Overheating

2000 FORD F-150
157,000 MILES • 4.6L • V8 • 4WD • AUTOMATIC
Avatar
GDANGERFIELD
  • MEMBER
  • 4 POSTS
I recently bought the truck listed above. When I bought it had sludge in the coolant reservoir, I managed to clean some of it but it’s still overheating when I drive it. It doesn’t do it when it’s in park. I also replaced the thermostat what could be the problem?
Apr 1, 2022 at 10:40 AM
Advertisement
Avatar
JACOBANDNICKOLAS
  • ✓Experienced Mechanic
  • 110,240 POSTS
Hi,

Overheating can be caused by a few different things. First, did you flush the cooling system? If there was a lot of sludge in the system, that should have been done.

Here is a link you may find helpful:

https://www.2carpros.com/articles/coolant-flush-and-refill-all-cars

Next, was there any evidence of coolant mixing with the oil or oil with the coolant? Take a look through this link and let me know if anything mirrors what you see:

https://www.2carpros.com/articles/head-gasket-blown-test

Let me know. Also, let me know if you have other questions.

Take care,

Joe
Apr 1, 2022 at 3:20 PM
Avatar
GDANGERFIELD
  • MEMBER
  • 4 POSTS
When I took the cap off I only seen sludge on the cap it was a lot.
Apr 1, 2022 at 8:06 PM
Avatar
JACOBANDNICKOLAS
  • ✓Experienced Mechanic
  • 110,240 POSTS
Hi,

If it was a creamy tan/brown sludge, that could indicate coolant is mixed with the oil. Is it possible for you to take a picture of the cap and upload it for me to see?

Let me know. Also, let me know if you were able to check the other things in the link I provided. For example, air bubbles in the coolant.

Let me know.

Joe
Apr 2, 2022 at 1:16 PM
Avatar
GDANGERFIELD
  • MEMBER
  • 4 POSTS
There isn’t anything on the cap, it’s sludge. When I go 50MPH it overheats.
Apr 2, 2022 at 2:02 PM
Avatar
JACOBANDNICKOLAS
  • ✓Experienced Mechanic
  • 110,240 POSTS
Okay, I'm confused. You indicate there was sludge on the cap two posts above and I'm not understanding when you say nothing on the cap it's sludge when I go 50+.

I'm sorry for the confusion. It's a little more difficult when emailing back and forth.

If the truck only overheats over 50 MPH, I need to know if the cooling system was flushed when you replaced the thermostat and cleaned the reservoir?

Let me know.

Joe
Apr 2, 2022 at 2:19 PM
Avatar
GDANGERFIELD
  • MEMBER
  • 4 POSTS
I replaced the thermostat, but I somewhat cleaned the radiator because I didn’t have a water hose.
Apr 2, 2022 at 2:54 PM
Avatar
JACOBANDNICKOLAS
  • ✓Experienced Mechanic
  • 110,240 POSTS
Hi,

If there is sludge or corrosion in the system, it can be causing the issue. By chance, is the flush something you could do now? Also, not just flush the radiator but also the engine block.

Let me know.

Joe
Apr 3, 2022 at 9:59 AM
Join 2CarPros for free, one of the most advanced car repair communities on the internet. From first-time drivers to seasoned mechanics, everyone is welcome to reply, share details, and get better answers. You can add a temporary image or video first; uploads are limited to 20 MB.
Ask a Free Question
Repair Safety Notice: This information is for general instructional purposes only. Vehicle repair can be dangerous. Verify all information, follow manufacturer service procedures, use proper tools and safety equipment, and consult a qualified repair shop when needed.