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Bronco 2


85 Red

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Hi I need some help on an issue with my Bronco 2. My mechanic repaired and fixed the a/c system and it caused it to start to overheat then he put a new radiator ( new but has been sitting around the shop ) and still overheats. the fluid in the radiator is not bubbling up like is the usual sign of a blown head gasket but maybe it's not bubbling up because it's a thicker radiator I'm not sure. There is no fan shroud on this truck I ordered one in ( since the mechanic said that this is worth trying to start with) but they haven't worked on it since the part came in most of the shop has had covid all last week. He said the fan is working like it should and it shouldn't be the fan they also recently changed the thermestat switch. Does it sound like its a blown head gasket? Why else would it be overheating? The heat gauge goes up pretty quick even if you don't stop at red lights or anything.
 


RonD

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Welcome to the forum

Cold engine
Take radiator cap off, should be full to the top if there are no leaks
Start engine
Watch coolant at cap opening
Should not be over flowing, might have on "burp" on start up then no flow in radiator at all, coolant should just sit there

If it starts to over flow then yes, looks like a blown head gasket or cracked head
A cylinder is pumping "air"(exhaust) into the cooling system, displacing coolant in the heads and pushing it out the radiator cap opening

If coolant just sits there then no bad head gasket or head

Water pump bypass may be clogged or blocked
Water pump bypass is also know as the Heater Core, lol
The heater hoses send coolant from upper intake(thermostat) to heater core(firewall) and then another hose brings it back to water pump
This needs to be clear passage of coolant
If outside you can take off both heater hoses and put a garden hose on the heater core and flush it out to see if there is good flow, in both directions
And just a heads up, you should swap heater hose around at the firewall every 2 years when you change coolant, that reverses the flow thru it and will help it last longer

Are water pump and fan spinning the right way, serpentine belts can be install backwards on water pump pulley so way less cooling

Bad thermostat, yes new, but YOU are the one testing this new part, so if its a bad part................

Regardless you need the shroud but not your issue
 

85 Red

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Thanks RonD I am going to have to pass this on to my mechanic They've been sick so things have come to a stop but when they were working on it earlier he said there was no bubbling in the radiator and I think that he probably knows enough to know about the flowing over at where the cap is like you were describing he didn't mention anything about overflowing or anything. He thought as I said earlier that the radiator got clogged so he installed a new one.

I'm hoping it's a clog in the heater hose they should be able to check that or possibly a bad although new thermistat they just installed a new one but could be bad anything is better than a blown h gasket I already had the head gaskets blow a few years ago and had them shaved. It has been running perfect since the last time nice and cool so I know they did a good job when they blew years ago. Thanks again I'm going to pass this on to them at the shop they have a big shop with an outside area in front they should be able to test the blocakage in the hoses.
 

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I had the water pump impeller get loose on the shaft. Caused overheat problems. I've heard that the impeller blades can somehow disappear and that would also cause overheat.
 

85 Red

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I had the water pump impeller get loose on the shaft. Caused overheat problems. I've heard that the impeller blades can somehow disappear and that would also cause overheat.
Thanks alwaysFLOored I'm going to pass it on to the mechanic about the impeller. Do you mean disappear as break off and lost somewhere?
 

85 Red

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I had the water pump impeller get loose on the shaft. Caused overheat problems. I've heard that the impeller blades can somehow disappear and that would also cause overheat.
This overheating started as soon as they repaired the A/C does that tell you anything?
 

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This overheating started as soon as they repaired the A/C does that tell you anything?
Yes...

Having a functioning A/C system adds a heat load to the incoming air to cool the coolant.
 

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I drove a Mercury Grand Marquis for a while. I had to do some work under the hood and removed the fan shroud. Not realizing how much air they direct over the motor. Never had overheating issues on that car, until I removed that shroud.
 

85 Red

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Hopefully the shroud will make a huge difference I havent had it on there since I bought the truck 5 years ago but then again I never had a functioning A/C either Like mentioned above the hot air that the A/c has going on by functioning might be the big factor involved too.
 

85 Red

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Welcome to the forum

Cold engine
Take radiator cap off, should be full to the top if there are no leaks
Start engine
Watch coolant at cap opening
Should not be over flowing, might have on "burp" on start up then no flow in radiator at all, coolant should just sit there

If it starts to over flow then yes, looks like a blown head gasket or cracked head
A cylinder is pumping "air"(exhaust) into the cooling system, displacing coolant in the heads and pushing it out the radiator cap opening

If coolant just sits there then no bad head gasket or head

Water pump bypass may be clogged or blocked
Water pump bypass is also know as the Heater Core, lol
The heater hoses send coolant from upper intake(thermostat) to heater core(firewall) and then another hose brings it back to water pump
This needs to be clear passage of coolant
If outside you can take off both heater hoses and put a garden hose on the heater core and flush it out to see if there is good flow, in both directions
And just a heads up, you should swap heater hose around at the firewall every 2 years when you change coolant, that reverses the flow thru it and will help it last longer

Are water pump and fan spinning the right way, serpentine belts can be install backwards on water pump pulley so way less cooling

Bad thermostat, yes new, but YOU are the one testing this new part, so if its a bad part................

Regardless you need the shroud but not your issue
I spoke with them today and they said they already tried running water through the heater hoses and it wasn't. I'm hoping they will check the water pump for issues like you said or the thermastat. I emailed them this thread so hopefully he will try all the possible hangups.
 

85 Red

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I drove a Mercury Grand Marquis for a while. I had to do some work under the hood and removed the fan shroud. Not realizing how much air they direct over the motor. Never had overheating issues on that car, until I removed that shroud.
Did you put the shroud back on and did it then continue overheating afterwards?
 

RonD

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The Shroud prevents fan from pulling air from the sides of engine bay, so air is pulled in thru the radiator, point of the fan
When you are driving at speed air is forced thru the radiator so fan is not really used
When stopped or driving slowly then fan and shroud ARE used

So if there is no overheating at speed(engine generating the most heat) but there is overheating when stopped or driving slowly its generally a fan issue
 

85 Red

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The Shroud prevents fan from pulling air from the sides of engine bay, so air is pulled in thru the radiator, point of the fan
When you are driving at speed air is forced thru the radiator so fan is not really used
When stopped or driving slowly then fan and shroud ARE used

So if there is no overheating at speed(engine generating the most heat) but there is overheating when stopped or driving slowly its generally a fan issue
Then It's probably not the shroud like you mentioned earlier, because it overheats while going at higher speeds. It starrted overheating in the shop they noticed, while they were working on the a/c. Then the mechanic said to bring it home till the shroud gets shipped in to make room in the shop and I noticed it was overheating on the way home cruising at higher speeds.
 

RonD

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So that's a lack of circulation, thermostat not open all the way, would be best call since its new

Water pump maybe, but awfully sudden if it was old age
i.e. you would have noticed it running warmer over time

If you have it at your place then open rad cap to make sure its topped up
Start it up and let it idle
Upper rad hose should be cold to the touch until thermostat starts to open, 4 to 5minutes
Feel it after 2 or 3 minutes, if its heating up the thermostat is partially open so a sign it may be bad

The upper rad hose will start to heat up after 4 or 5 minutes of idling, heater hoses should be HOT in comparison
After upper hose gets warm feel lower hose, it should start to warm up as well meaning good circulation thru new radiator by water pump
Lower hose should be 15-20deg cooler than upper hose
If lower hose is not heating up very fast then poor circulation, water pump most likely since its a new radiator(assuming thermostat passed its tests)

Upper hose should get HOT, 190degF
Lower hose 170degF
That's normal operating temp

Temp gauge in cab should be just below 1/2 at this point, 1/2 is approx. 205degF on Ford Temp gauges
 

85 Red

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Thanks I will pass this on to them and we'll see how things go from there. Yeah it seems like at this point that matching the temps on the hoses would say a good bit about the issues and coolant flow.
 

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