On Compression ... AGAIN!

[Alex(AUS)]

I just wanted to post some good news. I have measured the compression for the second time but I didn’t want to post any numbers until I have verified it. The first time I got a compression check I did it at a mechanic. He measured the compression without disconnecting the coils. Therefore, due to spark and fear the engine would fire (it did) he stopped the measurements short (only cycled the engine a few times). The readings were basically 165-168 on all front cylinders.

More recently I pulled off my supercharger to fit o-rings on the URD injectors and I measured the compression again (with my own quality compression gauge). The readings were so high I was very sceptical. All cylinders registered between 212.5 and 225 odd. I assumed that the gauge was stuffed or that the readings were wrong due to the supercharger being off.

So, I did it again today (only the front 3 cylinders, supercharger on - dead cold). The results were the same (or similar) 205-212.5 all three.

Should I try it hot? Can it go down when its hot?

Alex

[Alex(AUS)]

Ok so to save the question and for the sake of science. I warmed up the car and I measured the #6 cyl again (I couldnt be bothered doing them all again ...). I got 232.5 ... Now I really think my gauge is out! I did get 225 last time so I guess 7.5 from the heat (ie expansion) is possible

Alex

[Mole]

are getting such high readings bad though?

[Vampire]

According to Toyota, when you test the compression you should:

1. warm up the engine
2. remove the coils, wires and all 6 plugs.
2. make sure the battery is fully charged

The range should be 145-218 psi with a difference equal to or less than 15 psi. If a cylinder is low, add some oil and retest. If the compression comes up you probably have some bad rings. If it doesn't you may have a leaking valve/seat or head gasket. Of course it could be a lot of things but you seem fine.

[Alex(AUS)]

Yep ... thats what I did! I followed alldatadiy which says exactly that. I did check all cylinders with all the plugs/coils removed when the charger was off. I got the same result. As I said earlier, I did also check it when it was warm (only 1cyl front bank) and I got a slightly higher result. I assume they will all be the same ... but I can check them all if you like.

Joe had 225 on 1 cylinder also.

Oh and alldatadiy says 218 or more. So more is good ?

Alex

[Alex(AUS)]

are getting such high readings bad though?

Anyone know ???