3B compression numbers

[jfrench]

After a trip at altitude I posted this:

https://forum.ih8mud.com/diesel-tech-24-volts-systems/571230-diesel-smoke-question.html

It was recommended I perform a compression test and in the process of doing that I posted this:

https://forum.ih8mud.com/diesel-tec...ick-time-help-middle-3b-compression-test.html

Finally got the compression numbers and either my engine is really healthy or I'm in over my head, or both.

#1 460 psi
#2 440 psi
#3 460 psi
#4 440 psi

What say ye diesel cruiser gods?

And related back to the first thread above any more diagnostic tests recommended or should I just turbo and go?

Thanks

 

[lumpy70]

Those are stellar. I believe the FSM lists 420 lbs as spec, so you're good.

My old 3B pre-rebuild was 310-300-300-290. Diesel will not fire below 290 lbs so it took A LOT of cranking to get it started.

Post-rebuild I was at 430-420-420-420 and everything was good.

You should be happy with those numbers.

Craig.

 

[amaurer]

After a trip at altitude I posted this:

https://forum.ih8mud.com/diesel-tech-24-volts-systems/571230-diesel-smoke-question.html

It was recommended I perform a compression test and in the process of doing that I posted this:

https://forum.ih8mud.com/diesel-tec...ick-time-help-middle-3b-compression-test.html

Finally got the compression numbers and either my engine is really healthy or I'm in over my head, or both.

#1 460 psi
#2 440 psi
#3 460 psi
#4 440 psi

What say ye diesel cruiser gods?

And related back to the first thread above any more diagnostic tests recommended or should I just turbo and go?

Thanks

Never seen a 3B over 435 or so... didn't think it was possible. You sure you did the test right? Has your engine been worked on before? The head shaved or something?

 

[jfrench]

As far as I know it hasn't been worked on before. I was confused by how high the numbers were too because I haven't seen anyone post them that high.

I removed all the glow plugs, unplugged the EDIC and one by one checked compression. I cranked until the gauge stabilized. Each time it got up to 420-430 quickly and I kept cranking until it stopped going up which resulted in the 440 and 460. The first go around on #1 was 400 psi before the adapter broke but I don't think I cranked as long as this time.

I'm going to do it again and see if the numbers are reproducible.

I should mention that I was using a $30 diesel tester from Harbor Freight. Maybe the gauge is off? Adapter was sized right. Does torque on the adapter make much of a difference? Not sure I torqued to the 15ft/lbs recommended for glow plug installation.

I'll repost with new numbers in a few days

 

[roscoFJ73]

I should mention that I was using a $30 diesel tester from Harbor Freight. Maybe the gauge is off?

I think so,good ones cost several hundred dollars. The good news is that the numbers are are fairly consistent.

 

[fjbj40]

Glow plug torque is only supposed to be 9ft/lbs according to the FSM. 3b 13bt manual

 

[jfrench]

Anybody in the Denver area with a good tester I could borrow in exchange for some adult beverages?

 

[jfrench]

Glow plug torque is only supposed to be 9ft/lbs according to the FSM. 3b 13bt manual

Right you are. I misremembered. But does torque on the compression gauge adapter affect numbers?

 

[roalco]

As long as it's seated ( taper seat) firm, it shouldn't make a difference.

 

[crushers]

higher compression readings could show carbon build up, not a big issue.
i would say turbo and enjoy ...

 

[wombat]

I borrowed a top of the line tester from the Toyota Dealer and got 440-440-450-450 on my 3B with 120,000 miles so your numbers sound ok to me. Maybe slight carbon build up from city driving.

 

[lostmarbles]

I got 440/380/380/400 on my 1B back in Sept 08 when I checked.

But it still starts and runs fine so I've done nothing.

Makes me think how much "even better" it would be with a bit of a recon though

(Too much on my plate right now to even contemplate doing it.....)

 

[xtremitys]

whats stock compression for a 2H then ? might check mine

 

[lostmarbles]

whats stock compression for a 2H then ? might check mine

The 2H manual says:
STD 427psi
LIMIT 284psi
DIFFERENCE less than 28psi

(Same as B-series)



(But I think "10% of the average" is a more sensible figure for DIFFERENCE. So if your average was 400psi this would give your "acceptable maximum difference" as 40. Whereas if your average was 284psi your "acceptable maximum difference" would be the FSM figure of 28.)

 

[amaurer]

The 2H manual says:
STD 427psi
LIMIT 284psi
DIFFERENCE less than 28psi

(Same as B-series)



(But I think "10% of the average" is a more sensible figure for DIFFERENCE. So if your average was 400psi this would give your "acceptable maximum difference" as 40. Whereas if your average was 284psi your "acceptable maximum difference" would be the FSM figure of 28.)

For whatever reason nearly every "fresh" 2H compression test I've seen on the board has been over 427, however. That has always confused me.

 

[Wes]

As far as I know it hasn't been worked on before. I was confused by how high the numbers were too because I haven't seen anyone post them that high.

I removed all the glow plugs, unplugged the EDIC and one by one checked compression. I cranked until the gauge stabilized. Each time it got up to 420-430 quickly and I kept cranking until it stopped going up which resulted in the 440 and 460. The first go around on #1 was 400 psi before the adapter broke but I don't think I cranked as long as this time.

I'm going to do it again and see if the numbers are reproducible.

I should mention that I was using a $30 diesel tester from Harbor Freight. Maybe the gauge is off? Adapter was sized right. Does torque on the adapter make much of a difference? Not sure I torqued to the 15ft/lbs recommended for glow plug installation.

I'll repost with new numbers in a few days

Did you ever re-check your compression? I checked the compression on my 2B yesterday, and got high results as well. I have no idea if my engine has ever been rebuilt or not, but I do believe it is fairly low mileage for its age (approx. 135,000 km).

#1 - 490 psi
#2 - 475 psi
#3 - 480 psi
#4 - 490 psi

 

[jfrench]

Never did recheck and now the 42 is in the hands of wileycoyote. He has the compression test kit I used too so if you're REALLY interested you could ask him. It was a strong running engine so I think the numbers were consistent with its performance even if inappropriately high due to "carbon build up" or whatever.

 

[crushers]

did you ever test your compression tester on another engine to confirm?
you can get the testers tested to confirm accuracy.

 

[rustybucket]

I borrowed a top of the line tester from the Toyota Dealer and got 440-440-450-450 on my 3B with 120,000 miles so your numbers sound ok to me. Maybe slight carbon build up from city driving.

How did you manage to borrow some tools from a dealer? did you know the shop manager or something?

I like to do a compression check on my 60. It has 460k on it and often, hard to start. Should I want to do a rebuild, can it be a partial rebuild like, replace the cylinder liners, pistons, rings, conrod bearing shells and have the head checked for cracks? I did a coolant pressure test recently and found no leaks.

 

[crushers]

at 460K count on cracks between the valves in the head and all the prechambers having serious cracking.
also, at that mileage you need to check the oil pump for scoring, oil cooler and container for sludge build up.
water pump will be on its last legs if you have not already replaced it.
liners might actually be fine, test them before replacing.
better yet, just order a kit and do it right the first time. From Oz or Akella, Akella has access to most of the factory parts if you want to go that way.
the amount of work you are about to tackle, it just doesn't make any sense to cut corners.