Riddle me this...coolant issue. | Ford Explorer Forums - Serious Explorations

  • Register Today It's free!

Riddle me this...coolant issue.


Active Member
March 21, 2011
Reaction score
City, State
Carlyle, Il
Year, Model & Trim Level
99 5.0 EB
Just replaced my radiator yesterday...

I can drive 40 minutes, have hot heat, park it and coolant in coolant in radiator/and cap is cold.

Doesn't overheat, temp is normal.

Hoses, are not hot.

Hoses don't have as much pressure as I would think they should, but they do have pressure.

On another note, the truck cools off extremely quick as in what the gauge reads. I can have it shut off for 5 minutes and temp gauge is near the bottom when i start it back up.

All these symptoms were existent before and after I replaced the radiator. Reason for radiator change was seal leak between plastic and metal.

I'm stumped. Any ideas?

Join the Elite Explorers for $20 each year.
Elite Explorer members see no advertisements, no banner ads, no double underlined links,.
Add an avatar, upload photo attachments, and more!

I don't think you have all the air bubbles burped out yet. The coolant sensor is in "open air" which explains the fast "cool down"

Raise the front of the truck up real high to get the rad cap higher than the heater core inlet hoses. Run the truck till warm, full reservoir. Once it is warmed up shut the engine off, and wait for cooldown. While cooling, listen for bubbling noises in the reservoir.

Once it is cooled a bit you can remove the radiator cap, and refill the radiator. Do this several times until the radiator level remains full.

It's kinda difficult to get the system burped correctly, and does take quite a few burps.

I picked up a thermostat today, didn't grab one when I did the radiator, so after I swap that out, I'll try what you said. Thanks for the quick reply.

my guess would have been stuck open thermostat .

That was the only thing I could think, between that and air, hopefully I get it figured out.
Possibly, but with the thermostat stuck open it would take forever to heat up, especially with your cold weather.

Well I'm almost certain it was the thermostat. It was a motorcraft thermostat, wouldn't doubt if it were original, almost everything on this truck is.

My temp gauge actually fluctuates now, where as before it always warmed up to one point and didnt move.

System builds pressure and the radiator is now hot on top and bottom.

Heat is as hot as ever, can't keep it set at 90 anymore, it'll melt your face off.

Been a busy week with this truck, not a single day I haven't worked on it.

Changed the fluid in the rearend, finally replaced the front driveshaft, radiator, hoses and thermostat. Changed the plugs and oil. I once again love my truck. Less than an oil change away from 200k and its running great.