rokblok

iTrader: (1)

Well, my 3RZ swap has developed a hiccup. It lasted flawlessly for about 75K miles. But...

I was on the way home to Tennessee from Miami. Around Orlando it started to get warm on the gauge. By the time I got off at an exit and checked the coolant level, it was hot. 220* according to the OBDII scanner. But I popped the cap, and it took a whole half a quart... Coolant temp went back to normal and I drove on home. That was two weeks ago. Then a couple days ago, I had driven an hour to check out moms car, and on the way home it got hot again. Limped it home, never getting more than 215* on the scan tool. Popped the cap today and put in a quart of coolant. When I started it up, I got a good deal of pressure and started spewing coolant back out. And I smell fumes in the radiator, almost exhaust smelling, along with a steady stream of steam.

So, I'm sure we have a head gasket/head issue. Any thoughts before I take it off? I wondered about doing a re-torque of the head bolts, just to see what that would do. Thoughts?

I will take it apart anyway, since I want to do an MLS head gasket and finally install the ARP studs for the head...

JasonYota

iTrader: (1)

Sorry to hear that. Really only way to know is pull the head and see if it's cracked or just the head gasket let go.

rokblok

iTrader: (1)

I was sorry to find it out. Lol. Any thoughts as to why it may have let go?

I will try and get it apart tomorrow. Not in a massive hurry yet though. The wife's '88 Runner will be here Thursday and I finally get to start her 3.4 swap. Yay!

rokblok

iTrader: (1)

Took the head off this morn, only took a couple hours, and drove it 45 min to the machine shop. I will pick it up in the AM. He said no cracks, and everything looks ok. He shaved a smidge off, nothing drastic. Gasket was blown between #3 & #4 cylinders. And from cylinder 4 to a nearby water jacket via the head gasket. No coolant/oil mixing, no coolant in the cylinder. Cylinders look awesome, crosshatch still flawless. A little bit of carbon on a couple spots of the pistons, but all cleaned up now. Head studs and new gasket set hopefully going in tomorrow. I will post final outcome.

HighLux

Sounds like you're on it. Pretty rare for one of these to pop a gasket. Mileage?

rokblok

iTrader: (1)

Approximately 75K since the rebuild when it was swapped. But the machine shop re-used the TTY (torque to yield) bolts, so I'm hoping that was the root cause. When I loosened the head bolts, there were a few that were significantly tighter than the others. I'm thinking the several "looser" bolts allowed uneven clamping pressure and allowed the gasket to fail. I was going to do an MLS head gasket, but that requires the block and head to be accurately machined, and I didn't want to pull the block for that.

I had the ARP head studs for the rebuild, but I didn't get them from LCE by the time the machine shop put it back together... So I saved them, and they're going in now.

rokblok

iTrader: (1)

Well, I replaced the head gasket, used ARP studs, tightened them down in 7 steps going up to 80lbs-ft. Everything went back together great. But it still has excessive pressure coming from the radiator and overheating. So a new head gasket and studs didn't fix it. Machine shop said it checked out fine, no cracks found. So what am I missing?

Is it likely that the machine shop didn't check it well for cracks? I certainly didn't see any. They did machine the head a few thousandths, saying it didn't need hardly any removed.

What else could cause overheating, excessive pressure in cooling system, but no oil/coolant mixing?

JasonYota

iTrader: (1)

Did you check the mating surface on the block with a straight edge and feeler gauge?

thefishguy77

iTrader: (1)

If they machined it then they probably pressure checked it for leaks. If compression is good and no water leaks I don't think it's a head. Could a previous owner have used a bars-leak type product and you just had a piece break off and plug a cooling passage or at least partially? Just guessing. Really weird problem. Did you put a high flow water pump on? ( do they even exist?). Just guessing. Keep us posted on what you find out. Good luck.

rokblok

iTrader: (1)

I did check the block while it was in the truck. It appeared flat from any direction I tried to get a feeler gauge under.

And there has been no Stop-leak put in this engine. With the swap it was completely rebuilt, new radiator, etc.

I'm gonna have to guess the head is cracked somewhere...