smoking engine

[Tipsy]

My 1975 Mercruiser 888 (Ford 302 block) which was rebuilt in the early 90's and only has 500 hours on it recently started smoking, but only after a short fast run, slow speeds or idle does not result in any smoke. Appears to be coming from the outside edges of the valve covers or below that. It's sort of a rubbery smell. Last season the engine coupler was replaced. I replace the oil and filter every season (about 45 hours) and right now the oil is at the proper level and is very clean. Occasionally hear a clicking or tapping sound but not always.Any ideas what this might be?

 

[achris]

Re: smoking engine

Some owners are so irresponsible!!! Haven't you been listening to the medical fraternity? Smoking is bad for the health! Now you really need to get the engine on a Quit program....

Ok, joking aside. Sounds like the exhaust manifold gaskets are getting hot and 'burning in'. Any idea whether the rebuilder used genuine gaskets, or after market? It could also be that with the higher exhaust temperatures the paint around the ports is burning off. It doesn't actually sound like it something to worry too much about to me.

Chris....................

 

[Haut Medoc]

Re: smoking engine

Welcome to iboats.....
Have you checked the tightness of the valve covers?
Sometimes a little oil will seep out & get down to the exhaust manifold....
​

 

[Boomyal]

Re: smoking engine

What's your temp guage say? I'd also check the temperature of you risor exhaust boots.

 

[Tipsy]

Re: smoking engine

To Boomyal: My temp gauge reads just fine. I just replaced my pump impeller last season. They usually last five or six years for me. It's early in the season and the Illinoois River water I run on is still a bit cold so my engine temp stays pretty cool.
To Haut Medoc: Yes I checked the tightness of the valve covers. They seemed a bit loose, four pounds of torque is a tough one to check on the river without my torque wrench but I'm going back to the marina today to double check them.
To achris: I can't imagine exhaust manifold gaskets waiting ten years after a rebuild to finally "burn in" but I'll consider it and check it out.
Thanks to all of you!
I also had a thought in my dreams last night, I changed my spark plugs last weekend and I did it when my engine was a bit warm. Could my plugs possibly not have seated fully due to engine block expansion and now exhaust gas is seeping by the plugs?
I'll be checking that one out today as well since my engine will have cooled down completely from yesterdays's ride.
Thanks again everybody!

 

[Tipsy]

Re: smoking engine

Wanted to bring this question back to life. Since we last talked, I've replaced the valve cover gaskets, PCV valve, oil breather cap and the smoking stopped for a few weeks. Yesterday I went out for a short fast run by myself and noticed the smoking again, when I raised the engine cover it was only coming from the port side of the engine. Couldn't tell exactly where but it looked like it just might be coming from the head gasket area all along that side. Could I possibly have a blown head gasket? I'm planning a compression test very soon.
Boomyal, you had mentioned checking my exhaust riser boot temperature, can you explain why I should check that? I will check it next time I'm at the boat. My engine temp gauge does read just fine.
Any other ideas or things to check or look for are greatly appreciated!
Thanks!

 

[Tipsy]

Re: smoking engine

bump