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New Cylinder Head Install - when to do leakdown?

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Old 07-28-2021, 04:34 AM
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Default New Cylinder Head Install - when to do leakdown?

Hello all,

I'm going to be installing a brand new, never used, cylinder head on my F22. Is it too early to do a leakdown test as soon as I'm done torqueing the head bolts? Or should I run the motor up to operating temp a few times before doing the leakdown?

I have issues with a warped head/HG, and I don't want to go through the hassle of putting everything back together entirely if I can verify that I don't also have piston ring issues earlier in the process.

Thanks in advance!
-Dustin
Old 07-28-2021, 05:11 AM
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Leakdown through the head gasket should be 0, at any temp.

So even if you're getting blowby from the rings, you can assess whether the HG is leaking by seeing if any of the leakdown test air is leaking into the cooling system and pressurizing it.

Obviously this means you'll need to assemble and seal up the cooling system before doing the test.
Old 07-28-2021, 05:36 AM
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Originally Posted by B serious
Leakdown through the head gasket should be 0, at any temp.

So even if you're getting blowby from the rings, you can assess whether the HG is leaking by seeing if any of the leakdown test air is leaking into the cooling system and pressurizing it.

Obviously this means you'll need to assemble and seal up the cooling system before doing the test.
Right... I'm confident the head/HG will be perfect as it's all brand new. So I could, in theory, do a leakdown test and if my numbers are good, I'm good... if they are bad, it may be difficult troubleshooting without everything put back together. Correct?
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Old 07-28-2021, 08:15 AM
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Originally Posted by Dizings2k
Right... I'm confident the head/HG will be perfect as it's all brand new. So I could, in theory, do a leakdown test and if my numbers are good, I'm good... if they are bad, it may be difficult troubleshooting without everything put back together. Correct?
Yeah, exactly. You can do the test. But an undesriable result won't tell you much until you assemble more.

I did mine before even installing the cams. All the valves were closed.

Via smell, I could tell that at least some of the leakdown air was coming from the crank case, lol.

All 5 senses, I guess.
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