Compression Test Results/milky oil - Head Gaskets? Please Help!

[V8BoatBuilder]

I think I may have a headgasket problem on my truck. It's a 1997 with 5.0 V8 and AWD. It has 107,000 miles on it.

Symptoms:
1) Excess white smoke from tailpipe.
2) Coolant consumption
3) tiny bubbles on engine oil dipstick after running. The oil was just changed, Havoline 5w30 with Mobil 1 filter.
4) This just appeared today: VERY milky substance on inside of oil filer cap and oil filler pipe.
5) Intermittant knock on shutdown.

I ran a compression test. (ran engine for 10 min right before 1st cylinder)

Cyl #1: 145psi
Cyl #2: 145psi
Cyl #3: 150psi
Cyl #4: 150psi
Cyl #5: 120psi
Cyl #6: 125psi
Cyl #7: 150psi
Cyl #8: 150psi

Those readings seem OK to me - but obviosuly something is wrong.

How do you guys interpret the problem, and where should i go now.

How exactly is a leakdown test preformed? My compression test kit comes with the ability to put pressurized shop air into the cylinder, and I have a compressor.

I originally had this going in "Under the hood" but think it's better in here.
Dead Link Removed

Thanks a bunch,
Aaron

 

[JDraper]

From your symptoms, I'd say you either have a head gasket leak, a warped head or a cracked head. The problem probably is between cylinders 5 & 6 from the readings you gave.

You can do a leakdown test by getting the cylinder in question to TDC and then pressurizing it. It should hold the compression fairly well. If it doesn't there's a problem. However, from your description of the symptoms, I don't think you even need to do that. I'd pull the head and check it for cracking/warpage. If that's ok, I'd install a new head gasket.

A more rare occurance is a crack in the cylinder wall from the cylinder to the water jacket, but with 2 adjacent cylinders down on compression, I'd lean towards either a warped head or a head gasket.