should exhaust be comming out from the prop? and another exhaust question


Old 04-28-09, 04:31 AM
Thread Starter
Join Date: Feb 2008
Location: New Haven, CT
Posts: 107
exhaust - billowing white smoke question

Hi there,

Note, I am not in any way knowledgeable about engines other than how to replace spark plugs, add oil and gas.

Engine: 1990 Mercury 2-stroke 135 hp

end of last season i bought a boat. I took it out for the first time and the water impeller failed. I know I am suppose to turn off the engine immediately. I let it cool but since i was close to home base I decided to try to push it home. Half way home driving about 5mph i start to see signs of overheating (this is well past the point where it starts beeping at me) i.e. smoke - not fire smoke just the type of smoke you would expect from something getting really hot. End of the story - i got towed back.

So now I begin to summerize the boat after having a place winterize it for me. I turn the engine on and its certainly billowing white smoke. I have tested the engine about 3 times for about 30 seconds each thus far.

I have read in the Seloc repair manual that this can be an issue with a cracked powerhead or cylinder where the water from cooling is leaking in causing a bad mixture and creating the white smoke. I have also read this could just be an issue with bad o-ring sealers that keep the water out (which could be the case with an engine that overheated?)

Knowing all of this, could we narrow down the possible issues or have I already found as much as I can before taking it in? is there more information that i could give? Is 30 seconds even long enough to indicate anything? Ive read that this could just be the engine warming up from being stored for the winter for the last few months and letting it run for a few minutes is better (but i need to figure these things out first because i am afraid of damaging the engine even more)

I have not done a compression test yet and I would probably have the mechanic do that as I am not confident in performing one.

Also: I do bring the engine up to the point where it is peeing out water from cooling, but have not run the engine up to its normal operating temperature. Is it safe to run up to normal operating temperature? I am afraid of making a possible issue worse by doing so and would like some advice.

Thank you for your time everyone.


Last edited by Capslock; 04-28-09 at 04:48 AM. Reason: removed irrelevant question - changed title
Sponsored Links
Old 04-28-09, 09:39 AM
Join Date: Jul 2006
Location: Virginia Beach
Posts: 221
The white smoke may be from a fuel additive or from having lubricated the intake with a fogging spray to protect the vlaves and injectors if any over th elong sitting period. Try calling the shop that did it and ask what all they did.

If the outboard is "peeing" out water, then the good news is the impeller is working providing fresh water cooling to the engine. No different than a motorcycle or other engine that requires cooling. IF you ran it too hot before, there may be a possibility the water intake tubing or other o'rings/washers may have melted a little from the engine heat. Happened to me once in a small outboard. Typically the motor will begin to shut down if it overheats or at least will run crappy. I would go ahead and start it up on water supply of course with observed peeing water, and let it sit and run while observing it's behavior etc. or until the white smoke began to clear out. Be prepared to shut down quick it if begins to sound horrible. Prior to, i would check plugs, fuel filters/bowls, fuel lines for cracking etc. etc. Just like you would for an old car when trying to isolate a problem. Chances are though it's winterization related and will be fine.
Old 04-28-09, 07:53 PM
Join Date: Jul 2008
Location: Montgomery MN
Posts: 541
As boater 59 stated it could be fogging oil causing the smoke, it smells like burning oil and takes a while to burn off. If you have replaced the impeller and the tell tale is squirting water just let it run sometimes it takes 15 min. to burn off. If you are running it on a hose let it run for at least 20 min to get it up to temp if it doesn't clear up or if the alarm starts I would be concerned. If you take it to the lake try to run it at the dock or close to it just in case something goes wrong.

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

Thread Tools
Search this Thread
Display Modes