Opinion on my motor blowing?

[DETurbine]

Well it is finally time to see what is wrong with my motor. Ending of last summer I was tunning my car with my new Nismo FPR and while in the process of doing some test pulls blew my motor. I gave it a pull and noticed an dramatic power loss followed by smoke pouring out my exhaust. I then took it back to my friends house (a few blocks away) and opened the hook to see oil sprayed on the side of my strut tower (shot out from my HKS BOV). We then did a compression check on it and it was as followed....first 5 were about 110psi and cylinder #6 was only 25psi. We looked into the cylinders through the spark plug wholes and noticed quite a bit of oil in the cylinders, especially #6. I took the intake piping and intercooler off and it was drenched in oil. A few days later we start it again and start to notice that it is making a sputtering/ knocking kind of noise (not sure if it was really knocking, to me it sounded like more of a compression sputtering noise). I am not sure what the problem is and wanted your guys opinion on what it could be. I am going to do a leak-down on it at the end of this week to narrow it down and hopefully find out what the problem is for sure. Just wanted to see what you guys thought before I did that.

When it blew I noticed a dramatic power loss and it seemed like blueish/white smoke. I did not notice if the water temp was climbing or not, since his place was only two blocks away. Before this had happened I have always noticed oil coming out of the turbo, so I am sure that is where the oil came from and probably totally gave out when I turned up the boost to 14psi on that test run. I took my top section of the intake manifold off a few months back and noticed that there were puddles of oil down the gallies.

I am really hoping that it could be the head gasket, but something is telling me since the compression test was an even 110 (almost all the way through) except #6 (25psi) that it is probably the rings or ring lands...or can a head gasket have that same compression test result?.

Let me know what you guys are thinking if you could.

Thanks,Zach

[mmatl16]

i was about to say check the turbo....but since u did i would say head gasket for sure

[NissanTurboSix]

To check rings:

Squirt a little oil in the spark plug holes. This will help the compression rings make a seal against the cylinder walls.

If this helps compression results, its the rings. If the results d o not improve, it could be the head gasket.

Remeber, there are 4 main ways oil can get into the cylinders:

Head gasketIntake gasketOil control ringsTurbo

Only 2 of those will cause a low compression results.

Good luck!

[DETurbine]

To check rings:

Squirt a little oil in the spark plug holes. This will help the compression rings make a seal against the cylinder walls.

If this helps compression results, its the rings. If the results d o not improve, it could be the head gasket.

Wish I could do this test, but there is already oil on top of my pistons from the turbo seal going out on my turbo and shooting oil through out my system. My head is probably filled with oil, since I took off my top portion of my intake manifold and looked down the runners and there are puddles of oil in them.

I am just thinking by a head gasket going out, could it evenly have low compression (cyl 1-5 had 110 and then #6 was at 25psi) through the cylinders?......or is that most likely the rings/ring lands that could cause almost equally low compression?

Can a headgasket cause a sputtering almost knocking noise when blown?

[gawdzilla]

the leakdown should tell you if its the rings or the HG. try to listen for or feel where the air is leaking out from. to be SURE of where its leaking from, you can pull the exh mani, int mani, oil pan, and feel for it.

[Imissmyturbo]

From what you are describing it sounds like you broke a ring land on # 6 cyl which caused compression to fill into your crankcase and that pressure what vented into your intake manifold. Since the pressure was much higher then the crankcase is designed for oil made its way to your intake. Did you notice if any oil shot out your dip stick? You will most likly need to replace that piston and maybe some others as well. If money is tight you can try and source some stock ones. If you have the money I would upgrade your pistons and rods. Funny thing about rods are if they take a hit, they can loose there strenght internally and let go at a later time.

[yellow_jacket]

Personally, I would pull the head and figure out what the problem is. The compression is so low in that cylinder I would think it was a burnt valve or severely shattered rings.

If by some chance enough oil built up in that cylinder from the turbo seals going, it could have shattered a ring. And if it was enough to shatter the ring, I would definetely tear the motor down, replace the rods, pistons, and the valves on that cylinder. I've had too many bad experiences with pistons breaking up, rods being slightly bent, and even rods breaking.

[fito]

you blew the pistons.