Sophrony

Hello, I recently purchased a 2000 Cherokee (RHD) for work.


After the purchase, I replaced the valve cap gasket and flushed the coolant/radiator system. Although the coolant had a brownish, rusty look about it (but not particularly oily), the oil looked good without any sign of creaminess.


On route, after 3 or 4 hours of driving with the engine running well, the temperature spiked at a stop. I checked the engine and only found the coolant to be low, about halfway between low and full. I added more coolant. I thought that perhaps I had left some air in the system after flushing it and that this would probably solve it. I let it cool down, before taking it back on the route. The same issue occurred again - at a stop the temperature spiked. I called the supervisor to be pulled out, thinking that the water pump may have been broken. Seeing that the temp only spiked at stops, I figured I could make it back home. I didn't make it, because the temp spiked again while going 55. I pulled off at the nearest location and saw steam coming from under the hood. The coolant tank was up to the cap with brown liquid and floaty oily stuff. Steam was coming up from the middle right of the engine, in the middle where the air intake and outtake meets the head. Two puddles were under the car, one was oil and the other was coolant, but they were distinct puddles. Oil had gone up and out through the dipstick, which showed the oil was creamy. I had it towed and now suspecting the head gasket and maybe also the head might need to be replaced, I've taken it apart.


Removing the valve cap showed mixing, with creamy stuff in the oil. The air filter had oil/coolant slime all over it. However, draining the oil and it just looked like normal oil.


Looking at the head,

• The head gasket looks new.
  
• There was no visible crack or coolant streak on the head.
  
• There are no observable fractures or cracks under 7X magnification.
  
• I could not find any evidence of minor warping using a metal straight edge and a 0.0025 gauge.
  

The head is a 0331, but no evidence of cracking between 3 and 4.


I know the previous owner rebuilt the block about 4 years ago. I've looked at the block for warping and cracks too, but didn't find any.


I am hesitant to put it back together, since I have no idea where the failure occurred. Any suggestions for what might have gone wrong?

doublechaz

If it wasn't for the overheating "oil" in coolant can rarely be trans fluid from an auto trans.

In your case I would have a machine shop check the head with dye or magnaflux for the crack.

Sophrony

I'm considering just popping the head back in with new gasket. If it doesn't fix the problem, then I think I'll get a shop to test it. I'm thinking this is a fairly low risk option.

Randy Bobani

It's an 0331 head. They all crack and cracks are invisible most of the time. Don't even bother paying to have an 0331 head magnafluxed, it's cracked. Waste of $. TUPY heads are widely available and they are the best option for a replacement. I just installed a TUPY head on my 00'. It was $100 for the head and $400 at the machine shop for cleaning, magnaflux, resurfacing, valve job, new springs & seals. I used a FelPro Permatorque MLS head gasket, Victor Reinz manifold gasket & Mahle head bolts. She sealed up great and I have no more coolant in the oil which was verified by Blackstone Labs.

Sophrony

At $500 why not just go with a new head?

Honestly, $500 is the 2/3 the price I paid for the car.

I have an extra head from a salvaged jeep, but I put the head back on to see what'd happen.

Randy Bobani

The only new cast in the USA head is $1500 from Edelbrock. What casting do you already have?

dave1123

I'd be willing to bet if you keep driving it with that 0331 head, you'll wipe out the bearings with coolant and then you'll be replacing the whole engine. There are 2 simple options, a "Tupy" head or a "Clearwater" head. An older 0620 head will fit, but you'll need adapters for the exhaust and intake manifolds and brackets to mount the coil rail.

Randy Bobani

You mean an 0630 head? There was never an 0620 casting. It was 2686, 7120, 0630, 0331 & 0331 TUPY. While there were minor changes to the intake and exhaust ports on each casting, exhaust and intake manifolds are all cross compatible. Bosses for the coil rail were added to the 0331 castings. Also that Clearwater/Promaxx head is a Chinese casting, machined and assembled in the US, no thanks.

dave1123

You will find the exhaust ports on the 0331 head are smaller than the earlier heads and do not seal on the older exhaust headers. An adapter is needed and the adapter also extends under the intake manifold to keep the mounting bolts the same height. Okay, I made a mistake on the head numbers, but you got my point, didn't you?

I bought a Clearwater head in 2015 and it was manufactured by Odessa Cylinder Head in Clearwater, FL. It now has over 100K miles on it with no problems. How do you know for sure it's cast in China? The Tupy is cast in Brazil at the Tupy Foundry by contract with Chrysler Corp. Go ahead and spend the money for an Edelbrock if you like. I doesn't bother me in the slightest.

Sophrony

I went ahead and just replaced the head gasket. This fixed the problem. I guess I got lucky and the head isn't cracked yet. I've put 1000 miles on it since the fix.

Rogue4x4

Tick...tick...tick

One of these days, baby...milkshake, BOOM!!!!

Bonus points for anyone who gets the reference