Halfcut compression test numbers

[MWP]

Hi all,

Im looking at buying a 1UZ halfcut (92,000 on the dash odo).
I had the guy selling it do a compression test and this is what he reported:

cyl1 - 180
cyl2 - 155
cyl3 - 155
cyl4 - 145
cyl5 - 140
cyl6 - 145
cyl7 - 150
cyl8 - 155

This is an engine that hasnt be run in who knows how long, and the test was done cold.

Opinions?

[turbo_gze]

LS400 & SC400 - 10.0:1
SC300 - 10.2:1
Compression Pressure - 178 psi (12.5 kg/cm²)
Minimum Compression Pressure - 142 psi (10.0 kg/cm²)
Maximum Variation Between Cylinders - 14 psi (1.0 kg/cm²)


By the way the engine wasnt tested at normal operating tempature cant full confirm if this makes a difference.

Doesnt seem to be to bad but there is some wear and tear on that engine.

[rob]

you also have to remember a halfcut/wrecker engine could have been sitting for however long and the rings are binding to the pistons

so you will never know what you are going to get

you can get some oil into the bores to seep behind the rings but there is nothing much else you can do other than buy it get it running and hope it comes good or pass on it


also try a leak down test it might help you make a decision

[wa5]

can the importer not fire it up and do a hot compression test?

[LeeRoy]

Was it done correctly? Throttle open? Did they wet the bores?

[CrUZida]

Guarantee'd at least third of the valves aren't sealing properly.

The only way you can do it is to run the motor till its warm, then give it some light 'thrashing', then test it.

But even then you really need to get it out on the road under some load.

[jfallen]

try having a leak down test done. Basically it works by pressurizing each cylinder to 100psi at TDC and measuring how much blow by there is. A good engine will have around 15% leakage, and anything over 40% is a walk away. But like a compression test evenness is just as important.

Cheers
Jordan

[JustCallMeOrlando]

It's hard to tell because as you said, you don't know how long it's been sitting. My 1GGTE in the XX had compression all over the shop. Wasn't a happy camper at all, even with a little bit of oil. Once I'd driven it, heatcycled it a bit and generally given it a good thrash the compression came up perfect across the board.

[BlitzRacing]

as above..see if they could warm the engine first...

they will need somehting to pump fuel and if nothing is missing it should start.

See if they can guarantee in writing the numbers would be within a certain margin when running?


haahah its just cyclinder 1....

[Hurricane]

i would run a leak down test and a wet comp test and see if it changes much and go from there. leak down will tell you if its valves or not, and wet will let you know if rings a warn

[The Real Roadrunner]

Guarantee'd at least third of the valves aren't sealing properly.

The only way you can do it is to run the motor till its warm, then give it some light 'thrashing', then test it.

But even then you really need to get it out on the road under some load.

i would hazard a guess that you are 99% correct but you don't actually need to start the engine to get it sealing correctly (unless the rings are stuck)

when we check my 3s it was waaaay down on comp but about 5 taps on each bucket later (with the leakdown tester on it) it had less than 10% leakdown which is very good.

comp numbers are only good for comparisons between cylinders and you can have on the odd occasion an engine that comp tests well but still has average leakdown.

cheers
linden