Compression Numbers....

[Nissan2367]

I decided to compression check my RB25 again last night just to make sure i have bent valves before i started to buy all the parts i needed... well the numbers looked low to me but it really didnt indicate bent valves. here were the numbers and let me know what you think!1. 1102. 1103. 1154. 1205. 1206. 120Now from what i have researched average is 140-165. Now all i did was pull the plugs and screw in the gauge and crank,... i am not sure it thats how its done but i thought thats all you had to do. Let me know what you think!

[bmadd2402]

those numbers do look low, but they are consistent. I think the low limit is 120 for the rb25, but that is a warm comp check, and i dont know if you did the check at operating temp or not.

[Nissan2367]

That is a good point. My problem is i cant keep it running so it was at garage temp (33 degrees, I hate WI) So that might be another reason compression was low but was i correct in thinking the valves are ok?

[Neejay]

That is a good point. My problem is i cant keep it running so it was at garage temp (33 degrees, I hate WI) So that might be another reason compression was low but was i correct in thinking the valves are ok?

Was the engine at operating temp though? + WOT?

[fast_s14]

With those numbers you definately dont have any bent valves. What makes you think that you had bent valves? Try doing a wet compression test to see if the numbers go up. Your rings and or pistions might be shot too from detonation.

[Joe]

Was the engine at operating temp though? + WOT?

bingo

if you keep your throttle closed you will get a significantly lower number.

the temp helps, but wont cause a 40+ point drop.

[Kansei240sx]

Also, on top of keeping the throttle open, adding a tbl spn of oil to each cylinder to do a wet test will help bring those numbers up a bit.

[S14eva1]

^^^^^so you guys recommend doing the comp. test with throttle wide open?

[Neejay]

^^^^^so you guys recommend doing the comp. test with throttle wide open?

That's how you're supposed to do it. lol

Like today, I did a compression test, and on #1 cylinder, I didn't go WOT. Got 150.

Remembered that I didn't do it WOT, re-tested and got 161.

[Coolwhip]

That's how you're supposed to do it. lol

Like today, I did a compression test, and on #1 cylinder, I didn't go WOT. Got 150.

Remembered that I didn't do it WOT, re-tested and got 161.

OT, how did the rest of your Compression test go?

[Nissan2367]

This is all good to know! The reason i thought i did is i cant get the car to run right. when i took off my timing belt to do the water pump and oil pump when i first got the engine my firend (now old friend) decided to hit the crank with an impact and spun it until it stopped. right now the car basicly wont even idle, i timed it perfect, the fuel pres is dead nuts at 42psi, and the spark is there but yet my wide band maxs out on the rich side and you can smell fuel in the exhaust. i figured i bent an exhaust valve but these numbers show i didn't )thank god!!! Now i am lost on what to look at next! I am starting to think it a wiring issue...I am going to try the test again with the oil and WOT. the car wont run so i cant get it to operating temp... now ill be testing it at 5-10 degrees!

[Carl H]

did you remove the injectors?perhaps some seals were pinched or destroyed?

[Nissan2367]

That is a good thought!!! Ill have to check that! Any other ideas?

[Nissan2367]

Does anyone know where i can get injector seals?

[Neejay]

Does anyone know where i can get injector seals?

injector seals? o-rings?

[Nissan2367]

Yeah the o-rings. I was told by a friend that maybe the Supra ones are similar. I am going to just take them out and go to the auto parts store and see what i can find!