[Healeys] Overheating

Sun Mar 7 17:27:55 MST 2021

Gents found what I was looking for ... do read this.
http://www.enginebasics.com/Engine%20Basics%20Root%20Folder/Engine%20Cooling.html
BTW flow direction is out at top.
rg

On Sun, Mar 7, 2021 at 2:53 PM Michael Salter via Healeys <
healeys at autox.team.net> wrote:

> Not wanting to nit-pick Harold but I believe that this statement is
> incorrect and could result in considerable confusion:
> *"If the water flow rate decreases by 20% the water temperature at the top
> of radiator will increase slightly and will drop slightly at bottom of the
> radiator." *
> Coolant exits the engine from the water pump and is pumped to the bottom
> of the radiator.
> With everything else being equal, a decrease in the rate of flow of the
> coolant will result in the coolant staying in the radiator longer thus
> allowing more time for the transfer of heat to air.
> The result of the slower flow would be a LOWER temperature at the outlet
> "top" the radiator assuming of course that the radiator inlet temperature
> remains constant.
> Of course with slower flow the converse will occur within the engine
> because, as there is more time for the heat of the engine block to be
> transferred into the coolant, the coolant will be hotter as it exits the
> block at the water pump and travels to the radiator inlet "bottom".
> We 100 owners think about such things a lot :-)
>
> M
>
>
> On Sun, Mar 7, 2021 at 5:27 PM Harold Manifold via Healeys <
> healeys at autox.team.net> wrote:
>
>> Like many of you I have been cooped up for the past 12 months waiting for
>> a vaccine and for life to return to normal. I have been happily occupying
>> my time doing a complete restoration of a BT7 and had lots of time to
>> consider what upgrades or modifications are recommended to overcome some of
>> inherent Healey problems. I come to realize maintaining a consistent
>> temperature of the cooling water is an issue. With little else to do while
>> in lock down I looked into the factors that affect cooling to see if it
>> would point to any obvious upgrades. The design of automobile cooling
>> systems is very complicated but can be distilled down to a few key factors.
>> Identifying the factors that have the greatest influence on the system will
>> help to point to possible solutions or remedies. I will suggest some of the
>> factors may not be as obvious as others.
>>
>> The job of the cooling system is to remove the engine heat generated. If
>> the capacity of the cooling system to remove heat (i.e. BTU's or HP) is
>> greater than the engine heat generated in all situations then the system
>> will reach a steady state. For most Healey's driving on flat road at 60 MPH
>> when ambient temperature is less than 80 F everything is in balance. For
>> many Healey's the situation changes at lower engine RPM's and vehicle
>> speeds. What are the critical variables that affect the water
>> temperature the thermostat sees:
>>
>> 1. Engine heat generated.
>> 2. Radiator heat transfer coefficient.
>> 3. Air temperature or more importantly the difference between air
>> temperature and the radiator cooling fin temperature.
>> 4. Water flow rate.
>>
>> At slower engine/vehicle speeds hotter air from the engine bay can
>> surround the radiator and the water flow rate drops. We can estimate the
>> influence of each:
>>
>> If the air temperature at the radiator core increases from 80 to 100 deg
>> F the water temperature will increase approximately 20 deg F. All things
>> being equal the water temperature will increase approximately 1 deg F per
>> degree increase in air temperature.
>> If the water flow rate decreases by 20% the water temperature at the top
>> of radiator will increase slightly and will drop slightly at bottom of the
>> radiator.
>>
>> If the water temperature was above the full open temperate of the
>> thermostat when driving at 60 MPH then the thermostat is no longer
>> controlling the system and the water temperature will change when one of
>> the critical variables changes. Often the conclusion is changing
>> thermostats, fans or using some exotic coolant. I will risk the wrath of
>> this forum and suggest one of the clues to solving the slow speed problem
>> is look at what is happening at 60 MPH. If the water temperature is above
>> the thermostat rating while driving at highway speeds then factors 1 and 2
>> above are likely the issue. In other words there is no reserve capacity in
>> the cooling system and soon as air next to the core gets hotter the water
>> temperature increases.
>>
>> The engine heat generated is a major factor, the less heat the marginal
>> Healey cooling system has to deal with the better. If the engine heat
>> generated can be reduced by 20% the water temperature will decrease by 22
>> deg F. The factors that affect engine heat generated are: losses due to
>> friction, air/fuel mixture and engine timing. If the air/fuel mixture is
>> too lean it will cause the engine to generate more heat. A fuel pump that
>> maintains the minimum required fuel pressure at all engine speeds and well
>> tuned and jetted carburetors are important. The correct ignition timing and
>> the mechanical and vacuum advance curves are very important to reduce heat
>> generated.
>>
>> Lastly we have the radiator heat transfer coefficient. The coefficient is
>> based on the design of the radiator, number of tubes, rows of tubes, type
>> of fins, density of fins, area of radiator, materials used to construct the
>> radiator, etc. The units are BTU/hr/deg F. If some radiator tubes are block
>> or have reduced flow, if the fins are damaged or fowled with debris, if the
>> radiator has cracks or spilt seams or if the radiator top tank is not full
>> the radiator will not perform at its optimum. If in doubt have a radiator
>> shop boil out the radiator and pressure test.
>>
>> It seems some Healey's don't have a problem with over heating while
>> others do. One possible explanation is the Healey cooling system is
>> marginal at best and all of the factors that could affect overheating must
>> be in harmony with little room for forgiveness.
>>
>> The upgrades I have done are a plastic 5 bladed fan, new stock radiator
>> core, 123 ignition and bungs on the exhaust for oxygen sensors. Time will
>> tell if these helped tame the cooling system.
>>
>> I hope this helps and isn't killing a fly with an elephant gun.
>>
>> Harold
>>
>>
>>
>>
>>
>>
>>
>>
>> ------------------------------
>> *From:* Healeys [mailto:healeys-bounces at autox.team.net] *On Behalf Of *Leonard
>> Berkowitz via Healeys
>> *Sent:* Sunday, March 07, 2021 7:08 AM
>> *To:* healeys at autox.team.net
>> *Subject:* Re: [Healeys] Overheating
>>
>> So first step is to make sure your temperature gauge is accurate. If you
>> are still running hot I solved the problem by adding an additional row to a
>> factory original radiator.  Haven't had any problem with overheating since.
>> I had already tried adding an electric fan, an oil cooler and a Texas fan.
>> Nothing worked.
>>
>> ------------------------------
>> *From:* Healeys <healeys-bounces at autox.team.net> on behalf of
>> rfbegani at gmail.com <rfbegani at gmail.com>
>> *Sent:* Saturday, March 6, 2021 4:58 PM
>> *To:* 'Michael Salter' <michaelsalter at gmail.com>; 'Bob Spidell' <
>> bspidell at comcast.net>; 'Ahealey help' <healeys at autox.team.net>
>> *Subject:* [Healeys] Overheating
>>
>>
>> Bob & Mike:
>>
>>
>>
>> You both may have seen my requests on overheating of my BJ8 and the
>> response from the group.  As a result, I purchased an infrared thermometer
>> to determine if my water gauge was giving accurate readings.  The
>> thermometer gun told me that my water gauge was 30 degrees higher than the
>> temperature of the sensor attached to the block.  At the same time, I
>> noticed my gauge will show 120 degrees at rest instead of going down to 90
>> degrees which would indicate a 30-degree high reading.  In May when I leave
>> for cool Michigan, I will send the gauge to Nisonger to be rebuilt.
>>
>>
>>
>> I began to test the temperature of the water going through the cooling
>> system at the inlet to and outlet from the block, inlet and outlet to the
>> radiator and the upper and lower hoses while the engine is running at idle
>> and at 2-3 Thousand rpm.  The chart I created to record these temperatures
>> allowed me to produce observations or averages because the flow of the
>> water is dependent upon the rpms of the engine.  The engine has overheated
>> all of the 40 years I have owned it and has only 1000 miles on the new
>> speedo since rebuilding to 20 over.
>>
>>
>>
>> At the radiator inlet 134 outlet 85 at high rpms with electric fan
>> operating.
>>
>>                         inlet 103 outlet 94 at idle rpms with electric
>> fan operating.
>>
>>
>>
>> The above temperatures are recorded at the inlet and all along the hoses.
>>
>>
>>
>> These temperatures indicate the pump is circulating water with sufficient
>> gallons to cool the engine only when the engine is at high rpms.  At idle
>> the pump does not circulate sufficient water to keep the engine cool.  This
>> is especially true when you have been operating the engine at high speed
>> and come down to 30 – 40 mph and stop and go traffic.  Maybe the real
>> answer is to install an electric pump for constant cooling water?
>>
>>
>>
>> In the past week, I have installed a large Dorman coolant recovery tank
>> and a new 7 psi 1 inch radiator cap because I learned that our radiators
>> have a long neck.  Both those changes have reduced my problem of very high
>> overheating and resulting boiling over.  In addition, when my water gauge
>> shows 212 degrees the water temperature is actually 30 degrees less or
>> approximately 185 degrees.  Also, I am not boiling over and loosing
>> coolant.  Nevertheless, the engine water temperature is still spiking to
>> 210 plus degrees true when coming off highway speeds.
>>
>>
>>
>> In my review of various sites, the radiator equipment suppliers and
>> others are recommending increasing the pressure in the classic car systems
>> to 15 psi plus, and coolant recovery tanks “if your coolant system,
>> radiator, hoses etc. is new” and therefore can hold the pressure.
>> Unfortunately, I have not found any maker of a 1 inch depth x 2.33 inch
>> diameter radiator cap except our 7 psi cap so I can try such a pressurized
>> system.
>>
>>
>>
>> Another suggestion on an older discussion at the British Car Forum
>> indicated some of the Ontario car owners had switched to Evans Waterless
>> Coolant rather than 50/50 coolant water mixture.
>>
>>
>>
>> I still have no idea why a minority of our group has overheating
>> problems.  More ideas?
>>
>>
>>
>> Regards,
>>
>>
>>
>> Bob Begani 67 BJ8
>>
>>
>>
>> *From:* Healeys <healeys-bounces at autox.team.net> *On Behalf Of *Michael
>> Salter via Healeys
>> *Sent:* Saturday, March 6, 2021 12:20 PM
>> *To:* Bob Spidell <bspidell at comcast.net>
>> *Cc:* healeys at autox.team.net
>> *Subject:* Re: [Healeys] 100 water pumps
>>
>>
>>
>> Yes Bob, there is something wrong with our assumptions regarding the
>> cooling system not being "large" enough.
>>
>> My wifes Maxima is around 300 HP and the radiator has less area than the
>> 100. Certainly it has a couple of very effective electric fans but they
>> really don't cut in very often unless you have the AC on.
>>
>> I'm suspicious of the rate of circulation but I've talked to Larry Varley
>> about this subject and he indicated that increasing the size of the water
>> pump annular orifice didn't make much difference when he tried it.
>>
>>
>>
>> M
>>
>>
>>
>> M
>>
>>
>>
>> On Sat, Mar 6, 2021 at 11:42 AM Bob Spidell <bspidell at comcast.net> wrote:
>>
>> I sold my late father's 1955 Thunderbird to my BFF. These cars have a
>> very similar problem to Healeys overheating, esp. at idle. When Ford
>> stuffed the 292ci Y-Block into the T-Bird, they found the engine was
>> (essentially) too short for the long-hooded car, so they 'engineered'--I
>> use the term loosely--a cast iron spacer to move the fan closer to the
>> radiator. The spacer had the added 'benefit' of severely limiting coolant
>> flow through the pump and radiator; there are some aftermarket fixes and my
>> friend, after doing the usual radiator re-core, better fan, etc. installed
>> both a better pump (larger vanes) and a re-engineered spacer. Attached pic
>> is not of the spacer he used--I can't find the link to it--but it shows the
>> general idea (Ford basically put a 'dam' in the cooling system to block
>> flow, and the improved spacers mostly remove it). It appears this approach
>> has improved cooling, though the engine probably still gets warm if it has
>> to sit too long at idle. Link is to one of the improved pumps:
>>
>>
>> https://www.classictbird.com/Water-Pump-Modified-for-Higher-Output-1-Per-car/productinfo/8501HO/
>>
>> Anyways, after doing all the usual stuff to increase cooling, esp. on my
>> BJ8, I've wondered if a similar approach would work on Healeys. Their pumps
>> have very small vanes, and the cavity in which the vanes operate seems
>> pretty small for such a large lump of cast iron (I'm guessing an uprated
>> radiator core won't help much if the coolant flow is still hampered; at
>> least, that's what I've found). This is probably not an option as, of
>> course, our engines don't have a similar spacer to be improved upon, and it
>> would be a major task to increase both the cavity's size and the pump (but
>> I can dream).
>>
>> ps. The overheating issue with Healeys is usually attributed to too big
>> of an engine in too small of an engine compartment, and too little airflow.
>> But, the engine bay in an old T-Bird is huge by comparison--and the engine
>> not terribly larger in displacement--and still suffers the same problem.
>>
>> Bob
>>
>>
>>
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