White Smoke - 3.2 Carrera

[LivinIn84]

Hey all,

I've got a friend with a 1988 Porsche 911 3.2 Carrera and its exhibiting some strange smoke behavior. I've read all the threads on this, but still don't feel like it's quite matching the issues other folks have experienced.

Here's what I've found on spending some time with it (I am not a mechanic, just handy):
- Cold start, puff of smoke. Idle settles down nicely. Occasionally smokes at cold idle. First cold start in a couple weeks, smoke exited exhaust when pulling out of garage.
- Hot start, no puff of smoke
- Car warm, light smoke at idle
- Rev car while warm, white smoke billows from exhaust on first few revs, getting less smoke each time. Wait a bit, rev it, smoke comes back.
- Oil level is on the nose at 1/2 on the dipstick measured on a flat surface at idle
- Last compression test was 2020 and 4,000 miles ago. 180psi on all 6 cylinders
- No smoke on decel or acceleration. Just at idle and when revving at idle.

The car sits a lot between drives. I am going to strongly recommend it be diagnosed by a competent shop, but I'm wondering if the group has any thoughts on what it could be and what the diag will take/cost.

Many thanks!

[PeteKz]

Need more info:
How many miles on the engine? What last work was done and how many miles/years ago?

"White smoke" usually has a bluish tint to it, which comes from burning oil. It's not uncommon for higher mileage cars to start with a little oil smoke. This comes from the oil in the external tank draining down into the engine case, and rising high enough in the case for some of it to seep into the bottoms of the cylinders (remember, it's a flat engine). It's often worse if the car is parked on a slanted driveway. It also gets worse the longer it sits in between drives, because that gives more time for the oil to drain into the case and seep into the cylinders.

Another source of burning oil is worn valve guides , which is why we need to know how many miles the engine has. Given that the engine smokes more when revved, this is likely.

If it starts from cold easily, smokes for a few seconds, then runs normally, continue driving it.

Do a compression or leak down test and post the results.

[mikedsilva]

Originally Posted by LivinIn84

- Rev car while warm, white smoke billows from exhaust on first few revs, getting less smoke each time. Wait a bit, rev it, smoke comes back.

sounds a lot like valve guides and probably worn seats too.

[911obgyn]

If you follow that car and it gets into higher revs you will probably see smoke, just cant see it in rearview mirror. Valve guides, check oil consumption.

[yelcab1]

White smoke is water vapor. White smoke is entirely normal during the process of combustion. Sometimes you even see water spewing out the exhaust when a car accelerates hard. The "hydro" in hydrocarbon is converted to H2O during combustion. It has to come out the back in vapor or in liquid form.

Blue smoke is oil being burnt. That would come from oil seeping past valve guides or rings. Unless you lose a quart of oil every 500 miles, I would not worry about it.

[917_Langheck]

The term "'white smoke' usually has a bluish tint" was used correctly to describe oil burning combustion, as opposed to "black smoke" caused by too much fuel in the combustion process.

The OP's description of the events is much too much and too frequent to be water vapor in an oil-cooled car. A car that produces that much water vapor would have to be water-cooled with a failed head gasket. Most people are savvy enough to be able to distinguish between water vapor, which doesn't linger, and oil smoke.

[EC900]

This time of year in 3 and 4 season climates of cool nights & warmer days sure will see moisture related tailpipe emittance.
Moisture in the oil and gas tanks vapor will dissipate readily. The hot-cold cycle tends to build up tank condensation if engine doesn’t reach +185°.
If it’s worn valve guides, the smoke is a bit heavy and lingering with the oil odor that will take around 5 mins to burn off.

If Livinin84 and the owner are new to the air cooler I see how it can be a concern. Worn guides not the end of the world, it’s common for high milers.
If the owner does a bit more driving at higher speeds and longer duration the problem tends to be less obvious, except for oil level. Hopes are that the car isn’t just isn’t being started up, run for 15 mins, then shut off for another 2-3 months at a time.

[PeteKz]

EC900: His description does not describe water vapor condensation, which does not occur when the engine is warm:

- Hot start, no puff of smoke
- Car warm, light smoke at idle
- Rev car while warm, white smoke billows from exhaust on first few revs, getting less smoke each time. Wait a bit, rev it, smoke comes back.

[brianlay]

No mention of whether the car still has a cat.
Cat can mask a lot of oil smoke. I learned that the hard way when I first switched to SSIs

[JSV798]

White smoke usually indicates that brake fluid is being sucked in from the brake servo. Your servo may be due for an overhaul. You could try capping off the vacuum line to the servo and see if the white smoke goes away. Of course then the brakes will not have the benefit of a servo.

Roy

[PeteKz]

Or just check the brake fluid reservoir. If it's low, and you aren't leaking fluid from the MC or calipers, then it probably got sucked back into the engine.