Overheating

Tizzy

Registered User
Joined
Jul 4, 2022
Posts
17
Reaction score
10
Location
South Carolina
I recently had a turn-key 7.3 IDI put in my 93 F350 and am experiencing some overheating/close to overheating issues. I have had the engine in the truck for around 3 months. Initially, the truck ran cool all the time almost like it would not warm up. The other day the truck overheated. (Boiling coolant) Granted...it was almost 100 degrees outside, the A/C was on, and the truck had been running for quite some time however, it was not pulling or under any load. Now the truck is staying within the "normal" range, yet I feel running too hot without being ran under load.
I have used an IR temp thermometer to check the temps....here is what it looks like after about 30 minutes running on a 90 degree day with AC running....no high load or hauling anything.

190 at the upper radiator hose
210-220 across radiator
230 (highest temp)- just below radiator cap-radiator hose feels like it is under allot of pressure at this temp

When cruising down road truck heats up....
Maintains/slightly lowers temp stopped at stop sign.
Lowers temp when pressing accelerator.

There is no coolant in oil or oil in coolant.
I have "burped the radiator".

If the truck did not noticeably overheat the other day then I would just think that it is a faulty factory gauge, and the engine likes to run warm on hot days. However, since the truck always ran on cool side previously, not it runs on the hot/overheating side....I have to think something is wrong.

Any advice/suggestions?
 

Cubey

Van dweller
Joined
Oct 18, 2017
Posts
4,066
Reaction score
1,580
Location
USA
AC will drive up the temperature easily. Hate to say it but buy heavy duty 12v truck fans and put down the windows.

Your fan clutch may be weak too. When at full operating temperature, turn off the engine and see how easily you can move the fan blades. It should be very difficult if it's locking like it should. My old fan clutch was so weak that I could move it with a pinky. A new fan clutch dropped temps 10-15*F instantly.

Get a real temperature gauge too like Equus 6242. It's cheap and good. I run it in my RV.
 
Last edited:

Jesus Freak

Full Access Member
Joined
Apr 3, 2022
Posts
3,204
Reaction score
3,607
Location
Crestview, FL
My truck doesn't run hot when I'm pulling 8rolls of hay on a trailer up hill. I'd suspect that the radiator has some mild clogging. And I'm with Cubey on the fan clutch, check it out too.
 

snicklas

6.0 and Loving It!!
Staff member
Joined
Aug 7, 2006
Posts
6,164
Reaction score
2,342
Location
Greenfield, Indiana
Is you bottom radiator hose collapsing/sucking shut when the RPM's are raised. Seen that happen. Originally that hose would ahve had a spring inside, where the coolant flows to prevent this. I've red the new hoses are "built differently, and don't need a spring", but have seen them suck shut......
 

Cubey

Van dweller
Joined
Oct 18, 2017
Posts
4,066
Reaction score
1,580
Location
USA
Is you bottom radiator hose collapsing/sucking shut when the RPM's are raised. Seen that happen. Originally that hose would ahve had a spring inside, where the coolant flows to prevent this. I've red the new hoses are "built differently, and don't need a spring", but have seen them suck shut......

My RV had the original lower hose when I got it, and it sprung a leak a few weeks after i got it (after a 300 mile drive from where I bought it! I'm insanely lucky like that), when I was diagnosing vacuum, so I caught it on a cold engine that had only been idling for the vac pump.

Anyway, it still had the spring, so I moved it to the new hose and it fit fine. And here's a pic of it with the original hose if anyone wants to see what it looks like:

You must be registered for see images attach


So, if the hose feels very hard, it might be the spring inside. (I forgot about it until snicklas mentioned it)
 
Last edited:

Big Bart

Tow&Slow
Joined
Dec 22, 2020
Posts
1,481
Reaction score
950
Location
Newport Beach, CA
I recently had a turn-key 7.3 IDI put in my 93 F350 and am experiencing some overheating/close to overheating issues. I have had the engine in the truck for around 3 months. Initially, the truck ran cool all the time almost like it would not warm up. The other day the truck overheated. (Boiling coolant) Granted...it was almost 100 degrees outside, the A/C was on, and the truck had been running for quite some time however, it was not pulling or under any load. Now the truck is staying within the "normal" range, yet I feel running too hot without being ran under load.
I have used an IR temp thermometer to check the temps....here is what it looks like after about 30 minutes running on a 90 degree day with AC running....no high load or hauling anything.

190 at the upper radiator hose
210-220 across radiator
230 (highest temp)- just below radiator cap-radiator hose feels like it is under allot of pressure at this temp

When cruising down road truck heats up....
Maintains/slightly lowers temp stopped at stop sign.
Lowers temp when pressing accelerator.

There is no coolant in oil or oil in coolant.
I have "burped the radiator".

If the truck did not noticeably overheat the other day then I would just think that it is a faulty factory gauge, and the engine likes to run warm on hot days. However, since the truck always ran on cool side previously, not it runs on the hot/overheating side....I have to think something is wrong.

Any advice/suggestions?
Some things to look at -

You said it is a new engine, suggesting things changed and it did not run hot before the engine swap? That it ran cool with the new engine for a while but now it runs warm. That you are pushing the limits of the truck in a sense as it is 100* outside and you are running the AC in the cab. Is that accurate?

1) Folks have had heat issues with non Motorcraft thermostats. Start there if you did not put it in. Even if the shop says they did, I would confirm and at this point replace it. You mentioned it ran cool for a time but now it does not. Perhaps you have a aftermarket thermostat or you got a bad Motorcraft one.
2) Incorrect IP timing can cause the truck to heat up when on the hwy and it tends to get worse when pulling a load. I would check your timing. 90% of shops do not have a meter, so if a shop put it in, likely they did the timing by butt dyno. Butt dyno or folks who say they do it by ear are not setting your timing they are guessing. (The only thing you hear when your engine is at 2,000 rpm is a bunch of noise.). Maybe your IP has moved a little due to vibration or line tension.
3) I do not recall if when the timing is advanced or retarded the timing causes the hot issue. But check you IP advance solenoid when the engine is hot to see if it has +12v? It’s the electrical connector closest to the window on the IP. It should shut off at 130*.
4) Coolant does not really cool better than water. It really just keeps your coolant from freezing and helps prevent rust and corrosion in the cooling system. So if you are running more than 50/50 coolant to distilled water, take some out and adjust to 50/50.
5) Your dash temp gauge is pretty worthless and not accurate. So your IR gauge is far more accurate. Most have installed an aftermarket temp gauge.
6) Many report that running the AC in hot weather up hills pushes there temp up and sometimes past 230*. So maybe try turning off the AC to see if the temp goes down a few degrees.
 
Last edited:

Cubey

Van dweller
Joined
Oct 18, 2017
Posts
4,066
Reaction score
1,580
Location
USA
1) Folks have had heat issues with non Motorcraft thermostats. Start there if you did not put it in. Even if the shop says they did, I would confirm and at this point replace it.

That's why I believe in testing before installing. I stuck the new one I got in a pot of cold water and heated it up to boiling on the stove to be sure it opened and closed.
 

Tizzy

Registered User
Joined
Jul 4, 2022
Posts
17
Reaction score
10
Location
South Carolina
Thank you for the replys. The information is much appreciated! I checked the bottom radiator hose...while I do not feel that it has a spring in it, it was not collapsing. I normally prefer to figure out and work on my own equipment, however I did notify the shop that put the engine in since it is under warranty. They immediately stated that they would not only come and towe it from my house to their shop... but were addement about checking it out because they thought temps were too high and wanted to make it right. I can't argue with a shop that stands behind their work.
I will inform everyone as to what they diagnose was the potential issue if any.
Thanks again for the help!
 

Joezam

Registered User
Joined
Jan 17, 2022
Posts
13
Reaction score
8
Location
Nevada
There are 2 sensors on the head for temp, the upper sensor is engine and the lower sensor is for the hot light.
 

Tizzy

Registered User
Joined
Jul 4, 2022
Posts
17
Reaction score
10
Location
South Carolina
All,
I wanted to inform everyone as to what the verdict was.......bad thermostat. New Motercraft installed and all is well. Temp reading at radiator neck is 175. Once again, thanks for the information all have provided.
 

Big Bart

Tow&Slow
Joined
Dec 22, 2020
Posts
1,481
Reaction score
950
Location
Newport Beach, CA
All,
I wanted to inform everyone as to what the verdict was.......bad thermostat. New Motercraft installed and all is well. Temp reading at radiator neck is 175. Once again, thanks for the information all have provided.
Tizzy,

I am glad you got it fixed.
 
Top