Runs cold always and forever...help !

[fordtoy91]

I've lived with this issue since I've had this truck (4 years, 91 w/351w stock). Want to see if someone can shed some light.

The temp gauge always stays in the cold area, even in the hottest weather. I know I know, you can't rely on the factory gauge. But along with this, it puts out very little heat from the heater core. So in the winter it sucks because of so little heat. Drive for hours, it never warms up.

I have tried 4 different stats, no change. The truck has been running for 45 minutes (right now) in the drive way. The top rad hose is ice cold. (This mean the stat is not open, but after 45 min???) The heater hoses are barley warm. The intake and valve covers are cool to the touch. This is after 45 min running time.

How can this be with a big v8? My other cars are at full heat in 15 minutes, don't dare touch the rad hoses or engine.

Can anyone explain this?

 

[blacksnapon]

Try removing a heater hose from the heater core, then filling with anti freeze. Sometimes you can get a nasty airlock in the 351w and the 302. Other than that, verify that youre getting coolant flow from the water pump. At times the impellers can separate from the shaft.

 

[fordtoy91]

Wouldn't a separated impellor cause it to over heat?

 

[blacksnapon]

Wouldn't a separated impellor cause it to over heat?

Yes, most generally. You do have the thermostat in there with the "pill" toward the motor, right?

 

[5.0Flareside]

aint making any sense at all... subscribing just in case i come up with something so i can find it easier..

 

[fordtoy91]

Yes, most generally. You do have the thermostat in there with the "pill" toward the motor, right?

Absolutely

 

[5.0Flareside]

anything thats rolling through my head like pluged up rad, or coolant passages or messed up water pump, would all cause over heating, not to cool conditions. definatly odd...

have you hooked it up to a true temp gauge?

 

[fordtoy91]

anything thats rolling through my head like pluged up rad, or coolant passages or messed up water pump, would all cause over heating, not to cool conditions. definatly odd...

have you hooked it up to a true temp gauge?

I have not , but I used a laser temp gauge and I'll tell you everything read cool, except exhaust manifold.....been awhile can't remember the temps....will re try tomorrow.

 

[Skandocious]

Just a shot in the dark, but how about a seized up fan clutch?

 

[flareside_thunder]

Or clogged heatercore.....Shoot them temps.... You may need to put a piece of cardboard in front of the radiator if the fan clutch is indeed still good.

 

[Skandocious]

Or clogged heatercore.....Shoot them temps.... You may need to put a piece of cardboard in front of the radiator if the fan clutch is indeed still good.

A clogged heater core wouldn't explain the top rad hose being ice cold after 45 minutes of running though.

 

[fordtoy91]

Pics Pics Pics

 

[fordtoy91]

The pics are after 1 hour of running today. Tested the heater core, flows fine. Clutch fan blowing alot of air. Water pump replaced about 2 years ago, when I got serious about chasing this issue (so pump should be functioning fine)

Heater hose: 125-134 degrees after 1 hour

Upper rad hose: 106

Lower hose: 92

Intake: 97

Valve cover: 123

Temp gauge: just above cold

Heater; Only blowing warm air

Exhaust maifold: 400 degrees


Boys, we have the miracle engine. Any comments ideas?

OH by the way....the system is not holding any pressure......which is could be a hint. After an hour I removed the rad cap ...absolutley zero pressure.

 

[Skandocious]

Clutch fan blowing alot of air.

That's not necessarily normal... When the engine is cold, the fan clutch is supposed to let loose and free wheel (even though they are never COMPLETELY released).

 

[73F100Shortbed]

Is the rad. cap good?

 

[89PSD]

have you changed any of the smaller heater hoses?...
The 5/8" ones coming off the intake/water pump neck/water pump. Can you take a pic at the them?.. I would like to see how they are routed.

what ratio of water to anitfreeze are you running.

 

[89PSD]

Im suspecting weird routing of those smaller rad hoses. I think they could be bypassing the thermostat, preventing the engine to warm up. which would explain why there is no pressure(heat).

 

[Lost]

I vote fan clutch or heater core . The core even with air pocket r problem

 

[fordtoy91]

After 50 minutes of running

 

[fordtoy91]

Today after 50 minutes of running

Stat housing after 50 min. The highest reading I got after finding the hottest area was 143 degrees.

Obviously the 195 stat will not open at 140 degrees.