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100/4 Coolant Recovery Tank

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Qldelsie Silver Member Giles Cooper
Benowa, Queensland, Australia   AUS
I have tried searching this subject in the forum but can't find anything - If it has been addressed before, please point me in the right direction.

My understanding is that the BN1 100/4 cooling system in a non-recovery system, so any fluid lost out of the overflow pipe due to boiling / expansion is, well, lost. One has to manually top the radiator up as required to replace any such losses.
The radiator cap is a 7 lb unit, I understand from the manual.
So can a 100/4 system be upgraded to a recovery system whereby the radiator cap is changed, and any overflow goes to the recovery tank which is pressurised ? Once the car cools down, a vaccuum is formed in the radiator, and the special cap allows fluid in the recovery tank to return to the radiator. Can this be done on the 100/4 ? Or is it not possible due to other limitations of the system ?

And on a slightly different note, what happens if you run (for example) a 15 psi cap on a Healey which normally uses a 7 lb cap ? Does the increased pressure cause problems elsewhere in the colling system / engine ?

While I understand how the systems work, I am struggling to understand what the implications are (if any) of running a recovery system on a 100/4. Or am I worrying about nothing ?

Thanks,

Giles



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Michael Oritt Avatar
LUSBY, MD, USA   USA
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.



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)



Edited 2 time(s). Last edit at 2018-05-09 10:07 AM by Michael Oritt.

Qldelsie Silver Member Giles Cooper
Benowa, Queensland, Australia   AUS
Thanks Michael, I look forward to seeing the pics when you have the chance. I am trying very hard to find a space to fit a recovery tank if we proceed - Unless its the size of a matchbox !
I do understand the basic operation of a recovery system - My question is more whether it is worthwhile ? I have read extensively on the internet (admittedly not always an indisputable fount of wisdom, I acknowledge) and the feeling I get is that if one DOES fit a recovery system to an older vehicle (in this case a 100/4), there is minimal benefit. My understanding is that the car won't run any cooler, all that it may do is enable you to check water levels at a glance via a see through bottle, rather than having to remove the radiator cap to check the level.
Additionally, I am led to believe that the fitting of a higher rated pressure cap may well be detrimental to other aspects of the cooling sustem. Boiling point increases by only 3 degrees for each psi pressure increase, so increasing a pressure cap from 7 psi to 13 psi will only increase the boiling point from 233 deg F to 251 deg F. But if the car is not boiling over in the first place, raising the temperature limit won't make any difference, while it may also possibly cause problems with the system.

So apart from making it easier to check fluid levels via a see-through recovery bottle, what is the benefit of a recovery system ?

Giles



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

Attached is a pic of the tank I have fitted to my 100. I used the first method of plumbing I described in my earlier post--the hose from the radiator goes into the bottom of the tank and so is always under water, assuming there is any fluid left in the tank to recover, and the top hose shown is simply a vent to atmosphere and runoff to ground were the tank to fill while the engine is running. I cannot get a good pic of the underside of the tank but it came with a hole in the bottom tapped for pipe thread and I simply screwed in an elbow and ran a hose from the inlet nipple to the overflow hose on the radiator neck. The other hose shown vents the tank from the top as stated and as you can see my radiator is out because I am still working on the timing chain job, but that is another story....

As to your question of whether to fit a recovery tank to your car, it provides no real benefit if your car does not normally boil over as its primary purpose is to hold a quart of coolant that has been expelled by the radiator due to fluid expansion/boil-over for later recovery--hence the name. So while it will not in and of itself make the engine run cooler it does provide a means of easily keeping the radiator topped off, which should provide a lower running temperature in less stressful conditions.

It also provides a secondary benefit of eliminating or minimizing the amount of coolant lost into the environment/onto the garage floor, etc. and that is the reason I fit the tank to my car as though I do not experience boil-overs when running I did, prior to installing the tank sometimes find a puddle of coolant under the car due to the coolant's getting hotter after shut-down. Now, with the tank fit I do not have to wipe coolant off of the floor nor top up the radiator to make up for lost fluid.

Hope this helps.



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)



Edited 1 time(s). Last edit at 2018-05-09 10:09 AM by Michael Oritt.


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Recovery tank.jpg    47.7 KB
Recovery tank.jpg

Qldelsie Silver Member Giles Cooper
Benowa, Queensland, Australia   AUS
Thanks Michael - Perfect. And kind of answers my question - Something "nice", but not really "necessary". I hear you on the "spillage on the garage floor" subject - Good point.
I also note that your recovery bottle is metal / chrome. One of the big ("nice"winking smiley advantages I saw of the recovery system was that if you had a plastic see-through recovery bottle, you could check the water volume just by looking at the level in the bottle. With an opaque recovery bottle, you still have to take the top off in order to check the level - Which kind of defeats part of the purpose, doesn't it ?

So given that there is no removable "top" on your recovery tank, did you just change the radiator cap from a "non recovery 7 lb cap" to a "recovery 7 lb cap" so it would suck the water back in ? I am interest to know what type of caps people are using.

Giles



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

I added the recovery tank at least ten years ago and do not now remember whether I replaced the cap but certainly a cap with a vacuum disc is a must if a recovery system is to work.

I used a metal tank because the plastic translucent ones just look cheesy.



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
You wrote "I used a metal tank because the plastic translucent ones just look cheesy."
smiling smiley
I agree 100%. Which is why I am hesitating..........



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1957BN4MFixer Avatar
1957BN4MFixer Rod Shepherd
Brisbane, Queensland, Australia   AUS
1957 Austin-Healey 100-Six "The Beast"
Giles,
I don't think you can buy a 7lb cap with the recovery valving that fits our cars, the aperture where the seal fits is a bit longer than normal and you would need to modify the refill neck to suit modern radiator caps. Also when the system is operating correctly Full level is about 1 inch below the aperture rim.

Rod Shepherd.

Qldelsie Silver Member Giles Cooper
Benowa, Queensland, Australia   AUS
Thank you Rod - If one can't buy a 7 lb recovery cap, that kind of settles it, doesn't it ?!!

However I will add that of course we do not have a standard radiator. We have fitted a new style and more efficient core into the radiator frame. I have to go back to our radiator man next week to double check on neck specifications.

Thanks for the info,
Giles



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

Only after reading your post did I recall that when preparing to install a recovery tank I had the neck of my radiator modified to work with a "modern" radiator cap and also had the metal overflow pipe switched to the right side as the cold air box and trunking left no room to install a recovery tank on the left side.

Thanks for the reminder!



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)

ahchummy Avatar
ahchummy Patrick Quinn
Sydney, NSW, Australia   AUS
Hello Giles

I am travelling down a similar path with our 1948 Healey Duncan. The early Healeys have an unpressurised system so when the coolant expands there is nothing to stop it from being dumped. However as long as the filler cap completely seals it will work. I bought a recovery tank from a Triumph TR6 which is a plastic tank of about a litre with metal bracket, cap, pipe etc. I bought it from Rimmer Bros in the UK and it cost $58 landed in Australia. Have a look on the Rimmer Bros website. Best wishes Patrick

Qldelsie Silver Member Giles Cooper
Benowa, Queensland, Australia   AUS
gramos Avatar
gramos Graham Foster
Kefalonia, Greece   GRC
I fitted a tank recently , bought from e bay , well made and just the right shape and size for the 100 engine bay ,
it stays at half full but is there for higher running temperatures in the summer


Attachments:
IMG_20180512_192908.jpg    23.1 KB
IMG_20180512_192908.jpg

Qldelsie Silver Member Giles Cooper
Benowa, Queensland, Australia   AUS
Thats exactly where I reckon I can fit a tank, Graham - Angled onto that upright. But yours appears to be on the right hand side ? Ours would be on the LH side (RHDrive).
Thanks for that photo. But I still like the idea of a see-through plastic catch tank so you don't have to take the top off each time to check what is in there !
I have also found out that you CAN buy a 7 lb recovery cap for our car - But that may be because we have a different radiator. The neck on ours is exactly 20 mm from the shoulder inside up to the top edge.
I am also learning that there are 4 different options.
1) Standard, with an overflow pipe just going to ground.
2) Catch tank, where the overflow pipe goes into a catch bottle, so you could manually tip the water back into the radiator if you want to.
3) Non pressurised recovery system. This uses a different cap on the radiator which has a return valve so when the radiator cools, it will suck the water back in from the overflow bottle, which is not pressurised.
4) Pressurised recovery system, where the cap on the radiator is just a seal, and the pressure cap is actually on the pressurised catch tank. Used on more modern cars as pressurised system not suitable for older car.
Thats what I have found out so far..........Sure someone will add / change this in due course !!
Giles



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