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Chronic turbo leak - I have tried it all I think

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Old 12-02-2016, 06:25 AM   #1
Vince964T
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Default Chronic turbo leak - I have tried it all I think

Hello,

I am not about to give up but this engine is really complex...

I have an oil leak on the bearing housing hotside of my turbo chargers. Stock K16s. This has been going on for some time.
Here are the exact symptoms and so here is what has been done.

1 - It starts to leak when the engine is turned on and it warms up. It comes when you rev the engine. Possibly a little extra when you switch it off. Not leaking anymore when the engine is switched off and the car is parked.
The car burns oil when driven hard. 30mins track, burned 1,5liter last time I was out (after 1st turbo rebuild, I HAD TO drive that race ...).
Intermittent puff of smoke on start up. sometimes nothing, sometime a little, doesn't seem to matter how long the car has been sitting. It's not smoking for ages like some have had.

2 - The car has the check valves from FVD. It has the return lines from RUF.

3 - The oil pump works correctly. No oil lines or vent line are plugged or malfunctioning, correct flow in the return lines. Tried stock and the RUF ones with no changes.

4 - There is no oil in the intercooler/throttle body.
There is no oil in the exhaust collector.
Prior to this leak i drove the car a whole track season with NO oil consumption what so ever despite running pretty hard.

5 - Leak down done max 2/3% (recently rebuild engine). Leak down done at 2 separate shops with similar good results.

6 - Oil is Motul 10W50

7 - Small oil filter is 993 107 203 04 i.e. the latest updated filter (in Europe). The filter has been swapped a few times across the whole search process with no changes.

8 - I have had the turbos refurbished - It made no change

9 - I borrowed turbos K16s from another 993TT, 120000kms on them. Miracle... NO LEAK

10 - From there I ordered brand NEW K16s.

Guess what they leak... In the same way


Any suggestions from here, I already tried to steal the old borrowed turbos so that's not a credible solution (yet!), would be highly appreciated.
A very good bottle of wine will be sent to the one who actually helps diagnos this correctly !

Thx a lot in advance chaps !
The car is worth fighting for, such a blast when it goes but damn I have had my shares of trouble with it.

100% track car by the way.
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Old 12-02-2016, 06:41 AM   #2
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Some more details - FVD 440HP tune. 100c Cats. No muffler. So not a lot of back pressure, in case it matters.
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Old 12-02-2016, 09:02 AM   #3
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talk to Kevin at UMW. He will likely be able to help.
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Old 12-03-2016, 11:09 PM   #4
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Id send the k16s back and get a new set or have yours rebuilt. I doubt your tune has anything to do with it.....
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Old 12-04-2016, 12:02 PM   #5
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I recently changed my plugs and when I reinstall the turbos I leave the turbo vent lines off start the car and warm up to check the oil scavenging. Well this time the driver side turbo tank was filling with oil faster than the scavenge pump can pump. I double checked and retried thinking the pump wasn't fully primed. My setup is different from stock but I had the exact same problem when stock. In this case I changed to a smaller restrictor and problem went away. I guess the restrictor I had was on the ragged edge of being to much oil for the pump.
If oil gets into your vents the vapors will get in your intake manifold below the intercooler.
So I you remove the vent lines put a oil pan under each turbo start the car cold rev it up a bit to create as must oil pressure possible. If oil leaks out than change the restrictor inside the check valve.
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Old 12-04-2016, 06:11 PM   #6
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Thanks for the suggestions, keep them coming.

Discussion initiated with FVD whom I bought the turbos from and with Kevin (thx).

Tacker - Definitly worth a try. The restrictor is before the checklines right ? I was not aware there was a restrictor in the aftermarket oil checklines... Or may be they act as a restrictor ? Thx !
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Old 12-04-2016, 06:22 PM   #7
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A while ago I had both turbos start to leak significantly all at once and worried the scavenger pump might be bad. We often hear about getting larger oil pumps but rarely hear about doing anything with the scavenging pump or a scavenging pump going bad. I did not know there were restrictors. Must be tricky sizing adequately to get good oiling at high rpm and scavenging properly.
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Old 12-04-2016, 09:21 PM   #8
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The fitting that goes between the turbo housing and check valve should have a restrictor. IIRC .040". Just start the car with vent lines off. Make sure it's cold that will give you high oil pressures and the lowest scavenge flow. Let the car idle for a while the scavenge pump doesn't work all that well at idle speed. If oil starts leaking out the vent then you owe my a bottle of red
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Old 12-05-2016, 02:43 AM   #9
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Quote:
Originally Posted by Basal Skull View Post
A while ago I had both turbos start to leak significantly all at once and worried the scavenger pump might be bad. We often hear about getting larger oil pumps but rarely hear about doing anything with the scavenging pump or a scavenging pump going bad. I did not know there were restrictors. Must be tricky sizing adequately to get good oiling at high rpm and scavenging properly.
Hej Basal. What was the issue on your car ? Scavenging pump ?
Agree on the restrictor, tricky. But may be something is wrong with mine.

The fact that it worked with these 2 old turbos points to something wrong with either the install of the new ones or the new turbos...

Last edited by Vince964T; 12-05-2016 at 03:32 AM.
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Old 12-05-2016, 05:15 AM   #10
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Quote:
Originally Posted by tacker View Post
The fitting that goes between the turbo housing and check valve should have a restrictor. IIRC .040". Just start the car with vent lines off. Make sure it's cold that will give you high oil pressures and the lowest scavenge flow. Let the car idle for a while the scavenge pump doesn't work all that well at idle speed. If oil starts leaking out the vent then you owe my a bottle of red
Ah no red for you
No oil leaking from vent but still leaking at turbo bearing housing. I am good on scavenhing it seems.

Probably means the leak is not from "under" either, ie due to issues with crankcase pressure. Am I correct ?

Thx for the suggestion though
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Old 12-06-2016, 01:52 AM   #11
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Vince it was my turbos.. bad luck (not really it was my own doing). This was on my stock engine with relatively new turbos a number of years ago -there's a thread somewhere.. found it. http://rennlist.com/forums/showthrea...ferrerid=28499
That thread has some nice pics of the work I did on the stock headers (which are on my current engine).

I didn't explain what happened to the turbos on that thread. I had been (and still use) a super lubricant additive but I miss calculated the concentration. I added more additive to oil that had higher level of additive already premixed as it was meant for motorsport use. And essentially melted my bearings on the turbos...
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Old 12-06-2016, 02:58 PM   #12
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I went with the 996 check valves after I had my stock turbos rebuilt
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Old 12-06-2016, 04:35 PM   #13
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Slightly off topic but...

A fellow rennlister (2 actually, but one has since passed on ) had lunch with Franz Konrad some years back and he entertained with stories of racing GT2s back in the day.

Apparently at the Paul Ricard circuit the GT2s would lose power near the end of the main straight but would be fine when they returned to the pits. This frustrated all involved as no issue was found. Eventually Franz cut the engine on one of the cars at the point of the power loss and had it towed back to the pits. The sump was found to be over-full with oil - apparently on a long straight at high RPMs the scavenge stage wasn't removing oil from the engine sump fast enough so the crankshaft was thrashing in the engine oil losing power.

On the quiet he installed an uprated scavenge stage and stole a march on the factory cars and they didn't find the same fix till some 6 months later.
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Old 12-06-2016, 05:06 PM   #14
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Quote:
Originally Posted by doublecabmel View Post
I went with the 996 check valves after I had my stock turbos rebuilt
Thanks, got these already !
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Old 12-06-2016, 05:10 PM   #15
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Quote:
Originally Posted by Basal Skull View Post
Vince it was my turbos.. bad luck (not really it was my own doing). This was on my stock engine with relatively new turbos a number of years ago -there's a thread somewhere.. found it. http://rennlist.com/forums/showthrea...ferrerid=28499
That thread has some nice pics of the work I did on the stock headers (which are on my current engine).

I didn't explain what happened to the turbos on that thread. I had been (and still use) a super lubricant additive but I miss calculated the concentration. I added more additive to oil that had higher level of additive already premixed as it was meant for motorsport use. And essentially melted my bearings on the turbos...
I hope I ll smile on my turbo issues in a few years as well 🤗
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