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windridge98 05-01-2011 04:43 PM

Cooling System
I bought a 98 Wrangler last week with 80,000 miles. When I get it home I start doing the checklist of things I should have done before I purchased it. I open up the radiator and yuck. It is filled with brown globs of goo with the consistency of sticky custard. It is not oily and I donít think I have a bad head gasket, but Iíll keep watching for other signs. So I go to the forum and start doing searches and find it may be bad dex and to flush the cooling system. I buy the Prestone flush, enough for my F150 also, and a bunch of green Prestone.

After running the flush, I decide to run another bottle of flush through the system, it was pretty dirty in there. When the engine was running it spiked temperature almost to red line, the check engine and check gauges lights came on, and the heater went cold. I gave it throttle and it cooled back to 210 where it had always ran, the check gauges light went off but the check engine light stayed on. I figured the thermostat must have got a glob of the goo plugged in it. After finishing the flush, I replaced the thermostat. The old one was in terrible condition.

With the new thermostat in place, it now runs at 195 degrees where it should, but I have a hard time getting much heat out of the heater. When it idles it is barely warm. If I drive it around, it warms up but if I go back to idle it cools to about room temperature. I have heard Jeeps have super heaters so I am a bit concerned for next winter.

Does anyone have any ideas about:
1. If flushing a radiator twice will permanently eliminate the very sticky brown goo
2. Should my heater be pushing out more heat, if so any ideas
3. Short of taking it to the dealer to pay $$$ to turn it off, should I be concerned about the check engine light

Thanks for any input.

SilverTJMike 05-01-2011 05:07 PM

Have you tried directly flushing the heater core by disconnecting the hoses?

UnlimitedLJ04 05-01-2011 07:20 PM

1. No, the sticky goo is nearly impossible to remove. My guess is somebody overheated the motor, the heat gasket started to fail, and the previous owner bought some SilverSeal or similar head gasket sealer. That stuff goes into the radiator in an attempt to seal a head gasket. It basically turns to glass in the heat of combustion. My friend had to use this stuff in an attempt to save the motor in his truck, and we spent several hours trying to flush it. The thermostat was similarly plugged with the junk. We ran a garden hose with flush kit for hours, reved the motor near redline trying to pump that junk out, and it just kept spewing out. It coats everything in the motor, radiator, water pump - EVERYTHING, and sticks to it like peanut butter sticks to the roof of your mouth. We gave up. he's gonna sell the truck with the understanding the motor needs fully rebuilt.

2. yes the radiator should be pumping out lots of heat. its clogged with that goo. you can try flushing the crap out of it by directly hooking it to a hose, but my guess is you'll just end up needing to replace the entire heater core to get maximum efficiency.

3. the CEL was likely due to the overheat condition. disconnect the battery and the CEL will clear. would be good to know what the code is, in case its something more serious.

Also, I wouldn't use anything Prestone in a Jeep (or Ford depending on year). Jeep's now spec HOAT antifreeze, like Zerex GO5. All newer Ford's also use HOAT. This is what you want to run. Prestone does not make an HOAT antifreeze.

The other possibility is the goo is Dex-Cool contaimination. Basically, you'll need all new radiator, new heater core, new water pump, all new hoses and to flush the remainder of the system the best as possible. If you can't get it out of the block & heads, you're looking at a new motor. If you've got a warranty from the place you bought it, this would be a good time to take it back and use that warranty.

TTTE 09-29-2013 01:54 PM

I had the same issue with the heat...Something strange worked. Most vehicles will pump heat with the a/c setting...less humid air. Mine, [2000TJ] would not. After flushing coolant/heater core the simplest fix surprised me. Try using settings on the knob without the snowflake. Yea its more humid air, but it is hotter than hell. Very odd, but it worked for me. Hope you have luck.

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