Cooling Question on an XJ and a Blazer

Ricky B

Ricky B

Wiiide Open
Joined
Mar 20, 2005
Location
LKN - Tha Dirty Mo (Mooresville, NC)
Got two questions that are pretty related.

My little bro's xj (an 88 w/ 4.0) has the closed cooling system. His temp gauge doesnt work and i know cherokees are notorious for over heating so I'd like to either get his working again or just put in a new aftermarket temp guage. If I do try and fix the exsisting guage where is the actual sending unit located and would replacing that be my first step? I

f I were to just put in a whole new guage which I would prefer, where would I put in the new sending unit that comes in the guage kit? It has a couple of fittings that look like they need to be welded in that have threads for the sending unit. Same with an 85 K5 Blazer I want to install a temp guage and I'm not sure as to how to put int he sending unit, like i said the temp guage kit I got for it has like a bunch of fittings that look like they need to be welded in.
Thanks
 
Not sure where the temperature sender is on the XJ, probably in the block near the thermostat. I'd find where it is and make sure the wire is attached and not corroded.

As for the closed cooling system...
coolingsystemflipoff.jpg

Get rid of it!!! I would boil over ever trip to URE.

Converting it to a open system is easy, go to a junk yard and find a heater valve from a 90-92 xj to replace the one you have and toss out that resevoir. Also find one of these, an in-line radiator cap. Mines a Moroso from Jeggs.
coolingsystemcap.jpg


Then I installed a cheapie overflow tank and I was golden! The system has never overheated since this change and runs a few degrees cooler. I think I have less than $75 in the conversion, one of the best mods on my XJ.
coolingsystemoverflow.jpg


Gary
 
^^ True. True. ^^

You can also tap a wire into the aux. electric fan so you can put it on a switch and turn it on (like... in traffic, slow trails, etc.) when you want. That'll give some more airflow to help the radiator work.

But, let's face it... XJ's without major mods are just gonna run hot.
 
Clogged coolant passages are what cause the majority of them to overheat. I ran an old stlye open system in my MJ/buggy , turning 5 to 6 grand with a stroker motor for sometimes several minutes at at time trying to heat tires and get over an obstacle it never ran more than half way up the gauge. Why?....because it was a fresh motor that had the passages cleared by throwing it in the vat at the machine shop. Before I rebuilt it I couldn't drive from the pay station (NC side) to trail 4 (about 3 miles or so) at Tellico with out it wanting to run hot. I'm sure someone may offer an over the counter "mechanic in a bottle" type flush for the cooling system, no where near as thorough as the rebuild, but I'd try that first.
 
yea the thing runs fine so far but we havn't really driven it for very long either yet. Since the temp guage is broken im worried that its gonna overheat and me not know about it so fixin the guage is a priority. I'll have to try and find out whats messed up with it.

What about the guages i menationed where you can just go buy a whole aftermarket kit, all the ones I've seen have like metal fittings you have to install that the sending unit goes into. Where would you put that?
 
usually, you can put the new sending unt in place of the non-working factory one. Thats what all the adapters are for, so your new sending unit matches the threads and depth of a factory location.

BTW, not sure on your model year, but my 4.0 has 2 temp sensors, one works the gauge, and the other is for the ecm.
 
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