Highway overheat

[BlueHealey1951]

I just spent the last hour and a half pouring through all the posts about overheating. There where a few that had the same problem I have, overheating at highway speeds (210-220). I have a rebuilt engine and recored radiator. I took out the belt driven fan and put in an elecric pusher fan that turns on at 190 degrees. It does a fine job of keeping the temps at 190 degrees until the speed is above 50 MPH. I recently put in a thermostadt blanking sleeve to improve water flow, but it did not help. I read a few posts that reported problems with replacement water pump castings, not sure if this could be an issue. I hate to fix or replace things that aren't broke, any ideas where to begin? I have a 67 BJ8. Thanks for your help, Steve

 

[DerekJ]

A pusher fan blocks the flow of the air over the radiator. I would remove it.

 

[Healey Nut]

A pusher fan blocks the flow of the air over the radiator. I would remove it.

Ditto

 

[RAC68]

I agree with the previous posts that the pusher fan blocks the air flow at speed when mounted directly in front of the core.

If you want to keep the electric fan and it is presently mounted on the radiator, I would move it forward as far as reasonable and down as far out of the direct path between grill and core as possible. With the fan angled upward toward the core, its air stream will intersect with the core fins to produce a greater heat transfer and carry-off. As I see it, by moving the electrical fan, you will create greater air flow at speed without the fan and will also provid good cooling when the fan is activated.

Although I have tried an electric fan on my Healey, I eliminated it in the mid 1990s and installed a Texas Cooler. I have eliminated the engine fan on my TR7 and now depend upon 2 electric senor-controlled air conditioner cooling assist fans mounted low and angled upward toward the core. The low mounting of the fans allow no frontal air obstruction at speed between the core and grill for a cool run.

All the best,
Ray (64BJ8P1)

 

[Keoke]

A pusher fan blocks the flow of the air over the radiator. I would remove it.

And reinstall it as a puller fan if there is room.

 

[steveg]

Agree with Keoke - it would be interesting as a 'science project' to move it to the puller position if there's room between the water pump and rad and if it's possible to reverse the direction. If the fan blades are curved for pusher use, they won't be as efficient if run in puller configuration unless you're able to flip the fan over.

 

[Healey 100]

How many miles do you have on this engine? A freshly rebuilt engine usually has a lot of friction that generates more heat to remove. I suggest you take the pusher fan off and get some miles on your car. Drive it at slow speed in cool weather if necessary to get it loosened up. I find 500 to 1000 miles are needed to loosen up a tight rebuild.

 

[Patrick67BJ8]

I have a pusher fan and AC condenser with no highway heating problems. How is your radiator shrouds, (they direct air towards your radiator)? Have you checked all the usual stuff first: timing, carb richness, etc. My electric fan rotates freely when "off".

 

[RAC68]

Although I do favor puller fans on the engine, I have found that many of the more common electric cooling fans are optimized for use in one direction and are less efficient in the other. However, due to space restrictions, I would expect the mounting be directly on the core or the radiator and, because of the usual high number of blades and housing, block free air flow unless the fan rotates freely as per Patrick's fan. After achieving operating temperature, I would expect this restricted air flow would require the electric fan to be powered at all times (when the Healey is stopped as well as at speed).

Your right Steve, it would be interesting to see if I am correct or in error.

Ray (64BJ8P1)

 

[Brinkerhoff]

If what was suggested about the fan does not work try putting a thermostat back in. You could have too much flow with the coolant not staying in the radiator long enough to cool down.

 

[Brinkerhoff]

BTW I run a Texas cooler style fan from Moss, a std. radiator that's been recored, and a 160 degree thermostat. I stay under 175 degrees in the summer .

 

[Keith_M]

In my (admittedly limited) experience, this is an odd problem for a Healey. More typically, overheating occurs when stopped at a traffic light, when air flow through the radiator is low. At speeds above 50 mph, neither a pusher fan nor a belt-driven fan is probably contributing much to the overall air flow; most of it is just caused by the speed of the car. I would be looking to something like timing or possibly mixture that is causing overheating at high engine speeds.

 

[DerekJ]

Keith, the reason he has the problem at speed is precisely because the pusher fan is blocking the airflow over the radiator.

 

[Keith_M]

Keith, the reason he has the problem at speed is precisely because the pusher fan is blocking the airflow over the radiator.

Then why doesn't it overheat at speeds below 50?

I have a pusher fan that I use while in traffic on hot days. It helps some under those conditions, but it has little or no effect on my temperature at speed. As long as I'm moving along at a constant speed over about 30 mph, my car runs right around 190 no matter what the speed (unless I'm climbing a hill). I think most of these cars behave similarly.

 

[Lotuswins]

Hi Steve,

The high speed heating is indeed unusual for these cars, but not unheard of. I have a few suggestions to check, starting with the least expensive first:

1) check fan belt tension. The belt is still providing torque to the water pump and generator/alternator and at speed it is the highest, if slipping the water pump may not be providing maximum flow.

2) reinstall a thermostat. The thermostat provides a back pressure to the cylinder head to lessen the chance of steam bubbles forming from the higher power needed at speed. Any bubbles formed and pushed into the water stream creates havoc in the radiator, reducing the ability to transfer heat to the fins.
3) since this is a rebuilt motor, did you retorque the cylinder head after a few heat cycles? It may be that you have a cylinder gasket leak that only shows itself at higher combustion chamber pressures. some shops provide a service to see if combustion byproducts are in the coolant. You may try removing the radiator cap and look for bubbles when the car is warm, may or may not show something.
4) i assume you have the stock air deflectors in place? you may also want to install a plate below the front of the radiator, between the frame rails. this will prevent the scavanging affect of the front shroud from pulling air down from in front of the radiator, increasing the pressure in front of the radiator. some make the plate into a scoop to bring fresh air up into the radiator providing additional pressure. i've tried this on my own car, and it does help.
5) you say you recored the radiator? what are the specifics on the recore? i had my radiator done by a local shop, and he installed a 'modern' 3 row, serpentine fin, 1 3/4 in. deep radiator core that was insufficient to the task and i had to have it redone to a 5 row, staggered tube, flat louvered fin that is deeper (2 7/8). It does exceptionally well at speed. Few seem to realize the options available to them when recoring a radiator, as i learned the hard way.

All this assumes, of course, that your gauge, carbs, and timing are spot on, and no brake dragging is happening.

let us know how its going?

 

[BlueHealey1951]

Thanks for all the help. The radiator was recored to a 4 row non staggered tube, the air diflectors are in place.Planning to spend the weekend removing the fan and reinstalling the thermostat,( going to call the local radiator shop about different recore options)
will keep you posted. Thanks again, Steve

 

[RAC68]

I was not aware that you are not using a thermostat in your engine. Many LBC engines have incorporated a bypass that allows the engine that allows approximately 1/4 of its coolant to bypass the radiator as a means for initial quick warm-ups. The use of a sleeved thermostat is quite important, for when the car reaches operating temperature, the sleeve on the thermostat slides down to blocks the bypass. If you are not using a sleeved thermostat (American type) or no thermostat at all, a large quantity of coolant is not blocked from passing through the bypass and does not pass through the radiator for cooling. As a result, the temperature of your coolant can raise under speed.

I would suggest you replace your thermostat with a proper sleeved thermostat to block the bypass and send all your coolant through the radiator for cooling at speed.

All the best,

 

[steveg]

I was not aware that you are not using a thermostat in your engine. Many LBC engines have incorporated a bypass that allows the engine that allows approximately 1/4 of its coolant to bypass the radiator as a means for initial quick warm-ups. The use of a sleeved thermostat is quite important, for when the car reaches operating temperature, the sleeve on the thermostat slides down to blocks the bypass. If you are not using a sleeved thermostat (American type) or no thermostat at all, a large quantity of coolant is not blocked from passing through the bypass and does not pass through the radiator for cooling. As a result, the temperature of your coolant can raise under speed.

I would suggest you replace your thermostat with a proper sleeved thermostat to block the bypass and send all your coolant through the radiator for cooling at speed.

All the best,

British Car Specialists sells a Robertshaw 160 degree t-stat with the sleeve added. I bought a 180 Robertshaw and moved the sleeve. This was discussed on a previous thread.

 

[BlueHealey1951]

regarding the thermostat, I originally had a sleeved thermostat in the car , then replaced it with a sleeve that prohibits the bypass but allows free flow of fluid. Neither made any difference in temperature

 

[nevets]

I'm speaking from limited knowledge /experience but might ignition timing and fuel mixture be contributing factors? Also the obvious proper lubrication?