Coolant system opinions please
Coolant system opinions please
(OP)
Given this is a hobby, I did not want to post this in any of the automotive forums
The attached illustration is of a 70’s design deTomaso Pantera that had a reputation of having cooling problems. The rear mounted engine is a Ford Cleveland that utilizes a special design thermostat for a high flow bypass during warm up (to sweep the block and prevent hot spots)
The original design used a swirl tank on the thermostat discharge that was fitted with venting pressure cap and a recovery tank. The original radiator was baffled for front/rear pass. A high point vent tube was on the rear pass outlet tank and routed to the radiator outlet pipe. The heater core flow is taken before the thermostat and returns to the pump suction. A throttling valve would control its flow. (The upper illustration)
Later revisions were to re baffle the radiator for a lower/upper pass and to add a vent to the upper reversing tank and route it back to the swirl (not shown). A recommendation was to remove the pressure cap from the swirl tank and place it on the recovery tank. Add a vent from the swirl to the recovery and drain recovery tank to pump suction, thus converting the recover tank into a surge tank. The radiator vent is then rerouted to the new surge tank. (The center illustration)
My proposed reversion would be to add a 4 port heater control valve to limit coolant in the passenger cabin and it having the ability to maintain flow for the heater bypass. The heater return would then be routed to an educator supply. The radiator vent would be rerouted to educator suction, with the educator discharge into the surge tank. The surge tank will be partially filled to allow for the coolant’s thermal expansion. I am thinking there will be about 5% increase in volume. If filled proper, the compressed air volume from cold to hot should provide the 13 psig of the cap relief setting.
So is my proposed over engineering or would there be any benefit to having the heater core by pass flow going to the surge tank to degas the coolant (like a deaerator)? I have heard that entrained air reduces the coolant’s efficiency.
Any discussion or comments?
http://files.engineering.com/getfile.aspx?folder=8...
The attached illustration is of a 70’s design deTomaso Pantera that had a reputation of having cooling problems. The rear mounted engine is a Ford Cleveland that utilizes a special design thermostat for a high flow bypass during warm up (to sweep the block and prevent hot spots)
The original design used a swirl tank on the thermostat discharge that was fitted with venting pressure cap and a recovery tank. The original radiator was baffled for front/rear pass. A high point vent tube was on the rear pass outlet tank and routed to the radiator outlet pipe. The heater core flow is taken before the thermostat and returns to the pump suction. A throttling valve would control its flow. (The upper illustration)
Later revisions were to re baffle the radiator for a lower/upper pass and to add a vent to the upper reversing tank and route it back to the swirl (not shown). A recommendation was to remove the pressure cap from the swirl tank and place it on the recovery tank. Add a vent from the swirl to the recovery and drain recovery tank to pump suction, thus converting the recover tank into a surge tank. The radiator vent is then rerouted to the new surge tank. (The center illustration)
My proposed reversion would be to add a 4 port heater control valve to limit coolant in the passenger cabin and it having the ability to maintain flow for the heater bypass. The heater return would then be routed to an educator supply. The radiator vent would be rerouted to educator suction, with the educator discharge into the surge tank. The surge tank will be partially filled to allow for the coolant’s thermal expansion. I am thinking there will be about 5% increase in volume. If filled proper, the compressed air volume from cold to hot should provide the 13 psig of the cap relief setting.
So is my proposed over engineering or would there be any benefit to having the heater core by pass flow going to the surge tank to degas the coolant (like a deaerator)? I have heard that entrained air reduces the coolant’s efficiency.
Any discussion or comments?
http://files.engineering.com/getfile.aspx?folder=8...





RE: Coolant system opinions please
The word you seek is 'eductor'. It may not work as you expect here; at low motive flows it becomes an inefficient tee. ... but at least it has no moving mechanical parts.
It appears that the factory never got the cooling really sorted out, but they had more resources than you do, and more engines to kill in experiments.
Start with what the factory did, proceed with caution, instrument the hell out of the installation, and pay attention to what's going on. At least instrumentation is cheaper and more flexible than it used to be...
Mike Halloran
Pembroke Pines, FL, USA
RE: Coolant system opinions please
When was the overheating the problem?
Hot engine - running wide open at full speed on a desert track on hot days?
Hot engine - idely for a long period of time at 0.0 speed ? On hot days? Or on cold days?
Cold engine - but just at startup, when the full-sized radiator is "too much" coolant area so the engine doesn't warm up fast enough?
Cold engine - but when trying to immediately rev up to full speed with cold coolant and a cold block so the emissions and heat are not balanced as they are when running for a while?
RE: Coolant system opinions please
the other historical errors noted from dealer bulllitens was the inadaquate filling resulting in air pockets in the radator and rear engine. factory production was stopped shortly after the revisons to add the radiator vent to the swirl. the latter non Ford produced cars and earlier models that were plumbed as per the second illustration have operated acceptably. my pieces are as per the original configuration.
an intersting discovery for me was that my revison was something I mulled over just in though for years and after I made the illustrations and wrote the question for here, even to me, the ideal seems pretty much unjustified. Going back to the need to isolate cabin coolant to the heater core, just simple manual double isolation valves worked prior
thanks for the replies as sitting around the house just thinking can lead to trouble
RE: Coolant system opinions please
But of course these days we can do three things that De Tomaso didn't have available for production
a) instrumentation - thermocouples and thermistors are cheap, and you can use an Arduino or the like to monitor them
b) electric water pump.
c) electric cooling fans
Good luck.
War story: once upon a time we were offered PWM motors for our prototype electric cooling fans. We spent many happy days testing these variable speed fans, logging which speeds caused resonant issues, and generally refining them. We put in predictive algorithms, so that the engine coolant temperature did not vary as the a/c cut in, and so on. Then the bean counters struck. Out went PWM. In came 2 speed +freewheel. Well, as it turned out, we had already logged the variable rpm we needed for the fans, so picking the fixed speeds we could live with was dead easy. The most interesting result from all the logging was that most of the time the fans were just ticking over, pushing the air the right way through the rad.
Cheers
Greg Locock
New here? Try reading these, they might help FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm?
RE: Coolant system opinions please
As for monitering, the engineer in me wants a massive instrument cluster, but the automotive entusiest wants only the orginal minimal provided.
RE: Coolant system opinions please
RE: Coolant system opinions please
It can be blank when you don't need it or serve as sound system or climate control display.
Jay Maechtlen
http://www.laserpubs.com/techcomm
RE: Coolant system opinions please
Cheers
Greg Locock
New here? Try reading these, they might help FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm?
RE: Coolant system opinions please
This might be something that your local radiator shop could fabricate, putting a much-improved core into the existing radiator. Drop in installation.
RE: Coolant system opinions please
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RE: Coolant system opinions please
I have not measured and determined the lenghts and transitions, but the basic turbing size is 1 1/4" both for radiator inlet and return.
the radiator vent tube I was planing on added would be about 3/8 to 1/2" with the thought it would possibly have some scavanging flow not just air venting, hoping I could get a little suction from the eductor. another option would be have the radiator vent on the turning tank so there would be the second pass head to produce the venting flow.
RE: Coolant system opinions please
In practice, it depends a lot on the people...
and resources.
We've all seen examples of someone who has an idea, and the power to make it happen - but they're wrong.
And it goes into production with <maybe> enough patches to make it kind of work.
Jay Maechtlen
http://www.laserpubs.com/techcomm
RE: Coolant system opinions please
will a radiator cap provided the function of an accurate pressure relief valve given there will be an air volume under it as per my proposed configuration. I am thinking radiator caps may be designed expecting coolant fluid to be appled, not hot air and vapour.
RE: Coolant system opinions please
The cap should work fine.
Mike Halloran
Pembroke Pines, FL, USA
RE: Coolant system opinions please
is there any advantage of a coolant system with a recover tank versus expansion tank.
with recovery tank the system is filled "solid" under the relieving radiator cap, there fore as soon as any heat causes thermal expansion of the coolant, the pressure builds quickly to relief pressure.
with an expansion tank filled with an air volume greater than the coolant expansion at rated temp, the pressure of the coolant gradually builds with temperture and the water expansion compresses the air. if the initial fill volume was 2X air volume cold, the pressure would be ~15 psig at rated ( the cap relief)
so is one better than the other? the "solid" or the "soft" pressure?
AND on the use of an eductor to assist the venting of the remote radiator, the manufactors of 1/2" eductors are very proud of them! over $200. but their expected performance with the system conditions did indicate a sufficient suction would be generated
RE: Coolant system opinions please
The lasercut flats are exactly as they came from the lasercutter, with no beveling and no deburring done by me. There exist a lot of internal leak paths where the edges don't quite seal to each other, e.g. at the six flat surfaces that form each of the hexaplanar cones.
The eductor was designed to suck condensation from the inner bore of a jacketed exhaust pipe, which also contains hot exhaust from turbochargers.
It worked just fine, certainly well enough to drain a basement.
My point is that the commercial eductor manufacturers' products perform very, very well, but you can make an eductor that performs less well, but adequately for government work, from, well almost anything. Just eyeball the internal dimensions of the commercial units from their marketing illustrations, scale them to the size you need, and start hacking from there.
Mike Halloran
Pembroke Pines, FL, USA
RE: Coolant system opinions please
There are millions of examples of cars with recovery tanks on the road today.
Their ancestors all had expansion tanks, which were a constant headache, with corrosion above and below the air/water interface, and all manner of gooey sludge at the interface and in the radiator cap.
Moving the air/water interface outside of the pressure boundary was a _huge_ improvement. Don't waste your time by learning that the hard way.
Mike Halloran
Pembroke Pines, FL, USA
RE: Coolant system opinions please
This is true. I once made one using a pool noodle and a blow-off nozzle.
RE: Coolant system opinions please
For some reason the majority of the online info I keep finding discusses going with the seperate expansion tank, some even have a schader valve for "precharging" the air volume. I wonder if the air volume is not in the proximity of the radiator core would lessen the generation of sludge and initation of corrosion
RE: Coolant system opinions please
If you want to use an expansion tank as a recovery tank, go ahead, and even call it an expansion tank when you brag to the folks on the Internet. Just vent it like a recovery tank, try to put the radiator cap near the top of the car, e.g. by putting it in an expansion tank that you keep full of cooant, make sure to get all the air out from the system, and keep it out.
Mike Halloran
Pembroke Pines, FL, USA
RE: Coolant system opinions please
But I can't see why you would want to.
As Mike notes, there are millions and millions of cars on the road demonstrating the efficacy of a recovery tank design.
RE: Coolant system opinions please
two out of three have are expansion tank design, 2001 yukon & 2004 silverado, but the 2004 monte carlo SSSC did have a recovery. I don't know all the details of those two with expansion tanks but I did see the upper radiator vent and the tank hose back to pump suction.
RE: Coolant system opinions please
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: Coolant system opinions please
RE: Coolant system opinions please
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: Coolant system opinions please
RE: Coolant system opinions please
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: Coolant system opinions please
You want to avoid air bubbles in the engine, the radiator, and in the main cooling lines.
Since the Pantera has long hoses/pipes going to/from the radiator, it would have a greater change in volume than a car with the radiator right next to the engine.
It should be much easier to provide that large volume as a recovery tank than as a pressurized expansion tank.
However, a pressurized expansion tank might be less sensitive to small leaks in the cooling system which might keep an expansion tank from doing its job.
In the previous article about Pantera cooling, there was a referenced link which is obsolete.
this is may be what was referenced:
http://stewartcomponents.com/index.php?route=information/information&information_id=14
Jay Maechtlen
http://www.laserpubs.com/techcomm
RE: Coolant system opinions please
the coolant volume is 6.4 gallons.
I figured if all the coolant went from 70 to 195F the expansion would be 47 in^3, the original resovior tank is 14" tall X 4" diameter so a rise of 3.7". if the cold filled volume leaves 7.4" (halve full) the resulting expansion would result in 15 psig. being cold filled between 4 and 7" should result in a 15 psig cap relieving, but no coolant being expelled.
If the original resevior tank is plumbed as a "solid" dearition tank with cap relief, a quart resevior would work.
the big installation differance between going with an expansion tank with >4" air space cold and dearetion tank with resevior would be raising the 14X4 tank the >4"
an interesting observation I have made while persuing this "hobby"...the manufactors of water pumps throw out claims of increased flow, BUT they never provide a flow/rpm curve! the same is true of radiators, they do not provide pressure/flow information
RE: Coolant system opinions please
You know- after reading the info on the Stewart site, seems to me that four instruments would tell most of the story:
Pressure and temperature coming out of the motor.
Pressure and temperature returning to the motor.
(or psig at either point and delta-P across the motor)
You wouldn't need the pressure gauges once the system was debugged, but might tell you a lot while testing.
Regards
Jay
Jay Maechtlen
http://www.laserpubs.com/techcomm
RE: Coolant system opinions please
consider the following situation;
having a solid system with a 15psig cap. this would have the boiling temp about 250F. the car is pushed hard and as the coolant expands, the cap keeps the pressure at 15 psig. the temp increases to 240F and then the driver backs off and the temp drops to 210F. Given the cool off from 240 to 210F will result in a coolant contration, would the system pressure drop for 15psig (to a vacuum) and cause the coolant to flash?
RE: Coolant system opinions please
RE: Coolant system opinions please
All the hoses relax a bit (the flex hoses do expand a bit, don't they?)and when the gage pressure drops a skosh below zero it will start pulling from the recovery tank.
Presuming the cap and recovery tank are functioning correctly, the pressure in the coolant system would only drop enough to suck from the recovery tank.
Anyone know the required pressure delta to pull from a typical coolant recovery tank?
Jay Maechtlen
http://www.laserpubs.com/techcomm