84 Bronco overheating problems

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Qualoon

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I have an 84 Ford Bronco with a 302 and cannot figure out why it is overheating so any help will be greatly appreciated. I recently purchased the truck from a guy who claimed the 302 had been freshly rebuilt. I have taken it on the highway 2 times and both times it has overheated. **** if I drive it around town long enough it will start heating up. I thought my thermostat might be sticking so I decided to do a coolant flush. after the coolant flush it overheated again. I went looking for the thermostat hoping to find it had simply been put in backwards only to discover there is no thermostat. the coolant coming from my engine after the flush looked like coffee which im guessing it shouldn't look like that. the inside of my radiator is still pretty filthy and gunked up so im thinking a new radiator might solve the problem. im not a mechanic nor do I claim to be one. I usually work on my other bronco with nothing more than a Chilton catalog, youtube videos, and beer. can someone please help me and let me know if I am overlooking anything? thank you in advance.

 

miesk5

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yo Qualoon,

WELCOME!

Is Green or Blue coolant a 50/50% mix?  btw, Ethylene Glycol (green) and GM  Dexcool (orange) are not compatible. When mixed together they form a rusty brown gel-like substance that stops coolant flow and consequently the engine overheats.

Is it losing coolant when engine is cold or during first sign of overheating?

Any white exhaust smoke evident?

Try flushing it out until clean.  While  I was Hosp. for awhile last year, #1 son took Bronco into shop for trans fluid flush & fill under normal maint. sched., shop also "TOPPED OFF ALL FLUIDS" but used GM Dex-Cool coolant (Orange)

"...Overheating can be caused by anything that decreases the cooling system's ability to absorb, transport and dissipate heat: A low coolant level, a coolant leak (through internal or external leaks), poor heat conductivity inside the engine because of accumulated deposits in the water jackets, a defective thermostat that doesn't open, poor airflow through the radiator, a slipping fan clutch, a collapsed lower radiator hose, an eroded or loose water pump impeller, or even a defective radiator cap.

Exhaust restrictions can also cause the engine to overheat. The exhaust carries a lot of heat away from the engine, so if the catalytic converter is restricted, or a pipe has been crimped or crushed, exhaust flow can be restricted causing heat to build up inside the engine.

It's also possible that your engine really isn't overheating at all. Your temperature gauge or warning lamp might be coming on because of a faulty coolant sensor. Sometimes this can be caused by a low coolant level or air trapped under the sensor.

Leaky Head Gasket. A leaky head gasket can allow coolant to seep into the engine's cylinders or crankcase. Symptoms include a loss of coolant with no visible external leaks, and white steam in the exhaust, especially after restarting the engine when it has sit for awhile. A leaky head gasket can be diagnosed by pressure testing the cooling system, or by using a "block checker" that pulls air from the cooling system into a cylinder that contains a special blue colored leak detection liquid. If there are any combustion gases in the coolant, the color of the liquid inside the detector will change from blue to green. A leaky head gasket can often be temporarily sealed by adding a sealer product to the cooling system. But for bad leaks or ones that cannot be stopped with sealer, the head gasket has to be replaced..."

READ MORE

by http://www.aa1car.com/library/overheat.htm

 

 

This is by Ford for a 95, but similar to your 84

Cleaning Cooling System

To remove rust, sludge and other foreign material from the cooling system, use Ford Premium Cooling System Flush D6AZ-19A503-AA (ESR-M14P7-A) or equivalent. Flush system using Rotunda Cooling System Flusher 106-00010 or equivalent. Removal of such material restores cooling efficiency and avoids overheating.

Always remove the thermostat prior to pressure flushing. A pulsating or reversed direction of flushing water flow will loosen sediment more quickly than a steady flow in the normal direction of coolant flow. In severe cases where cleaning solvents will not properly clean the cooling system for efficient operation, use the pressure flushing method. Various types of flushing equipment are available.

Do not back-flush cooling systems that have a water shutoff valve in the heater system, or damage to the valve can result.

Radiator

Internal Cleaning

Do not use caustic cleaning solutions or copper/brass radiator cleaning agents on aluminum radiators (8005). Internal cleaning of the aluminum tubes can be accomplished with sonic cleaning equipment.

Engine Overheats

  • Damaged water thermostat (8575).
  • Damaged water pump.
  • Internal engine coolant leak.
  • Cooling fan inoperative.
  • Plugged radiator.
  • Plugged heater core.

PINPOINT TEST B: ENGINE OVERHEATS

 B1 CHECK COOLANT LEVEL

NOTE: If engine is hot, allow engine to cool down before proceeding.

Remove radiator cap and check coolant level at radiator coolant recovery reservoir.

Is coolant level OK?
Yes

GO to B2 .

No


REFILL as outlined. GO to Pinpoint Test A.

 B2 CHECK COOLANT CONDITION

Check coolant for contaminants such as rust or corrosion. Also, check for color discoloration.

Is coolant condition OK?
Yes

GO to B3 .

No


FLUSH system as outlined in this section. RETEST system.

B3 CHECK FOR AIRFLOW OBSTRUCTION

Visually inspect A/C condenser core (19712) and radiator (8005) for obstructions, such as leaves or bugs.

Is there any obstruction?
Yes

REMOVE obstruction and CLEAN A/C condenser core and radiator as outlined. RETEST system.

No


GO to B4 .

 B4 CHECK HEATER CORE OPERATION

Install radiator cap.

Start engine and allow to run.

As engine starts to warm up feel the inlet and outlet heater water hoses (18472). They should feel the same after three or four minutes.

Is outlet heater water hose the same temperature as the inlet heater water hose?
Yes

GO to B5 .

No


TURN engine off before it overheats. REFER to Pinpoint Tests in Section 12-00. RETEST system.

B5 CHECK WATER THERMOSTAT OPERATION

Allow engine to run for 10 minutes.

Feel the inlet and outlet heater water hose and the underside of the upper radiator hose (8260). Are the upper radiator hose and heater water hoses cold? Yes
REPLACE water thermostat (8575) as outlined in this section. RETEST system.

No


LEAVE engine RUNNING. GO to B6 .

B6 CHECK COOLING FAN & BELT

  • Check for proper cooling fan clutch operation as outlined under Component Tests.
  • Did cooling fan clutch (8A616) operate OK?
arrow.gif
Yes
 

Spin the fan. A light resistance should be felt. If there is no resistance or very high resistance, the minimum and maximum fan speeds must be checked as follows:

Refer to Fan Clutch Specifications at the end of this section.  miesk5 Note; Ford test requires Strobe Light, Tachometer, timing light, and a throttle adjusting tool or helper that has a steady foot.  If you need the test,  see it for a 95 @ https://www.motorcraftservice.com/pubs/content/~WSSJ/~MUS~LEN/19/SSJ33015.HTM

.

No

REPLACE fan clutch as outlined in this section. RETEST system.












 
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Bully Bob

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Welcome Qualoon,

I think you're on the right track.

I would flush a time or two more 'til the water runn'n out is clear. This will pretty much clear out the block.

Then remove the rad. & have a rad. shop boil/rod it clean.

If it's really ugly then replacement IS in order. 

NO THERMOSTAT will cause overheating as the water is moving too fast to be cooled in the radiator.

 

Seabronc

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I'd add one additional check to Miesk5's list.  Is the fan shroud in place?  Some people remove them and fail to put them back,  that causes inefficient air flow through the radiator.

Good luck,

:)>-

 

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