Low compression on a newly rebuilt head. (1 Viewer)

[Fantastika]

Hello,

I have replaced my broken head with a new head and reconditioned bits done by a specialist. I have put everything together but pressure readings are on the low side from what ive read. Ive got 420psi, 350psi, 350psi and 360psi. Did i mess it up bad or should i just crack on and not worry about it?

 

[GTSSportCoupe]

Hello,

I have replaced my broken head with a new head and reconditioned bits done by a specialist. I have put everything together but pressure readings are on the low side from what ive read. Ive got 420psi, 350psi, 350psi and 360psi. Did i mess it up bad or should i just crack on and not worry about it?

Is this a cold or hot compression test?

How did the cylinder bores look when you had it apart?

How does it start? Smokey and hard? Does two glow cycles (7 sec on, 1 sec off, 7 sec on) make a cleaner start?

Was the head carefully shimmed?

 

[Fantastika]

Is this a cold or hot compression test?

How did the cylinder bores look when you had it apart?

How does it start? Smokey and hard? Does two glow cycles (7 sec on, 1 sec off, 7 sec on) make a cleaner start?

Was the head carefully shimmed?

Cold, the engine hasnt been started in 4 months.
The bores looked good, nothing out of the ordinary.
Havent gotten to starting it just yet, but back when it did start it was steamy, but i hope that was because the massive crack in the head. I would like to think that the head was shimmed correctly, ive used this shop for tractor heads and never had any problems.

 

[GTSSportCoupe]

Maybe it's just the fact it was cold and the bores somewhat dry. I'd say drive it a bit, and try again on a hot engine?

When I tested mine it came out to 450psi per cylinder (warm). Nothing is perfect about my motor; probably typical 250,000km which received a new head along the way.

I removed all glow plugs and unplugged the electronic injection pump. This allows faster turn over and no diesel injected. I put battery charger to top my battery also.

 

[Fantastika]

Maybe it's just the fact it was cold and the bores somewhat dry. I'd say drive it a bit, and try again on a hot engine?

When I tested mine it came out to 450psi per cylinder (warm). Nothing is perfect about my motor; probably typical 250,000km which received a new head along the way.

I removed all glow plugs and unplugged the electronic injection pump. This allows faster turn over and no diesel injected. I put battery charger to top my battery also.

Started the old beast, sounds healthy, will bolt it all together tomorrow and let it run for a bit longer.

 

[GTSSportCoupe]

Started the old beast, sounds healthy, will bolt it all together tomorrow and let it run for a bit longer.

Sounds fine. I bet it'll test ok next time.

 

[4Ruster]

Yeah when I did a compression test on my brand new rebuilt engine it test 350ish all around. Then I drove it up to temp and I got 450. As long as there's no smoke are hard starting issues it's probably fine.