MR240FACE

Alllllright.

So, I was briskly driving down a canyon road, keeping it pretty high in the rpms for about 20+ minutes. I was unaware the whole time that one of the posts on the bottom of my radiator snapped off, causing my coolant to drain out almost completely.

The temp gauge on my cluster doesn't work either, so when my car started overheating, I had no idea. it actually ran well all the way to my house, and I didn't notice anything at all the next morning when I started it up. fired right up and ran perfectly (probably all the way up in the H, but I had no idea being the temp gauge was dead.) it ran fine for about 5 minutes until I was getting on a freeway onramp, and my car lost all it's power, and my car would crank over, but not start.

So I pop the hood, and of course there is smoke everywhere, and after popping my radiator cap off, it was a steam pipe for several minutes, being that there was no coolant for so long. so I proceed to pull my head and sure enough the head gasket is completely blown, looked like this:





So I proceed with the rebuild. which was very budgeted.

I bought a fel-pro intake gasket set, as well as head gasket. cleaned all of the coolant/oil combination off the tops od my cylinders. and cleaned out my intake manifold. I re-installed everything, torqueing every bolt to FSM specs and working slowly to make sure I did everything correctly. I installed a new knock sensor being that my old one was cracked and melting from the severe meltdown.

I also, for the sake of troubleshooting, simplified the EGR system and removed the plate with all of the hoses and sensors, leaving only a T. One end went to the tiny vacuum hose on the back of the intake manifold, to the FPR, and I T'd in the line that comes from the gas tank. Dunno if it's correct or not, to be honest... just went off my best judgement:


So I put all that together, and when I tried to crank it over, the starter turned the flywheel and it would all move in unison smoothly, all my cam timing was dead on as was my distributor timing being on #1 at TDC. and of course my car would not fire up, just keep cranking over and over.

So, I have fuel, I have spark, and my timing is correct. so I proceed with the compression test.

#1 returned 115psi, #2 showed 61psi, #3 gave me 67psi, and #4 was at 95psi.

Would that kind of low compression mean my head is warped/cracked? Or perhaps some other problem? Would bad piston rings cause a no start?

Little lost at this point. any help would be greatly appreciated. Thanks in advance!

theboy

ya dude you warped the **edit** out of your head if thats all your getting for compression. It should be way higher on all cylinders (around 180psi, anything lower than 150psi and its a new boat anchor).

You probably k.o.'d the pistons with that much heat as well. Your looking at a full rebuild and a new head for sure.

Did you even check the head out before you re-assembled the motor? At least even a nice cleaning/visual inspection.

MR240FACE

Yeah I gave it a solid cleaning for the new intake gasket and what not it seemed pretty straight to the naked eye. I put oil in the cylinders and did a wet compression test and they all jumped like 20 psi, then went back down. fried?

R33E8

Yeah, if you went through all that your head is warped for sure.. Possibly even the block (but they usually don't warp as easy..)

MR240FACE

Would the low ass compression/warped head be the reason it's not firing up? assuming everything else is hooked up correctly?

Pro ViZIon

Did you get the head milled down and cleaned the block off really good? Are you positive cam timing is correct?

__________________
1990 Nissan 240SX w/KA24DE - New project
1984 Mazda RX-7 GSL-SE 13B

MR240FACE

I'll take some pictures of the timing tomorrow but yeah they're facing away from eachother when the dowel pin on the block is on the second notch in from the left.

And no I haven't touched the head yet, gonna have it decked if it's not too bad.

Pro ViZIon

You should normally get the head millled down whenever you remove it. You could have a machine shop test it and pressure check it while your at it. I don't think those compression numbers are going to get any better. Did you use new head bolts when you put it back together?

__________________
1990 Nissan 240SX w/KA24DE - New project
1984 Mazda RX-7 GSL-SE 13B

MR240FACE

Actually this is my first rebuild ever so I'm learning as I go. I didn't replace the head bolts which, now that I think about it, probably expanded when I overheated the car. so I'll replace those and get the head evened out.

Do you think the compression numbers are what's causing the car to not fire up? or does a car usually at least run for a second with those kind of numbers?

Thanks again I really need my car back!

Pro ViZIon

if all else its working correctly its possible for it to fire up. But with those numbers they're pretty far below the minimum. 151psi. Your also gonna need another head gasket. that one cant be re used. And you want new head bolts because the factory ones are torque to yield which means that when you torque down the head to specs they stretch to hold better. So once you torque them down they are no longer good after you remove them.

__________________
1990 Nissan 240SX w/KA24DE - New project
1984 Mazda RX-7 GSL-SE 13B