Coolant does not flow with thermostat installed

[Stanglover]

Reading through all this is baffling for sure as to the cause of the problem.

I came to a theory that may or may not fly, but worth checking into if it were my car. Nothing make sense to me. As I have mentioned many times, I only go from my own experiences and this isn't one of them, but here goes.

1, It pressure tests okay cold. What about when hot?

2, You added 1 gallon of water. Where the heck is it going?

3, All your basic checks appear okay, T/stat working, correct stat with "hat", installed the RIGHT WAY UP? Hoses all new (spring in bottom hose?) etc. etc.

4, it overheats when driving and gets hard to start. Okay, here's my theory.... and it's only a theory.

When the engine is cold, no leaks are visible anywhere including from the cylinders. BUT when the engine is hot, it mysteriously gobbles up a gallon of water!! I believe you have a head gasket leak that is only present when the engine is hot. It may be very small, but it's there. The hard starting and knock is over pressurization of a cylinder because of the water (non-compressible), but which cylinder?

5, Do you see ANY whitish smoke/haze from the exhaust? You may need someone to follow you as you drive to observe the exhausts. Assuming you have dual pipes, your observer could see which bank is smoking. That narrows it down to one or the other head gasket that needs to be changed and SOON!! Major damage could occur and a total rebuild necessary.

As stated, this is NOT something I personally have experienced and I hope I never do on the Mustang. I did once have a head gasket blow on a T-Bird and that left a plume of white smoke behind the car for miles. I had to be towed home. Damn Fords!!

Anyway, I hope this offers some ideas that may not be what you or others want to hear or agree with, but I didn't see any mention of a blown head gasket when hot anywhere else in the posts.

I hope I'm wrong and it proves to be something simple and not as expensive as my "theory" would be.

Geoff.

 

[justford]

You said radiator was serviced. What was done to it?

 

[eddyw]

The lower rubber water hose/intestine not kinked ??

Bad water pump...

:chin:

 

[basstrix]

Please provide some details regarding the hard starting as the engine temp came up. Does the engine crank over at normal speed but just takes longer to start or is the starter having difficulty cranking the engine? One case indicates a possible flooding issue, the other would be timing related...or possibly water in the cylinder. This is why I was asking you to check base timing in an earlier post.

 

[Stanglover]

Please provide some details regarding the hard starting as the engine temp came up. Does the engine crank over at normal speed but just takes longer to start or is the starter having difficulty cranking the engine? One case indicates a possible flooding issue, the other would be timing related...or possibly water in the cylinder. This is why I was asking you to check base timing in an earlier post.

Good point(s). I keep re-reading this and still can't really explain it. There is one more thing I did not notice and that is simply this, IF the stat IS open and the rad cap is holding pressure, the top return hose should be as hard as your **** , hot as well!! If the hose is hard, then the stat IS opening and water flowing. If it's not, then there are probs elsewhere. Anyone think of partially or totally blocked passageways in the block. Has the block been cleaned internally? ......and the list goes on.....

 

[justford]

Another puzzling question is where the coolant is going? Should be some evidence of it being discharged somewhere??

 

[rocket366]

^^^Agreed where is the coolant going? Leaking it, burning it or its getting into the oil are the three choices.

Remove the radiator cap Do U see bubbles coming up to the top of the radiator with engine running?

Not unheard of for something to be up with the water pump impeller.

Paul

 

[Stanglover]

Like I said, the list goes on! Not what Klinton994 wants to hear I'm sure. He was hoping for a simple answer, but there isn't one it would seem. I think he will need to go back to the basics and start over eliminating one possible cause after another. If he had to put a gallon of water in, then it's leaking somewhere, externally or internally whether it be seen as white smoke, steam under the hood, whitish sludge in the oil or filler cap or just a leak on the ground. We are assuming from his post it is losing coolant, not just needing more added.

If it were the water pump, there would be reduced or no flow, it wouldn't lose water, but it would definitely over heat.

When I put my engine back in at the start of summer, I did have to add coolant after firing it up, but not a gallon. So yes there could have been air pockets that worked out requiring additional water ( actually, I hope he's using at least 50/50 Prestone) That would be the only reason to add coolant as far as I can see.

One more thing I just thought of. I HOPE you are NOT using a Flex Fan. Not only are they dangerous, they do not cool well at high rpm's. A friend just had this issue and after it was pointed out, he changed to a stock fan and problem solved.

Klinton994, we would love to hear back from you.

 

[klinton994]

You said radiator was serviced. What was done to it?

I took it to the local radiator repair shop and explained I was having over heating problems. When I picked up the radiator, he mentioned it was a heavy duty radiator, there was very little debris within it, and it was definitely not the cause of my overheating. Sorry I cant be more informative

 

[Don C]

Do you know if any work has been done on the heads, like porting or valve guides? If there's a leak on the exhaust side you wouldn't see it when you crank it with the plugs out, unless the exhaust valve were open and it dripped into the cylinder.

 

[klinton994]

Reading through all this is baffling for sure as to the cause of the problem.

I came to a theory that may or may not fly, but worth checking into if it were my car. Nothing make sense to me. As I have mentioned many times, I only go from my own experiences and this isn't one of them, but here goes.

1, It pressure tests okay cold. What about when hot?

2, You added 1 gallon of water. Where the heck is it going?

3, All your basic checks appear okay, T/stat working, correct stat with "hat", installed the RIGHT WAY UP? Hoses all new (spring in bottom hose?) etc. etc.

4, it overheats when driving and gets hard to start. Okay, here's my theory.... and it's only a theory.

When the engine is cold, no leaks are visible anywhere including from the cylinders. BUT when the engine is hot, it mysteriously gobbles up a gallon of water!! I believe you have a head gasket leak that is only present when the engine is hot. It may be very small, but it's there. The hard starting and knock is over pressurization of a cylinder because of the water (non-compressible), but which cylinder?

5, Do you see ANY whitish smoke/haze from the exhaust? You may need someone to follow you as you drive to observe the exhausts. Assuming you have dual pipes, your observer could see which bank is smoking. That narrows it down to one or the other head gasket that needs to be changed and SOON!! Major damage could occur and a total rebuild necessary.

As stated, this is NOT something I personally have experienced and I hope I never do on the Mustang. I did once have a head gasket blow on a T-Bird and that left a plume of white smoke behind the car for miles. I had to be towed home. Damn Fords!!

Anyway, I hope this offers some ideas that may not be what you or others want to hear or agree with, but I didn't see any mention of a blown head gasket when hot anywhere else in the posts.

I hope I'm wrong and it proves to be something simple and not as expensive as my "theory" would be.

Geoff.

Stanglover,

I took the car out for about a ten mile highway trip to visit a gearhead buddy of mine. During the trip down, and back home, the temp gauge remained betweent the letters "E" and "M" on the temp gauge.

This morning when I checked the radiator, it was again, down a gallon on water. Knowing that the pressure test while cold held a 16 lbs, I decided to try pressuring testing when it was warm.

My cars situation this morning is as follows.

1. Added a gallon of coolant.

2. Allowed car to reach operating temperature on gauge.

3. Hearing the knocking sound I have mentioned, I turned the engine off. The sound persisted and could be felt in the upper radiator hose. The upper hose was firm with pressure and hot to the touch. The lower hose was warm. I believe the sound I am hearing is percolation or air in the cooling system.

4. I Turned engine off, carefully removed the radiator cap and inserted a thermometer. The thermometer only read 100 deg, and water could be touched with my finger.

4. I started engine. With thermometer still in radiator fill cap I squeezed the upper radiator hose, and could feel no passage of water, and the hose was very hot.

Summary.

Temp gauge on dash indicates motor is at operating temperature.

I can not see any water movement within the radiator, or feel it in the upper hose.

Water temperature is only 100 degrees at the radiator fill neck.

Previously bench tested the thermostat and it opened at 160deg

Previously removed upper radiator hose from radiator, started engine, and verified pump was working. I have also removed pump, inspected it for slippage, end play, or missing props. All looked good

Pressure test procedure while engine is warm.

The car is at an idle, the engine has warmed up. I pump the pressure up to 16lbs. within a minute it begins creeping up to 20lbs. When I increase the rpm's, the pressure drops back down to 16lbs. I'm assuming this is indicative of motor compression entering into the cooling system. Am I correct?

If so, could this somehow create a continuous air pocket that is blocking passage of water through the thermostat?

 

[basstrix]

Do you have a recovery tank and recovery style radiator cap?

What about the hard starting? i asked for more details in a prior post.

When you bench tested the thermostat, what was the procedure? I recall you said at one point you used a heat gun......I'm asking because overheating a t-stat will often time ruin it. It has a pellet of wax under a small piston...as the wax heats up, it expands and opens the piston...get it too hot and some of the wax leaks out..requiring a much higher temp to open the t-stat.

 

[klinton994]

Do you have a recovery tank and recovery style radiator cap?

What about the hard starting? i asked for more details in a prior post.

When you bench tested the thermostat, what was the procedure? I recall you said at one point you used a heat gun......I'm asking because overheating a t-stat will often time ruin it. It has a pellet of wax under a small piston...as the wax heats up, it expands and opens the piston...get it too hot and some of the wax leaks out..requiring a much higher temp to open the t-stat.

I do not have a recovery tank. I do have a pressure release type cap that I have tested.

I boiled the thermostat in water, where it opened at 160 deg.

With the car warm, I removed my upper radiator hose from the radiator. I started the motor and water pumped out of the upper hose. I believe the thermostat is working. Yet with the thermostat installed, I don't see the movement of water in the radiator, as I do without the thermostat installed.

The knocking sound begins when the motor is warm, and appears to be coming from the area of the water pump or thermostat housing.

I had pulled the pump off, and checked the impeller. Blades are metal, all intact. The shaft spun with slight effort. Holding the impeller I was unable to spin the shaft. No end play. Could there still be a problem with the pump that would cause poor circulation?

 

[basstrix]

I believe you've shown with clarity that the water pump works when you observed coolant flowing w/o t-stat installed.

Correct me if I'm wrong, but in both cases you were a gallon down, it was after you had taken the car for a drive. I believe your water is simply being pushed out the overflow tube. It's normal for some water to be expelled on a totally full system, but a gallon seems excessive.

In post #13, Mr 4x4 posted a diagram showing the proper orientation of the thermostat. Please confirm yours is installed per that diagram.

I'm also unclear as to what the original cause of overheat was and if that was solved. Was it an exceptionally hot day, low on coolant, lots of idling in traffic, or something along those lines that might explain why after 2 years it finally decided to overheat?

 

[Mister 4x4]

It sounds like a clogged radiator to me, or at least it's not flowing much at all.

If the thermostat wasn't open, the upper hose wouldn't be hot (since there's no heat source for the coolant in the hose unless the thermostat opens to begin circulation back to the radiator).

Since the upper hose is so hot, but the coolant temperature is only 100 at the filler neck, the hot coolant doesn't seem to be making it through the radiator - just backing up and staying in the upper hose and consequently, the engine, and never getting cooled (I don't think it's likely that a radiator fan can cool THAT effectively just sitting there at idle - I may be wrong, though).

Did you check with the thermometer to see if the temperature of the tank connected to the upper host is the same as the upper hose? You should see that as well as the temperature gradient between the upper hose side fall toward the lower hose/filler neck side. If it drops gradually and winds up at 100 on the lower hose/filler neck side, then it is working WAY better than it's supposed to.

The low temperature at the filler neck is suspect to me because I know when I've touched filler neck side of the radiator on mine, running at normal temps, it's hot to the touch... not lukewarm like 100 degrees would be.

I know you said the previous owner said he had the radiator serviced, but I would want to know what had been done, did he provide a receipt, who did the work, etc., so you can check back with them for more information and/or potential warranty work (if offered). Just like "new" doesn't necessarily mean "good" when it comes to parts, "serviced" doesn't necessarily mean "working properly" when it comes to mechanics.

My 1995 Honda had similar issues, which resulted in a blown head gasket, warped head, and the previous owner selling the car to me. When I pulled the radiator out, after having just drained it and removed the lower hose, it still had almost a half gallon of coolant in it. He had just gotten the car back from the Honda stealership's mechanics, where they charged him $650 for a new water pump, timing belt, and other related work.

I got the car running again (headwork, rebuilt the top-end, and sprung for a new radiator) and the temp gauge never climbed over 2/5.

 

[basstrix]

He said he observed water flowing through the radiator with t-stat removed.

 

[klinton994]

He said he observed water flowing through the radiator with t-stat removed.

Hey guys,

thanks. Yes, with the T stat removed, I can clearly see the water circulating at the top of the radiator. I can see the water flowing through the openings within the radiator and into the area below the filler neck

With the T stat installed, I don't see this circulation. It appears the T stat is functioning. With the stat installed I removed the upper radiator hose from the radiator, started the engine, and water pumped out of the upper hose. This tells me the t stat is functional.

Should I necessarily see the water flowing with the stat installed?

Could it be that the amount of flow without the stat installed is so much greater that I see water movement? That with the stat installed, and in the open position, the water flow is more restricted and thus I'm not seeing it circulate.

I would think I should see it circulate with the T stat installed.

 

[Stanglover]

From reading your replies, all I can say is wow!!!! This has to be very frustrating to say the least. You want to be out enjoying your car and then there's this problem, keeps on going like the proverbial E Bunny.

Did you have a look under the car for water along the frame and underfloor? It might be from the overflow tube, indicating that is where the water is going. You could used a plastic bottle on the overflow tube to see if it does collect some water from the tube.

If you had the rad checked off the car. it would be easy to see if water flows through correctly, proving it's not blocked. I don't know what else to suggest. There are many far more experienced members than am I and if they can't solve it???!!!

Anyway, hope you get to the bottom of it soon, keep us posted,

Geoff.

You were typing at the same time I was. Can you tell us exactly what T stat you are using, brand and number. NPD sells a so-called Cleveland stat , but IT"S NOT!! it's a Windsor or something. It does not have a HAT on it. I bought a STANT 13468 and 69 and have zero issues. I'm currently using the 13468 180 deg. If you don't have the correct stat, I'm guessing you WILL have problems.

 

[Mister 4x4]

He said he observed water flowing through the radiator with t-stat removed.

I guess I totally missed that. My bad. :whistling:

 

[klinton994]

From reading your replies, all I can say is wow!!!! This has to be very frustrating to say the least. You want to be out enjoying your car and then there's this problem, keeps on going like the proverbial E Bunny.

Did you have a look under the car for water along the frame and underfloor? It might be from the overflow tube, indicating that is where the water is going. You could used a plastic bottle on the overflow tube to see if it does collect some water from the tube.

If you had the rad checked off the car. it would be easy to see if water flows through correctly, proving it's not blocked. I don't know what else to suggest. There are many far more experienced members than am I and if they can't solve it???!!!

Anyway, hope you get to the bottom of it soon, keep us posted,

Geoff.

You were typing at the same time I was. Can you tell us exactly what T stat you are using, brand and number. NPD sells a so-called Cleveland stat , but IT"S NOT!! it's a Windsor or something. It does not have a HAT on it. I bought a STANT 13468 and 69 and have zero issues. I'm currently using the 13468 180 deg. If you don't have the correct stat, I'm guessing you WILL have problems.

I had taken the radiator into the shop and asked them to go through it. They said the found very little debris in it, and the radiator is not my issue.

I am using a motorcraft t stat supplied by west coast classic cougars.

it is for a 351c, 180 deg.1967-1973 mustang. However, it is not the hat design. I am using it in conjunction with the bypass restrictor plate that I purchased from WCCC. With the restrictor plate you don't use a Cleveland type t stat.

I'm thinking of trying to research and find an original brass restrictor plate and the correct thermostat.