Expansion Tank

[crosson9]

What is everyone using for an expansion tank? Should I use one?

[Conserv]

If your 02 needs an expansion tank, your system is not working correctly. In 40 years and 200,000 miles of '02 ownership, I have never needed an expansion tank. I will admit, of course, that figuring out cooling issues is not always straightforward!

Good luck,

Steve

[John_in_VA]

I used one on my '70 back in the 80s. Used a square bottle stuffed behind the headlight bucket, with a screw cap that had a hole drilled to accommodate the hose from the radiator overflow nipple, and a plastic CRS ("coolant recovery system" brand) radiator cap that used several gaskets to provide a seal to allow the fluid to run to/from the bottle/rad..

[TobyB]

They're actually a good idea-

anything will work, including a Gatorade bottle.

However, make sure you get a cap that can use

the 'recovered' fluid- not all have a solid

seal at the lip, and thus can't 're- draw'

coolant back into the radiator.

t

[ahlem]

portcityracing.com has some very nice ones for circle track cars. We keep their catalog in the men's room at work.

[TobyB]

It's not the extra fluid reserve so much as getting ALL the air out of the system-

no oxygen = no oxidation.

t

[ahlem]

Meaning getting all the air out in the men's room or all the air out of the cooling system. Seems both might be a good idea.

[crosson9]

Nice! Thank you all for the responses. Actually the leak has become a mystery of origin. I thought it was burping up coolant while cooling down in the garage. Now I think it might be the water pump or a freeze plug. I just need spare time one weekend to look deeper into it.

[M3M3M3]

curious...what are we talking about here?

there are expansion tanks, and there are overflow tanks.

expansion tanks require replumbing the cooling system to make the tank part of the flow system...ala the stock setup on E30's and later cars. an expansion tank is under the same pressure as the cooling system. any old gatorade bottle will not work for this.

overflow tanks are typically connected to the radiator neck overflow outlet tube. when pressure in the system gets too high, the radiator cap valve "opens" to allow the pressure and coolant to overflow out the tube. stock 02's just have a tube that runs to the ground. some folks run this tube to a tank. this would be an overflow, not an expansion tank. any old gatorade bottle will work perfectly for this, as long as the hose goes all the way to the bottom.

(fixed text, thanks toby!)

[TobyB]

the radiator cannot pull coolant from an overflow tank back into the system.

Sure, it can- when the system heats up, everything expands (especially air)

and, if you've filled the rad right to the top, it burps a bit out.

If there's a dip tube right to the bottom of the 'overflow' tank, then it'll snot

any remaining air out, and some coolant. When things cool off again, things will contract, and coolant will be drawn back into the radiator.

This requires a cap that both seals to the lip of the radiator and has

a one- way valving action built into it. Most do, as they'd collapse radiator

hoses if they didn't, and you pulled the cap off while things were even

somewhat warm.

I've had a half- dozen cars that worked this way- Mitsu Montero, Toyota

Land cruiser, Snoozooki Sidekick, Chebby Monza... and Jenn's 2002's set

up this way with a Volvo 'overflow' tank that has the intake molded into

the bottom of the tank...

unless I'm misunderstanding you?

t