IamSMC

No info on 993tt upgrades on their site.

Would like info pertaining to upgrades/products in stages per viperbob's recommendations.

martyg

about the turbo is there is a ton of oil thru the whole system. drop drop could be a loose hose clamp on the back side of Turbo. I had a small leak and fixed it myself at the same time I had smoke. All fised and no smoke.

Marty

hatchy

good to know, thanks Kevin.

don356

Re filters, according to my source: The early filters a #2 or 02 (?) had the valve at the base of the filter and improper tightening let to problems. Apparently the newer, current, filter has the valve inside the filter and doesn't have that problem.

Air Kuul TT

Don,

So are you in the clear now?

don356

So far so good but only time will tell. Apparently this isn't totally uncommon and mine was one of two in the shop with the same problem. Andial apparently has a different solution where they put an upside down "U" in the return to prevent siphoning. In mine they put in a check valve. If it had been consistent I could have understood the bad turbo, or bad filter explanation but it was sporratic and was only severe once so we'll just have to see if the valve traps the gremlin. This is left side (right pipe) only.

jmreiser

They all do this sooner or later. The car has a design flaw, fortunately they are relatively easy to fix. They all seem to have lots of motor oil in the throttle body, in the intercooler, etc. The more you have, the more readily it will smoke on startup.

The cause is too much oil going into the turbo oil sumps, more than it can return via the scavenge pump. NGoldrich helped me figure this out at MidOhio last year. What a mess I made. Anyway you can either rework the breathers (plumbing project), or you can do what Porsche did with the 996 turbo, which is to install check valves where the oil lines feed the Turbos. Tony Callas came up with this one. I think the reason it works is by acting as a restrictor, but I don't really know. I would check the intercooler to see if its dry after the mod, after cleaning it, and running it awhile.

The oil is not actually coming through the turbos, but everyone's first thought is to rebuild them. There are good reasons & benefits to that, but this is what has been going on in the cars I've seen. When the oil fills up the turbo sumps, it overflows back up the breather line, where it is inhaled right into the intake system. It is sucked in by the turbos, and blown into the intercooler. Check engine lights will eventually come on from this if you run it long enough.

jmreiser

And, yes the 993 GT2 has the same issue, not much was different between stock and GT2 street engines. GT2 Evo of course has everything different, for racing, but the first race GT2 was basically the street GT2 without heat exchangers. But even then they STILL had this problem. Remember when Rohr was winning Daytona with their GT2 Evo ("Whitey", not the yellow one), but then their engine took a crap at 2:30am? Their catch can filled to the top and then bad things happened. They never solved this problem. The GT2 was heavily restricted and then obsolete in top racing before anyone appears to have solved it, or if a few did, the knowledge died with their Gt2s at the hands of the Vipers. Roock for example ran long hoses for these turbo oil breathers up to the top of the roll cage, and did a loop the loop, so they were onto the problem, however that was not a great fix, and you still run out of oil that way. Seems like a long time ago now, but the Vipers took over LeMans and everything associated with it for a few long years, until the factory Corvettes came along that is. They'll get theirs one day with the CGT or a Cayenne-powered DP car or something

martyg

The line going from the bottom/back of the turbo to top IC, came loose and I dripped oil. At the same time my check ingine lite came on. I fixed the clamp at the bottom and was not sure what caused the check engine light. I gather its the 3.8 and all the fuel going threw the motor and out the tail pipe. So i have the problem you talk about. What is the fix and the eventual outcome?

Kevin

Marty;

It sounds as if your boost/pressure tube blew off.. If you have oil in the tube that blew off it will also be in your intercooler.. You will have to take your cooler off and drain/clean it..

Joel;

Most of these cars are not race cars like your 3.8ltr.. Most of these cars are seeing age on them and most DO need rebuilds if the filter have been changed and the oil levels are correct.. The scavenge pumps are fine and have been engineered to move the amount of oil that is collected in the sumps.. There is more capacity in the TT than the 930's.. You also have to remember folks that race cars have higher blow bye issues that are/were present in 24 hr races.. These engine had high base pressure due to piston ring wear that was happening in these races.. The high base pressure would fight the oil that was trying to get back to the engine case, and to the oil pump.. However, due to the higher than normal blow by (it only takes 1 hole to cause problems).. Oil would be passed through the sump breather tube..

If your turbochargers are leaking puddles like the pictures shown, change the filters.. If you have oil in the intake tract.. Your seals are most likely worn..

jmreiser

Kevin- You raise some excellent points for the race cars. Not expecting a challenge, I did not mention I had a 993 twin turbo street car from new, and it did this. I had friends with them, all the cars did this. New cars, oil in the tubes, oil in the intercoolers, oil in the throttle body. I have seen a number of these cars over the years, and never saw a dry one until one or the other fix was applied. Alwin Springer looked at one of them at a Sebring club race (1998), and he said to replace the hose clamps with heavier duty American ones, and to clean the hoses contact surfaces with brake cleaner. That did in fact solve my friend's problem of the boost hoses popping off, because of all the oil. But each and every time the hoses were taken off for any reason, there was more oil in there, and he (we) had to keep cleaning every time.

The scavenge pumps are fine, I agree with that, but the oil is still finding its way back up the breather pipes, into the intake system. There is an oil separator / check valve threaded into the throttle body area, however the lines are "Tee'd" back to the intake tract after the air filter and before the turbos. This is where the oil is being introduced that gets into the intercooler. It should not do that. If you look closely at the plumbing diagrams, you can see this possibility was not anticipated, and the Tee is a mistake. Check valves installed in the breather lines might be the ultimate solution, however that would allow oil to back up into the cambox, not something I have any interest in testing.

I suspect you are right, the closer someone is to just cruising and doing normal street driving their 993tt. It was once our cars went to the track in Driver Ed events that the volume of oil really got our attention. But the street driven cars report the problem too, in the form of the big black cloud at startup. So as far as I can tell, it is universal. I could be wrong, but so far there is no evidence that I am, actually all the evidence is as I describe.


Marty- See my writeups of this problem & solution on pca.org/tech, the Callas fix is described (using the 996 check valves that Porsche introduced to solve this non-existent problem), as is the other means of rerouting the plumbing. To Kevin's point, the latter may make more sense for a race car, the former for a street car or DE car. http://www.pca.org/tech/tech_qa_question.asp?id={542DF48F-D593-4E87-BDD0-AA72FEC37134} is an example of this discussion, or search for smoke or Callas.

martyg

have oil in that tube and of course if that is a problem I should fix it, no. Are the check valves easy to install. Are they just placed into the line like a water check valve. I do not track my car. Is this something I really need to deal with or be concerned with?

Kevin

Marty;

Did you check the inlet tube? I'm not talking about the pressure boost hose.. Turbochargers do not heal themselves. If you are fighting oil consumption your turbocharger gets the brunt of the carbon build up and wear from the carbon.. The 996TT check valves are a short term fix that many times does not work if you have a failed or failing turbocharger. I have stated that one can install new turbochargers on there car and they can fail. As previously stated, the bore and sealing ring gap on KKK turbochargers are in excess... even if buying new turbo's.. The reason is that the tooling that is used to bore the housing places the ring gap toward an out of spec measurement.. Oil will pass from the bearing housing through the turbine wheel and weep into the turbine housing. Unfortunately, these are all little issues that are being compounded. To address these issues, one has to keep the level from rising inside of the bearing housing. Running your oil level at the top mark is not wise, due to the fact that rarely does one check the oil when maximum oil expansion has taken place. Installing the correct oil filter, and installing it correctly. If your turbochargers are out of spec you will have oil migrating from the bearing housing and into the turbine housing, and no check valve or stand pipe will cure the problem..

jmreiser

Yeah if the turbos are shot, then I agree, no other bandaid is needed or helpful.

If the turbos are OK, and you have oil in the intake, then I would try the 996 solution.

Jean

VERY interesting thread Joel, it is great to see you here please hang out more often

It seems like the KKK adapted to our 993TTs are not as great as we think, longevity of the turbos yes, but I wonder if a completely redesigned oil feeding and scavenge system is not a must on these cars for whoever that is looking for some extra performance out of them, it could bring big savings in $$$ and headaches in the long run.