overheating tried everything. help!

[bullfisher]

Howdy! I have a 94 b4000 and my coolant dumps into my overfill tank within 5 min after startup starts spewing over and spikes the temp past normal. Its got a new t stat, water pump, rad. cap, temp sensors and did a coolant flush. I think my head gaskets ok theres no white smoke or foam under the oil cap. just cant figure out why it wont circulate through my motor and just spew out my overfill so fast. any Help?

 

[BillupsOMally]

I had the same problem, with a 2.9 mind you but it shouldn't make a huge difference, turned out my old thermostat was stuck, so I replaced it. Still had the same problem. I scratched my head till my scalp was raw, checked to make sure the rad, hoses, water pump, and galleries inside the motor were clean and working proper.

Finally decided to check the new thermostat. Turns out it was defective and stuck shut.

It's a 10 minute job, I'd recommend checking it.

 

[AllanD]

I've been chasing an overheat problem on my 4.0 which I now believe is an instrumentation issue...

But when your guage says the engine is hot it's hard, real hard, to ignore it...

It's harder to grind up and over the mountain to go anywhere

and even harder to leave the A/C on when the temp needle is
rising to the top of the scale...

AD

 

[weirdunclespongebob]

overheating

I am having the same issue. Have replaced thermostat, water pump, radiator (went to a two row), hoses, flushed block, fan clutch, temp sensor, heater hoses, heater core, and wired an auxiliary electric fan. Oil looks great, no milkshake in cap, no gunk in coolant, no white smoke out tailpipe. Put an adapter in the upper radiator hose to add an auxiliary gauge which indicates 220 plus sometimes! Truck still seems to run great. Beginning to think it's just the nature of the beast.

 

[bullfisher]

overheat

I've tested the new t stat thinking it was faulty. it wasn't. But I still cant explain the overfill tank filling and spewing all my coolant. is it possible to have a gasket problem without signs and would it cause this kind of problem?

 

[AllanD]

I think I killed my demon...

But I don't know what fixed it.

I replaced the IVR, Instrument Voltage Regulator (even though it tested "good")
I replace the guage movement (even though it tested good)

I cleaned the contact pads on the back of the cluster and applied conductive paste

I cleaned every ground strap and applied conductive paste to all of them.

And now the guage reads normal (FINALLY)

I've been going around and around with this for over two weeks.

But I just did two laps around the block with the A/C on and the
temp guage stayed in the bottom third of the range.

Have you verified that it actually IS overheating?

AD

 

[bullfisher]

overheat

good question and the answer is no. However I dont think instrument issues are the source of the coolant failing to circulate from the bottom of the radiator into the motor and back into the radiator. its as if a small amount of coolant goes into the motor and wont let any more in so it all goes out the overfill. or it goes in disappears and overheats before the rest of the coolant can go anywhere, all within 5 minutes. its driving me bonkers

 

[hickboy86]

Just a long shot but i've seen cylinder walls crack and force compression into the coolant system. I know it's a gas engine but it's fairly common with diesel engines and cylinder liners when they overheat horribly. The best way ive found to diagnose this prob. is to put a pressure tester on the radiator and see what it pumps itself up to with the engine running. If it goes beond what the cap is rated for or pumps up as soon as you get out of the truck from startin' it then odds are you have a cracked cylinder or blown head gasket.

Here's another question, Did the thermostat you put in have an air bleeder hole in the disc? If not it could be an air lock situation. Fairly simple to fix just drill an 1/8" hole in the disc, remove burrs and reinstall.

One more question, Is it the right rad cap, and did you test to make sure it holds the right amount of pressure. I'm not exactly sure but I think there supposedta be 13-15 psi.???

Hope somethin here helps.

 

[Nhaz]

Oddly mine is reporting low engine temp when its 31 degrees C outside and ive been running it for hours. Mid winter it would ramp right up to 3/4 and drop back to 1/4 as the thermostat opened and closed.

now it just sits barely into normal range. and the engine is Obviously hot im putting it down to idiot gauge syndrome.

 

[bullfisher]

overheat

I havn't pressure tested anything yet. it does have the right rad cap its brand new it is however a lever vent ive herd mixed things about them but never had a problem nor do i think one could cause this. the t stat is vented and installed correctly. If its not somthing simple then it must be somthing serious like craks or gasket right? or could it be a heater core issue?

 

[AllanD]

good question and the answer is no. However I dont think instrument issues are the source of the coolant failing to circulate from the bottom of the radiator into the motor and back into the radiator. its as if a small amount of coolant goes into the motor and wont let any more in so it all goes out the overfill. or it goes in disappears and overheats before the rest of the coolant can go anywhere, all within 5 minutes. its driving me bonkers

Ok, If the coolant isn't circulating there is really only one possibility, the radiator is clogged.

does the upper hose get hot with evidence of pressure buildup?

Does racing the engine make the coolant level in the drivers side tank drop?

AD

 

[weirdunclespongebob]

overheat

Sorry-realized later I kinda jacked your thread. A couple of years ago one of my drivers ran a 3.0 Aerostar out of coolant and it exhibited the same symptoms. The mechanic said he wasn't sure whether it it was a blown head gasket, cracked head or block. Didn't matter-we junked it anyway. Hope thats not what it is.

 

[calypso93]

I used a non contact thermometer (IR) aimed at the t'stat housing, just about where the upper hose connects. It read from 185-210 while the dash gauge read between "N" and "O". Getting an idea of the actual coolant temp may help in finding the real problem.
An even better tool is a thermal imaging camera. Found a few cooling system problems with one. Lucky we have a bunch at work. Check with some of your fire department friends. They may have access as well.

 

[bullfisher]

overheat

good info thanks guys. I think i've narrowd it down. tried to drive it today and was going through water like crazy trying to find a leak or something but was going through it faster than it was coming out the overfill. as if it had gotten worse so i checked my oil cap and found some creamy froth under it. indicateing a blown head gasket right? didnt seem like any more white smoke than the usual morning condensation. Because the problem has worsend I assume its a gasket and not a crack in the block.