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Old 09-27-2009, 08:28 PM   #1
vinnyvee's Avatar
Join Date: Sep 2009
Posts: 1
Smile thermostat question...

just bought an 89 wrangler yj...6 cyl had no heat so my brother and i flushed out core with hose and drain brown fluid out of system..also flushed back from top heater core hose to bottom radaitor hose and got alot of brown liqiud out of there...put it back together and we are getting heat but just as heat comes up the thermostat opens (at 170 degrees or so) and temp drops to like 140 then rises back to 170 and therm opens again...over and over and heat in car never really gets hot.....I called previous owner and he said his mechanic installed a thermostat to compensate for the blocked system...(i dont know what that means but i'm assuming he put in a lower range thermostat)....anyway i intend to put in a 195 thermostat and my brother says while we have it off we should do a proper flush with chemicals....I'm all for that but he thinks we should replace water pump while we are at it.....I know its not an expensive part but I'm trying to save where I heres my question (finally!) Is the therm change and flush enough to fix my symptoms or is my brother right and we change the water pump too....thanks in advance for your help....

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Old 09-27-2009, 08:43 PM   #2
buckshot500's Avatar
Join Date: Mar 2009
Location: Carolina
Posts: 798
If the water jacket in fact has a blockage it would run hotter. If it had a 170* t-stat, it's too low & you are on the right track with the 195* one.

If the water pump is leaking at either of it's weep holes it's a great ides to replace it.
if not, & it's working I would wait until it needs to be replaced.

The only exception to this would be if you live in a really cold climate & don't have a heated garage. You'd want to maybe replace it now instead of waiting.

As far as no heat goes, the heater core is always hot in these rigs. (There's no valve in the coolant line, rather they just close it off from the ductwork) Check to see if all the duct doors are working, cables, levers Etc. After it's warmed up, see if the heater core hose barbs are getting hot, don't burn yourself but lightly touch the barbs near the firewall in the engine bay.

Another thing to think about is this mod, I have installed the replacement YJ blower motor from autozone part # PM102, & it's a drastic difference.
Chevy blower motor for YJ swap Napa#655-1039 PM102
90YJ 98XJ
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