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100/4 Coolant Recovery Tank

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DTDuck Avatar
DTDuck Dan Marshall
Redwood City, CA, USA   USA
In reply to # 201325 by Michael Oritt Giles--

There is nothing difficult in setting up a recovery system on a 100.

The tank I use has an inlet on the bottom. You can also use a tank with an inlet on the top connected to a tube that runs to the bottom of the tank. The goal in either case is to have the end of the source tube submerged in overflow coolant.

When pressure within the radiator exceeds 7 psi the spring in the cap will compress and allow coolant to flow out the overflow tube of the radiator neck and into the recovery tank. When the coolant within the radiator contracts it forms a partial vacuum within the rad which will draw the coolant back from the expansion tank via the vacuum relief valve in the middle of the cap.
Easy peasy.

Recovery tanks are usually one quart capacity and are typically vented to atmosphere via a nipple coming off the side or top of the tank.
If you do decide to install this NO NOT put a pressure cap on the Radiator neck, replace it with a flat (non-pressurized cap, you can get one at any auto parts store) you put the pressure cap on the expansion tank (BTW a tank from an MGB or Spridget is a good choice) If you put a pressurized cap on the radiator when the car cools a few degrees the cap will close preventing the coolant from flowing back into the radiator. The whole idea/advantage of an overflow tank is to let the hot coolant "expand" into the overflow tank and then freely flow back into the radiator as it cools which requires a non pressurized cap on the radiator. I learned this from many years racing Spridgets.


Cheers,
Dan M.

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Michael Oritt Avatar
LUSBY, MD, USA   USA
Pressurized radiator caps commonly have a "dimple" return valve in the center which will pull open as the coolant contracts and pulls a vacuum which draws the fluid from the expansion tank back into the radiator.



Best--Michael Oritt
1954 Austin-Healey 100 (street)
1958 Elva Courier (track) FOR SALE
1959 Elva MK IV sports racer (track)
1961 Ginetta G4 (track)

DTDuck Avatar
DTDuck Dan Marshall
Redwood City, CA, USA   USA
In reply to # 202190 by Michael Oritt Pressurized radiator caps commonly have a "dimple" return valve in the center which will pull open as the coolant contracts and pulls a vacuum which draws the fluid from the expansion tank back into the radiator.
We are talking about two different systems, what I mentioned is an Expansion tank, what you are talking about is a Recovery/Reservoir tank set-up. There are several advantages to an Expansion tank vs. a Recovery tank, see the info here: http://blog.cantonracingproducts.com/blog/setting_up_your_cooling_system_expansion_vs_recovery
Personally I would use the expansion tank solution.

Cheers,
Dan M.

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Michael Oritt Avatar
LUSBY, MD, USA   USA
Dan--

Understand and agree. The two benefits of an expansion tank versus a recovery tank are:

1. In cases where the radiator filler cap is at or near the level of the top of the cooling loop a remote expansion tank can often be located at a place where its filler cap is higher than the highest point of the cooling system (usually the radiator upper hose/thermostat housing)

2. In cars that have limited cooling system fluid capacity an expansion tank may add another quart or so of capacity.

Whatever problems Healeys have in the cooling department these two are not among them and so a recovery tank with a vacuum valve or nipple in the cap will suffice. Of course, a true expansion tank setup will work as well, but for Healeys there is no real advantage to having an expansion tank over a recovery tank.

BTW I use expansion tanks on two of my race car because the sloped noses dictate that the tops of the radiators be lower than the water pumps. In both cases the remote expansion tanks are located toward the rear of the engines where the noses have sloped up somewhat making it possible to locate their filler caps higher than the top of the cooling loops, making it possible to fill the systems completely and getting all of the air displaced by water.



Best--Michael Oritt
1954 Austin-Healey 100 (street)
1958 Elva Courier (track) FOR SALE
1959 Elva MK IV sports racer (track)
1961 Ginetta G4 (track)

Michael S Avatar
Michael S Michael Salter
Dwight, ON, Canada   CAN
In reading through this posting I note that the question of increasing the cap pressure has not been fully addressed. In my experience the water pump used in the 100 WILL NOT tolerate much more than 7 p.s.i. and is therefore the limiting factor.



Michael Salter
Technical Chairman (Big Healeys)
Austin Healey Concours Committee

Michael Oritt Avatar
LUSBY, MD, USA   USA
That is what I use.



Best--Michael Oritt
1954 Austin-Healey 100 (street)
1958 Elva Courier (track) FOR SALE
1959 Elva MK IV sports racer (track)
1961 Ginetta G4 (track)

Qldelsie Silver Member Giles Cooper
Benowa, Queensland, Australia   AUS
Lou, what is the psi rating on that NAPA cap 703-1400 ? I can't find the psi details for that part on line.
Thanks,
Giles



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Louie Avatar
Louie Lou G
San Diego, CA, USA   USA
On the Napa site, it says 14-18 lbs.

https://www.napaonline.com/en/p/BK_7031400
One of our club members was working at Napa when I set it up, and sold me that cap.

I just went to my garage to look at setup, the radiator cap is the 4lb unit that Moss sells, extends about 1".
The tank cap is the plain flat cap. 7031400

We have taken the car on a number of hot drives -- coolant gets hot, but no overflow problems !
Through the high desert, the low desert -- we cook, the car's ok.
Radiator had core replaced about 16 yrs ago.
Denis Welch head.
NEVER any need to top up coolant.

I set up the same arrangement on my XK120 -- same result...

There's your physics ! it just works !winking smiley

Lou
San Diego, California

Qldelsie Silver Member Giles Cooper
Benowa, Queensland, Australia   AUS
Yes, we have lots of conflicting information here, none of which is "wrong" because it obviously works OK for the people using the different options, its just that we all have different set ups and ideas !! I also had been told that the standard coolant system overall was limited to 7 psi, and that THIS single fact was why a "recovery" system, not just an "expansion" system, won't work.

I fully understand how these systems work - My real query was just how people could fit a "recovery" system when (again based on what I was told) the lowest pressure "recovery" cap was 14 psi. Anyway, we have now just fitted an "expansion" system, using a 7 psi cap, and for the moment will go with that. So far the radiator has not sent any excess coolant to the "expansion" tank !

Our radiator is non-standard, with a more modern core which, I was told by the radiator man, is supposed to be "20% more efficient" than the old style core we had previously. Whether it is because of this radiator or some other reason, so far our temp sits on 160-170 deg F when moving, and goes up to about 180 or so when in traffic or at lights, but as soon as we move off, it comes back to 160 or so.
Need to do some longer runs but currently have a minor setback that we had to take the gearbox back out because it is still jumping out of 5th ! Grrrr.



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DTDuck Avatar
DTDuck Dan Marshall
Redwood City, CA, USA   USA
In reply to # 202324 by Qldelsie Yes, we have lots of conflicting information here, none of which is "wrong" because it obviously works OK for the people using the different options, its just that we all have different set ups and ideas !! I also had been told that the standard coolant system overall was limited to 7 psi, and that THIS single fact was why a "recovery" system, not just an "expansion" system, won't work.

I fully understand how these systems work - My real query was just how people could fit a "recovery" system when (again based on what I was told) the lowest pressure "recovery" cap was 14 psi. Anyway, we have now just fitted an "expansion" system, using a 7 psi cap, and for the moment will go with that. So far the radiator has not sent any excess coolant to the "expansion" tank !

Our radiator is non-standard, with a more modern core which, I was told by the radiator man, is supposed to be "20% more efficient" than the old style core we had previously. Whether it is because of this radiator or some other reason, so far our temp sits on 160-170 deg F when moving, and goes up to about 180 or so when in traffic or at lights, but as soon as we move off, it comes back to 160 or so.
Need to do some longer runs but currently have a minor setback that we had to take the gearbox back out because it is still jumping out of 5th ! Grrrr.
One thing to remember is that if you are putting a cap directly on the radiator, these radiators have a deep neck on them do you have to get a cap that is of the long neck (or extended) variety. If you use a standard cap it will never seal and as such it won't matter what pressure rating you are using, you will be at 0 lbs.


Cheers,
Dan M.

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