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Compression test results

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Old May 5, 2008 | 05:18 PM
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Default Compression test results

sooo I did 6 out of the 8 Cylenders today.. Im seeing 150 on all 4 cyclenders on the left (facing the engine) 145 on one on the right and the other is at 150.. so thats a pass on the 6 cylenders right? Presure holds just fine.. It began raining so I didnt get a chnace to do the last two, which are the PITA ones to do.. Also I noticed my exhaust does sseem to have a crack in it,, the last part that connects toteh tailpipe was leaking water this morning ( just regular color, which may account for my white smoke in the morning (oderless))..

Also the way I did the presure test is that I unplugged the Ignition coil, then took out spark plug insert gage and crank. lol Please tell me if Im doing anything wrong lol.

Thanks!

-Tim
 
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Old May 5, 2008 | 05:23 PM
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Default RE: Compression test results

The correct way is to take all of the plugs out, and disable fuel. If fuel is not disable it will lead to lower readings. Screw the gauge in, sit in the truck, depress the throttle and crank the motor over several turns (so that the piston you our testing hits its compression stroke 4 or 5 times. If you unplug the pcm, it will disable fuel and spark.
 
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Old May 5, 2008 | 05:26 PM
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Default RE: Compression test results

k, ill redo it tomorow, thanks for the info :-)

 
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Old May 5, 2008 | 05:44 PM
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Default RE: Compression test results

No problem. Those are decent readings though. I'd be interested to know how much higher they are with the fuel disabled. The idea is- with fuel spraying in there it washes the cylinder walls with gas and dilutes the oil. Also forgot to mentionmake sure you bring the motor up to operating temp. before the test.
 
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Old May 5, 2008 | 05:59 PM
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Default RE: Compression test results

Yeah he was at operating temp (185 -190 ish , as usual just bellow middle mark on the temp gage) I followed the direction with the kit, Unfortunatly I didnt unplug all teh plugs while doing it, so Definaly need to redo it tomorow, , with the PCM, just unplug the wires from it right?

Thanks again man, I love this foruM!! lol 2 months ago I didnt know how to change oil, now Ive read enough on cars to be paranoid about every little thing heh, My wife's car had a blown head gasket once, so Im paranoid about it.. Funny thing about that.. Those *** hats forgot to Flush the cooling sysgtem after they did the head gasket on it so there's still oil in the coolant resevoir of my wife's car, which pisses me off cuz they charged waaaay to much for the job (2100 bux!!! ) my new mechanic says he woulda done it for 1200.. now I could do it for 400 (with reman Head if warped) Although I really need a house with garage, Living in an Apt complex suxxorz

-tim
 
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Old May 5, 2008 | 06:58 PM
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Default RE: Compression test results

ORIGINAL: timsalas

Although I really need a house with garage, Living in an Apt complex suxxorz
I hear ya man. I have a small-ish garage that came with my apt, and my wife's 2004 Grand Cherokee fits in there just fine, but the Ram takes up most of the space in there to where there's no room to work.
 
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Old May 5, 2008 | 07:06 PM
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Default RE: Compression test results

hehe, oh man I wish I had a garage, Id be gettin all sorts of neat toys from freight harbor tools lol.. The wife and i are thinkin of moving south of seattle so We can actually afford a home for less than 200k, Up here its like 400k + for a crappy little condo in the city, a house OLD One is about 500-700k, If we move south though, Ima get me a geo metro, Im guessin those are easy to work on, so I can prolly buy a beater and fix it up for cheap to get the 40mpg it gets to go to work and back,, and use the truck for cruisin around :-)

all that as long as I dont get laid off :-( stupid budget cuts,...
 
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Old May 5, 2008 | 07:35 PM
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Default RE: Compression test results

To disable fuel when doing a compression test how do you want to do that? Or is that what pushing the gas all the way down does?
 
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Old May 5, 2008 | 08:53 PM
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Default RE: Compression test results

pull your fuel pump relay and try starting it before taking the plugs out...that will do the trick
 
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Old May 5, 2008 | 09:57 PM
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Default RE: Compression test results

Little hard on the injectors though, hammering dry and no fuel to cool them. I'd unplug the injectors and just jumper whatever's needed to get it cranking (would have to look at the diagrams) ...mopowar, I wouldn't think it'd crank without the pcm plugged in? Might though. It wouldn't be a bad idea to throw a charger on for a few minutes between tests, just for more consistent readings.
 
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