High temp and white smoke issue

[davidh86]

Hey i just changed the impeller because of a high temp problem and it didn't do anything to correct the issue. i noticed only after a few minutes of being on it starts to billow out a very white smoke, not the grayish blue smoke when an engine burns oil. At first i was worried i blew a head gasket because maybe i didnt notice the high temp while testing it on the lake till it was too late, but if that was true why would it take so long for the smoke to start, im assuming their is a problem with the cooling system which causes what little water is in the system to turn into steam once the engine warms up. How likely is it that the circulatory pump is bad the is about 30 years old lol?

 

[Bt Doctur]

Re: High temp and white smoke issue

depends what the circ pump and impeller are on.

 

[achris]

Re: High temp and white smoke issue

And the engine is a ...... and the serial number is....

Sorry, my crystal ball's in for service....

Chris....

 

[davidh86]

Re: High temp and white smoke issue

lol sorry guys its a late pre alpha from 1978 whith a chevy 305. I just changed the impeller in the lower unit thinking it was bad but the old one was in great shape. I checked all the hoses and they were clear, opened up the thermostat housing it was clean, even hooked a hose to all the hoses to the thermostat housing to see if water flowed freely. i changed one of the exaust manifolds last year and the riser which went with it looked in great shape, my next step is to do a compression test and tear down the other riser to see if their is a clog. How often do circulatory pumps go bad and what would the symptom be? oh and this is a fresh water boat so not too sure its the other riser.

 

[Bt Doctur]

Re: High temp and white smoke issue

If this is happening on land. pull the drive and use a washing machine hose cut in half in the water inlet to help isolate it.If a circ pump was bad the manifolds and risers would still be warm but not hot, just the engine would be hot

 

[davidh86]

Re: High temp and white smoke issue

If this is happening on land. pull the drive and use a washing machine hose cut in half in the water inlet to help isolate it.If a circ pump was bad the manifolds and risers would still be warm but not hot, just the engine would be hot

ok ill try that next. Should i even be worrying about a head gasket issue, would it cause the temp gauge to max out?

 

[dpoff]

Re: High temp and white smoke issue

I had a 1974 MC1 (pre alpha) that gave me a WHOLE lot of issues trying to diagnose an overheating problem.
I did something similar to the washing machine hose thing to the water inlet on the bell housing with the drive removed and the engine kept perfect temps.
Turned out just inside the bell housing there was an eroded hole in the pocket about the size of a dime that allowed water to escape from having full water pressure going up to the engine. Take a look. Hope you find your problem.

 

[davidh86]

Re: High temp and white smoke issue

I had a 1974 MC1 (pre alpha) that gave me a WHOLE lot of issues trying to diagnose an overheating problem.
I did something similar to the washing machine hose thing to the water inlet on the bell housing with the drive removed and the engine kept perfect temps.
Turned out just inside the bell housing there was an eroded hole in the pocket about the size of a dime that allowed water to escape from having full water pressure going up to the engine. Take a look. Hope you find your problem.

Yea i went over the bell housing pretty well but i cant say that i payed as much attention to the drive side of the seal. Im just gonna bypass the whole dive and clamp the hose into the thermostat housing, and run another hose to the drive to keep the impeller wet.

 

[Bt Doctur]

Re: High temp and white smoke issue

We know you said you put an impeller in, but did you do it correctly.did you replace the base, do you have all the gaskets correct, did you tighten it down to warp the housings, did you forget the keyway is the transom hose crushed, is the inlet corroded away, etc.,etc. If you did the impeller wrong, you dont have an impeller to worry about.
Remove the drive for testing. only 6 nuts and a gasket.

 

[achris]

Re: High temp and white smoke issue

A few things here guys...

1.

... its a late pre alpha from 1978 whith a chevy 305. ...

No, it's a Mercruiser 898 (or 228 if it's got a 4bbl carb) with a Mercruiser-1 drive (MC-1 for short)...

I had a 1974 MC1 (pre alpha) ...

No, you don't... Nobody has a pre-alpha, because there is no such thing...

Have a read of this -> http://forums.iboats.com/mercruiser...ve-needs-help-go-down-597987.html#post4160821

Now, bypassing the drive water pump.... Not a good idea. It could easily lead to further damage... Remove the drive and push a hose into the water feed, like the Doc suggested. Removing the drive is only a 3 minute job, and it gives you the opportunity to check other things...

Chris.......

 

[davidh86]

Re: High temp and white smoke issue

A few things here guys...

1.

No, it's a Mercruiser 898 (or 228 if it's got a 4bbl carb) with a Mercruiser-1 drive (MC-1 for short)...



No, you don't... Nobody has a pre-alpha, because there is no such thing...

Have a read of this -> http://forums.iboats.com/mercruiser...ve-needs-help-go-down-597987.html#post4160821

Now, bypassing the drive water pump.... Not a good idea. It could easily lead to further damage... Remove the drive and push a hose into the water feed, like the Doc suggested. Removing the drive is only a 3 minute job, and it gives you the opportunity to check other things...

Chris.......

Yes it is a 228 mc-1, good call ill pull the drive and report back.

 

[davidh86]

Re: High temp and white smoke issue

where to start everything checked out with two exceptions one being a small kink in the supply line where it attaches to the transom, it seemed very minor but i corrected it to be on the safe side. The second exception was a massive vacuum leak in the gasket between the carb and the intake manifold, like carb cleaner literally poured through the gap when i sprayed it, the bolts were finger tight to the point where it could have caused the engine to run too lean.