Very Hot Neo

[4R33L]

bit of an usual one guys but here goes....

So I have a R34 Rb25DET Neo with Tomei spec 2 cams, cometic triple layer head gasket, ARP head studs, high, mount, greddy plenum, pfc usual kind of stuff everyone has now days...

I was driving it yesterday down the fwy, when I pulled off the fwy I noticed my temp was at 106, I wasn't far from my mates house so I kept driving to his house, keeping an eye on the temp and it wasn't increasing as I was moving, I know this is still bad.... Anyway as im just about to pull into his street I notice my oil temp is almost maxed out on my temp gauge. So I shut the motor down and let it cool.

We found the cause of why the car got hot, simple coolant leak under plenum, repaired leaked, refilled with water, rebleed system and all seems fine now. The problem I am concerned about is now when it idles it seems to be a lot lumpier then it ever was before with the cams. I drove the car about 40km home, cracked gate a few times and all seems to be as normal.

I am wondering now if maybe serious damage has been done inside the motor after heating it so much? I am doing to dump all oil and water this week and change out the plugs, prob do a compression test also just to make sure all is OK.

Any ideas? anyone heard of this before? Should I check anything else?

[GTSBoy]

If you had local boiling in the head, or even if it was just dry in the head because you lost some coolant, then the head could have been hot enough to warp. I'd consider taking it to someone you trust to have a once over and perhaps look for any tell tales they might notice that you don't that there is a bigger problem than you'd hope for.

[34GeeTeeTee]

If your oil temp and water temp were that high be prepared to have a bad time! I would be getting it checked ASAP before doing much more driving!

[WMDC35]

It may have been alot hotter than the gauge says too, if it's lost enough water to overheat there may not have been enough water left in the system to give the sender a decent reading, probably why it didn't go up more as you drove further, doesn't sound good at all

[SargeRX8]

Doesn't sound good man. A note whenever the engine is running hotter than usual is to switch on your heater to max heat max speed. Ill keep an eye on this thread. I suspect the head may have been exposed to too much heat for too long and potentially warped which is a common effect of overheating. I just dont know how you diagnose this.

[4R33L]

Just an update for those that are intrested...

So we did a comp test on the motor last week, found cyl 3-4-5 all down around 115psi! Straite away suspected warped head, so we removed the head and sent it off for X-ray, preasure test and skim. Found head warped hard... Took 3 skims to get flat again but lucky that was the only damage done! No damage to valves and no cracks in the head or damage to the cams so stocked with the results.

Checked the block with a straite edge also just to be double sure and all is fine! Thank f@ck!

I have bought another triple layer Cometic head gasket but after I did I was told u don't need to replace after 1 use specially with the low ks mine had done (approx 3,000)! Does anyone know if this is correct? I'm fitting the new one now anyway but just intrested in finding out of this is correct...

[KiwiRS4T]

I don't know about the Cometic but my Tomei head gasket has been reused twice so far and is fine.

[blind_elk]

As I suggested in another thread, it's not a good idea to skim a warped head. Only the face gets skimmed, leaving the cam towers in a slight arc (might work for a pushrod engine, but not for OHCs). I believe the correct procedure is to shove it in a press and press it flat again - with heat if necessary.

Last head I warped is probably now a boat anchor.

I reckon if you measure the head thickness at both ends and in the middle, you will discover that it is thicker in the middle.

[scotty nm35]

^ Agreed.

I just used ARP L19 head studs and bolted the f*kr down hard. (although VQ heads are a lot shorter.)

[Ben C34]

True. I would only skim a head to tidy it up, not to correct warping

[Dan_J]

how much coolant did you lose ? 106 aint engine killing temps in my books

Edited September 2, 2013 by Dan_J

[scotty nm35]

It depends where the temp was taken from, and if there is no coolant flowing the engine temp could have been much higher...

I have seen 130+ degree water temp at the track without issues, other than a little flash boiling around the bore. I have alloy block and heads though, so the expansion rates are probably closer than cast iron/alloy.

[4R33L]

I have a greddy plenum so the water temp sensor remains in standard location. The hose on the cold start under the plenum was we're the leak was, the main supply hose let go so it pumped all the coolant out very quik...

I don't think the head was warped too badly as the head guy at first said it doesn't seem too bad with the figures I gave him. I will measure as u guys suggest but I also have arp head studs so maybe I can just tighten it down and pull back down flat?

[GTSBoy]

No, you can't pull it down and straighten it up once it has been skimmed. Once skimmed, the bottom is now flat, but the top still curved.

[533 RYC]

What were the measurements before any machine work? If it was bad enough for three skims, then it probably should have been straightened before any milling!

[4R33L]

No idea, didn't measure before sending off!

Can't have been too bad, car was running ok, no water in oil and comp was only down about 15psi...

I'm going to put it back together with stock cams see how it goes, if its no good ill pull it and buy new motor otherwise ill just screw boost and try get some fun out of it before it breaks!