74 bronco overheating, help please!

[jillips]

hello! i have a 74 ford bronco ranger in original condition. mechanically, it has been pretty good, but i can't seem to get this overheating problem fixed.

started with overheating while idling only.

replaced temp sending unit

then it really overheated, 230+ degrees, white smoke bellowing from hood

replaced thermastat (195 i was told), still happened

had mechanic put in (i believe 180) another thermastat

still problem, he took out radiator, sent it off to be tested, they said bad so replaced with new one

the general overall overheating fixed, but still overheats while idling (gets up in range of 210-230), starts droping down to norm, 195-200, once go

new water pump

mechanic read article about this problem in 72-74 models, suggestion of added auxilary transmission cooler didn't work

now we don't know what to do. he's put in fan shroud also.

one other piece of info, although i don't think it's the cause, there is a dealer installed AC. bronco overheats without turning on AC, but the AC radiator is in front of the engine radiator.

any suggestions would be great!
Thank you, Julie
Atlanta, GA

ps. i'll try to post a pic of my bronco

 

[70_Steve]

Does it have a fan shroud?

 

[TOFIC]

Overheating

Welcome Julie good to see new faces here!

As to your problem, here is a few suggestions. You have done the obvious fixes.

Check the rad hoses. Old ones wear down and collapse causeing restrictions in the system. The lower one is really known to do this. Change them both, as they are inexpensive.

Do the heater hoses while your at it. Sounds stupid but they can cause you grief. Buy some good quality replacement hose (should be 5/8") and change it. Cheap insurance.

You have new Tstat and WP so I would look at the belts. New ones are best but be sure the ones you have are the right ones and correctly installed.

As you overheat idling, where the waterpump does little, I would go after the fan(s). Ensure you have the correct/biggest fan that your engine can handle. Make sure you have a shroud on and it is correctly installed. You may want to consider a pusher fan in front of the rad. As the A/C puts a real strain on the cooling system this would be a very beneficial addition. Most of the Bronco Vendors can help you here. (I use Chucks outfit, support our sponsers you know)

One of these should cure your problem.

TOFIC

 

[Gummi Bear]

OK -

If you have a flex fan, take it off, and put a stock type 7 blade fixed fan on. These are low RPM and low speed vehicles, they need to move all the air possible.

Make sure that your fan is in the shroud properly, not too much space around it, and make sure that there aren't any major leaks between the shroud and the radiator, you want to draw all the air through it you can.

Check your coolant mix. 50/50 is what you want, no more, no less. If it's brown, go ahead and change it.

If it's still running hot, look into a 160* t-stat. That's what I run, but I'm in Texas where it's hotter than the sun in the summertime, I put some cardboard on the grill in the winter (it's easier than changing the stat).

If you haven't done a really good flush and fill, you need to. The water passages will collect some crud, and if you don't clean it out, they can slow or impair the flow of coolant. I make this an afternoon ordeal, first drain out all of the coolant, and leave the flowcock open, shove the water hose in the radiator and fill it up. Let the water run and let the truck run for a couple of hours, allowing the t-stat to open and close a few times, and you will see some goop come out from time to time. I do this about once a year.

If you put on another stock configuration radiator, well, they just don't cool as well as some of the aftermarket ones. I have one of the older Duff's 4 core models, and it's been in there for 6 years and thousands of miles, with quite a few trail miles in there too. I did have the tanks re-sealed last winter, but that's all I've done with it. Some folks will swear by Aluminum raidators, I'm afraid of it being punctured by a rock getting tossed up on the highway. I understand that the BC Bronco's radiator is supposed to be pretty darn decent, but I don't have any first hand experience with it.

I live in Texas, and did drive my truck daily (~100 miles) and have never had the temp peg out over 210*. It runs between 170 and 190 most of the time.

 

[Az Outlaw]

I had the same problem when I bought my first Bronco. Idle hot, cool right down at speed. I found the PO had installed the fan blade backwards, tring to push air through radiator. I know that seems obvious, but that was my fix.

 

[74bronc]

This 25 dollar fan from Summitracing.com will most likely cure your idle overheating woes.

I would also run straight distilled water in the winter with Redline Water Wetter as a corrosion inhibitor. Water disipates heat much better than any other type of coolant. You just have to make sure to have a 15lb cap on it and an anti-corrosion/water pump lubricant in the system.

I would bet the fan will cure your problem. you have already spent some dough figuring this thing out, what's another 25 bucks or so.

 

[74bronc]

sorry, forgot the pic

www.derale.com to get the part no for the 17" standard fixed pitch rigid blade fan

 

[chuck]

Do a search for "overheating" I made a list of 8-10 things to check and other people came up with some more that was not on my list so I added them. Makes a good check list.

 

[bob_lafrentz]

Do what Chuck said. Search for his list and follow it on down. I had the same exact problem you are discussing. the cheapest and quickest things I would do start the Bronco and put a piece of paper on the radiator. If it sticks, your fan is on right. If it doesn't, it is on backwards.

Then, in my situation I bought a stock EB fan off Ebay. Like $25 delivered to my door. This solved the problem! Keep in mind though, I have a staggered 4 core radiator and no AC.

Gut feeling is your problem is the fan. Count how many fins you have. The one you want will have 7. Good luck.

 

[Skuzzlebutt]

This 25 dollar fan from Summitracing.com will most likely cure your idle overheating woes.

I would also run straight distilled water in the winter with Redline Water Wetter as a corrosion inhibitor. Water disipates heat much better than any other type of coolant. You just have to make sure to have a 15lb cap on it and an anti-corrosion/water pump lubricant in the system.

I would bet the fan will cure your problem. you have already spent some dough figuring this thing out, what's another 25 bucks or so.

You have obviously never lived where temps get below freezing! Water Wetter can help cooling, but it is not an anti-freeze.

 

[72Sport]

A/C condenser may be plugged with dirt and not letting air get to the radiator. Hit it with the garden hose when everything has cooled off. Its best if you can get to it from the radiator side. Blow it back the way it came in. I had problems with my rice rocket a few years back. It acted like a vacuum cleaner and plugged everything up with dirt. It looked clean from the outside but it left a lot of dirt on the driveway when I was done cleaning. It cooled off after the cleaning.

 

[Hellonweelz]

I have a 74 as well and after I rebuilt my engine I was overheating. Mostly when I would sit and idle and on the road sometimes..pretty much at random. I messed around for weeks and it turned out there was simply air in the system. I haven't seen anyone post this but any ammount of air will get into the pump and stop the flow. That will overheat your engine very quickly. Since the system evidently worked before, I don't think buying different pumps, fans, shrouds is the way to approach it. Those are good ways to improve but not to fix a problem that just started.

I finally cracked the fitting on the tstat housing and let the air bleed out while I filled the radiator. Be very careful not to do this on a hot engine. After only coolant comes out of the housing tighten the fitting and run the engine at idle. You should see the fluid moving through the radiator. I usually wait until the tstat opens and the squeeze the top hose. You will see tons of air come out of the system. Do this and keep refilling until you can't get any more air to come out. And, remember to run the heater while you do this. If people remember to purge they will forget that the heater is part of this system.

Once I purged the air the problems went away. I lived in Albuquerque at the time and it would idle at about 205 deg in 95-100 deg weather. This is with the stock cooling system. So unless you do something radical to the engine, the stock system should be able to handle most weather conditions. Good luck.

 

[Blue71]

Did you check to see if your radiator cap is new? Mine had all the symptoms as yours and I tried everything as far as sender, thermostat, etc..All mine was was where I had the old radiator cap on and it wasn't sealing good. After a new cap..... it stays at 180-190. Sounds simple, but it worked. Hope you get it taken care of.

Good Luck,

Blue71

 

[74bronc]

You have obviously never lived where temps get below freezing! Water Wetter can help cooling, but it is not an anti-freeze.

sorry, that was as blatant a typo as I have ever done. whoops. I mean to say "summer" not winter. I have lived in Utah for about 10 years of my life, so I know all about antifreeze. I meant to say run water w/water wetter in the summer and switch back to 50/50 in the winter. I do that even in SoCal because I go into the mountains in the winter with my Bronco.

 

[jillips]

OK -

If you have a flex fan, take it off, and put a stock type 7 blade fixed fan on. These are low RPM and low speed vehicles, they need to move all the air possible.

THANK YOU FOR ALL OF YOUR SUGGESTIONS! A FEW HAVE MENTIONED "7 BLADE" FIXED FAN. I HAVEN'T BEEN ABLE TO LOCATE ONE, JUST 6 BLADES, I'VE CHECKED PLACES LIKE BRONCOGRAVEYARD.

DOES ANYONE HAVE A WEBSITE WHERE TO BUY?

THANKS AGAIN, COMMENTS HAVE BEEN VERY HELPFUL, JULIE

 

[Gummi Bear]

Here ya go girlie.


I found you one on Ebay



They look just like this:

 

[67EB_in_619]

You have obviously never lived where temps get below freezing! Water Wetter can help cooling, but it is not an anti-freeze.

Julie,
You are in HOT-Lanta... I suggest draining your radiator... add ALL distilled water with water-wetter (redline) or equvilent.. the remaining coolant circulating in the block is fine... redline has a great article on coolant vs water.

Water is better at dissapating heat... the more water.. the less heat.. I wouldnt recommend this as a year round solution IF you lived in montana.. but you live in GA.. 100% distilled water is fine (or garden hose water like I used).