Leak down tests
Addict
Lifetime Rennlist
Member
Lifetime Rennlist
Member
Joined: May 2001
Posts: 8,365
Likes: 81
From: Vancouver, BC
Kevin's opinion is that the best oil for the Turbo is the 20/50W Mobil V-twin, which most of us (including myself) are using on our turbos. A lot of us get our oil analysed, and I have noticed reduced metal wear numbers since I started to use that oil.
Porsche has over time gone to much thinner oils, like the 0W or 5W oils, but that oil does not seem to handle the extreme heat variations and soaks the Turbo has. The thing about v-twin is its designed for motorcycle engines, which are inherently the same as our air-cooled engines. The oil has very good tolerance of localized hot spots, which we experience especially in the turbo bearings when the car is shut off after a run (even after the recommended 2+ minute cool down). The downside is when its cool (like now in Vancouver) you can pickup some issues like slow pressurization of the lifters for a few seconds, but its not a bit issue.
Cheers,
Mike
Porsche has over time gone to much thinner oils, like the 0W or 5W oils, but that oil does not seem to handle the extreme heat variations and soaks the Turbo has. The thing about v-twin is its designed for motorcycle engines, which are inherently the same as our air-cooled engines. The oil has very good tolerance of localized hot spots, which we experience especially in the turbo bearings when the car is shut off after a run (even after the recommended 2+ minute cool down). The downside is when its cool (like now in Vancouver) you can pickup some issues like slow pressurization of the lifters for a few seconds, but its not a bit issue.
Cheers,
Mike
Instructor
Joined: Nov 2012
Posts: 214
Likes: 1
From: Midwest
So what decisions have you made Paul?
I was in a similar situation- maybe you saw my thread from about 1 month ago and my update. I bought the 28k mile '97 993tt despite lousy leakdown numbers during PPI due to everything else checking out fine and attributing the (consistent but) high %'s to inaccurate testing. Subsequent leakdown done by another indy shop showed 2%. Sleeping better now.
How about an update on where you are now in the overall process and what's gone into making your decisions?
I was in a similar situation- maybe you saw my thread from about 1 month ago and my update. I bought the 28k mile '97 993tt despite lousy leakdown numbers during PPI due to everything else checking out fine and attributing the (consistent but) high %'s to inaccurate testing. Subsequent leakdown done by another indy shop showed 2%. Sleeping better now.
How about an update on where you are now in the overall process and what's gone into making your decisions?
Rennlist Stories
The Best Porsche Posts for Porsche Enthusiasts
9 Vehicles Porsche Helped Engineer that Aren't Porsches
Verdad Gallardo
9 Features and Characteristics That Only Porsche People Understand
Verdad Gallardo
I've Written 500 Rennlist Articles: Here's How Porsche Has Changed Along the Way
Joe Kucinski
10 Most Unnecessary Porsches Ever Built (And Why We Love Them)
Verdad Gallardo
Porsche 911 GT3 S/C vs 718 Spyder RS: 10 Categories, One Winner
Joe Kucinski
This Builder Is Turning Heads With Its Slantnose 911 Creation
Verdad Gallardo
Porsche 911 GT3 Artisan Edition Pays Homage to Japanese Culture
Verdad Gallardo
Porsche Reveals Coupe Variant of the Electric Cayenne With a Fresh Look
Verdad Gallardo
10 Porsche Colors That Have More Personality Than Most People
Verdad Gallardo
Thread Starter
AutoX
Joined: Dec 2012
Posts: 11
Likes: 0
So what decisions have you made Paul?
I was in a similar situation- maybe you saw my thread from about 1 month ago and my update. I bought the 28k mile '97 993tt despite lousy leakdown numbers during PPI due to everything else checking out fine and attributing the (consistent but) high %'s to inaccurate testing. Subsequent leakdown done by another indy shop showed 2%. Sleeping better now.
How about an update on where you are now in the overall process and what's gone into making your decisions?
I was in a similar situation- maybe you saw my thread from about 1 month ago and my update. I bought the 28k mile '97 993tt despite lousy leakdown numbers during PPI due to everything else checking out fine and attributing the (consistent but) high %'s to inaccurate testing. Subsequent leakdown done by another indy shop showed 2%. Sleeping better now.
How about an update on where you are now in the overall process and what's gone into making your decisions?
Addict
Rennlist Member
Rennlist Member
Joined: May 2002
Posts: 1,403
Likes: 1
From: Redmond, WA
Hi Mark, I decided to not pursue the car. I don't believe that a car with only 14k could have such consistent poor leak down results. However, I'd be shipping the car 4k miles and couldn't take the chance. I was hoping the vendor would step up and have some more research done. I spent quite a bit for the initial PPI and didn't think that I wanted to put more money into it.
Racer
Joined: May 2001
Posts: 313
Likes: 0
From: Michigan and. Naples, FL
What are you your opinions on these leak down and compression values.. 67,000 miles. Have been burning oil terribly, now have the check valves installed and the oil cleaned out of the intake ducting, and intercoolers, which were "full" of oil.. 15w50 Mobil 1 now in there.. with Porsche Filters.. No oil burned at start up and anytime that I can detect.
Mechanic was not "confident" in the validity of the #6 cylinder values, he say he never seemed to get a good seal due to the angle he had to place the gauge.. as told to Drive for 1000miles and recheck..
Cylinder Compression Leak down
1. 130 3%
2. 130 3%
3. 130 4%
4. 130 4%
5. 135 3%
6. 120 60%
Mechanic was not "confident" in the validity of the #6 cylinder values, he say he never seemed to get a good seal due to the angle he had to place the gauge.. as told to Drive for 1000miles and recheck..
Cylinder Compression Leak down
1. 130 3%
2. 130 3%
3. 130 4%
4. 130 4%
5. 135 3%
6. 120 60%
Addict
Lifetime Rennlist
Member
Lifetime Rennlist
Member
Joined: May 2001
Posts: 8,365
Likes: 81
From: Vancouver, BC
The "angle" is no different on #6 , he does have to access it through the port from below, but I have had no issues. The end of the tools are threaded into the sparkplug hole, so it means he is not getting the tool threaded tight. Not sure how someone would be able to use that as an excuse - weird.
Also, if you do get a out-of-bound leak-down, the mechanic should tell you where the leak is coming from (i.e. exhaust valve would produce a sound from the exhaust, intake value - sound at the intake, and rings -sound at the case breather tube).
I agree, move onto a mechanic that knows what he is doing.
Cheers,
Mike
Also, if you do get a out-of-bound leak-down, the mechanic should tell you where the leak is coming from (i.e. exhaust valve would produce a sound from the exhaust, intake value - sound at the intake, and rings -sound at the case breather tube).
I agree, move onto a mechanic that knows what he is doing.
Cheers,
Mike
Instructor
Joined: Dec 2005
Posts: 173
Likes: 13
The PPI is only as good as the person doing it. It's been my experience that although there are a tremendous number of aircooled Porsche experts, few truly know the 993tt.
Last edited by Bgoldey; Feb 21, 2013 at 11:54 PM.