headgasket/ compression test

[apexiSR202nr]

Hey, I was wondering if anyone could give some advice on whats goin on with my S13 SR motor...

ok, so I took the motor out and replaced the headgasket with an apexi one and when I put the cams back in im pretty sure i got the camshaft alignment procedure correct and I torqued the head down following the FSM... so when I go to start it, it doesn't want to... it just cranks but no fire... but if I turn the key on and then pull the fuel pump fuse quickly so only a small amount fuel is in the lines it'll start but die out obviously(lack of fuel pressure). but if i leave the fuse in then it just floods the motor. I did get it to run once but i had the throttle plate full open and it was idling rough and wouldn't idle without the throttle floored.

I did a compression test on it today and it read about 57psi on all cylinders so that worries me very much... im not sure if i did the test correctly so i'll retest with the help of my friend but if anyone has any info i'd GREATLY appreciate it very much.


By the way here's a list of things i've tested and are ok..
-timing (15degrees, second mark from the right)
-mafs
-TPS
-coilpacks, ignitor chip, plugs
-ECU
-O2 sensor
-temp. sensor

[mjjstang]

yah if your getting 57 psi then somethings wrong, how did you do the test?

[SpeedMonkeyInc]

Did you have the head resurfaced? Did you have to scrape out the old gasket? Its kinda weird that you are getting horrible compression so evenly. Don't have any extra bolts left over do you? ahaha had to ask.

[apexiSR202nr]

well when I did the test I pulled the fuel pump fuse, disconnected the CAS, took out one spark plug and put the gauge in the motor then cranked it... the motor wasn't warmed up and i didn't have the throttle fully opened, and i did spay a little oil in the cylinder but that didn't help the compression any.

When I pulled the head I didn't have it resurfaced because before it never blew out and I made sure I got all the extra gasket material off. I did however gave the apexi HG a spay of copper gasket and used new OEM head bolts.

[Crono562]

well if you did do the comp test right then i would say its something with how you put the head back on because if it were rings then you wouldnt be getting consistently low across all 4. I would redo all the head bolts just to be sure, even if you thought you torqued them right the first time. 57 on all 4 is really low! or your valve timing could be off, since you said you took the cams out.

[apexiSR202nr]

I just got done redoing the compression test right this time and its still around 57psi for all 4 cylinders.

later tonight i will pull the valve cover and see if my cams are timed right... as far as the head bolts go should i loosen them all completely (following the FSM) and then retorque accordingly? I'll try to get to that tonight after work and see if the compression numbers rise any afterwards..

[slider2828]

Just remember to torque them with 2 ninety degrees after torquing it to the measure of the FSM. Its vague, but that is how it is done actually. Re-read the manually, and describe what are your torque down procedures. Secondly, how thick was the headgasket that you put down? 2mm or something? Let us know that too.

[statik]

I just got done redoing the compression test right this time and its still around 57psi for all 4 cylinders.

so you removed all 4 spark plugs and cranked with throttle open and still got 57psi?

[NIK90s13]

Man, it sounds like its the cam timing, to be that consistant. I'd double check that first. You have to remove the valve cover to retorque the head anyway, check the timing then.

[D-Cell]

Count 20 links between timing marks on your cam sprockets. Get a B13 Sentra factory service manual, it will have all the necessary information.

[apexiSR202nr]

yeah i just got around to checking the camshaft timing and it was way off... i dunno what i was thinkin when i did it the first time but i used the guide off enthalpy's site and did it right this time... i did another compression check and it turned up 147 on all cylinders.. the motor was cold and the new headgasket is 1.1mm thick so are these numbers reasonable? But thanks for all the advice, im very thankful for the help from everyone.

[sunnys14]

147psi cold seems about right. warm up the motor for about 7 mins, then recheck.