bad compression..wut should it be at?

[sil820]

my motor sucks and it makes me mad...comp:118,112,113,116,107,113wut should a rb20det comp be at?? any1 know where i can get a knock sensor for my motor or wut will match wit it, same goes for coil packs. thanks

[sil820]

i heard it should b around 150???

[Nathan]

Was it warm when you tested it? It's kinda unusual to see consistent, but low readings. If it was warm, sounds like your rings are shot.

[goofynick6]

Make sure you have the coil packs are unplugged and the fuel pump not running when you crank it over, also, hold the throttle wide open so the engine can get enough air. Crank until the gauge stops climbing, and numbers will be lower if the engine is cold.

Nick

[sil820]

they did that with the engine cold..and all the coil packs were unplugged and everything else..aero dyne did the test. does anyone know what it should be at? i baught the motor from a shop in brea, but they got it from a shop in san deago called "west coast powerhouse". the only problem is i baught the clip last year.

[goofynick6]

Do a leak down test, if the results don't change much then it might be a headgasket since it's all the way across, which leads me to think it's not a bent or stuck valve.

Nick

[sil820]

i also have no knock sensor.. i need one right away any1 know where i can get one? also i heard taht if i dont have a knock sensor that the motor could detonate improperly n mess sumthing up bad

[littlemilla3]

they did that with the engine cold..and all the coil packs were unplugged and everything else..aero dyne did the test. does anyone know what it should be at? i baught the motor from a shop in brea, but they got it from a shop in san deago called "west coast powerhouse". the only problem is i baught the clip last year.

What shop in Brea did you get it at? I live in Brea!

[Joe]

i have a feeling you didnt do the test properly

throttle wide openno fuelALL spark plugs out.

[fito]

my RB25 has 130 on all 6 of them with a 1.5mm head gasket. hope it helps

[sil820]

I GOT IT DONE AT AERO DYNE..WOULD IT BE HIGHER WITH THAT 1.5MM HEAD GASKET OR LOWER?

[sil820]

BUT I GOT THE CLIP AT OPTIONS AUTO SALAN OFF IMPERIAL AND HARBOR KINDA

[sil820]

Should it be 130 across? or wut is the proper compression?

[sil820]

**** mines doin really bad then.. u think its the head gasket? or do u think there internal damage?

[sil820]

do you think you can help me out with my motor.. i really have no clue whats wrong with it.all i know is that my compression is low and its not running that fast at all .another thing is that my check engine light isnt wired'up, i have no knock sensor hooked up.. one of my coil paks are bad(so its only running on 5 cylnd). think you guys can help me out? thanks i live in southern cali

[Fiendish]

my RB25 has 130 on all 6 of them with a 1.5mm head gasket. hope it helps

I thought the compression should be 185 with a margin of 14 on a RB25DET.

[Joe]

185 is very high for a 25DET

[Yellow4g63]

do you think you can help me out with my motor.. i really have no clue whats wrong with it.all i know is that my compression is low and its not running that fast at all .another thing is that my check engine light isnt wired'up, i have no knock sensor hooked up.. one of my coil paks are bad(so its only running on 5 cylnd). think you guys can help me out? thanks i live in southern cali

If you have money I can point you to a few shops that should be able to help you out.

[Yellow4g63]

my motor sucks and it makes me mad...comp:118,112,113,116,107,113wut should a rb20det comp be at?? any1 know where i can get a knock sensor for my motor or wut will match wit it, same goes for coil packs. thanks

Did you retry it yet with the car warm? Make sure you step on the Gas when you do it too.

[sil820]

i would like 2 redo it.. since a shop did it last time.. wut do i need 2 do it my self? a compression tool and is taht it?

[Yellow4g63]

yup

[sil820]

thanks..ima try doing it with the help of andy on sunday.. and ill see what it reads out..cuz i dont think any1 ever took the head off but i hav no clue.. i hope thats just the problem..cuz its runnin like **** right now..

[WDRacing]

Here's a quick rundown, warm up the motor, pull the plugs, fuel pump fuse and disconnect the cam alignment sensor plug. Screw in the compression tester, hold the throttle wide open and turn the motor over a few times, meaning about 3 revolutions. Then look at the compression gauge. Repeat this on all the cylinders. If they are still really low, try pouring a cap full of oil into one of the cylinders and rechecking it. If the compression goes up, you have bad rings or worse. If it stays the same, it could be a headgasket or valves.

Another thing you can do, if you have a compressor, is to put the piston ATDC, screw in a air fitting and see if she'll hold pressure, listen to your intake side or exhaust side for an air leak. Also check your radiator for bubbles or bubbling noises.

WD

[sil820]

thanks ill try that this week and wellc what happens..i hope its just a head gasket..cuz if its not ima just get rid of my car..

[sil820]

hey wutsup man sorry i havnt been able 2 get a hold of u lately i just called but no one picked up..are still on for 2morro? thanks

[Yellow4g63]

what time are you goin to make it down? I have to run to the wrecking yard to find a brain for my work van.

[sil820]

well after andy helped me re-compression check the motor i got a lot better readings this time: 140,140,140,141,145,143. that sounds like regular compression right? my motot is also running a lot better after replaceing a bad coilpack..the motor runs a lot smoother now.

[Yellow4g63]

lol yeah who ever did it the 1st time wanted some more money from you lol.

[xjon]

Good job yellow!

Glad to hear your your engines running better. Did you get the knock sensor installed yet? how about the wiring/tach problem?

[sil820]

found out that there wuz no knock sensor missing..good ol aero dyne told me there was missing one though.....and Mckinney fixed my wiring/tach problem! thanks mak