Whats your Engine Compression Test

Finny · Post by **Finny** » Sun May 03, 2009 7:52 pm

The manual says that compression on a Grey motor should be 110 or higher on each cylinder.

Interested to hear what results you have had.

1=?, 2=?,3=?,4=?, 5=?, 6=?.

Whos got the highest and lowest, and biggest differences ?

jazzar02 · Post by **jazzar02** » Sun May 03, 2009 9:36 pm

Well i done a test earlier today and got i think 115 on the first four and 107 on the last 2.

Finny · Post by **Finny** » Tue May 05, 2009 11:23 pm

SPL CAmry, that's pretty good.

Mine is 105, 110, 95, 97, 80, 115.
At least I got a good result on cylinder 6, it was 0 (nil) before I had the head done.

jazzar02 · Post by **jazzar02** » Wed May 06, 2009 6:46 pm

yeah the car only has 22,000 miles on it and has only been sitting in the same spot for 4 years and has only been started a dozen times since it has been parked up.

Craig · Post by **Craig** » Thu May 07, 2009 6:57 am

Did mine last year Finny all around 120

Finny · Post by **Finny** » Thu May 07, 2009 8:51 pm

Craig wrote:Did mine last year Finny all around 120

Which one ?
The Grey or the Red/Grey

FCCOOL · Post by **FCCOOL** » Sun May 10, 2009 2:31 pm

i have a red with the CR reduced pretty much as much as it could to take boost from a supercharger.
125, 126, 125, 125, 125, 124

thropzed · Post by **thropzed** » Mon May 11, 2009 11:22 am

Whats a compresion test?
Cheers Theo Z..............

Cal · Post by **Cal** » Mon May 11, 2009 2:29 pm

Theo, you take out your spark plug, then you put it some contraption, crank the motor, and it measures the compression in that cylinder

FB MAD · Post by **FB MAD** » Mon May 11, 2009 5:46 pm

120 psi readings from a 138 grey is what you would expect from a good condition engine bearing in mind they are relatively low compression engines anyway.

In an ideal world, all cylinders would have the same compression pressures but it never ends up that way due to production differences in head chamber castings and different wear rates from cylinder to cylinder as the engine ages.

Usually a 10 to 20% pressure variation between the highest and lowest cylinder readings is workshop accepted.

More modern higher compression engines would be lucky to start with a reading around 80 psi but I've known some well used greys to run reasonably well even with a reading as low as that.

Sunnytims readings are good with little variation between cylinders.

Finny...well...sorry to have to say this but your readings don't appear to be real good for an indicator as to the engines usability

however some engines do lose their ring/piston/bore sealing ability to some extent over time especially if sitting idle for a number of years and they can actually bring up better pressure readings after a good solid engine load bearing run.

Don't throw your engine away just yet.

Finny · Post by **Finny** » Thu May 14, 2009 9:46 pm

FB MAD wrote: Finny...well...sorry to have to say this but your readings don't appear to be real good for an indicator as to the engines usability
Don't throw your engine away just yet.

I found another grey motor.

I had it all along, but forgot I owned it.
It was in the parts car, but because it wasn't driveable, I never though of it.

But I only need the bottom.
So I'll see if it turns over and what compession it has.

Will probably need to put the top of the motor back together again first, I think ??????

It was on an auto, but shouldn't make any difference. Or should it ?????

FB MAD · Post by **FB MAD** » Fri May 15, 2009 5:21 pm

Nup, should be all the same but check if it has a brass spigot bush in the back of the crank before you try fitting it to a manual box.You won't need all the auto linkage on the carby setup either.

If it's the original auto engine it won't have a spigot bush but easy enough to fit one into back of crank.