Interpreting compression test results

[GTSSportCoupe]

Some of you may recall I did my head gasket this past summer. Had a small leak to a coolant passage from cylinder one that was causing me a bit of grief while towing. Head was in great shape with no cracks (magnefluxed). I had already ordered a brand new one, so thats what the engine has now.

Anyhow, while doing the job, I noticed the head was not the original and had already been replaced (in Japan). It had cleary been rushed, which is why the gasket had failed. The other thing I noticed, is the rear three cylinder bores were stained/pitted from when the first head must of let some coolant/water in. It was pretty dissapointing.

Since then I've been wanting to test compression to see if I should consider getting a core and doing a bottom end rebuild. Recently I borrowed a compression tester from Rob (Diesel cruiserman).

Today I finally had a chance to test. I got the engine up to operating temperature and did the test:

Dry and hot: #1 440psi #2 410psi #3 405psi #4 410psi

Did another test with a bit of oil to test the rings. This was about 1 hour later and the motor had cooled down a bit: #1 445psi #2 440psi #3 420psi #4 430psi

The factory spec is 441psi, 284psi minimum, difference of 71psi or less.

Anyhow, what do you guys think? Keep beating on it, or look for a used bottom end to rebuild and swap in at some point? The perfectionist in me wants to rebuild it and have things perfect. However the practical side of me says nothing has got worse about this motor since I've owned it, so why bother fixing something that aint broke.

 

[cruiserpilot]

I think you could probably get a couple more summers out of that before you need to rebuild.
Re-test same time next year. My unscientific opinion. J

 

[GTSSportCoupe]

I think you could probably get a couple more summers out of that before you need to rebuild.
Re-test same time next year. My unscientific opinion. J

Yeah, thats a good idea. Heh, maybe the compression will get better as the cylinders wear smooth again...lol.

Sorta was eyeing up this to rebuild and prep for a quick install: Toyota 2.4 2L-TE Diesel Engine Short Block | engine, engine parts | Kamloops | Kijiji

I'm sort of sick of putting money into this truck though.

 

[slowandsteady BJ]

Hahaha.... its all good man.

Ive seen turbo'd 3b's run at 20+ lbs of boost with compression in the mid 300's.

Most likely there will be another failure long before the compression numbers drop. Just run it, enjoy it and have a V8 gasser ready to swap in

Don't be a perfectionist with a Land Cruiser, it takes the fun out of it.

 

[GTSSportCoupe]

Hahaha.... its all good man. Don't be a perfectionist with a Land Cruiser, it takes the fun out of it.

Awesome advice, thanks Cam!

I just did some reading on one of the Surf sites and found my numbers are pretty typical. I'm feeling a lot more at ease now.

 

[bikersmurf]

I'd run it.

Rather than rebuild your current motor, I'd swap in a better one when the time comes, or you find a good deal on one.

 

[seapotato]

Don't think I've ever owned a 3b with compression numbers that high.

Had more than one that ran great in the low 300's.



Think you might just have to find something else to worry about. .

 

[GTSSportCoupe]

Thanks lads!

 

[wombat]

When working on a Landcruiser one must keep repeating over and over "We ain't building the Taj Mahal here"
I was cleaning out a box of Cruiser junk yesterday and i found my compression numbers for my low mileage 3B and they were 450 450 440 440
so i think those numbers you have are good.

 

[GTSSportCoupe]

I helped a friend compression test a 200,000km HDJ81 yesterday also (final check before buying). Numbers on the 1HDT with this same compression tester were 400-450psi. I realized that the hose on the compression tester probably reduces the readings somewhat. I calculated the compression tester hose air volume and it's around 12-18cc (the pressure release valve is at the gauge end, and the total hose length is 50cm). On my 2LTE the cylinder volume at TDC is about 28cc, on the 1HDT it's about 37cc. Add the 12-18cc of the compression tester to that and it will throw out the readings quite a bit. I think around 50psi or more. Something to keep in mind. Look more for differences between cylinders than the absolute measurements. Makes my #s look better, as it would put them all over spec (carbon buildup I'm going to guess).