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After a short run sometimes less than an hour, my 1967 Galaxie 500 xl 390cu - FE Block - C6 Auto transmission, displays "HOT" on temp dash. Solenoid starter replaced, Complete radiator flush with new anti-freeze/over heat fluid. There's no leaks. Have to wait until it cools down, to start up again. Not sure why it;s displaying "HOT". Fan belts etc all working ok.
Any ideas please, need help, don't want to seize the engine up by excessive engine temp.
Thanks so much
 

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Discussion Starter · #2 ·
More info, Radiator is relatively new OEM and the coolant has been circulated throughout the cooling system no air trapped and been burped. Could this be a thermostat issue or water pump? Thanks ,
 

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So it began to run hot SINCE the new radiator etc? What was the trigger to replace the radiator and coolant? No other work on the engine since? How many miles on the 390?

Other random thoughts.

Is there ANY chance the fan is installed backwards (been known to happen)? It should be sucking air through - so easy an test is to check if a piece of paper in front of the radiator is pulled to it (obviously don't leave it for long if it passes that test).

And I guess if the coolant is flowing well, the lower hose is plenty stiff (i.e, it has not collapsed) well as the upper hose? Given your observation the coolant is flowing adequately it seems like the thermostat IS opening. FWIW, 195 degree thermostats are quite OK in my experience.

Finally, nerd that I am, I would check the temp with an infrared thermometer at the thermostat housing and compare to the temp at the point it leaves the radiator.

Others more clever than I will chime in soon enough
Kevin
 
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Discussion Starter · #4 ·
So it began to run hot SINCE the new radiator etc? What was the trigger to replace the radiator and coolant? No other work on the engine since? How many miles on the 390?

Other random thoughts.

Is there ANY chance the fan is installed backwards (been known to happen)? It should be sucking air through - so easy an test is to check if a piece of paper in front of the radiator is pulled to it (obviously don't leave it for long if it passes that test).

And I guess if the coolant is flowing well, the lower hose is plenty stiff (i.e, it has not collapsed) well as the upper hose? Given your observation the coolant is flowing adequately it seems like the thermostat IS opening. FWIW, 195 degree thermostats are quite OK in my experience.

Finally, nerd that I am, I would check the temp with an infrared thermometer at the thermostat housing and compare to the temp at the point it leaves the radiator.

Others more clever than I will chime in soon enough
Thanks so Much, Kevin, those are good suggestions - I;ve only recently purchased the vehicle, but the new radiator was already installed and working fine apparently for years. The fan, I checked is on correctly and the hoses appear in good shape, no cracks. As you say, the thermostat is probably ok, if it wasn't then it would overheat almost immediately, once it got up to temp. I'll have to get a mechanic to the temp using a infrared thermostat, but that's a good idea.
Could it be water pump or crank pulley issue? Would these be directly related , causing it to overheat? I really don't know. The car doesn't have Air Conditioning. Thanks
 

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So it began to run hot SINCE the new radiator etc? What was the trigger to replace the radiator and coolant? No other work on the engine since? How many miles on the 390?

Other random thoughts.

Is there ANY chance the fan is installed backwards (been known to happen)? It should be sucking air through - so easy an test is to check if a piece of paper in front of the radiator is pulled to it (obviously don't leave it for long if it passes that test).

And I guess if the coolant is flowing well, the lower hose is plenty stiff (i.e, it has not collapsed) well as the upper hose? Given your observation the coolant is flowing adequately it seems like the thermostat IS opening. FWIW, 195 degree thermostats are quite OK in my experience.

Finally, nerd that I am, I would check the temp with an infrared thermometer at the thermostat housing and compare to the temp at the point it leaves the radiator.

Others more clever than I will chime in soon enough
Kevin
As pkevins noted, first thing is verify that it is really overheating. Use a cheap IR gun on the upper radiator hose close to the thermostat housing or insert a thermocouple along the edge and into the upper radiator hose at the thermostat housing. You can also monitor the heater hoses ONLY if the car is a heater only car from the factory as the flow is continuous.

Also does the car have factory Air Con? This changes quite a bit as far as type of radiator, fan, shroud and heater core flow, etc.

What size radiator did you use? 2 row? 3 row? Double density core or standard core? Brass/copper or aluminum?

The more we know the more we can help.

Cheers
 

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Discussion Starter · #6 ·
Thanks so Much, Kevin, those are good suggestions - I;ve only recently purchased the vehicle, but the new radiator was already installed and working fine apparently for years. The fan, I checked is on correctly and the hoses appear in good shape, no cracks. As you say, the thermostat is probably ok, if it wasn't then it would overheat almost immediately, once it got up to temp. I'll have to get a mechanic to the temp using a infrared thermostat, but that's a good idea.
Could it be water pump or crank pulley issue? Would these be directly related , causing it to overheat? I really don't know. The car doesn't have Air Conditioning. Thanks
Sorry, it has 46,500 miles on the clock, which I believe is genuine :)
 

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Discussion Starter · #8 · (Edited by Moderator)
Thanks DesertXL and Kevin, you are pretty knowlegeable chaps. The car has no factory AC and is heater only. Its a 4-Row radiator, I dont know if its standard or double, nor not sure if it;s brass or copper, looking at the receipt it cost $550 10 years ago. Added a couple of photos of engine bay

With the IR Gun, what should I be looking for when pointing at upper radiator hose clamp?
When you say, verify that it's really overheating, what do you mean please? What is causing the temp indicator to display "HOT" if it wasn't? Thanks so much
Motor vehicle Vehicle Car Automotive design Hood
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Thanks DesertXL and Kevin, you are pretty knowlegeable chaps. The car has no factory AC and is heater only. Its a 4-Row radiator, I dont know if its standard or double, nor not sure if it;s brass or copper, looking at the receipt it cost $550 10 years ago. Added a couple of photos of engine bay

With the IR Gun, what should I be looking for when pointing at upper radiator hose clamp?
When you say, verify that it's really overheating, what do you mean please? What is causing the temp indicator to display "HOT" if it wasn't? Thanks so much
View attachment 52275 View attachment 52276
Hello LarryM1961,

All good questions. A cheap IR gun will probably not have an emissivity setting, so you want to aim it at a black body to get the closest to accurate reading. In other words on the black radiator hose itself right above the thermostat housing.

Now since it's a heater only car, it wouldn't hurt to take a reading on the heater hose that comes off the intake, not the coolant pump as that's the return.

The HOT and COLD lamp are controlled from the same sender that is directly behind your distributer in the forward coolant tract of the intake manifold. It's measuring the coolant coming out of the heads which is the last stop before the radiator if the thermostat is open that is.

When does it overheat exactly? Are you idling? Are you in a low cruise say 30-40 MPH or highway >55 MPH?

I noticed you do not have a fan shroud. The '66's with FE came with a fan shroud even if no AC and the '68 had a partial shroud with an FE and no air. A full fan shroud wouldn't hurt either way. What type of fan is on the coolant pump? ( I can't see exactly). It'll probably be a factory flex fan 5 blade.

Your radiator looks like a brass copper and that's a good radiator providing it is clean internally. When the engine is cold and you remove the radiator cap, is the level roughly 2 inches from the top? There's no overflow tank on these cars, the radiator uses its top portion as the expansion tank so you never fill them all the way up to the top. If you do it's no big deal as the excess will just dump out the overflow tube.

As a side note the factory temperature sender turns on the HOT lamp around 240˚F and turns off the COLD lamp around 110˚F or so.

Cheers
 

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Hello LarryM1961,

All good questions. A cheap IR gun will probably not have an emissivity setting, so you want to aim it at a black body to get the closest to accurate reading. In other words on the black radiator hose itself right above the thermostat housing.

Now since it's a heater only car, it wouldn't hurt to take a reading on the heater hose that comes off the intake, not the coolant pump as that's the return.

The HOT and COLD lamp are controlled from the same sender that is directly behind your distributer in the forward coolant tract of the intake manifold. It's measuring the coolant coming out of the heads which is the last stop before the radiator if the thermostat is open that is.

When does it overheat exactly? Are you idling? Are you in a low cruise say 30-40 MPH or highway >55 MPH?

I noticed you do not have a fan shroud. The '66's with FE came with a fan shroud even if no AC and the '68 had a partial shroud with an FE and no air. A full fan shroud wouldn't hurt either way. What type of fan is on the coolant pump? ( I can't see exactly). It'll probably be a factory flex fan 5 blade.

Your radiator looks like a brass copper and that's a good radiator providing it is clean internally. When the engine is cold and you remove the radiator cap, is the level roughly 2 inches from the top? There's no overflow tank on these cars, the radiator uses its top portion as the expansion tank so you never fill them all the way up to the top. If you do it's no big deal as the excess will just dump out the overflow tube.

As a side note the factory temperature sender turns on the HOT lamp around 240˚F and turns off the COLD lamp around 110˚F or so.

Cheers
Hi DesertXL,
Yes thank you Sir, that's all good info you have provided. Its overheating when its idle, when I;m parking it actually, after say an 1 hr- 45mins drive. There is about 2 inches from the top when I remove the radiator cap. I do remember the fan and I think you';re right its a 5 blade factory flex.

So what part of the engine exactly is overheating?
I can purchase a Fan shroud if that will help cool it down. I can take more photos of the radiator.
With the IR gun, what reading should I get and what will it tell me? Will it tell where its overheating? How I can I use this to diagnose where the problem is?

I;ve indicated red lines on the photos of where I should direct the IR gun. Are these correct DesertXL? please see attached photo
Thanks so much
LarryM
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Discussion Starter · #12 ·
Hi DesertXL,
What are the normal temperatures on the Upper Radiator hoses and heater hoses? So, if they are excesively high, what does that indicate? where would the problem is. I'll try and get hold of a IR Temp gun
thanks
Larry
 

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Morning LarryM1961,

Again all good questions, do not be afraid to ask. Let's tackle the first one; what part of the engine. If it is indeed overheating, it would be all of it. In order to understand why, let's review the coolant flow paths of a typical automotive engine. In your cars case there are two constant coolant paths and one controlled path.

The coolant pump obviously does all the work of pushing coolant around. The first and most standard flow path is just around the engine. The coolant pump will push coolant out through both outer elbows into the front of the cylinders of which 95% of it flows directly to the back of the lower block washing across all 8 cylinders. When the coolant reaches the back of the lower block there are passages that allow the coolant to flow up into the rear of both heads and then the coolant washes forward on both heads. So picture a sideways U where the coolant is pushed in the front of the lower block, it goes to the back, rises up and is pushed back towards the front of the engine. Easy peasy.

So the coolant is pushed to the front of the cylinder heads and there are passages at the front of the heads that allow the coolant streams to tie at the front of the intake manifold. In this forward intake area there is a small hose on the front of the intake that allows a small contiguous coolant flow back to the coolant pump inlet and this is one complete coolant path that always circulates if the engine is running.

Just a side note, where I mentioned about 95% of the coolant takes the long way around the sideways U through the engine 5% takes a shortcut as there are small coolant holes around each cylinder directly to the cylinder head above. This removes any trapped air or steam and gets it out towards the radiator eventually. This is not terribly important but something to keep in mind when understanding the cooling system.

The second coolant path which is continuous in your cars case is the heater core path. At the front of the intake is a logical place to take any warmed up coolant for heat in the car. You can see one heater hose coming out of the top of the forward intake and that's hot water pushed out to the heater core and the other heater core hose returns to the suction side of the coolant pump. Now on 65-68 heater only cars that coolant flow is guaranteed continuous. On 65-68 factory air con cars at times that flow is shut off.

The third coolant path is the path through the radiator. At the front of the intake manifold the thermostat is monitoring the coolant as it's cycling through the engine being warmed up. Remember the constant flow paths are always circulating coolant around the engine and in the front of the intake where the thermostat is sampling the temperature. When the coolant reaches the temperature rating of the thermostat (there are three common ones) it will start to open and allow that flow to exit out the top of the radiator hose into the radiator where it is cooled down by the heat exchange through air and then back into the lower radiator hose and back into the suction side of the coolant pump.

The thermostat regulates the circulating coolant temperature of the engine by allowing more or less coolant through the radiator. It's just that simple.

I feel it important to understand how something works fully in order to picture the problem and then find solutions easier.

In just focusing on the cooling system, the overheating can be cause by:

1.) Low coolant flow; in other words some obstruction in the cooling system or even a broken or rotted impeller in the coolant pump.

2.) A sticking thermostat; the thermostat may be sticking and cannot open enough to let enough hot coolant into the radiator to be cooled.

3.) Calcified radiator; Some people like to use tap water for coolant only or to mix with antifreeze. This is what NOT to do. Tap water usually has a high mineral content that precipitates out on a hot surface (ie radiator) and builds up an insulating layer inside the radiator slowly making it more ineffectual at removing heat. You should always use distilled water as a mix with regular pure green anitfreeze.

4.) Extremely soft lower radiator hose. If enough engine oil leaks on the hose it can become so soft it can collapse from the suction of the coolant pump thereby restricting the coolant path through the radiator. This is usually a high speed instance as idling or slow driving doesn't spin the coolant pump fast enough to collapse the lower hose.

The next couple applies mostly to classic cars because of their extreme age.

5.) Mismatched or missing parts. You mentioned you recently bought the car there's no telling the amount of modifications and bad workmanship the car has had. That's one reason why pictures are helpful. The moment the engine bay starts looking like a advert for a Summit Racing catalogue it usually spells trouble.

6.) Sludge in the engine. I've personally encountered this on 3 of my FE Fords that either sat or were run for decades without a coolant change. Antifreeze will break down after awhile and also it has rust inhibitors that are only good for a few year at best. When the rust inhibitor chemicals are used up, the iron engine begins to rust, the antifreeze breaks down and the two form a nasty sludge that is so heavy it sinks and builds up in the bottom of the block. Eventually it gets so bad, the cylinders can run hotter and it parts of the sludge will break off and start to plug the radiator and heater core. The only fix for this extreme condition is removal of the engine and tear down of the engine including the core plugs and a hot tank or a pressure washing all that gunk out.

7.) Incorrect placement of head gaskets. If the cylinder heads were removed for whatever reason, the head gasket can be put on backwards. The head gasket has the main cooling passage blocked on one side and open on the other. If it's flipped around accidentally, the coolant path goes from the front of the block at both front cylinders then straight up into the intake and it never goes all the way back, up and forward. In other words no sideways U. It flows more like a ] where it's barely in, up and out and of course the engine overheats. However the engine would over heat rather quickly in about several minutes from a cold start if this was the case.

Now to answer your other questions, you'll want to measure on the upper radiator as you circled but obviously only when the engine has been run and the HOT lamp is on. If the engine is cold, the thermostat will not open and that hose will remain cool. However if you measure the heater hose coming off the top of the intake that is a constant sample of the engine coolant temperature and another good place to measure assuming the heater core isn't plugged.

The common thermostat temperatures available are 160, 180 and 195. Based on the above explanation this is the regulation point of the engine coolant temperature. If you chose the 160. When the circulating coolant temperature of the engine reaches above 160 the thermostat will start to open and do its best to keep coolant around 160. Usually the coolant will run several degrees higher than the thermostat rating in realistic conditions.

I know this is a long post, but I felt it was important to fully grasp how it works and the possible failure modes.

I would have a look at the Ford Master Parts Catalogue for 65-72 and see what kind of fan shroud is called out for your particular car, being an FE heater only. I have 66's and 68's Ford full size cars all with FE's and '67 is a bit of a mix between the two and off hand I can't remember if it's a partial or full shroud and whether it's plastic or metal; 66's are metal and '68's are plastic.

Cheers
 

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All of the above outlined by DesertXL are spot-on.

Do I understand correctly that the warning light comes on since the day you acquired the ride and NOTHING else has been changed under the hood since?

Any chance the fan belts aren't adequately snug? As a SWAG, I think the deflection midway between the upper pulleys should be less then 1/2" (with the engine off course).

Infrared temp readers are easily acquired at places such Home Depot - useful in the kitchen too.:)
It just has to be good enough. I forget the difference to be read between the upper and lower hose, but figure at least 20 degrees. I hoped to get my ride out today and would have checked for a data point, but other in-house repairs are taking precedence.

11 years ago when I drove home the ride in my sig (after my Dad gave it to me permanently) the mechanical gauges indicated as shown in the attached heading west on I-80.

Kevin
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Discussion Starter · #15 ·
Thanks So much DesertXL and Kevin :). Desert Xl - you should be University Lecturer, very detailed explanation, thank you so much :). It helps me understand it much better now. Sorry for the delay in replying, time zone difference,
Yes Kevin, nothing has changed under the hood, its all pretty well much original. The mechanic did check the fan belts and they were pretty firm.
The comment about Summit racing is amusing, I know what you mean LOL

I wish you were here in Australia, you could fix my car :) LOL

To answer some of your questions DesertXL.


1.) Not sure where this is...rotted impeller in the coolant pump.

2.) I have a new Thermostat I purchased earlier but never installed it. However, according to the service/receipts, it looks like its never been changed, not for at least for 14 years anyway So are you saying that Thermostats can intermittently work, rather than completely broken or work 100%? Is it necessary to drill a hole in the Thermostat?

3.) Calcified radiator; - When I did the radiator flush, the mechanic did use tap water to flush the radiator out, then I asked him to use distilled water mixed with coolant/anti-freeze, but it probably has some tap water in it, since he topped it up using tap water.. So probably it has a mixture of distilled and tap water in at the moment. Should I flush it out again and put only distilled water/coolant in? I don't need to purchase another radiator , do I? :(

4.) Extremely soft lower radiator hose. I don't think the engine is leaking oil as I can see no oil spills

5.) Mismatched or missing parts. I;ll post for photos of the engine

6.) Sludge in the engine. I believe the car has been run in Wisconsin, in the winter time, they use to put it in storage.
I'll get some more photos, that;s an excellent breakdown DesertXL,
So should I change the Thermostat to start off with, do you think?

Kind Regards
Larry M
 

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Some one spent some $ on the cooling system hoses. Nice touch.
The red stripe heater hose is correct for post- December 1967 vehicles.

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Thanks So much DesertXL and Kevin :). Desert Xl - you should be University Lecturer, very detailed explanation, thank you so much :). It helps me understand it much better now. Sorry for the delay in replying, time zone difference,
Yes Kevin, nothing has changed under the hood, its all pretty well much original. The mechanic did check the fan belts and they were pretty firm.
The comment about Summit racing is amusing, I know what you mean LOL

I wish you were here in Australia, you could fix my car :) LOL

To answer some of your questions DesertXL.


1.) Not sure where this is...rotted impeller in the coolant pump.

2.) I have a new Thermostat I purchased earlier but never installed it. However, according to the service/receipts, it looks like its never been changed, not for at least for 14 years anyway So are you saying that Thermostats can intermittently work, rather than completely broken or work 100%? Is it necessary to drill a hole in the Thermostat?

3.) Calcified radiator; - When I did the radiator flush, the mechanic did use tap water to flush the radiator out, then I asked him to use distilled water mixed with coolant/anti-freeze, but it probably has some tap water in it, since he topped it up using tap water.. So probably it has a mixture of distilled and tap water in at the moment. Should I flush it out again and put only distilled water/coolant in? I don't need to purchase another radiator , do I? :(

4.) Extremely soft lower radiator hose. I don't think the engine is leaking oil as I can see no oil spills

5.) Mismatched or missing parts. I;ll post for photos of the engine

6.) Sludge in the engine. I believe the car has been run in Wisconsin, in the winter time, they use to put it in storage.
I'll get some more photos, that;s an excellent breakdown DesertXL,
So should I change the Thermostat to start off with, do you think?

Kind Regards
Larry M
Hello LarryM1961,

Thank you for the kind words.

The impeller is the part that spins inside the coolant pump and forces coolant out the side elbows of the pump by centrifugal force. The reason why I brought that up was just a possibility of it being part or all of the problem.

On the topic of thermostats, they can stick open or close or anywhere in between. Age (use) and sludge into the cooling system can cause them to stick, then again I've had brand new ones that were just plain defective right from the get go.

On the topic of the radiator, since they are so expensive, I'd drain the coolant and change it with fresh coolant and distilled water. Keep in mind draining the radiator does not drain the entire engine. There will be coolant in the lower block up to the level of the coolant pump outlets. The block does have drains on both sides, but they probably will not come out without fight if they were never removed and even if you do get them out there might be sludge behind them and nothing will come out anyway.

If you look into the radiator cap opening, since it's a vertical flow, how does the tube columns look? If you can see a whitish buildup that's minerals but if you can see they are more or less copperish looking then it is clean. Those brass copper radiators are about 800 bucks now new, so you want to take good care of it. Do not get the cheaper all aluminum radiators, take care of the brass copper one and it will outlive you. The aftermarket aluminum ones will not. I'm still using the original 1968 Ford brass copper radiator in my '68 XL and it still works like the day it was built.

With that fixed pitch 4 bladed fan you will need a fan shroud. It doesn't move much air at low RPMs and a shroud is a must. The proper placement of the fan blade with respect to the shroud should be about half way of the blade width. If you're in a hotter climate you could always put the factory air con 7 blade fan replete with thermostatic fan clutch along with the shroud on the car.

However lets not forget the original diagnostic procedure of verifying the overheating actually exists. The problem may be there is no actual problem or it could be something simple like the lack of the fan shroud (which I would obtain regardless) or it could be a blend of aforementioned possibilities.

Not that I wish to overburden the subject but there are other factors that may contribute to an overheat. Running the air fuel mixture at stoichiometric produces the most heat in the combustion chamber. Actually running leaner or richer lowers cylinder temps. Another possibility is too retarded of timing causes excessive cylinder temperatures.

Now usually a cooling system in top notch shape can deal with the above problems adding more heat that usual, but if the cooling system is sub par then the above factors play a role in the overall problem.

I just wanted to impress a broader outlook on the situation.

Cheers
 

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Hi Desert XL, Thanks, another detailed great response. I've attached some pics of the coolant in the radiator, what do you think? Should I do another flush? As I said I did one about 4 weeks ago. Where can I purchase a fan shroud for this Galaxies 67 XL and impeller? They don't sell them here locally. So do you think I should replace the thermostat? Hopefully, with all these, it may resolve the issue.
 
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