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Oil in exhaust

K

kinghans

Member
"got a 1976 mercruiser ford 35

"got a 1976 mercruiser ford 351, twin screw inboard boat, the problem is the starboard engine looks to have a little oil that comes out of the exhaust after you start the engine up, this has happened after a 800 rpm troll fishing and not running the engine at a higher rpm to burn everything of good from the slow troll. Engine temp, oil pressure and all basic operations are normal. Any ideas for this oil in exhaust?"
 
Assume you mean you are gettin

Assume you mean you are getting some blue smoke?
Rebuild the engine?

Sounds like valve guide seals may be shot if everything else is working OK. You may get buy with just changing them. If they have not been touched in 32 years chances are they are toast.

Rod
 
Tim:

do you have to add oil

Tim:

do you have to add oil between changes or does the level on the dipstick drop any? Are you spark plugs black and wet?
 
"Guy:

have not had to add

"Guy:

have not had to add oil since the first change at june 1st, does not appear to be using any oil either. repalced the plugs, cap points, rotor, and checked timing June 1 2008 , I have put about 75 miles on it and about 30-35 hours, using quaker state straight 30 oil, also plugs are dry looking and normal color, after engine runs for a while do not see any oil. Might want to let you know I purchased this boat in May and do not know a lot about the engine history on this boat,the prior owner did not use it very much the last few years,, just was over due for a tune up when I got it. This just started saturday afternoon and this morning,, smells rich w blue smoke,, planning on rebuilding carbs this winter, any ideas?,, thanks a lot,, have had the ford motors before, just not this problem."
 
"Tim:

Assuming the engine h

"Tim:

Assuming the engine has good compression, which you should check, follow Rod's advice about the valve seals or a rebuild."
 
"I would think that the compre

"I would think that the compression should be around 180 psi +/- for that year. It does not really matter what it is as long as all 8 cyclinders are within 5-10% of each other.

Of course if they are all very low then that is a different issue.

I personally would not be that concerned about a small amount of blue smoke. Yes your guides and or seals may be worn but if you are not using oil and you can deal with the smoke just let it be.

A good mechanic with the propper tools and experience could possibly do the seals without removing the heads. The valve guides need the heads removed to replace.

One other thing to consider, in 1976 there was still leaded gas. If you choose to have the heads reworked the shop that does the work can install new valves and also install hardened valve seats (needed for unleaded fuels).

You also may be able to just replace the heads with some that are unleaded ready and then it is just a simple swap and no rework needed.

Just an option............

KGHOST"
 
"thanks for the input, the smo

"thanks for the input, the smoke does not bother me, its the oil slick on top of the water that concerns me, won't be to long and someone will complain to the marina every time I start it, Are there any additives that I could add to the oil to help recondition the valve seals? thanks for the help"
 
"...any additives that I c

"...any additives that I could add to the oil to help recondition the valve seals?"

No; valve stem seals are hard as a rock.
 
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