Rebuilt Head Problems

[gregmercer]

I have a Volvo 230. About 2 weeks ago I checked compression on #1 Cylinder to find 50psi. The other 3 cylinders had 150psi. I took the head off and took it to the machinest, he said the head was warped and all the valves were good so he planed the head and gave it back to me. A couple nights ago I put the head back on, now.... number 1...2...and 3 cylinders have 150 psi and number 4 cylinder has only 75psi. I put a new head gasket on it and I know I tourqued all the head bolts to correct specs.

What could my problem be??? I have a feeling the machine shop messed up my head, I don't know how else it would be loosing compression on #4 cylinder...

I am tempted to try to tourque the bolts on number 4 cylinder down just a tiny bit more and see if it makes a difference.

What do you guys think?

THANKS!!!!

Greg

 

[Don S]

Re: Rebuilt Head Problems

I am tempted to try to tourque the bolts on number 4 cylinder down just a tiny bit more and see if it makes a difference.

Don't, it won't help, and will probably make things worse.

What you need to do now is do a leakdown test on the low cylinder and determine what is leaking.
Get that cylinder on TDC on the compression stroke and pressurize the cylinder.
Then listen in the carb, the exhaust, the valve cover for the air leak.
Also take the cap off the expansion tank and check for bubbles in the cooling system.
After that, you will know where the compression loss is coming from.

 

[lilmandavis]

Re: Rebuilt Head Problems

a rebuilt head? or a planed head? rebuilt woould of been ground valves and seats. with magna flux. then boiled and painted!!

 

[KaGee]

Re: Rebuilt Head Problems

If your hear a leak in the intake or exhaust, before panicking, pull the valve cover and inspect the push rod. At top dead center you should be able to slightly turn the push rod between your thumb and finger. If you cannot, then the valve may be over adjusted or stuck.

Don't ask me how I know that. :%

 

[ron7000]

Re: Rebuilt Head Problems

torquing any of the head bolts down a tiny bit more will most likely result in an overstretched bolt, ruining the bolt, so don't do that. You can be quite far away from the bolt torque spec and still get a correct static compression measurement before starting the motor.

I don't know anything volvo, what motor is a 230?

first thing, and easiest thing hopefully, will be to pull the valve cover and check your lifter preload. Hopefully you know how to tighten down all the rockers properly?

If you tighten down a rocker too much the valve will not fully seat and be the cause of no compression. It might be as simple as that. Second thing that comes to mind and it depends on the motor and what valvetrain it has is if the rocker arms are non adjustable. If you had material taken off the head there's a very good chance your valvetrain geometry is off and just bolting the head back on like it was has not compensated for it. You may need to change the pushrod length or may need shims under the rockers, because since the head sits lower now the pushrod is too long and may be holding the valve open.
What you should also check and it may be worth sacrificing the head gasket, is pull the head and check the block deck. If that's not flat then you'll have problems just the same as a head that's not flat.