skeletorvongreyskull

I posted last week about my little overheating problem- Put in a water pump and a radiator- took it on the highway 120 miles, was awesome , everything was cool. Get to the city, starts to get hot at stoplight. not overheating, just hot like 2/3 to redline.

Okay, get on here, do the forum search, decide its the fan clutch. I go to napa, get a heavy fan clutch, install it- bam. got about 10 degrees cooler, but still gets hot at a stop light, or while idling.


Fumble around under the hood, realize I have no fan shroud, figured its a "possibility" the extra give or take 10 degrees of heat are coming from the air not being routed correctly under the hood-

go to junk yard, get one off a comanche, bolt it in-

got me about 3 more degrees cooler.

So at idle (or stoplight), I'm still about 1/4 past the 210 mark.-

I check my electric fan. It comes on at about 230. I gotta try and get it hot, see if it turns on. one time it does, one time it doesn't/

I unplug the wire from the thermostat and the thing spins like normal, so i dont tink its the fan. maybe the relay? where the @#$EWRT is the relay?

From what I'm reading it should kick on at 218' but it only gets hot up to about 220 now, when i flip on my a/c is goes back down again-


SO.

Am i asking to much of these analogue gauges? Will I EVER get to stay at 210 at a stoplight? will it always get a lil hot at idle or in traffic?

The only damn component of the cooling system i havent changed this week is the thermostat. But if it runs beautifully on highway, cools back down when it starts moving, is it the nature of the beast? could i have crud on one of the sensors?

WTF? My best friend had a jeep years ago and had a similar heating problem (albeit a bit more serious) and said he could never get to the bottom of it-

Im determined as hell now to get this thing running 100%

any suggestions?

djb383

Always a good idea to verify temp with a IR temp gun pointed at the t-stat cover. Gauge could be wacked. If the stat is the last cooling system component not replaced....why not? Any motor will run a little hotter at slow/no vehicle speed due to reduced air flow thru the rad.

tjwalker

Agree with djb383 on this one. You could have inaccuracy in the coolant temperature sending unit, the coolant gauge on your dash cluster, or both.

Job #1 is to verify. Beg, borrow or buy an infrared point and shoot temp gun. It is one of my favorite tools and I use it for many things other than automotive. My Raytek MT6 is about $50 and I've seen other infrared temp guns for as low as $25. Any shop will also have one and would probably test your temp for little or no cost.

Point it directly at the thermostat housing of a hot engine. Then you'll KNOW for sure what the coolant temp is.

Good data = good decisions.

Good luck and keep us updated.

skeletorvongreyskull

I'm gonna get a temp gun tomorrow and i already have a tstat and gasket already so might as do that.

funny note is the oil pressure gauge reads a little high as well- seeing that its new to me and the last oil change from paperwork was 800 miles ago, oil looks clean as hell, right levels, a lil leak at the filter. nothing serious like 2 drops a day- I'm guessing its just a crap oil filter. I had the same problem with my comanche, he only liked mopar or wix.


ill keep you posted

skeletorvongreyskull

no heat gun

I think this is what i really need. Everything seems fine. hopefully its the damn gauge. Relay works, fan kicks on fine, while moving 0 problems- stays at about 190ish-200. fan kicks (though at about 225-229ish and cools is down fine) so i think (hopefully) the gauge is off about 10 deg.

heres crossin my fingers.

tjwalker

If you find out that there is inaccuracy, I have found that the coolant temperature sending unit that provides the input signal TO the dash gauge is usually the culprit.

And they're relatively inexpensive, so if the gauge reads differently than the I.R gauge, I'd swap in a new sending unit. If it's still off after that, the gauge is all that really is left. At that point, I think I'd live with it and just know that you are "X" degrees off.

djb383

What's your ambient temps? How old is the fan clutch?.....and other cooling system components? This time of year and for the next several months (cool/cold ambient temp), the efan on our XJ will never "turn on" (unless a/c compressor is engaged) because coolant temp won't get even close to the 218 efan "on" temp. If all cooling system components r in top notch condition, the main belt driven fan should keep coolant at or slightly above t-stat open temp when driving in cool/cold ambient temps, especially if the heater is being used.

skeletorvongreyskull

Fan clutch was just replaced with napa zj fan. Water pump new, radiator new, coolant new.

Its 65-70 degrees here.Don't use heat, don't use A/C but they both work.

Cruising highway speed is just a hair under 210. Doesnt move at all. The second the vehicle stops, idles, hits traffic, or goes under 15 mph, temp rises to 230ish.

skeletorvongreyskull

trying to find a heat gun to verify actual temp.

skeletorvongreyskull

HARBOR FREIGHT IR GUN!!!!!!!!!!

Gauge is double the actual increment in temp. highest i got today was 213 with temp gun and on gauge 220ish.

cruising temp was 204.

Coolant flowed through @ 195. Fan never came on while i was out there. Fan will most likely kick on around (real temp, if calculations are correct) 223.

I hope that means my problem goes away, but I'll know for sure next time in traffic.

djb383

213 still seems a tad warm for 65-70 ambient maybe but certainly acceptable and far from overheating.