Bronco Forum - Full Size Ford Bronco Forum banner

1 - 20 of 25 Posts

·
Registered
Joined
·
4 Posts
Discussion Starter #1
Hello, I am looking for some help diagnosing a overheating issue with my 1989 bronco, it is a 302 automatic.

It has just recently starting overheating on me. A few months back I had a unknown fluid leaking into my passenger side floor and have read that my heater core may be the problem. I have lived without running the ac in it for a good time and heard that I could bypass the heater core. is this a likely solution to my problem?

I know there are other solutions but i believe this is the most likely of them all due to the signs. thanks for your help.

BRONCO LIFE!!
 

·
Roller rockers are gay
Joined
·
19,191 Posts
lets start with a stupid simple question.......

does it have coolant in it?
 

·
Registered
Joined
·
133 Posts
The heater core leaking will only cause overheating if it leaks out enough to have low coolant in the radiator. Yes it can be bypassed. Look on the passenger side firewall under the hood. There will be two hoses. Those are the supply and return from the heater core. Just unhook one at the firewall and the otherat the motor and hook the hose from the firewall to the motor. But it's best to just replace the core. Make sure the hoses aren't leaking at the firewall first though. Could be a loose connection and it will wick the water in. I assume there's no water leaking from the water pump? Usually when they go bad they weep water.
 

·
Premium Member
Joined
·
9,990 Posts
I agree but BEFORE you do anything I suggest you put a pressure gauge on the radiator neck and really check for any other possible leaks then go from there.

This might be a good time to "backflush" the cooling system with plain water until it flushes clean, wash any re-useable radiator/bypass/heater hoses in detergent, clean out the over flow tank, check the T-sat to make sure it's working by placing it in hot water etc. or replace with the correct OEM degree, mine is 195*, check test the radiator cap or replace then top off with a good quality anti-freeze and you're good to go for a while not to mention the nice heat in the winter depending where you live.

Definately repair or replace the heater core and take the old one into the auto store to match it up, don't rely on the store because as I've mentioned before many stores don't carry the correct double humped HC (aftermarket) you need as a "standard" product, Napa and Pep Boys no longer offer this HC we need, they've gone to a different aftermarket manufacturer and it doesn't fit into the HC box correctly and there's no way to mod the box to accomodate it so if you purchased their correct HC some time ago with a lifetime warranty it simply means you just get a refund for price and tax.

Fortunately O'Reillys carries the OEM aftermarket style that fits in our Broncos BUT it's a special order now and cost twice as much, $25.00 for my last one and the new OEM aftermarket style cost $47.00 + tax but it fits correctly and now I have 1 new HC in the BKO and one spare to be repaired if need, I also have the full metal tanked aftermarket radiator that was in the Bronco when I bought it 8 yeras ago in a box to be repaired if need.

Make sure you clean out the coolant residual in the HC box with something like simple green that smells nice otherwise the coolant smell will continue coming thru the vents.

Best advice, hit the JY's and find as many OEM HC originals as you can find and spare up or sell some if you are over supplied......lol lol....

Good Luck ~ :thumbup
 

·
Registered
Joined
·
31 Posts
Is it fluxuating? Or just slowly overheating? Agreed it should be pressure tested for leaks, and if no further diagnosis work, I'd start by replacing the cheapest thing. In your case this is likly the t-stat. Fairly straight forward replacement.

I would also recomend you NOT bypass the heatercore especialy with winter neering. If you are to bypass this you will not have heat :smilie_slap, and will likely loose use of your defrost.
 

·
I scrape on both sides
Joined
·
3,035 Posts
Stuck closed thermostat could be it too. But pressure test it first
 

·
Roller rockers are gay
Joined
·
19,191 Posts
JKoss i swear you must have the whole "backflush" post saved on your desktop or something. :rofl:

OP, did it stop overheating AFTER you filled it back up with coolant?
 

·
Premium Member
Joined
·
9,990 Posts
LOL LOL, yes, yes I do.........AH, NO ........BUT I just think it's so over looked as regular preventitive maintainance that would expose many of this issues BEFORE they become a major problem and easily delt with before hand.....it's basically a VERY CHEAP but effective procedure, wouldn't you agree....

AND yes, I know you're only kidding....BOOOYAAAAAHHHH!

Good Luck ~ :thumbup
 

·
Roller rockers are gay
Joined
·
19,191 Posts
LOL LOL, yes, yes I do.........AH, NO ........BUT I just think it's so over looked as regular preventitive maintainance that would expose many of this issues BEFORE they become a major problem and easily delt with before hand.....it's basically a VERY CHEAP but effective procedure, wouldn't you agree....

AND yes, I know you're only kidding....BOOOYAAAAAHHHH!

Good Luck ~ :thumbup
i completely agree with you. except if it's overheating only because the coolant level is low, finding/fixing the leak must be done before doing all the backflushing and shit. otherwise it's just shooting one's self in the foot. know what i mean?
 

·
Premium Member
Joined
·
9,990 Posts
Checking coolant level first is a given, no?

That's why I suggested using a "pressure guage" on the radiator neck......in my first sentence Brother....lol lol


BOOOYAAAAAAHHHH ~ :thumbup
 

·
Registered
Joined
·
580 Posts
Yes agree, Pressure the system up and look for leaks . You could even get some of the dye to add to your coolant. The dye allows you to use a black light to find the accumulation of coolant. The HC will more than likely be a big PIA to change. Ford likes it like that. Another possibility would be the fan clutch if the 89's still had them. A simple test for that would be to have someone start the truck. While they are starting the truck you need to lay a shop rag on the fan blades. Let it drag on the shop rag . If the rag stops the fan from turning the clutch is going bad. If it spins right up and takes the rag away from you the clutch is still plenty strong. When doing this exercise try to use head out of ass rules so you dont get your hand in the fan.
 

·
Registered
Joined
·
4 Posts
Discussion Starter #14
Thanks for all the helpful tips. Well so far I just added some coolant and have not overheated since (2 days of driving). I would barely drive 5 miles before she nearly got to overheating before adding the coolant.

To answer some of the other questions I read:

No the temp does not fluctuate, it was a steady increase all the way to redline.

I will definately search the junk/salvage yards for oem parts.

I will try the shop towel on fan trick

I will also do a pressure check.

I am not any type of mechanic nor inclined mechanically at all so bare with me if I ask any more dumb questions.

thanks for all the help, I will keep you posted on how it turns out.
 

·
Premium Member
Joined
·
9,990 Posts
This is how you start learning to become mechanically self reliant Brother just jump and start doing it, picking up tools and tips along the way, that's why we're all here AND think of the money you save by doing it yourself.....

Good Luck ~ :thumbup
 

·
Super Moderator
Joined
·
26,988 Posts
yo
for the Coolant Pressure Tester w/Adapters, #OEM27049


try AutoZone's Loan-A-Tool® service
"...Just leave a deposit at the store when you pick up the tool. When you're through, just bring it back, and we'll refund the deposit..."
 

·
Premium Member
Joined
·
4,792 Posts
overheating is either

1. Massive coolant leak
2. clogged radiator/heater core/ engine block (ie flush the coolant system with one of the plastic flush kits) Make sure new coolant is 50/50 (concentrate and water)
3. Weak water pump
4. Stuck t-stat
 

·
Registered
Joined
·
1,326 Posts
overheating is either

1. Massive coolant leak
2. clogged radiator/heater core/ engine block (ie flush the coolant system with one of the plastic flush kits) Make sure new coolant is 50/50 60/40 or 70/30(concentrate and water)
3. Weak water pump <UM NO
4. Stuck t-stat
5. BAD Rad cap !!!
 

·
Registered
Joined
·
580 Posts
3. Weak water pump
OK guys for real, I know there is some mystical magic surrounding the operation of a water pump. However, they are a very simple little gadget that mystifies people that havent seen one in pieces. There is a shaft with a pulley on one end and an impellar(propeller like on an airplane if you will) on the other. There is a bearing and a seal pressed onto the shaft sort of in the middle. The belt turns the pulley the shaft is attached to and this makes the impellar on the other end of the shaft turn as well b/c they are attached to the same shaft. The bearing makes it turn true and the seal keeps the water on the wet side of the shaft. This happens until the bearing becomes worn out and doesnt spin the shaft as true or could even lock up. When the bearing becomes worn it will eventually wollar the seal out and cause the waterpump to start leaking out of the weep hole. This lets you know the water pump is going bad and will soon lock up and leave you stranded somewhere if you dont change it.

So with this being said, there is no weak water pump unless maybe you are dealing with an electric pump on racecars. I suppose an electric motor could start to get weak and not circulate the water at a normal rate.

A mechanical water pump doesnt get weak. They burn the bearing up and they quit. Up until the moment it locks up no matter how many miles are on it or how many yrs old it is it will pump water at the rate it is designed to pump it.
 
1 - 20 of 25 Posts
Top