Overheating issue

[Mac]

OK guys, let me pick your brains. My 66 289 is running hot, after idling awhile, gage goes around the "P" on the "temp" letting on gage. Spits a small puddle when shut off.

The engine was rebuilt (.030" over) in the 90's but just got it running. When it was rebuilt a new water pump was put on. Since then the following items has been replaced new:

- radiator (3 core - brass/copper)
- 2-1/4" fan spacer (distance of 1" from front of fan to face of radiator)
- 6 blade fan
- 180 deg Motocraft themostat
- hoses
- Fomoco fan shroud
- running 50/50 mix Prestone/water plus on bottle of water wetter

T added to line and back flushed until clear water ran out.

My question is since it was bored .030"over is this normal to run hot or should I replace the water pump just to be safe? My next step I am considering is a 160 deg themostat.

Comments/suggestions are most welcome.

Thanks!
Mac

 

[giantpune]

If you remove the radiator cap on the engine and crank it up, you should be able to look down into the radiator. When the thermostat opens, watch water flowing through from the hot side into the cool side. If you see that, then the water pump is pumping.

Are you sure you have the correct water pump? Some of them pump backwards for different style pulleys. Like if you go with a water pump from a 90s 302 with a serpentine belt, those are supposed to rotate counter clockwise.

And no, boring an engine 30 over does not make it run hot.

I would suggest trying a mechanical thermostat and gauge. At least until you know what's what. It could be that your engine is running fine but the sender or gauge has an issue.

 

[Mac]

OK guys, let me pick your brains. My 66 289 is running hot, after idling awhile, gage goes around the "P" on the "temp" letting on gage. Spits a small puddle when shut off.

The engine was rebuilt (.030" over) in the 90's but just got it running. When it was rebuilt a new water pump was put on. Since then the following items has been replaced new:

- radiator (3 core - brass/copper)
- 2-1/4" fan spacer (distance of 1" from front of fan to face of radiator)
- 6 blade fan
- 180 deg Motocraft themostat
- hoses
- Fomoco fan shroud
- running 50/50 mix Prestone/water plus on bottle of water wetter

T added to line and back flushed until clear water ran out.

My question is since it was bored .030"over is this normal to run hot or should I replace the water pump just to be safe? My next step I am considering is a 160 deg themostat.

Comments/suggestions are most welcome.

Thanks!
Mac

Forgot to mention timing set to spec and a new temp sensor & radiator cap.

 

[Sheriff41]

Are you using the stock four blade fan? Is your fan completely inside the shroud? It should be spaced so the blades are half way inside the shroud opening. Does it have AC? Are you running a trans cooler in front of the radiator? Consider adding a coolant recovery tank for the overflow.

 

[72mokk1]

Is your fan a clutch fan? Those go bad. Do what giantpune said about checking the water flow, careful though, I have seen them spew if you have an air bubble. Temp sensor might be off or for a different gauge?

 

[c9zx]

+1 on using a shroud properly (Sheriff1). Use an IR thermometer pointed at and relatively close to the thermostat housing for a more accurate temp reading. https://flex-a-lite.com/blog/the-pe...he side of,not efficiently pulling it through.
Chuck

 

[will e]

Start with the simple stuff. Does the top hose get hot and do you 'see' water flow with the radiator cap off? If not then possibly a stuck thermostat (or installed backwards.. yep, I've done that). Easy to pull and test. Put it in a pan of water on the stove and set to bail. You should see it open up.

 

[Spike Morelli]

When I was doing servicing on cars that came in for overheating, the very first, and easiest, thing I'd do is pressure test the radiator cap, obviously, when the engine has cooled down. You'd be suprised how many times it's the cap that malfunctions. Second, I'd pull the thermostat and test it's operation in a pot of water on a hot plate with a thermometer to verify temp at opening. I have been in the habit of drilling a 3/16ths air bleed hole in the thermostat to bleed air. If everything is good to that point, a check of coolant flow, both water pump and radiator can impede flow characteristics. overheating at highway speeds can sometimes be attributed to the lower hose sucking closed if it doesn't have the wire spring inside it to keep it from collapsing. Obviously, as others have said, check that you have a shroud and the fan is positioned properly. Longshot, if the engine was only recently overhauled, the head gasket (s) will cause an overheating situation if installed wrong side forward., and can visually be determined by checking for the lower corner gasket tab sticking out under the head at the front. There's more, but that's the basics.

 

[Mac]

If you remove the radiator cap on the engine and crank it up, you should be able to look down into the radiator. When the thermostat opens, watch water flowing through from the hot side into the cool side. If you see that, then the water pump is pumping.

Are you sure you have the correct water pump? Some of them pump backwards for different style pulleys. Like if you go with a water pump from a 90s 302 with a serpentine belt, those are supposed to rotate counter clockwise.

And no, boring an engine 30 over does not make it run hot.

I would suggest trying a mechanical thermostat and gauge. At least until you know what's what. It could be that your engine is running fine but the sender or gauge has an issue.

Able to see water flowing after thermostat opened. Have the correct water pump installed. Will be installing a new instrument voltage reg on back of instrument cluster and a different temp gage to see if it changes readings.

 

[Mac]

Are you using the stock four blade fan? Is your fan completely inside the shroud? It should be spaced so the blades are half way inside the shroud opening. Does it have AC? Are you running a trans cooler in front of the radiator? Consider adding a coolant recovery tank for the overflow.

Using a ford 6 blade fan that sits half in half out of shroud. No AC. No trans cooler, auto transmission lines are connected to bottom of radiator.

 

[Mac]

Deci

Start with the simple stuff. Does the top hose get hot and do you 'see' water flow with the radiator cap off? If not then possibly a stuck thermostat (or installed backwards.. yep, I've done that). Easy to pull and test. Put it in a pan of water on the stove and set to bail. You should see it open up.

decided to go with a 160 deg thermostat. Installed it and temp now is approx middle of gage but will creep up if I let it idle for a while.

 

[Mac]

When I was doing servicing on cars that came in for overheating, the very first, and easiest, thing I'd do is pressure test the radiator cap, obviously, when the engine has cooled down. You'd be suprised how many times it's the cap that malfunctions. Second, I'd pull the thermostat and test it's operation in a pot of water on a hot plate with a thermometer to verify temp at opening. I have been in the habit of drilling a 3/16ths air bleed hole in the thermostat to bleed air. If everything is good to that point, a check of coolant flow, both water pump and radiator can impede flow characteristics. overheating at highway speeds can sometimes be attributed to the lower hose sucking closed if it doesn't have the wire spring inside it to keep it from collapsing. Obviously, as others have said, check that you have a shroud and the fan is positioned properly. Longshot, if the engine was only recently overhauled, the head gasket (s) will cause an overheating situation if installed wrong side forward., and can visually be determined by checking for the lower corner gasket tab sticking out under the head at the front. There's more, but that's the basics.

Thanks for the info. Replaced just about everything there is in the cooling system. Went with a 160 deg thermostat. Now reading is about mid point on gage. I also know that ford gages are not always accurate. One puzzling item, after running (idling) car up to temp and then shutting it down, the temp gage will spike hot if I start it back up then slowly go down to about mid point. Just changed the instrument voltage regulator on back of instrument cluster and swapped out a different ford temp gage since I had cluster out. Keeping my fingers crossed and will start it up tomorrow to see if anything changes.

 

[giantpune]

One puzzling item, after running (idling) car up to temp and then shutting it down, the temp gage will spike hot if I start it back up then slowly go down to about mid point.

When you turn the engine off, the water pump stops pumping. The coolant thats in the motor absorbs the heat, and that reaches your temp sending unit.

You start the engine, the water pump starts pumping, and cooler water comes in from the radiator, bringing your temp gauge reading back down.

 

[midlife]

These Ford engines run much better with a 180 to 195* thermostat. The temperature of the thermostat sets the lower limit of the engine temperature once the engine comes up to operating temperature, Temperatures can go above the thermostat setting for a variety of reasons, but the purpose of the thermostat is not to keep the engine at that temperature under all conditions. A lower temperature setting can induce sludge deposits, from what I understand.

Remember: these gauges should be treated not as absolute calibrations, but when things are normal or abnormal. If your normal reading is 3/4 high, then anything below or above that indicates an issue.

 

[Spike Morelli]

The cooling system on our 71-73 Mustangs is but one of the things improved over the original earlier Mustangs. We can be thankfull for the switch to cross-flow radiators, which our cars use. It's simply a more efficient cooling system. I had a good friend who, in our Senior year in High School, had a seriously cool '65 fastback, 4 speed, stroker 289, with professionally ported heads, big rowdy camshaft, 12 to 1 pistons, and a tunnelram with two Holleys and velocity stacks sticking up through the hood. I remember asking him if he had any overheating problems, and he quietly told me, ..." Don't tell anyone, but I have a crossflow radiator that I pulled out of a CHEVY that really keeps it cool". I've never forgotten that conversation. That Daytona Yellow fastback was one haulin' piece. That same guy, John Klumph, and I, would go on to be team mates in the Plymouth Trouble Shooting Contest, that is no more.......