opinion on blowing my motor?

[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

[Squizz]

You have nuked a piston.

[strutto]

You have nuked a piston.

Rebuild time...

[rob77]

When my engine blew oil sprayed out of my catch can all over the engine, not sure which pistons went but i did 2 of them... 3 and 6 i think. I was running over 350rwhp at the time mind you and 1.2bar of boost

[DezertEagle]

Same symptoms as mine. Just get a new motor in if you're not gonna go for big power later. Check to see it's got good compression, you may even be able to get a motor with a few mods etc.

Otherwise RB30 rebuild sounds good lol

[cameron]

Deffiently piston has goooone... Oh well, Time for a set of forgies to be put in

Number 6 piston is the most common one to go on RB25's.

It'll look somthing like this, Depends if you were on boost when it blew the rings.

Jun

[Duncan]

.........dramatic power loss followed by smoke pouring out my exhaust.  

......it seemed like blueish/white smoke......................

uh-oh....engines run on smoke, and you let it out of yours.....time to pull it out and rebuild....

[DETurbine]

Thanks for the reply guys. I was always aiming towards the thought that I blew my piston or cracked a ring land. I just was not 100% sure. I am going to take it apart hopefully in the next few weeks and take a look at it to find out for sure. If that is the case the I will be adding some new 87mm Wiseco's, ARP head studs, shot peen the rods, ARP rod bolts, turn the crank, 1.2 Grex head gasket, and then that should keep me happy for a while.

Just hope nothing else got damaged (rods, crank, anything in the head, etc....). For those that have blown a piston, was anything else damaged?

Thanks,

Zach

[cameron]

Depends on if you drive it much after blowing it up...

I've seen valve's been dammaged a little like its got detination on it ! And bits of piston plasted on them - nuthing too much that can be cleaned up. Score marks on the bore, depending on how bad it is usally get over sized piston so it doesn't need to be re-sleeved to standard size.

Jun

[DETurbine]

Thanks for the reply guys. I am sure it is a piston that gave out (#6), but I have a feeling that I cracked the rest of the ring lands on all the other five. Same thing happend to my friends RB26. I just hope that a build up of pressure did not get down into my crank case and cause damage to anything else. I went over there last night to check out a few things and checked the dipstick and there was no oil that was shot out of it, so hopefully that is a good enough sign to show that there was not that much pressure in the case. Normally even when pressure it build up in there, it does no damage to the rods. I am going to get my rods machined and checked and also turn the crank as well. Really hoping that I will have to do nothing to the head. Just really sucks not knowing what damage it really did and am not going to know for at least another 3-4 days. Oh well have waited this long, so a few more days is not going to hurt. Going to take me another 30min to pull the motor out (just the two mounts and tranny mounts left) then probably an hour to hour and a half to get my tranny off, motor on a stand and head and oil pan off as well, then will be able to see what went on.

I will keep you guys updated,

Zach

[R31Nismoid]

i did 3-4-6 half way to a fully blown motor

The only other damage was a bit of cylinder marking, but it came out with machining that had to be done anyhow

but yeah... rebuild is the go tried and proven is

Arias forgies

RB26 rods

Usual machining etc etc that goes.

Then your 25 will last a lifetime, great for 300rwkw too