ghost_masterCL

ok, so I've heard several people mention getting a compression test. My car only has about 55,000 miles, but I just was curious if the cylinders are still holding full compression or whatever it is. Where would I get this done? about how much should it cost? if they are not, what could the problem be?

thanks in advnace guys.

LCARUCA 97

you can buy a pressure tester at autozone or whatever auto supply store you have nearby. take out all the spark plugs and screw the gauge-hose right into the first plug hole just like a plug, then have someone crank the engine while you get the reading. a lower reading isnt necessarily bad, its when one cylinder is far off from the others. example....

180-180-180-180 = excellent!
180-180-140-180 = not good
150-150-150-150 = good not great, but good
150-150-150-120 = FUCK!

wilp99

u can do it yourself cheaper than having someone else do it. juse remove all the sparkplugs, buy a compression guage from autozone, screw it in like its a sparkplug tightly. have someone turn the engine over the needle will pump up every time the piston comes up. let it pump till it doesent go up anymore. that is your compression. if its lower than whatever it is supposed to be. add 1 table spoon of clean motor oil, and do the check again. if it goes up significantly then its the rings, if it doesent go up, then its eather the valves are gunked up with carbon, or bad head gasket. also if its very high, over 20 psi over the max, then its alot of carbon on the piston top and cylinder walls. anyways, repeat this process for all the cylinders. and write down all the numbers for each cylinder. if they are too different from each other than u need some work. but usually they will be like

1:180 2:183 3:175 4:186 5:182 6:187 just an example but if u have two cylinders side by side that have really high, and usually the same compression u prolly have a blown head gasket. as you can see theres alot of info u can tell from just doin a 30min job. and its not hard and u can usually do it every time u change the spark plugs. the hardest part is the info associated with it. holla at ya and good luck....

ghost_masterCL

crank the engine as in turn the key to the starter position for a second or two?

ok, well since you mentioned spark plugs, I don't have a torque wrench, so should I get one of those so I can put the plugs back in with the right tension? or does it not really matteer as long as the plugs are all in there at about the same tightness as they were when I took them out?

wilp99

if ur not experienced with installing spark plugs, get a torque wrench. also turn the key until the needle stops pumping. all the books say it should take somewhere between 5 and 7 pumps but ive only seen it take 7 or more to reach complete compression.

ghost_masterCL

I'm not experienced and I figure I should get a torque wrench anyways, since I'm picky about things being exactly as they should be.

what should the maximum ft-lbs be for the torque wrench I get? Apporximately how much should I pay for one? i just looked and I saw wrenches ranging from $30-$140.

god I feel like such a noob asking all this stuff.

ghost_masterCL

and should I disconnect the fuel pump and ignition fuses before I do this?

wilp99

yea its a good idea to pull these fuses.

as far as the torque wrenches go. u could just get one of those cheap needle type for 10-15$ or u could go to advance and get one there for around 35$. i have like 10 of them, all snap on. pretty expensive. but they range for different values. inch lbs., foot lbs. from 5 in lbs, to 200 ft lbs.

twizy

I know this is an old thread but how do you disconnect the fuel pump and ignition? Exactly which fuses should be removed?

ghost_masterCL

bust open the fuse panel inside teh cabin (by the brake and accelerator, adn look at the diagram to figure out which fuse is for what.

twizy

ahh, i was looking at the wrong fuse set, thanks. by the way how were your compression #s? what #s can i expect to see if the engine is relatively healthy?

ghost_masterCL

I never got my compression checked, but after more research (I was such a noob when I made this thread) it's not a mtter of correct compression numbers, but it's a matter of all your cylinders being around the same number.

for example if you get somethig like this for a 4 cyl: 172 168 170 171
then that's good, but if you get: 171 172 143 169
then that third cylinder might have some problems. I don't know if they necesarrily have to be THAT close though.