Crankshaft

Hi guys

Bit of technical advice needed please. A friend of mine just purchased a '70 911 2.2 T with the Zenith carbs. We don't know much about the history of the car. We do know it has been sitting for a long period of time. I charged the batteries and got it to fire even with the old fuel. I only let it run for about a minute though. I was not too surprised to see a good bit of oil smoke from the exhaust but the volume of oil that sprayed out of the pipe was considerable. Even with the short amount of runtime, a three foot spray of oil was left on the pavement. I am not terribly familiar with the flat sixes and was hoping for some input. Where is the liquid oil coming from? Is there a place that it could have collected while sitting and is just getting blown out or is this oil getting pumped out of the crankcase, ie. broken rings? Terminal problem or will it clear with some running? Thoughts please.

Thanks

Mike Murphy

It is common for a flat-6 engine to produce oil smoke on startup, even if it has only been sitting for a day or two. The reason is because the pistons are sitting on the side, and even a good seal on the rings and guides can produce oil drip over 24-48 hours.

Generally, if a car sits for a week or two, more oil smoke will be produced. So if this '70 has been sitting for a long time, it is possible for a large amount of oil to seep into the engine & exhaust system.

If a car has been sitting for over 2 years, I will pull the plugs and spray some lubricant into the cylinders. The objective is to loosen and breakdown the oxidation that likely has occurred on the piston rings. This prevents breaking a ring upon startup.

The only practical way to tell if you have a major problem is to run the engine up to operating temperature. Before you do this, I would change the oil, and try to change the gasoline, the oil filter, the fuel filter. If the engine continues to burn oil, then you probably have worn guides or failed rings.

Peter Zimmermann

It's possible that someone put too much oil in the car, which will cause your problem. Because the car has already run forget removing the plugs and lubing the pistons/cylinders. Drain the oil out of both the engine and reservoir, replace the oil filter, add 8 quarts of oil and you're good to go. Drain and fill the fuel tank with new premium fuel, don't start the car again with the old stuff! After you have the car running let it fast idle out in fresh air, it might smoke badly for as long as a half hour. Have a fire extinguisher close by, and don't leave the car. Watch the temp guage to make sure that it doesn't overheat. The smoke is from oil that found its way into the exhaust, and if the engine is sound it'll dissipate over time, but might take three or four drives to do so. Eight quarts in a 2.2L is easily sufficient to protect the engine, but the first time that you have the engine up to full temp it wouldn't hurt to top up the oil to about halfway between "min" and "max" on the dipstick.

Jay Laifman

... when the engine is running at idle, on flat ground.

(just to prevent another newbie problem).

Peter Zimmermann

Jay: Thank you!

Crankshaft

Thanks guys for the help...

After alittle more investigative work, it appears the offending cylinder is #2. I loosend the exhaust just enough to see which bank of cylinders was producing the smoke, and determined it was the left. I then pulled the plug wires one at a time in succesion. The smoke completely quit when #2 was pulled.

So, what are the pros and cons of replacing just one jug/ piston assembly?

And, are the Zeniths worth rebuilding?

I will do some searching as well on these topics but any info would be appreciated.

Again thanks,
Eric

ron mcatee

The ring on that jug could be stuck. I suggest following Steve's recommendations and only proceed if it still persists.

Peter Zimmermann

Correct, I certainly wouldn't pronounce the engine "dead" until you follow the above post, then put some very gentle miles on the engine.

Crankshaft

Update: The Zeniths are off the car and awaiting rebuild kits. Until they arrive, I am putting a bit of Marvel Mystery Oil down each intake and rotating things by hand. I have seen wonders worked in the past with this stuff. I'm hoping we just have some stuck rings.

Thanks for the 'newbie' advice.

Eric

Crankshaft

Guys, I would like to offer big thanks to all who contributed to the revival of the 911t these last few weeks.

Kudos to Peter! The car ended up having 13 qts of oil in it which of course was the primary smoking problem. The advice of cleaning up the fuel system before any more running of the engine proved to be the second half of the saga.

I pulled the fuel tank and what a mess! Following a good cleaning the car went for its first drive in any years. A bit smokey, but a drive none-the-less.

So fifty miles later she is running better and better. Amazing how well the freshened Zeniths are doing.

Thanks for all the help. I believe I may have been bitten by the air-cooled bug!