1989 SOHC zero compression from cyl. 2

[rdoni2]

Hi guys, so I'm pretty much at a loss on what to do right now and I would really appreciate anyone's input.

I picked up an 89 sohc 240sx with the engine not running. After inspecting the car, I knew the timing was off. Looked like it jumped two teeth. We reset the timing and did a compression test and the first two cylinders were bad.

So we pulled the head off to check it out. The valves for 1 and 2 were bent and had hit the pistons slightly, but overall the pistons looked pretty good. I took a picture of the pistons, so let me know what you think.


We went and got another head from a friend that looked good and put it onto the car. Set everything up, and it wouldn't start. My friend realized he 180'd the timing. So we did the timing again and it started right up.

Now the car is running slightly funny, so we did another compression test and sure enough it's only running on 3 cylinders. The number 2 cylinder reads ZERO compression.

So my question is, do you think that the piston rings are bad? Was it possible that one of the valves in cyl. 2 got bent because of the timing being 180'd? Or maybe the valves on the new head that we got were already stuck?
Check out the pictures and let me know what you think. Thanks guys!

[Sam_Well.13]

So let me see if i get this right.

When you first got the motor, cylinder 1 and 2 are bad. So you replaced the head from your friends SOHC. Now you did a head swap, Cylinder 2 is still bad.

Could be the head.

[rdoni2]

That's what I was thinking. On the original head, the valves were clearly bent and stuck open. I'm wondering if it's worth it to so another head swap with a head that I know compresses well or should I swap another entire motor in? The car has 230,000 on it, but the owner's took pretty good care of the car from what I can gather

[Sam_Well.13]

looks like the engine has been rebuilt. The piston looks WAY to clean to be 250K.

I say get the head rebuild. Worst come to worst, you can sell the rebuild head or use is with another motor.

[rdoni2]

So then you don't think anything is wrong with the piston rings or the block?

And also, I cleaned the pistons off, so that's why they might look so clean? haha idk

[Jaketenpointo]

You should put oil in cylinder 2 to see if the compression jumps up.

[rdoni2]

but there's absolutely zero compression coming from cylinder 2. The needle doesn't even jump

[Sam_Well.13]

What he meant is that, the oil will SEAL up the gap to cylinder 2 enough that you will get compression or the oil will sip in through the bad piston ring, if its the piston ring.

[rdoni2]

when we first got it, we put some oil in all of the cylinders and it was the same. So I'm not too sure what that would mean

[Sam_Well.13]

Well if thats the case, could be the head. Any reason why your friend got rid of the head? I mean was it still in working order even though he messed up the timing on the motor the head originally came from?

[rdoni2]

He had a few in his backyard and we picked the best looking one. I asked him if it was good, and he said yeah, but I mean who wouldnt? It was a free head though, so it's not too big of a deal. I'm just hoping nothing is wrong with the piston rings. The car isn't smoking at all when we drive it around or anything

[n8RPS13]

I'll sell you my virgin KAE if you want it man and it runs great! I have NEVER had any problems with it other than replacing the typical parts, thermo water pump when I did the thermo, starter. Other than that its stock. I am getting ready to put in a VQ35 PM me if you want it.

[rdoni2]

How much are you thinking of selling it for?

[darkdma]

Listen to the exhaust to see if there is any noise coming from the tail pipe, and listen to the intake to see if there is any funny noise either, if the exhaust sound funny then u got a bad exhaust valve, and if the intake sound funny then u got a bad intake valve. and also check the radiator pressure and make sure there is no compression leak into the radiator. Did you meassure the block surface to see if there is any warp or uneven surface?

[rdoni2]

Well we did another head swap today and I'm happy to say that she is now running good. Turns out the exhaust valve on cylinder 2 was not seating right. Thanks for all the help guys! I really appreciate it