SR20 issues

[tb13]

I have an S13 hatch that I just had a motor rebuilt for. Its a redtop SR20DET, brand new everything, had someone I know rebuild it and recently got it back into the car.

I was having issues setting timing and noticed he set timing really wrong. It was 2 teeth off at the cams. I fixed the timing issue and finally got it to start, kind of. It will kick over, start, then die. Throttle input does nothing to keep it running. Currently the car has subaru 550cc injectors, Z32 maf, GT2860rs and a PowerFC with a tune for the motor that blew up. It ran before the motor shit a rod out, but refuses to run now.

So I decided to compression test the motor... Cylinder 1 came back with 70psi of compression :ugh: The others were 150,160,140. I called up the guy who built the motor and he told me that it wasn't a big deal and that once it ran it would probably be fine. I don't think it will be. 70psi is incredibly low, especially for a BRAND NEW MOTOR.

I need some input on what I should do, seems like it isn't even worth the time getting it to start considering the compression is already low.

[rawgarage]

70 is fucked.... he's just not tryna fix it...

[BlackZenkiS14]

Yea 70psi in 1 cylinder like that is a blown motor buddy. I've rebuilt engines and had smashed ringlands in engines that still made 85psi...

[zombiewolf513]

70 is fucked.... he's just not tryna fix it...

I third this general opinion. Fuckin snake the guy that built it

[Mcflurry]

Man that's bad :( I hope you didn't pay him for the job... It's hard to imagine what he could have done to archive 70PSI. Perhaps he forgot rings? Where did you get the block? Presume you didn't reuse it if it threw a rod. Are you reusing the head? More info pls!

[tb13]

70 is fucked.... he's just not tryna fix it...

Yea 70psi in 1 cylinder like that is a blown motor buddy. I've rebuilt engines and had smashed ringlands in engines that still made 85psi...

I third this general opinion. Fuckin snake the guy that built it

Man that's bad :( I hope you didn't pay him for the job... It's hard to imagine what he could have done to archive 70PSI. Perhaps he forgot rings? Where did you get the block? Presume you didn't reuse it if it threw a rod. Are you reusing the head? More info pls!

You guys pretty much nailed what I was thinking, but didn't want to say... He is trying to tell me there is a "Compression Hole", but that sounds like utter bullshit and just another excuse. He also said a lifter could be stuck, but that doesn't have a damn thing to do with valves closing and holding compression.

I never saw the paperwork from the machine shop, but I know it has stock pistons, new rings, new stock headgasket and arp headstuds. The head supposedly had a valve job, new valve seals, resurfaced and some other shit done. All of the internals looked brand new before they were installed, but I think he really fucked something up when he was building it...

[zombiewolf513]

Have you done a leakdown?

[tb13]

Have you done a leakdown?

I have not, I waked away from it the other day because I was about to kick it off the jack stands... With 70psi of cold compression and above 140 on the other cylinders, I didn't even think it was worth it to try and get it running because it would just run like garbage and piss me off more.

Do you think its really worth the time to do a leakdown test?

[zombiewolf513]

I understand the frustration, and its always best to just come back to it with another approach and a more level head. Or else youre just pissed and more suseptible to bias.

The leakdown might give you an idea of whether its a valve issue or not. Oil in the cylinder during the compression test would let you know its the rings vs headgasket/other issue.

Did you have all of the spark plugs out when you did the compression test? Or just remove one at a time? Having plugs in could skew the results, because at that point youre just testing the strength of the starter and charge of the battery.

[tb13]

I understand the frustration, and its always best to just come back to it with another approach and a more level head. Or else youre just pissed and more suseptible to bias.

The leakdown might give you an idea of whether its a valve issue or not. Oil in the cylinder during the compression test would let you know its the rings vs headgasket/other issue.

Did you have all of the spark plugs out when you did the compression test? Or just remove one at a time? Having plugs in could skew the results, because at that point youre just testing the strength of the starter and charge of the battery.

Walking away from it was the best decision for sure, I didn't want to do something I'd regret. Thats why I posted here to see what others had to say.

I'll do a leak down test sometime soon, If its in the head I should hear air escaping into the intake or exhaust manifold, right?

The compression test was done with the plugs in, its what I usually do, but I see what you are getting at. I can pull them all and test it again.

[zombiewolf513]

Walking away from it was the best decision for sure, I didn't want to do something I'd regret. Thats why I posted here to see what others had to say.

I'll do a leak down test sometime soon, If its in the head I should hear air escaping into the intake or exhaust manifold, right?

The compression test was done with the plugs in, its what I usually do, but I see what you are getting at. I can pull them all and test it again.

I've done something similar. tested 180 on 1-3, then 130 on 4. had all the plugs in. tested 185 on all four the next day when i took the plugs out. it's kinda like tryna turn the motor with a wrench with the plugs in. Takes a lot more work and might skew the results.

Here's how you read the noises/effects of a leakdown:

Intake valve : Air whistling out of the intake, carburetor or throttle body indicates a leak at the intake valve.
Exhaust valve : Air heard hissing out of the tailpipe, turbocharger or exhaust manifold means an exhaust valve leak.
Piston rings : Whistling or hissing out of the PCV valve, oil filler cap hole or dipstick tube means the air is pushing past the rings. Suspect ring or cylinder wall wear.
Head gasket : Air bubbles in engine coolant seen at the radiator filler cap could mean air escaping into the coolant past the head gasket.
Cracked cylinder head : Bubbles in coolant or coolant being pushed up out of the radiator neck can also indicate cracks in the cylinder head or cylinder walls.


Source: https://mobiloil.com/en/article/car-maintenance/car-maintenance-archive/how-to-do-a-leakdown-test