MikeyBurnz

My brothers 99XJ has had a cooling issue recently. The coolant was disappearing. He had to top off the reservoir about every two weeks. One day his wife is driving it, and after an hour in traffic, the truck starts to overheat.

So we towed it to his house to find that a HUGE amount of oil had gotten into the cooling system. So we spent a couple hours flushing all the sludge out of the truck.

We figured he probably had a cracked head. So after we were done flushing it, we refilled it with radiator fluid and put a bottle of headgasket and head fix in it... The stuff with carbon fiber.

We followed the directions exactly. The final step includes running it for 15 minutes at 1200rpm. Motor was definitely staying at normal operating temp.

Next day the wife hops in it and about 30 minutes later, it starts over heating again. This time no oil got into the cooling system or fluid into the motor.

So now he's replacing the thermostat. There's no obvious fluid coming from the waterpump either.

Any suggestions? If its still overheating after we change the thermostat, we plan on doing the waterpump.

I'm looking for a little confirmation that were going about this the right way.

Looking forward to hearing your thoughts.

Donnie_K

Well... a little bit of hindsight... that additive you added to the block is junk... and will be hell to flush out. May as well plan on a new thermostat and water pump while you're at it at minimum because of that "sealant"... is this a late model 99 with the 0331 head? Can you feel water flowing through the radiator hose once it's up to operating temp (almost 200)? or is it just solid pressure?

Cherockee

Maybe if you suspect a cracked head stop wasting money on it and start thinking about replacing the motor. I doubt it's repairable, especially since you overheated twice.

nkraus03

Thanks for posting mikey... Its my jeep. It's actually a 98. You could feel the fluid pumping through... And it was cooling down the engine. So I was surprised when it overheated again. Almost seems to be underperforming...

nkraus03

Mikey used the same sealant in his Cherokee a 6 months ago and has had no overheating issues since. And since the oil and antifreeze aren't mixing I'd suspect that the sealant actually worked. The issue is now an underperforming cooling system.
Lastly I'm only $95 deep in parts ($60 of which were the sealant) idk how much your motors cost. But seems worth a couple hours time and 100$ before spending thousands on a new motor. Plus it's my DD. so it can't be off the road for weeks/months.

MikeyBurnz

I agree. I don't know what experience you've had with this sealer "junk" as you call it, but it's worked flawlessly for me. I've clocked a solid 10,000 miles with no fluid loss or overheating. Not to mention a half dozen trips between NJ and VT.

djb383

Four main cooling system components:

Radiator
Water pump
Fan clutch
T-stat

How long has it been? New rad cap, hoses, etc.?

Firestorm500

I know this seems minor, but has the sealant stopped up the heater core yet?

If heat is lacking, you have probably stopped up the cooling passages in the engine and/or the radiator. That could be why it's overheating.

Goodbye money.

Donnie_K

X2

MikeyBurnz

Heats working fine. Used a hose on the radiator and engine block and everything flowed alright.
Nick replaced the thermostat last night and said it was idling fine this morning. We'll see what he says after he gets to take it for a drive after work today.

MikeyBurnz

Not sure. Radiator and radiator cap look pretty new. He's only owned the truck for about a year. Hoses didn't look new, but no obvious bubbles/ cracking/ leaks.

The mechanical fan spins at startup. Not sure if its suppose to do that. It does it on my 2000. I didn't notice if the electric fan was turning on or not. Is that one suppose to turn on when the truck reaches normal operating temp?

djb383

Efan turns on at 218F or when a/c compressor engages. If no known cooling system maintenance has been done, might be time to start. Wifey will appreciate it.

nkraus03

Still low flow in top hose. Let it run at operating temp for about 15 minutes. Heat felt fine. Small amount of liquid coming from the water pump area... It's the last component. Going to change it tomorrow/Saturday ...

DFlintstone

"Mikey likes it!" (Ok, couldn't resist). $60 stuff with carbon fiber....The heat works fine after 10,000 miles, and so far your??? cracked head on your 2000 is getting along OK? Just in case you didn't see this info, I found this;

# @ Drivers side top edge

The heads that had trouble were the early #0331 heads (1999-2001WJ/TJ, 2000-2001XJ) before they were revised in late 2001 (revised heads have the "TUPY" foundry mark.)

1998 will have the #0630 head, which is typically subject to uncommon individual defects rather than a class-affecting problem.

MikeyBurnz

Yeah, I've read about the 0331 heads before. The fact that I've lost no coolant over the past 6months and have seen no mixing leads me to believe that while the head is still cracked, the sealant has SEALED it. It's probably not a permanent fix (but the way it's holding up it could be), but the alternative was putting a new head on or buying a new long block. Both of these options are significantly more expensive then the $60 sealant. Especially since the head would be pushing me to the limit of my mechanical abilities and might actually have to pay somebody to replace it for me.

Sooooooooo the money is still in the bank, my mechanical ability continues to increase. And my truck runs better then ever. It's approximately a $1000 more for the entire long block over just a new head. I plan on replacing the whole motor when the bandaids finally break down, because I just don't see why I would replace only the head at that price difference.

Anyway, I'm surprised that there is so much hate about this sealant. When my jeep started having the same issues months ago, it was in a jeep forum that I learned so much about the 0331 heads and that people had a lot of success with these sealants.

Anyhow, not one of you have said, I used the sealant and it F'ed up my jeep. But I can say, I used the sealant and it FIXED my jeep. Maybe it's temporary. Maybe it's not... Time will tell.

In the mean time, if you're experiencing the same problem, I wouldn't be afraid of trying it. Times are tight for a lot of people. And time is all we need! Haha.