ejj

iTrader: (5)

I finially got around to doing a compression test today. Here are the results (in PSI):

1: 182
2: 180
3: 179
4: 181
5: 186
6: 181

Note that these numbers are +/- 2 or 3 because my guage is marked in increments of 5psi. I just estimated numbers that fell in between marks.

Any thoughts? Any reason you wouldn't install the NOS? I know factory is 185, so these numbers seem pretty good for an engine with 60k miles.

Also...my kit came with an extendor of sorts that I decided to try to see if it made things any easier...using that piece my readings where all in the 160's. Anyone else seen anything like that?

Sonic

Either set of numbers would be good.

N1sMO

Where do we go to get a compression test done? And for how much? Thanks

ejj

iTrader: (5)

Medic - what you do mean "either set"?

Your driveway. $20.

http://www.harborfreight.com/cpi/cta...emnumber=39224

You can get a tester from the link above for $20. If you can change your spark plugs you can do a compression test.

Sprint

iTrader: (10)

i can't

Sonic

Even if it was 160, 162, 163, etc, those numbers are still fine. Your looking for a number that should be at least 145, so anything CONSISTANTLY above that number is fine.

Dave B

ejj5875:

How does it do test the compression? Does it pump air into the cylinder, do you turn the the crank, what? I would like to invest in one.


Dave

Chebosto

iTrader: (1)

you remove the spark plugs all of them, then you put in a pressure reader with an air gauge. crank the car three times and take the first and last numbers from the first and third crank.. then just take the reader out and go from valve to valve...

you'll need to get the compression reader from like an auto parts store. i think they go for like 100$? i dunno.

emax02

iTrader: (1)

Just unscrew all your spark plugs, then screw the compression tester piece into your spark plug hole. Then just go inside your car and turn the key and let the starter crank for 5 seconds. Then run out and look at the reading on your gauge. Do this to all 6 of your cylinders. I bought my compression piece at pep boys for $20.

ejj

iTrader: (5)

Dave -

What Emax said. The guage records the MAX pressure, not a clumitive (s?) one. So you can crank the engine for as long as you would like. It will just stop reading once it gets to the top.

The link above points to the site where I bought my tester. Its really easy to do. Like I said, if you can change spark plugs then you can do a compression test. I suppose I should do a write up, 'cause I don't think I've seen one any where that is Max specific.

Cheston - $100? Could you be refering to equiptment for a leak down test?

Sonic

You really should have 2 people doing the test, you want to see how fast the pressure builds also.

Sprint

iTrader: (10)

i thought you had to pull the fuel pump fuse?

ejj

iTrader: (5)

You should, but I read that you don't have to. I have a generic Automotive book ( my brother is an auto tech student so I steal his old books ) and it doesn't state that you have to. I was also looking around the 'net last night and found that there are several people who just recommend it, because if you don't it will make quite a mess and make the car harder to start when your done. You may even have to let it sit for a hour or so with no plugs to get the gas evoperate.

This is something that I'd have to look into further, 'cause I want to do a test on my gf's 92 Mirage, but can't find a way to kill the fuel pump...I may just have to deal with the mess. Anyone know an answer to this? Do you have to kill the fuel pump?

Sprint...why can't you do a compression test? Can you not kill your fuel pump?

medic - You can watch it from in the car if your hose on the guage is long enough. I just angled the guage so I could see what it was doing.

Sprint

iTrader: (10)

i am too stupid to do the test

Sonic

None of the ones I have used was long enough. Cool idea though...

ejj

iTrader: (5)

Yeah, it was not really possiable to read the guage, but I could see the needle moving, which is all I really wanted. I'm sure you could buy the fittings and hose to make your own extension if you really wanted. Hell, you could make it long enough to take the guage into the car with you.

ejj

iTrader: (5)

I'm sorry to hear that.

emax02

iTrader: (1)

If the gauge is half way decent and can hold the pressure then there is no neeed for two people. As for how fast the pressure builds? What are you going to learn from watching that? I don't think there is any thing you can learn from watching that.


Sprint, you can do it.

Sonic

A car with worn piston rings will show low compression the first 2 or three cranks, but if you aren't watching the guage, then you'll never know.

SuDZ

How fast should it go up? I mean if I am watching it is it the speed that it builds up or the number it builds up to on the first two I should look for?

SuDZ

ejj

iTrader: (5)

The guage will only "jump" as fast as the engine will crank. The less it cranks it takes to get to full pressure the better. Mine took 4-5 cranks to get there...and then would inch up about 5psi over the next 10 cranks.

Sonic

You should be at full compression within 3 cranks.

SuDZ

Cool. Thanks guys.

SuDZ

White96MaxSE

I think it is worth mentioning that you shouldn't crank and crank on your starter for long periods of time without letting it rest.

I think cranking for more than 15 seconds at a time is pushing it with out a short rest for the starter.

I think I'm going to check mine out with 178,000 miles on the clock and see where it is at.

White96MaxSE

TILLEYS99

iTrader: (4)

You can make a jumper wire to connect to the starter trigger wire and the other end to the battery to crank the car from under the hood just be sure its out of gear then your fuel pump wont run and you will be able to see the readings without getting in and out.

CandiMan

iTrader: (1)

Along with removing all the plugs, to keep the TB at WOT while getting your compression readings. I always thought that was the proper way to get the readings.