Kevin

There are some 993TT engines that will smoke, puke and leak oil constantly. The solution can involve something simple like removing a Mahle engine oil filter and fitting a proper Genuine Porsche engine oil filter. The worst will be a topend engine rebuild.

Over the years I have seen plenty of failures. I usually receive a email or call everyday regarding smoking or oil dripping on the floor or spitting out of the tail pipes.

I am going to start writing my latest account on a local customers car. I will add more content to this first post as edits.

Last year I installed a Ultimate Motorwerks Stage 1 tuning package as mentioned above on a local customers car. The car had 47K on the clock and in the turbocharger rebuild process, I installed brand new cartridges. For those that don't know what cartridges are > A turbocharger consists of 3 major components >> The compressor housing or "cold" housing which pulls air from your air intake and compresses the air and rams in into the intake >2> center section or cartridge (this is the guts of the turbo) it has a bearing housing or frame which houses the turbine wheel/compressor wheel and bearings. >3> turbine housing or hot housing..

I also installed the upgraded 996TT oil check valve kit. This was done to protect the turbochargers from future oil level failures.

The car ran flawlessly for a little over 6 months when it started to smoke. I went to the customers home and inspected the engine. Oil poured out of the plastic inlet pipes to the compressor housing inlets. Oil was in the IC. I drained the pipes and installed a new Genuine Porsche oil filter. The engine was started and it briefly smoked but it seemed to clear up. The customer drove the car for a few days with no luck. I decided that I needed to do a better job cleaning the oil and inspect the turbochargers. I drove the car and it didn't smoke like it had before. But when I parked the car, it would drip oil under the turbochargers. This is a CLASSIC OIL FILTER FAILURE. I joked with the customer before I took his car, that I should spin on another Porsche filter.

I decided to pull the sump tank plugs. Oil poured out of both sumps. More than what is typical. I pulled the oil cooler and removed the inlet pipes to the turbochargers. I looked at the turbochargers, the rotating assembly was nice and tight on both units. Since I was this far into this problem I pulled each turbocharger off and began to tear them apart.

With the sump tanks and turbochargers off the car I put two oil pans under the engine to monitor the oil migration from the engine. Please note that as of yet I did not drain the engine oil, or remove the oil filters. A week later I moved the car down in elevation. I noticed that oil continued to drip out of the sump return lines. I returned later to find a large amount of oil that had further dripped into the oil drain pans.

There was a constant drip/drip to the tune of 7 qrts of oil that I had to add to get a proper level. This problem puked out 7 qrts into the intake system, IC, tailpipes and eventually out the sump lines.

The solution to this problem has already been engineered by Porsche. On the 996TT/997TT Porsche has installed reverse "P" traps in the scavenge oil return lines that are routed from the turbo sump tanks to the intermediate shaft driven sump pump. Porsche also routed the scavenged oil into the midline of the engine case. The Porsche 993TT scavenge pump dumps it into a low level port. When the engine is shut off the oil back siphons back into the turbocharger sump tanks.

Basically the crankshaft is 7" above the centerline of the turbochargers. The engine oil level inside the engine case is 4 to 5 inches above the centerline of the turbochargers. You can see where this is headed. If the oil rises above the seals in the turbochargers oil wil force its way out into the turbine housing and compressor housing.

It is the classic case when someone changes his oil and oil filter to have smoking issues or have two puddles of oil under the turbochargers. You MUST change the engine oil filter. Most likely a MAHLE oil filter was installed. The bypass valve breaches and oil migrates from the main engine Reservoir. When you pour oil into your engine, it goes to a tank located in your passenger quarter panel in front of the rear wheel. Infact the oil tube routes thru the frame rail to fill the main tank. When you have a faulty engine oil filter. Oil follows a path thru the oil filter and fills the engine case. Under normal condition we should only have 2 to 3 quarts of oil in the engine case. As the oil level rises in the engine case the pressure forces oil thru the sump pump return/scavenge lines and the oil rises to find the "level" inside of the turbochargers. Oil passes the turbine side sealing ring and compressor side sealing ring.

I was desperate to find a solution. The turbochargers were perfect. I decided to build new sump lines modeled after the 996TT design.



The picture above shows the new sump scavenge line installed on the drivers side. You can see how high the elevation "rise" is.

The next picture is of the passenger side.



We know that "lines" were available years ago. I tried to purchase them for this car. With the NEW lines installed the engine is not smoking. It does not have the volume of oil migrating thru the sump tanks. I removed the sump tank plugs to see the amount of oil that came out of each tank. I removed around 2 oz from each side. In two hours I had around two tablespools of oil that had dripped out of the tank. 4 hours later I had around 1/2 teaspoon.

I have tooled up to manufacture these "oil sump lines" I have contracted a company to CNC bend the lines. I have also CNC'd fittings. A major improvement over the factory lines is the stainless fittings that I have made vs the factory cad plated fittings. This will allow years of corrosion free service. The actual line tubing is stainless.

The "cost" for these Oil Sump Lines is going to be $585.00 Please email or call me.

ca993twin

Kevin,

Great report. Thanks. I'm easily confused by all the various "lines" on the turbos. Is this an addition to the check-valve gizmo? My Ruf has some sort of modified oil lines... do you know anything about what Ruf does? Lastly... can a doofus install these new lines?

Ziad

Kevin,

I too am easily confused when it comes to turbo lines. These will do the same job as the 996tt Turbocharger check valve kit that fits the 993tt (with the braided pressure hose), right?

Thanks
Ziad

Kevin

Steve, Ziad the Porsche solution is to add the check valves to the oil supply or fresh oil supply to the center cartridge of the turbocharger. The design here is to stop the migration of oil from the cam-housings and oil supply when the engine is turned off. The check valves also have a "filter" built into the valve assy.

The second element is the sump return lines that mount to the scavenge side which I have just posted.

Steve the install is easy, provided that one doesn't have any corroded fittings.

dbf73

Kevin - from your pix, the sump end of this line is very accessible. what about the other end of the line - what if anything has to come off to access it?

Kevin

Doug to gain good access to the other end, I recommend that you remove the lower engine diaper tray and the rear tray bracket. To remove the bracket you need to remove 2 each 10mm bolts. The lines are held secure against the chain housing with two line clips (again remove 2 each 10mm bolts).

ScottMellor

I'm unclear as to why some suffer from this problem while others do not. (I apologize but I usually need a big diagram drawn in crayon to understand this stuff.)
Why do the check valves not solve the problem?
If it is a design flaw that is corrected with the 996 style lines, shouldn't they all suffer from this?

Steve, Doofus's should not be allowed near Rufus with any kind of wrench.

Kevin

Scott, the root cause is from a failed engine oil filter. Couple that with engines that start to accumulate miles on them and we have high levels of oil in the engine crankcase. Imagine your bathtub overflow getting plugged and you forget to turn the water off.. That's what is happening inside the bearing housings of the turbochargers. The only place that oil can go is out the sealing ring.

Scott I would also bet that if you have a late Andial engine build, you would already have these lines installed.

ScottMellor

Right but if you replace the filter with the correct one, does that not cure the problem? Or is it something that fails as a result of the wrong filter and/or just the passage of time that creates the high oil levels in the crankcase? And if so why do the check valves not take care of it?

I'l crawl under and have a look when I get home.

TrackDays247.com

Man, once again Kevin aces it all with the goods again! Cheers -

ttAmerica RoadsterAWD

Heh, chronic oil leakers...... sounds like a medical condition

LAT

Kevin, are these in any way similar to the Andial lines that were once available?
I believe they too had a steep angles.

Kevin

Lat, yes similar. However mine feature CNC'd fittings and all stainless steel tubing.

MarkD

+1
and, if not, why wouldn't it?

LAT

My car came with the Andial lines and they work great,
For anyone thinking of this retrofit, I for one recommend it.