Spark plug and leakdown test alysis.

ricardoa1

Registered User
Well I did some teardown of my engine and it all looked wonderful till I got to the number 3 and 6 cylinder where there was severe leakage. I could hear all the air rushing inside the intake manifold so I don't think there is cause for panic. But I think the heads need some attention I think they are not seated properly, not sure why. But as we all know those are the two cylinders that run lean so maybe I should be worried? :confused: I hope not.

The heads will be coming off and being donated to the anniversary due to the fact that these are stock sized rocker bolt heads. And the Anniversary already uses oversized stud mounted rockers. But I was hoping that I didn't need to go through the heads. I hope its just build up on the valve seats or something stupid.


Anyways here are the spark plug results and compression test results.





Number 1



Number 2



Number 3



Number 4



Number 5




Number 6



Number 1



Number 2



Number 3



Number 4


Number 5


Number 6
 
Pull the valve covers and make sure nothing came apart there. Then pull the intake manifold and the heads. From there you hopefully will see what is up. could be gasket failure but could be cracks.
 
All looks legit from the top side. Valve covers had to come off to release the rockers. But I even installed the valve coves back on to mute any crankcase leaking noises. It all seems to to woosh out of the intake manifold. This gives me a sense of relief. But you are right until the heads come off I won't really know what's up.

Gaskets are MLS and I had no reason to do this test, engine operated flawlessly two years ago with the AR bolted on

1 2 4 and 5 all seem to be in great shape. Although number two is also peculiar a little lower then the rest of the good ones.
 
Since the motor hasn't run in ages, I wouldn't get too worked up. When an engine is off some valves will be open. Valve seats will rust and/carbon will fall into them. Running the motor for a few miles generally fixes that. Nonetheless any flaws will be obvious when you pull them off and take them apart.
 
Thanks Dave.

Those were my thoughts also. I don't even want to pull the heads at this time so there is less chance of moisture getting on the cylinder and rusting things out.

But now im curious as a cat, it will be a torture till I pull the heads off.
 
It is better to pull the heads now because if there is any moisture in there you want to get it out and oil down the cylinders now rather than wait. There is no benefit to letting it sit as is.

Clean everything up and oil the cylinders with 5w20 and rotate the motor around until the cylinders remain clean. Then cover it up real good and lay some cardboard and/or carpet under the engine bay to keep condensation down.
 
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