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Discussion Starter #1
1995 Bronco 5.0L (auto tranny)

The truck is actually at my work right now (not exactly roadside), which means I do not have my full shop at my disposal- Just want I can carry in my toolbox.

Here are the symptoms:

A) Overheating- Drove 20 minutes fine, then stepped on it hard and watched the temperature rocket from "normal" to the red mark in matter of seconds. On following start-ups, it overheats within 5 minutes of running.

B) Initially, a small amount of coolant was released from the radiator overfill tank as a result of pressure build-up. Following start-ups didn't show this symptom.

C) Holds new coolant fine (no air bubbles)

D) Verified waterpump is working by removing cap from t-connector from past coolant flushing on heater hoses. Pumps out coolant like normal (although cooler coolant)

E) Removed thermostat to make sure it wasn't stuck close.

F) Top radiator hose is very hot when it says it is overheating and it bulging from excessive pressure when overheating (after t-stat removed). Yet I can stick a finger in the radiator fill neck and the coolant is luke-warm.


So even though I think the system is moving "some" coolant, I do not think it is moving enough and causing the truck to overheat with the added pressure behind the clog.

I know I should try to replace the complete radiator, but I would like to get it home as soon as possible to complete in my shop.

For a quick solution, I tried bringing rubber plugs and drilling a small hole in it to insert my compressed air pistol. The plugs make a seal while I pressurize an inlet to the radiator to break the clog-free.

I did this in the radiator fill neck and drain cock, thinking this was enough. It wasn't. :banghead

Thinking I need to try the main inlet and outlet of the radiator next - same trick.

Any other suggestions or tricks for a quick fix to get this home to my shop?
 

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a cold engine will not over heat in 5 minutes of run time, your gauge is wrong or your out of coolant and even then I have my doubts it would over heat in 5 minutes.
 

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a cold engine will not over heat in 5 minutes of run time, your gauge is wrong or your out of coolant and even then I have my doubts it would over heat in 5 minutes.
I was doubting it too at one point and pretty sure my coolant temp sensor in the water t-stat housing was bad (suppose it could be the gauge too) and was thinking about driving it home hoping for the best.

Then I realized that I couldn't take that risk of cracking a head by ignoring a sensor. Talk about regrets if it came to that...

Then I noticed the upper rad pipe bulging which is normally sign of a clogged radiator.

I should also add that the overheating on the gauge might have been steam from a coolant system not circulating properly. Even though it might have not been overheating at that exact moment, I think it was an indicator that certain overheating was imminent.
 

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I suspect the T-stat
If it was stuck closed, would that cause the top radiator hose to bulge from pressure? Within 5 minutes?

I say drain the radiator, put in CLR or some other flush, run it a bit, drain, and refill with water and coolant.

Also, you do have coolant in the mix and not just water, right?
 

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Discussion Starter #8
If it was stuck closed, would that cause the top radiator hose to bulge from pressure? Within 5 minutes?

I say drain the radiator, put in CLR or some other flush, run it a bit, drain, and refill with water and coolant.

Also, you do have coolant in the mix and not just water, right?
Sorry- no go. Already removed the t-stat assuming it was closed. And since I was refilling and flushing it vigorously, it only has water in it now.

Once this issue resolved, I will drain and add antifreeze to the mix.
 

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Incorrect timing could cause that as well as a plugged cat for the over heaTing. U can also turn ur heater on high and see if that helps keeping it cool.
 

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Internal colapse in one of the rad hoses? I did have that once in another vehicle. Just a thought. Could not see it from the outside had to have the hose off.
 

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Internal colapse in one of the rad hoses? I did have that once in another vehicle. Just a thought. Could not see it from the outside had to have the hose off.
Good point. I will keep an eye out for this when I return to troubleshooting this afternoon.
 

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FWIW: When i di my radiator, the PO did not use antifreeze, so the bottom of my radiator was clogged for about 10-12" and my FSB did not over heat.

I found the clog after popping off the radiator endtanks. I replaced my radiator with a unit from radiator.com and it runs very cool now.
 

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Put a new hose and tstat on truck.
 

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a cold engine will not over heat in 5 minutes of run time, your gauge is wrong or your out of coolant and even then I have my doubts it would over heat in 5 minutes.
:stupid
 

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Well if there is only water in there won't the water just turn to vapor and increase the pressure but do almost nothing as far as cooling?
 
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