when warmed up. After much research and experimenting, I figured out the best way to start my motor (how long to push key in, trim, throttle advancement, etc). But today, I noticed something new.

I noticed that air and smoke could be felt / seen coming out from underneath the cover that sits on the upper end of the outer exhaust housing. I have noticed oil dripping down the outer housing several times in the past but thought I had an oil leak around the carbs or something. Now I'm wondering if that oil may be residual oil leaking down from this exhaust I felt.

I thought the exhaust is supposed to exit through the prop only. Is there another exhaust exit that's supposed to be above the outer exhaust housing or does it seem that I have an exhaust leak behind that upper cover somewhere?

Has anyone ever experienced or heard of anything like this? Is this normal or do I have another problem on my hands? If so, think it's something major? Any feedback would be greatly appreciated!!!

I'm attaching a picture as well.

Thanks everyone!

 

[racerone]

Gasket between the block and exhaust housing is leaking or the gasket on the exhaust covers between the cylinder heads is leaking.--------Do a compression test before doing any work on this motor.

 

[emdsapmgr]

Agree. Probably the powerhead base gasket. About a 3 hour job to remove the powerhead and replace the gasket, part number 342513. A common V4 crossflow failure mode. It's not a critical powherhead failure. Problem is that it's an exhaust leak. It will flood the cowling with exhaust smoke when running and that smoke will get sucked back into the carbs when running. And the tarry substance is messy.

 

[mrecho76]

Thanks for the responses!

 

[racerone]

A factory replacement gasket under the powerhead is a better quality than some aftermarket ones.

 

[emdsapmgr]

Agree! make sure you get the paper gasket with a metallic coating on both sides.

 

[mrecho76]

Any idea how much this job should cost me? Don't want to get ripped off by a shop. Thanks.

 

[racerone]

Are there results of a compression test.----Be a shame to spend $$ and effort on a motor that is not in good condition !

 

[mrecho76]

Well last time I tested the compression, they were 95, 100, 95, 85. But when the boat was in the shop months before that, they tested it and said everything was around 110. I rented a compression tester at a local shop when I checked it. Don't know if the compression actually went down, if the tester I had sucked, or if the shop lied. Either way, the motor runs strong and seems to have no issues (aside from this exhaust leak). So far I've put on new spark plugs, 2 new ignition coils, a new VRO pump, new starter, new fuel filter, new fuel bulb with new fuel connectors, and had the lower unit completely serviced with all new seals. I also bought a carb rebuild kit which is next on my list. So spending a lot on this motor has already passed..haha.

The one cylinder that had low compression when I tested it does worry me, but then again, they're all pretty low. I'm planning on getting a compression tester from a different place to see if I get those same numbers. But as I said, then motor runs strong and idles smoothly so I believe everything's ok.

 

[racerone]

Remove the bypass cover on the cylinder with low compression.-----6 small bolts and a $2.00 gasket.-----Allows you to have a look at the piston and rings.---I picked up a 95 model like yours , it looks to be 2 years old but needs to be rebuilt.-----See this all the time too !!!

 

[mrecho76]

Ok, sounds like a plan. I'll start by doing another compression test. If the numbers are the same, I'll remove the bypass cover and check out the piston/rings. But if it turns out the the numbers are a lot better when I do the compression test, and I decide to move forward and fix the exhaust leak, what kind of an estimate should I be expecting from a shop? Any idea?

 

[emdsapmgr]

The factory considers a 10% variance between compression of all 4 cyls to be normal. It is also normal for the compression to vary (between both heads) maybe 5 lbs, due to manufacturing techniques on these crossflows.