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logdog (Forum Supporter)
logdog (Forum Supporter) GRM+ Memberand UberDork
4/16/21 8:06 a.m.

I fully admit this is a weird topic but it came up yesterday in a conversation with a coworker.  I made a simple coolant overflow/expansion container out of a brake cleaner can for the 'stangII and he said he was surprised it didn't already have one.  From everything I can tell, my 76 Mustang, 76 CJ5, 82 E100 all came with a hose running from the neck clipped along the radiator to spit on the ground.  While the CJ5 had a clearly aftermarket one plumbed in, both Fords were stock 1 owner with what appeared to be the original hose in the original clips.  I do remember "keeping the radiator topped off" being a regular thing my dad did when I was a kid.  My coworker believes GM was using tanks instead of hoses exclusively by the 60s at least, but cant say with certainty.  We also discussed the possibility it could have been something that was an option as both my Fords are base models.  I haven't found anything definitive on Google and its the kind of oddball topic that has made me curious.  I saw some references to them being used in the 30s and 40s but it seemed to be on the uncommon side.

Does anyone know if adding coolant jugs was a federal regulation and when it kicked in?

What is the latest year you can recall a vehicle not having one? Past 1982?

Just how common were little puddles of coolant on the ground in the disco-era?

MadScientistMatt
MadScientistMatt UltimaDork
4/16/21 8:15 a.m.
logdog (Forum Supporter) said:

My coworker believes GM was using tanks instead of hoses exclusively by the 60s at least, but cant say with certainty.

Pretty sure this wasn't standard on GM products that early. My '72 C10 did not have any factory provisions for an overflow tank (at least not by the time I bought it), and I can't find any sign they were offered with one.

Tom Suddard
Tom Suddard GRM+ Memberand Director of Marketing & Digital Assets
4/16/21 8:19 a.m.

I'm fuzzy on the timeline, but IIRC they were added in response to higher thermal demands. Standard practice back in the hose days was to allow extra coolant to go onto the ground, then when the car cooled back down you'd have an air gap in the radiatior. When they needed that extra cooling capacity, they went to coolant recovery tanks.

logdog (Forum Supporter)
logdog (Forum Supporter) GRM+ Memberand UberDork
4/16/21 8:46 a.m.

I have the Ford shop manuals for 1982 trucks and took a look.  Sure enough in the section on coolant recovery it says they are standard on F100-F350s, but they are not present on E100-E350.  I would be curious what the logic of that was.

 

No tank-

Tank-

logdog (Forum Supporter)
logdog (Forum Supporter) GRM+ Memberand UberDork
4/16/21 8:49 a.m.
MadScientistMatt said:
logdog (Forum Supporter) said:

My coworker believes GM was using tanks instead of hoses exclusively by the 60s at least, but cant say with certainty.

Pretty sure this wasn't standard on GM products that early. My '72 C10 did not have any factory provisions for an overflow tank (at least not by the time I bought it), and I can't find any sign they were offered with one.

That fits with one of my current unproven theorys, that cars would have got them first because it would keep the driveway clean under the family car, but trucks/vans were expected to leak since they were work vehicles in the day.

logdog (Forum Supporter)
logdog (Forum Supporter) GRM+ Memberand UberDork
4/16/21 8:51 a.m.
Tom Suddard said:

I'm fuzzy on the timeline, but IIRC they were added in response to higher thermal demands. Standard practice back in the hose days was to allow extra coolant to go onto the ground, then when the car cooled back down you'd have an air gap in the radiatior. When they needed that extra cooling capacity, they went to coolant recovery tanks.

This is the perfect subject for a deep investigative journalism story! laugh

 

Pete Gossett (Forum Supporter)
Pete Gossett (Forum Supporter) GRM+ Memberand MegaDork
4/16/21 9:03 a.m.

I don't remember any of the 1970's(70-78) full-size Fords I drove as a teenager having them. 

Keith Tanner
Keith Tanner GRM+ Memberand MegaDork
4/16/21 9:04 a.m.

A 1986 Mini does not have one. Neither does a 1966 Cadillac, a 1967 Land Rover or (if memory serves) a 1971 MGB.  I could be wrong about the last. I'll have to check the 1985 CRX but the 1985 Vanagon has both an expansion tank and an overflow. 

AngryCorvair (Forum Supporter)
AngryCorvair (Forum Supporter) GRM+ Memberand MegaDork
4/16/21 9:12 a.m.

My 1972 Monte Carlo had one that I'm pretty sure was OE

ShawnG
ShawnG UltimaDork
4/16/21 9:14 a.m.

Lots of the big 1930s cars were equipped with them from the factory. Usually a closed system mounted down on the frame, under the body.

The earliest one I've seen personally is on a 1930 Lincoln L but I'm sure there are are others that may have started earlier.

alfadriver
alfadriver GRM+ Memberand MegaDork
4/16/21 9:38 a.m.

Weird- my '73 Alfa has an expansion tank.  Odd to hear that cars in the 80's didn't.

Curtis73 (Forum Supporter)
Curtis73 (Forum Supporter) GRM+ Memberand MegaDork
4/16/21 9:38 a.m.

I always assumed that an overflow tank was a convenience thing.  Much like cars have evolved to include more creature comforts standard like power windows and A/C, I just guessed that the overflow tank was something to make your maintenance easier.  Most cars today have oil change lights, TPMS, and brake pad wear indicators were added decades ago so they squeal when you need to replace them.  Adding an overflow tank would be a nice marketing thing.  "no more refilling the radiator" would be a great selling point. 

So in pursuit of this answer, I googled.  The forum over at AACA had some good clues.  For GM, it was the Vega that first got it standard because its small cooling system was pretty sensitive to low coolant levels.  Someone mentioned that in 1939, it became an optional convenience accessory on GMs.  

When it comes to pressurized tanks, I always assumed it was simply an engineering response to a styling challenge.  Sloped noses.

On the first car, it's easy to make the radiator cap the highest point in the cooling system.  On the second car, not so much.  Simple engineering fix?  Add a pressure reservoir that is higher than the engine.

 

1980 Cadillac Coupe DeVille | Hollywood Motors

 

1993 Chevrolet Camaro Z28

eastsideTim
eastsideTim PowerDork
4/16/21 9:39 a.m.

My 71 Cutlass did not have one from the factory.  One of the few mods I made to it.  I think (but am not 100% sure) my 78 Cutlass did have an overflow tank.

Keith Tanner
Keith Tanner GRM+ Memberand MegaDork
4/16/21 9:51 a.m.

The interesting thing about pressurized expansion tanks is that they're not universal. You'd think they'd have a good solid engineering reason to exist or not exist, but they don't seem to. NC Miatas have one, ND Miatas don't despite the nose being much lower on the latter. Some XJ Cherokees have them, some don't and it sure isn't a packaging decision in that case. The XJ community seems to prefer the non-expansion system for effectiveness but I don't know the reasoning.

Curtis73 (Forum Supporter)
Curtis73 (Forum Supporter) GRM+ Memberand MegaDork
4/16/21 9:51 a.m.

Digging back through my cars' history.

62 Caddy did not
65 Impala did not
66 Bonneville did not
67 LeMans did not
73 Impala DID.  It was black plastic and hung from a wire basket on the core support
73 AMC Hornet did not, but it also didn't have power brakes, power steering, power windows, horsepower, radio, armrests, or any semblance of comfort accessories.
74 Maverick 302 DID have one.
83 Chevy celebrity DID
85 K20 DID
85 and 87 El Camino DID
87 Cutlass DID
91 Beretta did... in fact it might have been a surge/pressure tank.

spandak
spandak Dork
4/16/21 10:24 a.m.

In reply to Keith Tanner :

Ive noticed this as well. My german cars have all had them. My Mazda did too but our Subaru does not and its the newest car we've owned. Personally I prefer not having another pressurized part in the system, eventually its a failure point. The Mazda was too new to need one but the E36 and Boxster both cracked theirs.

L5wolvesf
L5wolvesf HalfDork
4/16/21 10:36 a.m.
gearheadE30
gearheadE30 Dork
4/16/21 10:59 a.m.

There are some reasons for the differences. The earliest engines had non-pressurized systems, which quickly went to pressurized with caps for two reasons: raise the temperature for boiling and reduce the risk of cavitation, which can cause coolant flow to stall resulting in boiling/overheating. You don't want the pressure to drop below 0 gage at the water pump, or it's likely the system will cavitate.

Pressurized systems with no recovery were fine for a while and are still used in some applications. As others have said, you end up with an air gap at the top of the radiator which would only be completely purged when the engine has reached its maximum temperature since the last time it was topped off. This system worked fine, particularly where the air gap in the radiator is somewhat higher than the highest point in the rest of the system. Low power density also allows it, as does a taller radiator core. the applications I'm aware of that still use this are mostly dirt bikes, where the radiators are much higher than the top of the engine, and where there is no temperature gauge so you can use the slight spitting of coolant to judge how hot you're running the engine and if it's about to overheat. The overflow is usually routed right over the exhaust header so you can smell immediately when it starts spitting.

Recovery bottles seem to have come about with higher power density and lower hood lines. That air gap in the radiator can easily result in air entrained in the coolant as it goes through the engine, which makes localized boiling in hot spots around the cylinder and in the head more of a concern and also increases the risk of cavitation at the water pump. No air gap in a properly functioning system = higher boiling resistance and better water pump flow in extreme (hot, altitude, high rpm) conditions. 

All of the above are non-positive deaerating systems: the system cannot remove air without heat cycles, and there is no part of the system specifically intended to remove air while the engine is running at constant temperature.

A lot of newer stuff (and some older mostly european or high performance stuff) uses a positive deaeration system, where there is a pressurized coolant reservoir. This allows the engine to purge air while running, allows the radiator to be lower than the engine, has much higher capability to prevent water pump cavitation, and is of course more expensive to design and build. The system has the usual coolant loop from the engine to the radiator and back, but it also has vent connections (Typically at the high points, either cylinder head, top of radiator, thermostat housing, etc) that allow coolant to leave this loop and go to the deaeration tank. This allows air to escape the main loop, and always has some flow. The tank is large enough to allow air to bubble out of the coolant before it is sucked back into the water pump via a fill line, which either connects directly to the water pump inlet or very close to it in the hose from the radiator. That fill line provides a direct coolant supply to the water pump to maintain positive pump inlet pressure, dramatically reducing cavitation risk. This deaeration tank is constantly allowing air to come out of the system, to end up in the air chamber in the pressurized deaeration tank, so you always have good clean coolant flow. Most systems are designed to fully deaerate within ~25 minutes if they are used and functioning properly, and if there are unique bleeding instructions, they can sometimes be pretty sensitive.

Positive deaeration systems are also very important in most vehicles with cooled EGR - EGR coolers get really hot, and localized boiling under pressure if there is air in the coolant will actually cause the water jacket to erode and eventually have pinhole failures.

Because the fill line provides a very low restriction path of coolant to the water pump, positive deaeration systems also have a bit of extra margin before cavitation if the pressure cap fails.

Saron81
Saron81 HalfDork
4/16/21 11:07 a.m.

In reply to Keith Tanner :

My 71 BGT had a metal overflow tank! 

Pete. (l33t FS)
Pete. (l33t FS) MegaDork
4/16/21 11:27 a.m.
L5wolvesf said:

Early 60s Ford Galaxie 

https://www.macsautoparts.com/1960-64-mercury-and-ford-including-galaxie-expansion-tank-for-352-390-410-428-60-33543-1.html 

That is more of an air separator than an expansion tank - it is directly inline with the upper radiator hose, so all coolant coming out of the engine goes through it.

Trent
Trent PowerDork
4/16/21 11:33 a.m.

Just for funzies I'm gonna walk around the shop and report. I will disregard the 50's and earlier cars unless they do have one

62 Jaguar E-type has an expansion tank

65 Jaguar 3.8S saloon does not

60's cobras had them. 

69 Maserati Ghibli does not

The cheapest new car available in the US in 1969 (fiat 850) had a nice expansion tank system

71 Lotus Europa has one

69 Ferrari Dino has one

69 Maserati Mistral does not

 

logdog (Forum Supporter)
logdog (Forum Supporter) GRM+ Memberand UberDork
4/16/21 12:43 p.m.

Looking at just the non-pressurized containers (to keep design choice/packing requirements out of the equation), it looks like the newest confirmed example so far for a "spit on the ground" hose is the 86 Mini.  Im actually kinda surprised it would make it that new just for the environmental concerns and wanting to keep Fido from drinking coolant.  It is also interesting seeing the various have/have not differences in the 60s/70s

Pete. (l33t FS)
Pete. (l33t FS) MegaDork
4/16/21 12:58 p.m.

In reply to logdog (Forum Supporter) :

If coolant spits on the ground, that is because someone overfilled the cooling system.  If there is no catch tank, you're supposed to fill the coolant to about 1-2 inches down from "full" and no more.

Radiators used to have full lines stamped into the tank that had the radiator cap.  Filling the radiator all the way to the top is a relatively new idea.

frenchyd
frenchyd UltimaDork
4/16/21 1:53 p.m.

In reply to Tom Suddard :

The first time I saw a coolant recovery tank was the big block Corvette of about 1972.   A beautifully formed aluminum tank. 

Honsch
Honsch Reader
4/16/21 3:04 p.m.

Look for changes in pollution laws.  At some point it became frowned upon to dump toxic coolant on the road.

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