Author Topic: Engine smoke and oil consumption  (Read 2499 times)

bubbl

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Engine smoke and oil consumption
« on: August 22, 2014, 18:13:47 »
My '69 280sl, automatic, had an engine failure "horrendous rod knock" at about 86,000 mi.  The owner, my son (now deceased) had Metric Motors rebuild the engine.  Over the next ten years, he put perhaps 2,000 miles on the car, and probably did not follow normal procedures for recheck of the head bolts and valve clearance, nor oil changes.  The car then went into storage for three years.

I have had the head bolts (somewhat loose), valves, all fluids, etc. serviced, and the car runs quite well,  The engine is quiet, powerful, etc.  However, it smokes VERY BADLY, and uses about a quart of oil every 400 miles.  It is an embarrassment to drive!

The plugs are oily, with lots of carbon, as would be expected, but are not fouled.

The common diagnosis is that the rings and cylinders were never broken-in properly (very bad news), or that the valve seals have deteriorated from lack of use (much better news).

Suggestions have been to do compression tests, leakage tests, bore-scope inspection, etc., which I will probably do.

Any members' confirming experience, or other opinions, would be most appreciated.

It may be interesting that I maintained a 190 SL for 43 years, and sold it recently with 303,000 miles.  I replaced the cylinder head 35 years ago, and had no further problems with it.  It did not smoke, and leaked more oil than it burned!  (Note: purchase price: $1,700; sale price $79,000.)  It pays to keep these cars up.

stickandrudderman

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Re: Engine smoke and oil consumption
« Reply #1 on: August 22, 2014, 19:05:16 »
Firstly, I am very sorry to learn that your son is deceased.

It's a relatively simple job to change the valve seals. I would suggest that is the cheapest way to find out what is wrong , assuming the obvious like compression test, leak test and vacuum test have been done..

Stick.

ja17

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Re: Engine smoke and oil consumption
« Reply #2 on: August 23, 2014, 06:46:25 »
Have you driven the car enough to see excessive oil consumption?  A blown diaphragm in the automatic transmission will also cause excessive smoke, and consumption of ATF.
Joe Alexander
Blacklick, Ohio
1969 Dark Olive 280SL
2002 ML55 AMG (tow vehicle)
2002 SLK32 AMG (350 hp)
1982 300TD Wagon turbo 4spd.
1963 404 Mercedes Unimog (Swedish Army)
1989 flu419 Mercedes Unimog (US Army)
1998 E430
1974 450SLC Rally
1965 220SE Finback