smoking 911

Greetings:

I have been driving my '78 911 SC only occasionally for the past month,
getting to know it and see how it runs before I start tinkering with it
(without problem). Yesterday and today the temps are in the high 80's, the
first warm weather I have seen in this car. Yesterday the car stalled twice,
when at running temp, and I figured that it was likely due to loose valves
and/or a need for new plugs-- I was told by the seller that the car had last
been valve adjusted some 7000 miles ago.

As the car was running warm today, about 3/4 of the gage, it began to stall
every time I went to downshift for a light (such that I started popping the
clutch or being light enough on the gas to keep the idle speed up). It was
also making obvious valve clatter and the fan belt sounded as if slipping
from the slight chirping noise. As I rounded the last corner to park the car
it began emitting quite a bit of smoke from the tail pipe. I kept an eye on
the gages, and oil level was at max, pressures were low (1-2 usually) as I
wasn't hitting the gas. As it stalled again I coasted to a stop and kept it
running long enough (very rough) to check that the oil level was fine --
middle of the dipstick. It smoked the entire time I was turning it over.

The car turns over but runs poorly and smokes after cooling down, with additional loud and strange noises. Has something
terminal occurred? I have not yet seen any obvious external reasons for the
smoke and stalling. I would also like to take any precautions before further
action with the car. Perhaps something was damaged when the car ran as hot as it did --
though not in the red.

I am hopeful that all will be well again!

Thanks for any help, John

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'78 911 SC 3.0

How does it run when you give it gas? Could be something as simple as your idle speed is set too low.



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Bill Krause
'79 911SC Euro

As the car was running warm today, about 3/4 of the gage . . . [though not in the red.] . . . the fan belt sounded as if slipping from the slight chirping noise. . . .additional loud and strange noises.

Do you mean the temp gauge was 3/4 of the way up from the bottom, or 3/4 down from the top. If the temp guage is in the middle the temp is high. An improperly adjusted fan belt can make a world of difference in cooling. If not properly adjusted no air is being forced around the engine.

I don't know what you mean by "loud and strange noises" I would not drive the car until checked out. Generally, if a car stops running because it is running too hot, there can be some serious damage to the motor. I wouldn't drive the car until its checked out by a wrench.
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Paul
78SC Targa



[This message has been edited by pbs911 (edited 04-11-2001).]

This doesn't sound like loose valves to me. Besides, I believe valve adjustments are necessary every 15k miles, at the outside.
Chuck

Oil level at max?

Part of the problem can be an overfilled oil tank. Take off your air filter and see if there is oil in your air box.

Loud noises from the engine compartment. Have you pulled off the valve covers and checked the head studs?

David
'83 SC Targa

I have pulled the airbox, no oil there, as expected since I have not added any recently.

By the way, the smoke is white, and not blue as with oil burning. I will pull the plugs to see if the mixture looked lean/rich. The valve covers may be pulled as well to check condition of guides and valves.

I was informed that it could be water in the tank, or even a lean mixture, as these older 911's will run lean after a time. That would explain the lack of idle possibly.

Any suggestions for a good compression tester, or a lead on a CO gauge to do the mixture edjustment?

Thanks

John,

It sounds like you have a rich gas/air mixture. Before you pull your plugs, run the engine until warmed up and then pull the plugs to see if they are wet. If they are, then your injection system needs to be looked at. Your pressure regulator may be the culprit.

Do a pressure test with the engine cold and then again with it warm. Check the control pressures against the specs at 20 C - 1.7 +/- 0.2 cold, 3.4 +/- 0.2 warm at idle speed, and 2.9 +/- 0.2 with engine stopped, but fuel pump running. System pressure should be 4.5 - 5.0 all pressures are Bar.


Steve

I am not sure, but I know that a broken piston ring can cause a white smoke. Loud noise may or may not be broken ring pieces and piston slap. Do not worry though, at least until you do a compression test. I am sure that if a piston has bad rings you will see big results. Just another avenue to check.

Jerry S

Your description sounds like mine did when the cylinder temperature sensor failed. If
your temp sensor is the single wire variety
you can test it quickly by grounding it's body with a jumper wire to a good ground. The
single wire sensors fail occasionally just because the dissimilar metals corrode and no longer provide a good ground. This assumes
your '78 uses the same sensor (at cyl #3) my '86 does.

George 86 911T
does.

oil does burn white as well as bluish white. the 78 has no head temp sensor. sometimes a stem seal gets loose and rides up and down with the valve stem, turning itself into a nice little oil pump that shoves oil down the guide. it doesn't take a lot of oil to make a lot of smoke.

oops

[This message has been edited by rstoll (edited 04-14-2001).]

Thanks for the heads-up on the fan shims. I was only planning on replacing the $5.00 fan belt.

Regarding the compression and leakdown tests by the home mechanic: where are folks getting the EGA (CO%) gauge and compression/leakdown tester that fits Porsche? I have checked Tweeks and Pelican and found nothing. An air compressor is an easier matter.

The suggestion for running the car to check for fuel on the plugs way be a tough one-- since the car idles very rough and I need to keep my foot on the gas to keep it from stalling, blowing smoke out the pipe the whole time.

The noises sounded mostly of valve slap and fan wobble. The car really wanted to stall out the other day, even though the temp was okay (horizontal needle puts it in the 250 range).

If fuel mixture is rich, then I am tempted to adjust the mixture screw down to see if there is at least enough improvement to get it idling on its own.

Thanks -- John

John,

Most people agree that 250 F is NOT an 'OK' oil temp ... it is too hot, very close to the 266 degree F max limit specified in the spec books for years!

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Warren Hall
1973 911S Targa