Emulsified residue in exhaust.

[Keith Buchanan]

Merc/Mariner 50HP 1990 3 cyl...After having a short overheat I have now changed the impeller, circulation and temperature is again normal..Whilst the lower unit was off I attached a hose to the end of the water take up pipe with the intention of flushing the system and running up the engine to test the t,stat and bypass valve. What I witnessed was the rapid build up of an emulsified residue in the exhaust, this was the first time the engine had been run since the overheat, I ran the unit for 20 minutes and with a flashlight this residue can be seen all the way up the exhaust to the bottom of the powerhead. A:, Is this normal, I cannot say I have noticed this before, otherwise it would be evident at the prop .<br />B:, Is there any gasket etc whereby water could cross into the exhaust at the powerhead, With water circulating and the engine off there is no water coming down the exhaust.<br /><br />Regards Keith..<br />Nearly there..<br /><br />Regards Keith B..

 

[andrewkafp]

Re: Emulsified residue in exhaust.

The exhaust usually contains unburt 2 stroke and carbon. It will burn away with continuous usage at high speed.A 2 stroke OB that it seldom used will also drip oil from the prop... Also normal.

 

[Merc90HPnewbie]

Re: Emulsified residue in exhaust.

I had the same problem, a grey (gray?) goop coating the exhaust holes around the prop nut. It was after an overheat and one person here told me it was aluminum ground off from the engine!! I'm still not sure what it was, but it wasn't storage oil since it was mid-season. Could be unburned gas but I think it would be a different color.

 

[Keith Buchanan]

Re: Emulsified residue in exhaust.

That's it grey goop!.. Did the problem persist or did you resolve the problem in the end, I'm nearly there I think and don't want to take it out till it is right.<br /><br />Hi Andy, it is not the usual stuff that drips from the prop, there is almost certainly water crossing over somewhere at the powerhead, this stuff is like grey moisturising cream (not that us Pommies use the stuff). Not grey anyway!!!!..<br /><br />Cheers all..

 

[Merc90HPnewbie]

Re: Emulsified residue in exhaust.

I am sort of new to boating so I didn't really do anything about it last season. In fact I just wiped if off a few days ago and after I put her in the water again (this weekend I hope) I will see if it comes back.

 

[Keith Buchanan]

Re: Emulsified residue in exhaust.

If it was fresh water I might have given mine a dip but I really do not want salt water to go where it shouldn't, I'm gonna hold fire untill we find the cause and hopefully the cure is out there, somewhere....<br /><br />Nearly there. Keith..

 

[Merc90HPnewbie]

Re: Emulsified residue in exhaust.

Hm, shows how bad my memory is. Here's the post<br /><br /> http://www.iboats.com/cgi-bin/ubb/ultimatebb.cgi?ubb=get_topic;f=29;t=009964;p=1#000015 <br /><br />from oct 27 2003. I guess I *did* notice it just after fogging engine. However "The Marine Doctor" says that burned fogging oil should be white and suggests that the grey stuff is the piston disintegrating.<br /><br />If the link doesn't work, do a search for my posts in oct 2003

 

[Keith Buchanan]

Re: Emulsified residue in exhaust.

No alloy in this goop, or fogging oil, all 3 cylinders purring away and compression okay, just water gettin where it shouldn't, any ideas where, what is involved with removing port side covers and inspecting, I beleive there are two gaskets to replace here, could either of these gaskets have failed during a short overheat or is there any other gasket more vulnerable. Only a very small amount of water is mixing with the exhaust, there is no evidence that it is entering any of the cylinders. Also another way to look at this is if the engine is momentarily started dry I get a small amount of exhaust smoke evident from the pee tube, there is definately a crossover somewhere..

 

[andrewkafp]

Re: Emulsified residue in exhaust.

The only issue with removing covers is breaking bolts whilst removing. This is more common on older motors and more around the water cover where the plugs go in. Sounds by the "Smoke coming out of pee'er" like exhaust gasket.

 

[Keith Buchanan]

Re: Emulsified residue in exhaust.

Hi Andy<br /><br />Just done a search on exhaust gasket etc, sounds very possible, also had a look at www.mercruiserparts.com, the gaskets look quite easily accessible, point taken on the bolts.<br /><br />Cheers Keith B (now 04:53 hrs local can't sleep)

 

[Keith Buchanan]

Re: Emulsified residue in exhaust.

Andy!!...spot on....exhaust manifold gasket to main block, and where it had failed was just above of number one pot, the aluminium was almost polished by all the steam cleaning..Have ordered all three gaskets but would like some coaching putting it all back tohether . <br /><br />Thanks all...This BBS is MMMmmmmmmmmm...

 

[Keith Buchanan]

Re: Emulsified residue in exhaust.

00:10 ish local, a little pished, I love u guys, I've always loved u lot despite what my mother told me,,.. He He!!!! New gasket set on the way,,hurry up Postie me want big Tope......thanks all, will report on Sea Pie...Happy fishing...Love you....P.S. I forgot, what's the torque settings on the port side cover. *********************X Keith..

 

[Keith Buchanan]

Re: Emulsified residue in exhaust.

Morning, anyone for Alka Saltzer..