Engine 1987 5.0 overheating at both idle and driving

Dylan87haych

New Member
Nov 26, 2020
3
0
1
23
Missouri
I've recently picked up my 7 mustang but my first fox a 1987 5.0. The car seems to be getting warm about 230-260. It has a new water pump. New thermostat and the fan clutch looks new as well and it has resistance when I turn it. All fluids are checking out. Is there something I might be missing before I replace the radiator? It doesn't look to be in terrible shape but it is 196k miles on it so it might just be time. Thanks in advance for any help!
 
  • Sponsors(?)


HemiRick

I'd be looking at jacking under the house
Jun 28, 2020
764
288
73
57
Memphis TN
sounds like a clogged/restricted rad....do you have an infrared heat gun to check it?
 

Monkeybutt2000

Advanced Member
Aug 11, 2019
604
403
73
50
Lafayette,IN
If it's not the radiator,which is highly suspect with that mileage you probably have air in the system. Get a Lisle funnel kit and you'll never have air in it again.
 
  • Like
Reactions: 1 users

7991LXnSHO

wanna catch the space herp
10 Year Member
Sep 1, 2010
5,221
1,658
194
Kearney, NE
If it is not the Radiator like Rick suggested, it needs burped or bled like monkeybutt says. Use the search for those terms. I have not had problems with this, but others swear having the nose up or squeezing the upper radiator hose are needed ways to get the air pockets out.
Visually inspecting the radiator inside for growths is free, as is burping the coolant system. That’s the order I’d go in, even without a cool thermometer.
 
Last edited:
  • Like
Reactions: 1 users

Cheapskate207

The left one hangs a little lower
Jan 12, 2020
455
345
73
29
Maine
I’d also recommend a no spill funnel. I finally got one this year.. it makes it easy. Not to mention no mess!
 

90sickfox

Wasn't a pretty sight...and I've got big hands
SN Certified Technician
Mar 2, 2015
5,790
4,886
203
43
Also beware that a couple people here have found brand new water pumps that were defective and didn't circulate coolant well.

I agree with proper filling and burping the system. Check the oil and coolant for a blown head gasket. There is a head gasket checker tool that most parts store will lend out. Its got to be straight water in the system and the directions need to be followed cemetery. Its not a complicated process.

Always makes me nervous to purchase a car that has a complete new cooling system. The previous owner was definitely having issues.

Another thing to check is the coolant temperature sender located in the drivers side of the lower intake...around top between the ac compressor and upper intake. If you don't have boiling over at 260 degrees then it could be giving a false reading to the guage.

When the temperature is in the middle you should feel warm air being pulled through the radiator by the fan. The fan shroud is also important and should be there and fully intact. If the air is cold coming through the radiator then its got a coolant flow issue....thermostat...low coolant....big air bubble....or water pump not circulating.

Another check is to wrap your hand around the upper radiator hose....and then around the lower hose. The upper hose should be hot...the lower hose should be warm. It the upper is hot and the lower is cold then the radiator has a restriction. If the upper is cold...no circulation...could be thermostat....air....or water pump. An extremely blocked radiator could cause a flow issue but would cause the lower hose to collapse when engine is revved....unless it still has the factory spring in the hose.
 
  • Like
  • Useful
Reactions: 2 users
D

Deleted member 215073

You found something better than my large soda bottles with the bottom cut off? :tss:
Yep
I don't even use the Lisle funnel kit anymore.

This is faster, removes all air pockets, and virtually no mess at all.
Screenshot_20201129-054743_Chrome.jpg
 

KRUISR

5 Year Member
Apr 16, 2015
870
332
83
51
Have you started the car with the rad cap off, wait for coolant to come up to temp and watch for flow coming out of the rad tubes. Once thermostat is fully open there should be quite a good flow coming out of them.