6.9/7.3 Cooling System Problem?

[Pino2234]

I was reading Dsl_Dog_Catcher's High Idle Manual Override and he said

"As you may or may not know, diesel engines have a large cooling system, which can take on a lot of heat but can dissipate it very quickly while idling. Extended idling of such engines will cause the cooling system to keep the engine cool enough that it may not maintain an adequate operating temperature. "

I bought my 86' 6.9 3 years ago and when it idles for extended periods it overheats. Even in the winter. I just recently bought a 91' 7.3 and when I was jumping someone a few months ago it the water temp rose and was overheating after 10 mintutes of working on this mustang. What could be the problem?

 

[gatorman21218]

my first thought is your fan clutch isnt locking up. When the engine gets hot that thing should be whirling

 

[rjjp]

Clogged radiator?

 

[rhkcommander]

I'd go with one of those probably, make sure you didn't board the radiator in the winter and forget ;p

 

[subway]

sounds like the rad might be getting old, when they get build up in them they cant dissapate enough heat.

x2 on making sure the fan clutch is roaring to if it gets that hot.

 

[Agnem]

Defintley crap in your cooling system. Check your air flow temp. I've seen a lot of guys with engines so hot, yet the air coming through the rad was barely warm. That's a sure sign of a clogged radiator or no coolant flowing. Get a new radiator, and install a coolant filter. There is no way in hell a 6.9 should ever overheat, yet along idling. You may need to pull your heads to check your coolant flow passages if the radiator doesn't fix it. There are grommets in the gasket with small holes that could clog in extreme cases.

 

[dakotajeep]

x4 on the radiator reducing coolant flow

I replaced mine and the cooling issues I had disappeared. I was hesitant to drop the cash on a new one. Once I did I couldn't believe that I had gone so long without replacing it.

Thad

 

[Pino2234]

I just changed the radiator from the wide one to the narrower one a few months ago. Both still used but what are the chances they are both bad? It still does it.

How do u check the air flow temp and i have a thermostat gun if I shoot the upper hose what should the temp be and what should it be for the bottom hose?

Also is there a way I can check the coolant flow and make sure it is flowing? I replaced the thermostat right before I changed the radiator and I dont think anything is wrong with the heads b/c the guy I bought it off of put a crate motor in it 70k miles ago.

 

[argve]

how is your fan shroud?

 

[Diesile]

You say it does this idling not running down the road. This has to be a case of lazy
fan, otherwise it would overheat all the time. As has been posted check the fan to
see if the drive is locking up and that the shroud is intact.

 

[Agnem]

...Both still used but what are the chances they are both bad?....

Pretty good. Spend some money and remove all doubt.