[Healeys] Overheating

Sun Mar 7 15:52:30 MST 2021

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
>
>
>
> _______________________________________________
> Support Team.Net http://www.team.net/donate.html
> Suggested annual donation  $12.75
>
> Archive: http://www.team.net/pipermail/healeys
> http://autox.team.net/archive
>
> Healeys at autox.team.net
> http://autox.team.net/mailman/listinfo/healeys
>
> Unsubscribe/Manage:
> http://autox.team.net/mailman/options/healeys/michaelsalter@gmail.com
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://autox.team.net/pipermail/healeys/attachments/20210307/36cbb504/attachment.htm>