Smoke!!!

[produceguy]

We took the boat out a couple of weeks ago and at high rpms we smelt exhaust and then seen white smoke, coumdn't tell were it was coming from and the temp gauge was fine. Got home and pulled the lower unit and found shard pieces of the flapper. Cleaned it out and took the boat out again and same thing, runs fine at lower rpms...

Today, I have risers off and pulled the other flapper(port), out of the y pipe,starboard flapper is gone. Pulled upper unit of drive and have found nothing in their. The water hose that feeds the lower unit is not blocked.
Changed impeller and pump last season.
All I found was that starboard exhaust boot is a little crispy on the inside. Could this boot be burning?

4.3 mercruiser, alpha 1 gen 1

 

[Don S]

Re: Smoke!!!

Check the impeller. All you need is one plastic bag in the water you didn't see to take out an impeller.

 

[produceguy]

Re: Smoke!!!

Thanks Don.

 

[ziggy]

Re: Smoke!!!

from what i get, for any overheat the first place to look is the impeller. specially for an alpha1. it sure don't take much to ruin one. impeller failure. i can attest to this too. every year (except this one) i just can't seem to go a season w/o an accidental start up on the trailer w/o the water on... i change my impeller yearly and every year i find minor damage to the impeller. likely from the dry run which is usually only seconds before i catch on to the errors of my ways. if the impeller failed, don't forget to go find as many pieces of it you can find so they don't wash upstream towards your cooling passages in the block where you don't want those pieces getting to.

 

[produceguy]

Re: Smoke!!!

Thanks ziggy. It makes sense that the burnt flapper could of blocked water flow and theirfor damaged the impeller. I'll have to start keeping extra impellers.

 

[Don S]

Re: Smoke!!!

A broken flapper will not block water flow. If it did, it would also prevent exhaust flow, and the engine wouldn't run.

A broken flapper normally gets stuck in the drive, or the bellhousing, it's a lot smaller than the exhaust passage in the Y pipe.

 

[produceguy]

Re: Smoke!!!

Thanks again. I have learned alot from you and ziggy over the last couple years and still learning. Thank you guys.
EDIT: Should I replace the pump everytime I change the impeller?

 

[Bondo]

Re: Smoke!!!

Thanks again. I have learned alot from you and ziggy over the last couple years and still learning. Thank you guys.
EDIT: Should I replace the pump everytime I change the impeller?

Ayuh,... Ya just gotta Look at it to know,...

If there's ANY signs of wear 'n polishin', or burnin',..
Ya, throw new parts into it,...

It's no place to skimp...

 

[produceguy]

Re: Smoke!!!

Thanks Bondo. You are always spot on. Thanks.