Mike J

Ok, this sounds like a classic case, but I thought I would ask the list. I was contacted by a local low mileage Turbo owner to help with an issue on his car, and here is some history:

Last oil change at 29,042, done at a local independent shop (reputable). The car went in for a clutch slave/accumulator failure. That was fixed, and as well both filters and oil were changed.

On customer pickup, the car was smoking from the exhaust and the customer as told told me to give it a week to see if it would go away (!!). It didn't and it got worst one morning and had he had towed in to get it checked. Mileage now at 29,161. The shop had the car for over a month. The independent found turbochargers oil seals failed, resulting in rebuilt turbos, and replaced pre-catalyst oxygen sensors.

When my friend picked the car up there was no smoke on start up and on the drive home. He started the car a couple of weeks later and idled it for 15 minutes with no smoke. Last week after the car sat for a week, and the car started smoking from both sides and it stopped on the left hand side after 5 minutes. He drove it for two days and there was some smoke on startup but when he drove it the smoking stopped and no signs of smoke during running. After the car was parked, he looked underneath and oil seems to be dripping from the exhaust. Last night and tonight he started it again and the smoke is now coming from the right hand side with little to no smoke on the left now.

Oil level is on the tip of the stick all the way down to the bottom indicator, so it it not overfilled at the moment. He got the temp to the bar just below the half mark before checking.

Ok, so here is my analysis:

1 - Smoking started right after the oil change. Classic sign of too much oil or over-tightened filter.

2 - Independent concludes Turbos needed rebuilding. Its possible they did given they might have seal problems due to the oil coking. My friend indicated that the car had never smoked before. Regardless, the turbos were rebuilt and replaced, even at less than 30,000 miles on the car.

3 - The car continues to smoke, even if the oil level is low. This points to me the secondary on-engine filter is too tight, or not Porsche brand. I have not seen the car (yet), but my conclusion is its likely an over-tightened oil filter.

What do you guys think?

What are the chances that the turbo's did not need rebuilding, or if they did, it was caused by the oil change?

My friend will go back to the independent to discuss the issue, but he is not confident he should take his car there anymore. I can work on it, but then that might release the independent of any liability.

Cheers,

Mike

Basal Skull

yup, change the smaller filter and go from there. When it fails, I understand it is the passenger side that tends to smoke. Unless the car had lots of hot shut downs, suspect oil filter issue was the cause of original smoking.

I don't like taking my car in to any of the local independents (anymore). There aren't many of our cars around in town and don't think they have much real experience. It also take way too long to do anything. I've figured out I can fix things faster in my spare time.

C4SJOHN

Mike, See if they installed Porsche fillers during the oil service, if not remove the fillers and use Porsche brand fillers.....

Mike J

Yup, my plan is to look at the secondary oil filter first, brand and tightness.

Cheers,

Mike

993MAN

I have the same issue and have just ordered Kevins check valves.
This will hopefully sort my issue.
Porsche did use the genuine filters as well.

tanger

My turbos had a chronic smoking problem. I always made sure the oil change was done perfectly and with the right factory filters, and even rebuilt the turbos (well, upgraded to hybrids but that is another story). Even idle for several minutes after each drive to cool turbos. But they would still smoke (sometime severely) intermittently. After a particularly bad episode with oil dripping from the right exhaust, I gave up and brought it into Tony Callas. He said that there is a fundamental design issue with the 993tt turbos and installed check valves of his own design. Have been smoke free since. Don't really even idle anymore.

Mike J

I think the idling method is to make sure the turbos cool down enough so, when you shut off the engine and the oil stops circulating, that you do not cook the oil in the turbocharger bearings. If that is true, then perhaps, even with check valves, you should still do the cool down cycle?

Cheers,

Mike

parsonii

bingo ... isn't it sad that there's a design flaw with our cars and only a few seem to realize and porsche still hasn't owned up to .... every 2 months there's thread on here about smoking turbos related to this or that (over-fill, wrong filters, filters too tight, not tight enough, needing upgraded turbo lines). im irked every time i see a thread about smoking turbos. i think ... really ..... 120k car. i just wish it didn't look so damn good.

geolab

Yes and no. I think this is a phenomena with all turbos.
The 2min idling method to me is totally stupid.
In my experience, when I was 15 yrs old, a neighbor bought a brand new 930 turbo, and when he finished his 2500 km break-in, he drove it like crazy.
Everyday when he arrived home, put his car in his open parking space, he used to WOT for a flip of a second, all the neighborhood heard the engine, and turn off the ignition.
But I recognized the engine sound before he parked, and would take a look out, watch him park, open the door, he bliped the throttle systematically (vroom) and turned off the ignition.
A week later, same scenario, same thing , he blips the throttle to the metal, turns off ignition, AND BOOM, huge explosion sound.
so much scared the **t out of me that I wanted to know what happened.

Turbo fan turns with acceleration to above 200,000 rpm
The fan of a turbo could NEVER be micro balanced because of sediments and micro particles that sit on the fans.
To balance the fan in acceleration and most importantly, in deceleration, oil is injected pressurized around the fan axle that acts as a bearing and cushion for the fan vibrations, together with the gapped metal bearings.
If there is no oil just bearing, the vibrations would break the turbo axle.
Now when the neighbor accelerated to above 6000 rpm, and shut the ignition key off, the engine goes down shut, the oil circulation shuts, and the turbos are still decelerating. Decelerating at xK rpms no oil circulating, boom.

I think if you're driving madly, and want to stop the car, the time necessary for the turbo's to stop is enough, and two minutes is overkill.
The oil cannot cool the turbo's to lower than the oil engine temperature.
In a running circuit, the oil or any liquid will always have a median temperature, with slight oscilations between under the piston , and in radiator, where delta is small.
So cooling the turbo's with oil circulation ? so infime. Oil in turbo's will never lower the turbo temps to lower than engine temp, so...
I would do it for max 10-15 secs but two minutes ????? I should be so wrong

No HTwo O

When I come back home from my weekend drives, and park in the garage, I open the engine lid, and put the fan I bought from Grainger under the car and blow air across the turbos for a few hours.

Felix

But the new cars didn't do it, right? So what's changed/worn that brought this to the fore?

Mike J

Check valves and p-traps in oil lines?

Kevin

I need t

Mike J

I do too!



This is weird since I got an email with the correct content, and not Kevin's response is cut. Strange.

Kevin

Mike did you get my reply copy and paste it.. I'll add to it.