289 Overheating...

[srestum]

Hello all, I just bought my first early Bronco. It's a 68 with the 289 and 50,000 original miles that I found sitting in a field in Montana (where I'm at). The truck runs great and I'm really excited about learning everything there is to know about both the 289 and the early Bronco in general. My question is this. When I get on the highway (something you have to do to get anywhere in Montana), it runs fine until it gets over 70, then it runs hot. It runs between 230 and 240 depending on the speed. It wants to run faster and I have lots of pedal left, but I'm afraid I'll do damage. Any suggestions on how to cool her down? I've flushed and cleaned the radiator and changed the thermostat, which didn't help much. Everything looks original and the water pump isn't making any noise. I don't know much about these old engines, but I'm learning quickly and would appreciate any thoughts the more experienced might have. P.S. This is the first of about 50 questions, but the most important right now, so be prepared to be sick of my questions. Thanks.

 

[bert]

Someone posted similar questions earlier. His had been sitting for awhile also.
How long has it been sitting before you started driving it?
The solution for the post metioned above turned out that the antifreeze had gelled inside the engine and radiator and the flush would not clean it out. I believe he ended up pulling the radiator to have it cleaned and also removed the waterpump to clean out the pump and cooling passages.
Most cooling problems I have seen where the engine gets hotter at higher speeds has been related to a blockage or restriction somewhere. At lower speeds everything worked good.
HTH bert

 

[srestum]

It probably sat about 3-4 months before I drove it. It was only driven occasionally though for the past five years.

 

[bert]

They cool best with a fan shroud. Make sure the front of the radiator is not plugged with bugs, dirt, leaves, etc.
It might be best just to remove the radiator and have it cleaned and tightened up just for peace of mind.
Let us know what you find.
bert

 

[jasondemitri]

mine sits for at least 3-4 months a year (military deployements) and i never have any cooling issues.

 

[mlogan24]

I don 't know if this helps, but hopefully it will. I put in a 94 5.8 block, and one of the few things I did on it was put a new water pump on (take note: it is a reverse-rotation serpentine setup) and I also put a new t-stat on.

I also put in a new 3-row radiator (stock copper/brass, nothing special) and a reverse rotation flex fan. I'm not running a shroud. My truck will stick to 180 (temp of the t-stat) in almost all weather, idel or not. The hottest its gotten has been about 200 (that was idle and after heavy use). Hopefully that info will be helpful.

 

[Skuzzlebutt]

Feel the radiator with your hand while it is hot. The temp should be even all over the fins. If an area is noticably cooler you have a blockage in there that should go to the pros.

 

[72Sport]

Remove the radiator cap and drain enough coolant so you can shine a light in the tank of the radiator. Dropping the level 6" should be enough. If the ends off the tubes have a white growth around them the radiator is probably restricted. Take it to radiator shop and have it cleaned out. It costs about $50.

Clean the radiator on the outside. I hooked up a piece of 3/8 steel line to the garden hose so I could hose it down from the fan side of the radiator. I bent the tube at a 90 degree angle on the other end and cut the end off so it had a slit in it. I use it on all of my vehicles every couple of years.

If the Bronco lived on a farm it may have more dirt on the outside than in the inside.

 

[jasondemitri]

hey mlogan, i just put the serpantine setup with a reverse flow pump and fan from bcbroncos, a new thermostat with a 3/16th hole drilled for continuous passage and she stays about 180-185. i havnt ran it very much, but it hasnt gotten over 190 and that was sitting in the sun, hood closed and running for 30 minutes. definately an improvement from what it was. before it would have been at 210 easily.

 

[srestum]

Thanks all, I think I'll start with a new radiator and go from there. Thanks for the input. Scott