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motormike86 09-09-2010 12:32 PM

Flush out cooling system
I just bought my first wrangler so I'm new at all this. I'm gonna attempt to replace the thermostat ( it's a 89 4.2L) and the Haynes book says to flush out the cooling system. Are there any tricks to do this and what should watch out for?

kik 09-09-2010 03:52 PM

You can use a radiator flush or just drain and fill. Make sure you get the correct temp.thermostat. Get what it calls for, I just don't remember what I installed in my 89 4.2 but I believe it was a 195, double check. Also when you fill the system it has to be "burped" to get the air out. With the cap off, let it get to operating temp., the thermostat will open, and air will be pushed out of the system. It will spill out but it's worth doing. Close everything up and only fill the expansion tank when cold as not to overfill it.

birdhunter 09-09-2010 04:41 PM

I asume its over heating thats why
your doing the stat?
most jeeps run at 210 and thats
with a 195 stat
that is normal

motormike86 09-09-2010 08:56 PM

It was over heating, the temp gage was in the red. The oil gauge also dropped to 0, I opened the radiator cap and there was no visual fluid. Is that normal?

motormike86 09-10-2010 08:12 AM

2 Attachment(s)
These are my jeeps
04 WJ Grand Cherokee
87 YJ Wrangler

kik 09-10-2010 09:22 AM

Definately not normal. Change thermostat and flush system. Also, check to make sure you don't have a leak around the water pump.

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