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Old 09-27-2013, 12:39 PM   #1
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Engine block leak down test

Can anyone explain how a leak down test on engine blocks works, whether the results are accurate and definitive, and what I should be looking for in terms of 'good numbers'? I am getting a head/valve job done on my 2001 S, and if the numbers look good can I reasonable conclude there is nothing faulty regarding the block? Thanks
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Old 09-27-2013, 12:43 PM   #2
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Can anyone explain how a leak down test on engine blocks works, whether the results are accurate and definitive, and what I should be looking for in terms of 'good numbers'? I am getting a head/valve job done on my 2001 S, and if the numbers look good can I reasonable conclude there is nothing faulty regarding the block? Thanks
A leak down is measuring how much of the normally compressed charge is leaking past the rings, valves, a blown gasket, or a cracked component. The device that runs the test pressurizes each cylinder while at TDC and measures the leakage in percent. The test is very definitive and widely used to determine the current state of an assembled engine.

A test value on an individual cylinder greater than 8-10% is reason for concern.
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Old 09-27-2013, 01:00 PM   #3
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Awesome, thank you. Is the test performed with the heads on or off? I'd like to perform this test, if possible, only on the block to isolate leaks to that portion of the engine
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Old 09-27-2013, 01:55 PM   #4
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The heads must be installed to contain the pressure & measure the leakage. If you are going to have the heads removed regardless the outcome of a leakage test have the cylinders measured for wear while the heads are off.
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Old 09-27-2013, 01:58 PM   #5
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Awesome, thank you. Is the test performed with the heads on or off? I'd like to perform this test, if possible, only on the block to isolate leaks to that portion of the engine
With the heads on, this test checks the head, block, gaskets, and even the rings.
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Old 09-27-2013, 03:38 PM   #6
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Being an 01 and you are asking this question I'd think that you had an intermix condition?

A cylinder head pressure check for these engines is worthless unless the heads are heated.
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Old 09-27-2013, 03:58 PM   #7
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Yep, you guessed it, mixing oil in the coolant. The chocolate milkshake. First time Porsche owner here too. My childhood dream is starting out on rough terms. I'm hoping its limited to a blown head gasket, but still its a nerve-wracking and wallet-lightening experience. I'm having the IMS replaced and RMS at same time.
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Old 09-27-2013, 05:49 PM   #8
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Yep, you guessed it, mixing oil in the coolant. The chocolate milkshake. First time Porsche owner here too. My childhood dream is starting out on rough terms. I'm hoping its limited to a blown head gasket, but still its a nerve-wracking and wallet-lightening experience. I'm having the IMS replaced and RMS at same time.
Experience has shown that these engines do not blow head gaskets, but they do crack heads. A second, and common source of intermix is a failed oil cooler, which is relatively cheap and very easy to replace. They can also be pulled and pressure tested outside the car easily.
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Old 09-27-2013, 06:43 PM   #9
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Its an '01- it has a cracked head. I only have a dozen 00-01 engines underway at this present that had intermix from this.

You probably lost the water pump first, you just didn't know it and you didn't know that it would lead to this type of symptomless failure.

We've had one single heat exchanger fail and lead to this. We have NEVER seen a head gasket blow. We just saved another car with intermix this week.

Good thing you are changing the IMSB, as 1% of coolant intrusion into the IMSB equates to an increase in bearing wear of 83%. Lots of people don't realize this and then after an intermix experience they lose an IMSB shortly thereafter.

Of all the failures out there, this one is taking out more engines than anything else at the present. See a ton of pics of engines we have saved in our photo albums at www.facebook.com/fixabrokensix
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Old 09-27-2013, 08:23 PM   #10
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What heat exchanger - radiator, engine oil cooler, or tranny oil cooler?

How did you come up with the number, percent coolant intrusion vs bearing wear percentage?
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...

We've had one single heat exchanger fail and lead to this. We have NEVER seen a head gasket blow. We just saved another car with intermix this week.

Good thing you are changing the IMSB, as 1% of coolant intrusion into the IMSB equates to an increase in bearing wear of 83%. Lots of people don't realize this and then after an intermix experience they lose an IMSB shortly thereafter.
...]
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Old 09-27-2013, 08:39 PM   #11
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Thanks, I had the oil cooler pressure tested and it showed tight (according to my mechanic). Had the seals replaced anyway. Found out a few hours ago one of the head gaskets is blown in several places. Should know by Tuesday if either of the heads are cracked. Please say a little prayer for my Boxster, feel like its on life support.
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Old 09-28-2013, 06:13 PM   #12
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How did you come up with the number, percent coolant intrusion vs bearing wear percentage?
Directly from our bearing Engineer and the manufacturers of the bearings as well.
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Old 09-30-2013, 02:05 PM   #13
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Update, one of 2 heads confirmed cracked. Gaskets blown as well. Any suggestions as to where I can find a cylinder head for a 2001 S? Also looks like the clutch flywheel is thrashed. Will likely overhaul transmission as well. I'm in a fetal position. Kids' college education vs Porsche.
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Old 09-30-2013, 02:32 PM   #14
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Quote:
Originally Posted by Dave2001S View Post
Update, one of 2 heads confirmed cracked. Gaskets blown as well. Any suggestions as to where I can find a cylinder head for a 2001 S? Also looks like the clutch flywheel is thrashed. Will likely overhaul transmission as well. I'm in a fetal position. Kids' college education vs Porsche.
Dave where in SoCA are you? & what shop has your car?
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Old 09-30-2013, 03:13 PM   #15
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Do a Google search on "rebuilt Boxster cylinder heads" - you will get many options. rebuilt for my 2003 was just shy of $2000. Make sure you get the right part!
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Old 09-30-2013, 03:23 PM   #16
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Have your heads repaired, buying unknown might have more issues. Then find the source of the crack, or it will find you again.
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Old 09-30-2013, 03:41 PM   #17
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I'm in 909. Car is at German Automotive Service Center in Glendora. Any ideas or reliable sources for a replacement head? Any other advice? Help. Sleepless nights in my future
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Old 09-30-2013, 03:44 PM   #18
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Jake - its possible to repair a cracked head?
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Old 09-30-2013, 06:37 PM   #19
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CostaMesa R&D repairs them
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Old 10-01-2013, 08:08 AM   #20
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Thanks, I'll look into them. Any experience with them, or with a 'repaired' cylinder head? Seems strange that a cracked head could be adequately repaired to stand a reasonable test of time.
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