5.0 overheating
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Mountain Pass
Joined: Feb 2018
Posts: 192
Likes: 1
From: DEWINTON Alberta
5.0 overheating
So I could use some help on an overheating problem.
My 88 w 5.0 seems to be running ok just normal driving around town
Temp guage hangs right around the the O & R on the normal written on guage.
When I start running it on highway increasing speed up in the 65mph range the temp guage starts to soar right at the hot mark and stays there.
Following is new.
Thermostat 195
Heater core
water pump
fan clutch
full coolant flush
rad cap
Bottom line just running around city , stop and go , no problem , once I put the gas to it out on highway it gets hot ?
Any ideas as to what I could check would be appreciated.
Thanks Dave.
My 88 w 5.0 seems to be running ok just normal driving around town
Temp guage hangs right around the the O & R on the normal written on guage.
When I start running it on highway increasing speed up in the 65mph range the temp guage starts to soar right at the hot mark and stays there.
Following is new.
Thermostat 195
Heater core
water pump
fan clutch
full coolant flush
rad cap
Bottom line just running around city , stop and go , no problem , once I put the gas to it out on highway it gets hot ?
Any ideas as to what I could check would be appreciated.
Thanks Dave.
Hotshot
Joined: Jun 2015
Posts: 12,784
Likes: 2,422
Is it actually overheating or is the gauge indicating that it is getting hot? How old are the upper and lower radiator hoses? It could be that one or both is collapsing not allowing coolant flow at higher engine speeds.
Thread Starter
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Mountain Pass
Joined: Feb 2018
Posts: 192
Likes: 1
From: DEWINTON Alberta
I checked resistance on ECT sensor , hot and cold and it fell within range.
I turned a 30 min run back home into a 2 hour trip stopping twice to cool truck down.
I didn't physically see any boil over but engine was hot as heck.
I can't say for sure how old hoses are but appear in ok shape.
The rad shop I had it in at last week did the flush and pressure check did not make me aware of any areas of concern.
When the truck was hot (temp guage) the upper rad hose was allot firmer when squeezed than at cooler temps.
I changed fan clutch out for a new one yesterday hoping that the old one was the prob. Nope.
As soon as motor really is put under load then it gets hot.
I turned a 30 min run back home into a 2 hour trip stopping twice to cool truck down.
I didn't physically see any boil over but engine was hot as heck.
I can't say for sure how old hoses are but appear in ok shape.
The rad shop I had it in at last week did the flush and pressure check did not make me aware of any areas of concern.
When the truck was hot (temp guage) the upper rad hose was allot firmer when squeezed than at cooler temps.
I changed fan clutch out for a new one yesterday hoping that the old one was the prob. Nope.
As soon as motor really is put under load then it gets hot.
Elder User
Joined: Mar 2008
Posts: 816
Likes: 2
From: Sandy Hook, CT
In my history of 5.0's (both in Mustangs & F-series) overheating can be caused by the following:
Bad T-stat- yes, they can be bad out-of-box
Worn or improper impeller blades in the water pump
Incorrect rotation of water pump
Bad rad cap
Head gaskets flipped sides disallowing coolant flow toward the rear-This one is frustrating as you need to pull the heads just to check.
Bad fan clutch
Dragging brakes
Collapsing Lower rad hose due to no spring/rotted away spring in it.
Air bound coolant in system, especially after power flushing
Bad T-stat- yes, they can be bad out-of-box
Worn or improper impeller blades in the water pump
Incorrect rotation of water pump
Bad rad cap
Head gaskets flipped sides disallowing coolant flow toward the rear-This one is frustrating as you need to pull the heads just to check.
Bad fan clutch
Dragging brakes
Collapsing Lower rad hose due to no spring/rotted away spring in it.
Air bound coolant in system, especially after power flushing
Last edited by Roger T. Pipe; Jun 18, 2019 at 12:24 PM. Reason: addition
Fleet Owner
Joined: Oct 2005
Posts: 20,784
Likes: 1,751
From: Kentucky
I would highly suggest investing in a temperature probe of some type to get an empirical reading of the true coolant temperature. If the overflow tank is not getting over full then spitting our coolant I would lean towards a false alarm of the true engine coolant indication. I have a cheap infrared temperature gun to use as a quick test for scenarios such as these.
If you installed cheap chinese knock-off radiator cap and/or thermostat, you very well may have introduced a bigger problem. Test and verify those parts are good.
Elder User
Joined: Sep 2018
Posts: 735
Likes: 8
From: NC
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Mountain Pass
Joined: Feb 2018
Posts: 192
Likes: 1
From: DEWINTON Alberta
Ok good advice .
i checked the ECT sensor ( good) and swapped the sensor for dash temp back and forth with a spare and no change there.
The overflow is filling up but not boiling over.
id like to think the rad company bled all air out of system.
You can see on dash guage when thermostat opens up and by top rad hose.
Not sure how to check rad cap but it's new out of box and yes I'm to assume Chinese crap.
Im going to borrow a temp gun as suggested and check coolant when in normal range and when I believe it's about to overheat.
Thanks for all the help and advice !
i checked the ECT sensor ( good) and swapped the sensor for dash temp back and forth with a spare and no change there.
The overflow is filling up but not boiling over.
id like to think the rad company bled all air out of system.
You can see on dash guage when thermostat opens up and by top rad hose.
Not sure how to check rad cap but it's new out of box and yes I'm to assume Chinese crap.
Im going to borrow a temp gun as suggested and check coolant when in normal range and when I believe it's about to overheat.
Thanks for all the help and advice !
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Elder User
Joined: Mar 2008
Posts: 816
Likes: 2
From: Sandy Hook, CT
I'd simply get another rad cap...like others have said, make SURE it is the correct pressure. I'm not one for throwing parts at a problem, but the cap is cheap enough and you could probably return it if need be.
Side note-try & get this problem fixed quickly since if the engine keeps overheating, it'll bring on bigger, more frustrating overheating problems that weren't there before (head gasket, etc) . Overheating issues are among the most frustrating, in my opinion.
Side note-try & get this problem fixed quickly since if the engine keeps overheating, it'll bring on bigger, more frustrating overheating problems that weren't there before (head gasket, etc) . Overheating issues are among the most frustrating, in my opinion.
Lead Driver
Joined: Jan 2019
Posts: 5,067
Likes: 863
From: N.W. Alabama
like My4Fordtrucks said, sitting and idling hoses may not collapse, but under load/at speed could be, have you popped hood when running hot quick check, before turning off?
if there was anyway you can get front(radiator) higher than back, like back into ditch, or jack front end up, and turn heat on and sometimes it will help burp system
if there was anyway you can get front(radiator) higher than back, like back into ditch, or jack front end up, and turn heat on and sometimes it will help burp system
Thread Starter
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Mountain Pass
Joined: Feb 2018
Posts: 192
Likes: 1
From: DEWINTON Alberta
Thanks roger, will try another cap, I did put a new 13 pounder on but maybe not releasing ?
I have done some damage to rad I suspect as when it cools off I find about 1/8 cup of fluid on ground come morning.
When I had to stop a few times on way home the other for a cool down I tried squeezing upper house, hot as heck and firmer than it should be. Air in system I guess or cap is not doing its job ?
i have seen the lever style caps and will get one.
That day I got the truck pretty hot I checked timing when I got home and it was a little up and down fluctuating 10-14 deg, seemed to be idling high, perhaps because it was way too hot.
When I et a minute I'm going to run codes again.
Btw the just touring around town staying in first 3 gears , rpms low when shift truck is quite nice to drive.
I have done some damage to rad I suspect as when it cools off I find about 1/8 cup of fluid on ground come morning.
When I had to stop a few times on way home the other for a cool down I tried squeezing upper house, hot as heck and firmer than it should be. Air in system I guess or cap is not doing its job ?
i have seen the lever style caps and will get one.
That day I got the truck pretty hot I checked timing when I got home and it was a little up and down fluctuating 10-14 deg, seemed to be idling high, perhaps because it was way too hot.
When I et a minute I'm going to run codes again.
Btw the just touring around town staying in first 3 gears , rpms low when shift truck is quite nice to drive.
Lead Driver
Joined: Jan 2019
Posts: 5,067
Likes: 863
From: N.W. Alabama
timing should do that with spout connector plugged in that is the computer taking over and managing time for the different loads on motor, also the reason you remove spout to set/check timing
Thread Starter
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Mountain Pass
Joined: Feb 2018
Posts: 192
Likes: 1
From: DEWINTON Alberta
Ordered a new rad that arrived today.
A thicker than stock, about 2".
A little mods around tin on rad to make shroud fit and put in after work today.
Just returned from a 1 hr trip on highway and back roads.
Tried to get truck to run hot as before and this time stayed nice and cool.
Ill call it a success for now, no leaks thus far either.
Thanks again for input from fellow members.
Dave
A thicker than stock, about 2".
A little mods around tin on rad to make shroud fit and put in after work today.
Just returned from a 1 hr trip on highway and back roads.
Tried to get truck to run hot as before and this time stayed nice and cool.
Ill call it a success for now, no leaks thus far either.
Thanks again for input from fellow members.
Dave