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6.5 with issues compression test results

T

trucknboatn

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Hamilton, Ohio
OK here's the deal I had all the symptoms of a blown head gasket, so I tore down the motor replaced the heads (new clear water) and gaskets etc. After assembly It seemed to run rough, smoked a little (white grey) at start and more after it got warm. I checked blow by just by opening oil cap after head rebuild and didn't notice anything, I took it for a short spin hoping there was just some coolant in the exhaust burning off, smoke did not dissipate and was pretty thick behind me the whole time. After the run I opened the oil cap and there was some blow by...

So I pulled it into the garage it sat over the holidays and I got a compression tester. Now of course the tester I bought from harbor freight that has "adapters for every diesel engine a US mechanic would use" didn't have an adapter for a 6.5 glow plug hole. I ended up making one out of one of the adapters, but i had to remove the valve in it for it to work. So it will not hold compression just jump and then exhaust...

Compression test results
cylinder #1, 3, 5, 7 ~280
cylinder #4 and 8 ~260
cylinder #5 unable to test but seems to have significant pressure with a finger over hole. not very scientific i know
cylinder #2 first time it was checked the needle jumped to 250 on first compression stroke then after that stroke it was making less than 10psi on compression stokes. I repeated test later and it did the exact same thing.
repeated it again and again and kept getting 10psi.

Here is the link to my cylinder head replacement thread
http://www.thetruckstop.us/forum/showthread.php?t=17902
 
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I should also mention the coolant is no longer pressurized and it is not loosing coolant. And there was an obvious blown section of gasket into cylinder # 8

Does anyone have any ideas as to what could be the culprit here?

I am hoping it would be something in the valve train, but no idea what it could be.

I swapped injectors from cylinder 2 to 3 and it did not make a difference in compression still around 10psi in #2, copper washer is in place, the # 2 cylinder seems to blow out the most fuel. If the lines were mixed up would that effect compression?

It seems to me if it were a snapped ring or something in the bottom end it would not even be capable of making ~250psi

I have already spent too much on this vehicle which I bought a month or two ago and only got to drive it less than 50 miles before the headgasket blew. The truck has 96,000 miles on it. It has truly been the truck from hell.

Any advice, help is appreciated and sorry for the novel it is my way of venting for now. I am no diesel expert but learn quick and I took my time replacing the head gaskets what i thought to be the right way.
 
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You need the valve in the gauge for your readings to be any good. Recall you spin the engine for 3 compression strokes to get your result.

Now 10 PSI... Sounds like missing the valve showed you your issue. Your intake valve is not moving on that cylinder. So air leaks in with engine not moving, good 1st hit, exhaust opens expels all the air, no intake valve opening pegs gauge at 0 sucks in or enough left over air for 10 PSI on all following compression strokes...

Pull the valve cover.
 
well i figured it out thanks war wagon just pulled the valve cover off the pass side and what do you know one of the push rods slipped out from under the rocker arm on the number 2 cylinder... rookie mistake must have not been seated in there all the way then when i cranked it the first time must have slipped off.

best i can figure is that with the intake valve stuck in the closed position, once it sat with the exhaust valve open it would equalize the pressure in the cylinder then it would have compression for the first stroke only, then afther first stoke it would be creating vacumme in the cylinder since the intake was stuck closed. I hope i didnt damage the engine any, the push rod is fine i checked it on a piece of glass and is not bent or damaged anywhere... weird huh
 
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