I broke a camshaft in my car I believe it was previous owners fault it was an acclaimed rebuilt motor, When the cam broke it tore up the cam caps and there was metal everywhere the head was basically useless so i got a new head, and cam shafts, I did everything to the book replaced head gasket torqued to spec and so on and so forth, The problem is after i did compression test the readings were outta wack! C1 170 C2 151 C2 190 C4 160. Can anyone explain to me why its all over the board ? is it safe to start my car like this ? how can i fix it. Thanks

possible slightly leaking valve(s). What condition was your cylinder walls when you had the head off?

All the cylinder walla seem to be okay when I did check

Do the numbers go up with adding a little oil?

Was this a cold crank compression test? Did you let the car run for a little bit to warm up? It's not going to hurt the motor to let it idle or even free rev the engine a little. It could just be a matter of some of the piston rings need to be worked and reseated to even out the compression readings.

Did the previous owner happen to tell you what the compression readings were? What head gasket did you end up using? Did you leave the factory head bolts in or was it upgraded to head studs? What pistons were used in the rebuild? Do you know what the piston rings were gapped to if they bothered to check the ring gap?

As far as i know is was an oem rebuild that maybe has race bearings at the most, the engine wouldn't start after the head was reassembled, I did a compression test prior to the head being assembled and trying to start the motor. c1 had low compression 60psi then we added oil to all and they all sky rocketed c1 was 180 c2 165 c3 210 which is the compression that should be in a diesel and c4 was 160. before the head was replaced the readings were , c1 140 c2 142 c3 135 c4 139. factory head bolts were left in and it was replaced with a oem head gasket,

Did you reuse the headbolts?

Yes i re used the bolts

Depending on how many times the bolts have been installed, that could be your problem. They're torque to yield, which means they get stretched from installation, and subsequent re-use can give you uneven torque loads across the deck of the block. If you eliminate all the other usual suspects related to compression, I would recommend installing fresh head bolts as a last ditch attempt.

Usually a head bolt failure will show compression leakage into the cooling jackets, it's not usually that much... I'm comfortable reusing TTY head bolts at least once, as long as I know it's the first time being disassembled.

A leakdown test would be more helpful in this case, IMO.

I agree as I've reused them in the past, but with an uneven torque load over the deck, which a third use set of TTY bolts can provide, I could see the uneven distribution of compression like what he's getting. I'm just trying to provide possibilities why he would see such an uneven compression distribution.

True, like I said though, a leak down test would be a good thing, see where it's leaking exactly.