Topic: compression testing procedure?

[spacoli]

I did a comresssion test tonight on my 22re with a borrowed tester. I never did this before so I just did the following.

It was a snap-on tester and there was various hose fittings for different size spark plugs. I found the right size, but it did not have the valve core in it, some had the core in and some didn't.

So what I did was just watched the gauge jump up and down as the engine was turned over. I was getting 118psi one one cylinder and 120+ on all the others.

Should I have installed a valve core from one of the others hose fittings? It seems like that would just keep increasing the pressure in the gauge with each stroke?

What is the correct procedure for testing?

[Tallchevy]

Put the core in. Remove the coil wire. Crank the engine for about 3-4 seconds & stop & read the gauge. The valve core will hold the pressure.

[k5kell]

It seems like that would just keep increasing the pressure in the gauge with each stroke?

It does not continue to pressurize it, it will just stay at the maximum pressure.
-Kell-

[spacoli [OP]]

Thanks, I'm going to retest tommorrow. Should I test with a warm engine or just test cold. My previous was cold.

[kneedownnate]

Test warm, ground the coil wire and open the throttle all the way.  Your compression should be WAY higher than that, toyota calls for a rebuild at about 120 or so.  It is a little better that they are pretty even, but the numbers are just too low!  You should reach full reading at about 8 revolutions too.

[yotaweelr]

Put the core in. Remove the coil wire. Crank the engine for about 3-4 seconds & stop & read the gauge. The valve core will hold the pressure.

better to unplug the coil or the signal from dizzy. the spark will ignite fuel coming from the cylinder and cause a fire otherwise.

[yotaweelr]

118 is way bad even cold, should be between 150 and 180- to be healthy. 120 to 150 if you are trying to sell it to unsuspecting buyers.

[spacoli [OP]]

Well, I did another compression test with the info I received from the forums.

I warmed the engine up, pulled all the plugs, pulled the EFI fuse and held the throttle open.

Here are the numbers with number of revolutions for each. I choose to do different revolutions, because it seems like everyone had a different number of revolutions that they suggested. So this would give everyone a comparision
to what they usally do.

First is 4 revolutions, next is 6, next is 8 and the max (until needle stopped moving around 10 revolutions)

#1 - 170,188,205,210
#2 - 170,185,200,210
#3 - 170,188,200,210
#4 - 165,180,195,200

[snutty]

while we areon this subject, I got kinda of a newbie question. Im about to do a compression check on my motor, but the thing hasnt been started in 6months and im not sure if it will even start.... how much of a difference should i expect if i did the compression check while the engine was cold?

[kneedownnate]

snutty: Shouldn't see more than a couple/few pounds difference.  You'll get a good enough reading to be able to figure out if your compression is in a decent range.

Well, I did another compression test with the info I received from the forums.

First is 4 revolutions, next is 6, next is 8 and the max (until needle stopped moving around 10 revolutions)

#1 - 170,188,205,210
#2 - 170,185,200,210
#3 - 170,188,200,210
#4 - 165,180,195,200

Ok, I should have been more specific, because you don't just go X number of revolutions, you just keep going until the needle stops moving.  I do eleventeen compression checks a year on our boats, and some engines will peg after 3 revolutions, some keep climbing after 15-20 revolutions.  Basically, all you need to pay attention to is when the needle pegs, and you don't even need to consider the first three readings you got, just the last where it stopped.  Your compression is great