2000 Explorer 4.0 OHV Overheating

[Tristan860]

Explorer attempting to run hot after 20 minutes of driving.

Things that were replaced after learning both heads were cracked (Ran great with no heating issues for 1 month):

Heads
head gaskets and all upper gaskets
waterpump
thermostat (198)
radiator hoses
Radiator was replaced 2 years ago

It gets close to the H but never reaches it because my commute is over before then. Ive rode with my scanner attached and temp has reached 225. What is normal? I understand that the thermostat is suppose to open at 198. Where should I start now I do not want to waste anymore time and this vehicle is my daily driver. Thanks for any help

 

[SupaSwope]

So its getting all the way up to 225 then the thermostat opens? Are you seeing it open on your scan tool when watching temps? If it does that repeatedly, I would guess bad/stuck thermostat.

I mean your not getting any gunk(oil,gas) in the coolant right? Its not bubbling(boiling) back into the coolant reservoir? Just getting hot? Not leaking? I am gonna go with thermostat.

Also when is the last time you flushed the system, added coolant? Could just not topped off/coolant needs to be changed.

 

[Tristan860]

So its getting all the way up to 225 then the thermostat opens? Are you seeing it open on your scan tool when watching temps? If it does that repeatedly, I would guess bad/stuck thermostat.

I mean your not getting any gunk(oil,gas) in the coolant right? Its not bubbling(boiling) back into the coolant reservoir? Just getting hot? Not leaking? I am gonna go with thermostat.

Also when is the last time you flushed the system, added coolant? Could just not topped off/coolant needs to be changed.

Thanks for the response.

So, I thought it was the thermostat and I replaced it the other day. I thought it was suppose to open @ 198. But my explorer is reaching temps around 225.

There is no gunk in the coolant. Its not bubbling back into the reservoir. Its just getting hot and I do not see any leaks.

When I replaced the heads I drain all the coolant. Then refilled it.

 

[Josh P]

dust in the radiator and a failing clutch fan could cause it to run hot. I'd probe the upper and lower hose with an infrared thermometer. Harbor freight has one for under $20.

 

[Tristan860]

dust in the radiator and a failing clutch fan could cause it to run hot. I'd probe the upper and lower hose with an infrared thermometer. Harbor freight has one for under $20.

I will check on that thermometer. I put a newspaper in the fan while running in park and it shredded the paper with no problem. So i'm thinking the clutch fan is good. Right?

 

[Josh P]

I will check on that thermometer. I put a newspaper in the fan while running in park and it shredded the paper with no problem. So i'm thinking the clutch fan is good. Right?

I wouldn't recommend using the fan to shred documents. If you can get a single sheet of newspaper to want to suck through the grille then you have a lot of airflow. Is the fan shroud good? All the blades on the fan ok?

 

[Tristan860]

I wouldn't recommend using the fan to shred documents. If you can get a single sheet of newspaper to want to suck through the grille then you have a lot of airflow. Is the fan shroud good? All the blades on the fan ok?

It wasn't an intentional shred just checking to make sure it didn't stop the fan. I will check the airflow. Yes the fan shroud is good. All the blades are in tack.

 

[Runnin'OnEmpty]

Could the thermostat be installed backwards?

 

[Tristan860]

Could the thermostat be installed backwards?

It was installed correct. with the charge cylinder (the long portion) installed first.

 

[alohamonte]

Have you checked the radiator cap lately? If it's bad it will run hot.

 

[Tristan860]

Have you checked the radiator cap lately? If it's bad it will run hot.

I actually just replaced it this weekend

 

[Littlefoott69]

what is your coolant mixture? straight water and it will boil at around 216 degrees at 16lb pressure so 225 would be boiling point with a high water ratio of coolant

 

[Tristan860]

i believe 50/50 but it is possible it has a higher water percentage

 

[Tristan860]

what is your coolant mixture? straight water and it will boil at around 216 degrees at 16lb pressure so 225 would be boiling point with a high water ratio of coolant

I believe 50/50 but it is possible that the water percentage is higher

 

[Runnin'OnEmpty]

Explorer attempting to run hot after 20 minutes of driving.

Things that were replaced after learning both heads were cracked (Ran great with no heating issues for 1 month):

Heads
head gaskets and all upper gaskets
waterpump
thermostat (198)
radiator hoses
Radiator was replaced 2 years ago

It gets close to the H but never reaches it because my commute is over before then. Ive rode with my scanner attached and temp has reached 225. What is normal? I understand that the thermostat is suppose to open at 198. Where should I start now I do not want to waste anymore time and this vehicle is my daily driver. Thanks for any help

The fact it ran great with no overheating issues for a month after the work eliminates the headgaskets being installed incorrectly. One thing that comes to mind is the coolant isn't circulating correctly. Maybe the pump impeller is spinning on the shaft and not actually pumping the coolant...? This is a long shot I know, but nothing else comes to mind with everything you've already checked. If you think this is a possibility, you could
disconnect a heater hose and place it in a bucket to check for coolant flow. Also check to see if the waterpump pulley isn't spinning on the shaft.
Was this a new pump or rebuilt?

 

[Littlefoott69]

if your return hose is getting hot, you have flow through the engine and that would make me further suspect the coolant itself

 

[Tristan860]

The fact it ran great with no overheating issues for a month after the work eliminates the headgaskets being installed incorrectly. One thing that comes to mind is the coolant isn't circulating correctly. Maybe the pump impeller is spinning on the shaft and not actually pumping the coolant...? This is a long shot I know, but nothing else comes to mind with everything you've already checked. If you think this is a possibility, you could
disconnect a heater hose and place it in a bucket to check for coolant flow. Also check to see if the waterpump pulley isn't spinning on the shaft.
Was this a new pump or rebuilt?

It was a new pump. But i will definitely give your suggestion a try.

 

[Tristan860]

if your return hose is getting hot, you have flow through the engine and that would make me further suspect the coolant itself

Yes, the hoses are getting hot. I grabbed a little preston coolant check and my mix was definitely water rich. I drained and added more coolant will give an update tomorrow. Thanks for your input.

 

[Tristan860]

Still doing the same thing after getting the coolant water mix better. Flushed and trying this evapo-rust thermocure to see if it will clean out my radiator will post again once the treatment is done.