1988 30hp Steam in exhaust

[blimp]

This is a newish to me motor, model J30RCCE, which runs very well. I recently replaced the thermostat ( it was stuck open, corroded) and broke 5 bolts off in the head getting the thermostat cover off. I took the head off, drilled and tapped up to the next size, replaced gasket with sealer, and all is well. Engine starts, warms up, idles great, WOT is great, i get to about 28mph on a 15' aluminum lonestar.

My issue is this, there is steam in the exhaust after coming to idle from WOT, and it keeps steaming for a good bit afterwards. I believe there may be a corroded or destroyed exhaust gasket under the exhaust plate, but I am worried about breaking more bolts to get to it. There is no evidence of water in the cylinders, they have some carbon build up, nothing looks steam cleaned, plugs do not look cleaned either.

Is it worth trying to get to the gaskets or should I just leave it, enjoy it, and not over-fix it?

I will try an post a video this weekend if I make it out onto the lake.

Thanks in advance, this forum is awesome, I have learned a lot about my motor with your help.

 

[Vic.S]

Re: 1988 30hp Steam in exhaust

Be sure that it is not overheating !

When was the last time the water pump impeller was renewed?

When I had steam from the exhaust relief port it was due to an obstructed cooling system causing overheating.

 

[blimp]

Re: 1988 30hp Steam in exhaust

I don't believe it is overheating, recent impeller change, can put hand on head after WOT and long periods of idle. Steady stream out of tell tale and plenty of water coming out exhaust relief port. I think the exhaust is coming into contact with water too soon.

 

[kenmyfam]

Re: 1988 30hp Steam in exhaust

My 140hp does the same thing. Head temps are right on, plenty of cooling water and running great. I think the seal on the exhaust megaphone are not the greatest anymore. I will be investigating in spring and will post what I find then.

 

[blimp]

Re: 1988 30hp Steam in exhaust

Any other advice? I am hesitant to break bolts off in the block of a perfectly good running motor while trying to take the exhaust cover off. I may just try and put some penetrating fluid on every time i go out, then deal with it next year...

 

[outboardnut]

Re: 1988 30hp Steam in exhaust

it sounds to me like you might be sucking some air when at WOT

You might be generating to many bubbles from your hull or something.

Also a weak impeller comes to mind.

 

[blimp]

Re: 1988 30hp Steam in exhaust

Good idea. The motor is now on a different boat, we will see if the problem follows.