Porsche Leakdown Test Opinion
02-10-2008, 01:00 AM
#46
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So, doesn't a top end rebuild cost something like $10k? And isn't it the case that, after a top-end, you can be pretty confident that the leak downs will be <5%? So, why $45-50k for a high mile car, if what you are worried about is the leak down? If I have a 60k mile car that I have kept in as-new condidtion, but has a leak down of 12%, to me, that car is worth $60k still if I know that I can get it to <5% and get 60k more miles out of it for $10k.
Let's be real, 10k is a decent amount of change, but the variability in prices on these cars is like $45k - 95k. What is a a top end rebuild in that range? Squatola. 20% of the variability.
Perhaps there is something that I am missing, but if it is true that a top end rebuild can assure a low leak down, and it costs only 10k, then I say big deal, I am going to care more about how perfect the car looks, and pony up the 10k to fix the leak down after the fact.
Let's be real, 10k is a decent amount of change, but the variability in prices on these cars is like $45k - 95k. What is a a top end rebuild in that range? Squatola. 20% of the variability.
Perhaps there is something that I am missing, but if it is true that a top end rebuild can assure a low leak down, and it costs only 10k, then I say big deal, I am going to care more about how perfect the car looks, and pony up the 10k to fix the leak down after the fact.
02-10-2008, 01:07 AM
#47
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It's cause and effect, valve guides within spec, will keep the valves on there seat margins with very little leakage. Worn guides do not allow the valve to be concentric and run tru in/on the valve seat. As this happens the seat and valve margin (surface area where the seat and valve touch) get pounded out, with no consistant or tru contact 360 degrees around the seat, the valve runs at hotter temperatures. The heat generated causes metal fatigue. You then lose the valve head (extreme case).. When the margin is beat out due to the valve not being able to run tru in the guide bore. Combustion chamber gases leak past the valve seat when the valve is closed.
Mark, I mentioned the oil consumption as a secondary effect. If you are doubting the leakdown numbers (from your mechanic) and want to have a visual check, drop the heat exchangers and check the condition of the valve guides/valve stem in the exhaust port.
Mark, I mentioned the oil consumption as a secondary effect. If you are doubting the leakdown numbers (from your mechanic) and want to have a visual check, drop the heat exchangers and check the condition of the valve guides/valve stem in the exhaust port.
02-10-2008, 10:24 AM
#48
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Honestly, though, even at $17k, there are other factors that are nearly as important to me. For example, I'd be willing to pay more than that to get a moderately personalized 993TT back to originality. So, for me, to bring a car's mechanicals back to 100% might be a lot easier than dealing with other issues.
I think the answer to this question depends on a lot of things, like 1) how much will you be driving it? 2) how will you be driving it? 3) how long will you be keeping it? 4) how much do you care about the sofer issues like colors, condition, etc?
The market is pretty small for these cars. It is often not possible to find exactly what you are looking for. If all you care about is getting a car with <8% leakdown, then okay, you probably can find one for less money than one with a 12%, but what if that 12% car is really the car that you want and would love? Pay the 10K and get what you want, I say. For me, not having certain options/colors was worth 10k, because I didn't want to have to go out to the garage every day for 10 years and see ____________(color omitted to avoid offending anyone).
02-10-2008, 11:36 AM
#49
I am a newbie to Turbos.I thought a Top End rebuild on a NA car was around 6 to 8k.Is a Turbo that much more work than a NA car?As far as I know you just have some extra parts to remove,like Turbo's and such.Is it the fact that it is a Turbo and therefore the price doubles?Or is it that Turbo parts are a lot more expensive?
02-10-2008, 11:46 AM
#50
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I am a newbie to Turbos.I thought a Top End rebuild on a NA car was around 6 to 8k.Is a Turbo that much more work than a NA car?As far as I know you just have some extra parts to remove,like Turbo's and such.Is it the fact that it is a Turbo and therefore the price doubles?Or is it that Turbo parts are a lot more expensive?
Of course, this does not include the "while you are in there" stuff.
Kevin,
I don't doubt "my mechanic"... though I do argue with myself at times
I am getting professional help with that.My only point was that guides themselves are not a primary factor in leakdown. You stated cause and effect. Exactly.
02-10-2008, 04:20 PM
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02-10-2008, 05:02 PM
#53
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On a good day a Turbo topend is going to cost you around $7,500.. If you need one cylinder head add $1,800.00 (each) If you need pistons and liners add $5,200.00 Some of these cars that I am seeing need one or two camshafts due to scuffing and pitting on the lobes. Most will address the turbochargers. Then you need to add $1,200 for new hydraulic lifters, toss in $340.00 for replacing a few rocker arm shafts. When you are done you are in the range of $12 to 15K..
02-10-2008, 07:54 PM
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On a good day a Turbo topend is going to cost you around $7,500.. If you need one cylinder head add $1,800.00 (each) If you need pistons and liners add $5,200.00 Some of these cars that I am seeing need one or two camshafts due to scuffing and pitting on the lobes. Most will address the turbochargers. Then you need to add $1,200 for new hydraulic lifters, toss in $340.00 for replacing a few rocker arm shafts. When you are done you are in the range of $12 to 15K..
the 996TT suddenly becomes more attractive....now back on subject.
02-11-2008, 12:27 AM
#56
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While you are in there you can twin plug your heads, you can also change the suspension and upgrade for some Moton , don't forget the Sport Cup tires, 6 piston brakes etc... about $20k all together..
I think we are going too far in this??
I think we are going too far in this??
02-11-2008, 05:47 AM
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02-11-2008, 11:24 AM
#58
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02-11-2008, 03:15 PM
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