Recovery tank height?

Do you need to mount the coolant recovery tank at a certain height on the car?

Meaning does it need to be above the engine or does it not matter?
 

Mike Pass

Supporter
I don't think the height matters so long as the coolant can be drawn back into the main system when the engine cools down. The pipe connecting the recovery tank should be at the bottom of the recovery tank so that coolant is drawn back and not air. Plain cap on the main tank and pressure cap on the recovery tank.

Cheers
Mike
 

Ken Roberts

Supporter
The pressure cap is on the main tank. It pukes the coolant out past the pressure cap and gravity feeds into the recovery tank.
 
Thanks Ken.

I am wondering if anyone has used this type of expansion/recovery combo system and if there are and advantages or disadvantages verses the two tank system?

I can see the advantages, are there any disadvantages?

I would think less plumbing and only having to deal with one unit would be a big advantage and if so, why aren’t more people using this type of system?
 

Terry Oxandale

Skinny Man
Supporter
The reason I haven't used the combination unit is size constraints. I've got room for two smaller separated tanks versus a single larger combo unit in a single location. Room for anything is a luxury under my rear bodywork.
 
Hi Again Steve,

Another disadvantage to the combination expansion/recovery tank in your picture (besides space constraints) is that the coolant recovery tank does not have a side mounted sight glass so that you can visually see the fluid level in the coolant recovery tank.

Once installed when the engine is cool, the expansion tank will stay full all the way up to the pressure cap, and the recovery tank will be about 1/4 to 1/2 full. When the motor is hot, coolant will expand and fluid (and air) will migrate into the recovery tank increasing its fluid level up to about 1/2 to 3/4 full. When the engine cools down, fluid (with no air) from the recovery tank will be sucked back into the expansion tank. The cycle just repeats over and over as the engine goes from cold to hot to cold. This configuration systematically bleed air out of the cooling system with every heat cycle.

Mostly the coolant levels in the car should stay the same for long periods of time. However if you do not have a sight glass then you run a risk of having too much coolant in the recovery tank and overflowing the coolant recovery tank when the engine is hot. Conversely if the coolant recovery tank ever gets empty then you run a risk of sucking air back into the expansion tank and therefore back into the system. So while a sight glass is not mandatory, it is very useful to be able to quickly monitor coolant levels.
 
Hi Again Steve,

Another disadvantage to the combination expansion/recovery tank in your picture (besides space constraints) is that the coolant recovery tank does not have a side mounted sight glass so that you can visually see the fluid level in the coolant recovery tank.

Once installed when the engine is cool, the expansion tank will stay full all the way up to the pressure cap, and the recovery tank will be about 1/4 to 1/2 full. When the motor is hot, coolant will expand and fluid (and air) will migrate into the recovery tank increasing its fluid level up to about 1/2 to 3/4 full. When the engine cools down, fluid (with no air) from the recovery tank will be sucked back into the expansion tank. The cycle just repeats over and over as the engine goes from cold to hot to cold. This configuration systematically bleed air out of the cooling system with every heat cycle.

Mostly the coolant levels in the car should stay the same for long periods of time. However if you do not have a sight glass then you run a risk of having too much coolant in the recovery tank and overflowing the coolant recovery tank when the engine is hot. Conversely if the coolant recovery tank ever gets empty then you run a risk of sucking air back into the expansion tank and therefore back into the system. So while a sight glass is not mandatory, it is very useful to be able to quickly monitor coolant levels.
Hi Bob,

Great information. As you know, I’m trying to complete my cooling system before I move on to the million other things needed to complete my car.

It seems to me that the combination system is neat and tidy and easier to install and maintain, but as you say, having the visual sight level is a major advantage.

I’ve been shopping for these tanks and many don’t have the sight tube. I wonder how many racers use the sight tube and how many do not?

Also, should I get one of the expansion tanks with the visual tube, what level should the coolant be?

The research continues!

Thanks again Bob, I’ll ptobably start a build thread soon, but my progress is so slow, I’d probrbaly bore everyone.

Steve
 

Bill Kearley

Supporter
I have the normal header tank with expansion tank. The expansion tank has a sight tube and an internal pipe from the bottom to almost the top ( a vent ) that will allow it to over flow down and out with a hose to the ground.
 

Terry Oxandale

Skinny Man
Supporter
One side note about placement of the tank. Keeping the pressure cap easily accessible and clear of immediate surroundings allows tools such as AirLift, etc, which fits into the radiator cap opening for easy vacuum filling of the coolant system.
 
I have the normal header tank with expansion tank. The expansion tank has a sight tube and an internal pipe from the bottom to almost the top ( a vent ) that will allow it to over flow down and out with a hose to the ground.
The problem with this is that if you want to take your car racing, they won’t allow you to spill coolant into the track. You’ll need a recovery tank.
 

Howard Jones

Supporter
I have a home made system with a header tank and a overflow tank. Pictures below. The header tank is located so that is as high in the car as possible to aid air removal. It has two bleed lines that come from the top of the radiator and the rear of the heads going to it. It also has the inlet located at the bottom of the tank and that goes to the main return coolant pipe at the point where it is connected to the pump inlet.

This is important. The expansion tank should be connected to the lowest pressure point in the system. This is as close to the pumps impeller intake side as possible.

Then the overpressure vented coolant is vented from the fill cap (radiator cap) neck outlet port to the top of the overflow tank back at the rear of the car. On the inside of the overflow thank this line continues to the bottom.

I located it behind the rear tires so that if it fills and needs to overflow the coolant doesn't end up on the tires. This final overflow line is also connected at the top of the overflow tank so that it must be full to vent coolant onto the ground. It holds a two quarts. This is a typical track setup and not a recovery type as used on a street car.
 

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Terry Oxandale

Skinny Man
Supporter
Because it is nearly impossible to place my tanks as a highest point, I do find it valuable on my set-up to have a bleed valve (Moroso for example) on a small cavity, at the highest point in the system (mounted on the intake manifold) that is used to bleed off small amounts of air. Once the system is hot or at full temperature, I shut the pump off, bleed the value until coolant is expelled, and then allow the whole system to cool and draw coolant from the tank. This expels air, and at the same time, releases some system pressure which causes an earlier pressure differential with which to draw coolant out of the tank when things cool down.

 
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I have a home made system with a header tank and a overflow tank. Pictures below. The header tank is located so that is as high in the car as possible to aid air removal. It has two bleed lines that come from the top of the radiator and the rear of the heads going to it. It also has the inlet located at the bottom of the tank and that goes to the main return coolant pipe at the point where it is connected to the pump inlet.

This is important. The expansion tank should be connected to the lowest pressure point in the system. This is as close to the pumps impeller intake side as possible.

Then the overpressure vented coolant is vented from the fill cap (radiator cap) neck outlet port to the top of the overflow tank back at the rear of the car. On the inside of the overflow thank this line continues to the bottom.

I located it behind the rear tires so that if it fills and needs to overflow the coolant doesn't end up on the tires. This final overflow line is also connected at the top of the overflow tank so that it must be full to vent coolant onto the ground. It holds a two quarts. This is a typical track setup and not a recovery type as used on a street car.
Great placement and I like the idea of keeping the overflow away from the tires.

I am building this with racing in mind; first because I really want to race and second, I don’t think I have the energy or inclination to fight the DMV to get proper registration and plates.

I’ve been toying about racing for years. I used to drive Porsche’s and always want to do track days but life always got in the way.

So with this build, I’ll be putting Hoosiers on it and hope to someday get her on the track before I keel over.
 
Because it is nearly impossible to place my tanks as a highest point, I do find it valuable on my set-up to have a bleed valve (Moroso for example) on a small cavity, at the highest point in the system (mounted on the intake manifold) that is used to bleed off small amounts of air. Once the system is hot or at full temperature, I shut the pump off, bleed the value until coolant is expelled, and then allow the whole system to cool and draw coolant from the tank. This expels air, and at the same time, releases some system pressure which causes an earlier pressure differential with which to draw coolant out of the tank when things cool down.

This idea could help me a lot! My radiator only has a release valve to eliminate air, I won’t have a tube from the radiator to the expansion tank. If if can tap into a bleed on the manifold, it may help keep the system operating properly.

Thanks
 
Hi Again Steve,

Another disadvantage to the combination expansion/recovery tank in your picture (besides space constraints) is that the coolant recovery tank does not have a side mounted sight glass so that you can visually see the fluid level in the coolant recovery tank.

Once installed when the engine is cool, the expansion tank will stay full all the way up to the pressure cap, and the recovery tank will be about 1/4 to 1/2 full. When the motor is hot, coolant will expand and fluid (and air) will migrate into the recovery tank increasing its fluid level up to about 1/2 to 3/4 full. When the engine cools down, fluid (with no air) from the recovery tank will be sucked back into the expansion tank. The cycle just repeats over and over as the engine goes from cold to hot to cold. This configuration systematically bleed air out of the cooling system with every heat cycle.

Mostly the coolant levels in the car should stay the same for long periods of time. However if you do not have a sight glass then you run a risk of having too much coolant in the recovery tank and overflowing the coolant recovery tank when the engine is hot. Conversely if the coolant recovery tank ever gets empty then you run a risk of sucking air back into the expansion tank and therefore back into the system. So while a sight glass is not mandatory, it is very useful to be able to quickly monitor coolant levels.
I found a C&R recovery tank with a sight tube. What’s interesting on this is the air valve. Looks like they put a air bleed valve on the recovery tank.

Looks like a good idea.
 

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