Help! '90 Bronco II Keeps Running Hot

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Lee
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Help! '90 Bronco II Keeps Running Hot

Post by Lee »

Eddie Bauer 4x4 2.9L V-6. Doesn't overheat, but consistently runs hot (past the "L" in "Normal" on the temp gauge) at highway speeds, especially on hot/humid days. Seems to do fine on surface streets...I can "see" the thermostat open & the temp drop. But once it gets up to speed, the temp creeps up & stays there until vehicle stops. No obvious leaks or spraying of coolant. Have flushed radiator, replaced fan clutch & water pump, had exhaust system replaced, and installed new thermostat (although old thermostat seemed to open fine when tested in boiling water. Also, truck runs hot even with no thermostat at all). Heater core is <2 yrs old. All V-belts are new. I am running out of things to fix! Also, I'm just about at my limit of what I'm willing to spend on this vehicle, so major repairs like an entire radiator or head gasket replacement are out of the question. Suggestions, ideas, recommendations etc. would be GREATLY appreciated!!

tia,

LeAnne
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Nobody
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Post by Nobody »

Is it actually running hot?..... Could just be a faulty sensor or guage.

Otherwise, depending on the history, the radiator or water jackets in the engine could be plugged with corrosion.
FatMan
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Post by FatMan »

i agree with Nobody on the bad sensor or gauge. i had a problem like that on my 79 and what i did was went to the local grocery store and purchased a turkey thermometer and ran my rig until the temp rose then i popped the thermo in and it read a perfect 190*. sending unit was faulty.
Darker than your average wheeler!!!!
TNMAN
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Post by TNMAN »

I was having problems with my 2.8 a few years ago...running hot on the trail. I replaced everything I knew of and still got the overheating.My solution":I drained the coolant and replaced it with plain water and aproduct called -40 Below. It lowered the operating temp by 20-25*. The additive is used by dirt track car racers to keep the engine cool after their radiators become clogged with dirt/mud. Now that I run a V8.I again had overheating probs. I was going to get some more -40 Below. but it seems that it was taken off the market(or so the parts house said..due to "enviornmental concerns"). I now use a coolant additive made by Royal Purple that lowers the temp. It doesn't seem to work as good as the other, but I am also using anti-freeze with it. This does not cure the problem but it does fix the symptom.
Lee
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Post by Lee »

Thx to all who replied. It doesn't seem like a problem with the temp gauge; the engine itself is definitely running hot. Hubby's going to try some kind of super-caustic flush & visually inspect hoses etc. to make sure there's no gunk blocking the flow of coolant. After that...pthbthbthbthb! <throws up hands in despair>.

Thanks again,

LeAnne
b2binbad
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Post by b2binbad »

Try the tauras 2 speed electric fan, I heard it does wonders for overheating. I know of a few people who have used it from Jeeps to B2s.
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FatMan
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Post by FatMan »

hey Lee nice to see a female on board hope you get the problem fixed. i agree with the tuarus fan idea. it's not to bad of a job to install.
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Born Again B2
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Post by Born Again B2 »

Lee, I was reading all the input to your over heating problem, and noticed no one thought to have you take a compression test of your motor. This would show you if you have a blown head gasket, or cracked head. If it shows a bad cylinder, there are lots of good sealents made now days, that if used right, won't plug up your radiator. Just an idea. Good Luck. :idea:
84 B-2. 4.0, Headers,Cam,Nitros,Ported Heads, D-35 & 8.8 with 31 spline axels, 4.56 Gears, Detriot Lockers. Built C-5.
Lee
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Post by Lee »

Hi, Born Again B2 & other recent posters. Actually we did consider the possibility of a cracked head and/or blown gasket. We were thinking of using an additive like ThermaGasket or the equivalent product from Bars-Leak (can't remember the name...Liqui-Gasket or some such). But wouldn't there be visible steam and/or water in the oil if the heads were going? We just changed the oil recently (no water) & haven't seen any steam. Xerex flush did loosen some corrosion & bits of gasket from an old repair, but the truck is still running hot. I think the next step is going to have to be medicating the symptom rather than finding the cure; I'm looking at using some stuff called 40-Below to lower the operating temp. That should get me through the rest of the summer (I hope!).

Thx for your comments,

LeAnne
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Post by Nobody »

Pull the fan shroud and see if the radiator is plugged with crap.

Also check the fan clutch.

If your ignition timing is off, that can cause an engine to run warm as well.

But.... from the symptoms you claim, it really sounds like a plugged up radiator. If you don't want to replace it, you might try removing the plastic wheel wells. That will let a lot of heat out of the engine compartment. Wouldn't hurt to wash any gunk off your engine either.
TNMAN
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Post by TNMAN »

I mentioned in my previous reply that the product...-40Below...was off the market. NOT SO! I found some at an AutoZone(yes...I do sometimes go there!). It was about $26.00 a can. This stuff really does work. Just be sure to drain it out of your cooling system before the weather drop s below freezing.
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