Illegal Vette

I found an interesting article today about cooling, and it describes how a "surge" or expansion tank works. I had never understood the difference between and overflow tank and an expansion tank, but it's an important difference particularly if you have an LS engine. The idea is for the air in the system to be purged, and an expansion tank will do this while an overflow tank won't. I've researched this a little bit, C3's had these on some of the early cars but later C3's like my '82 don't. I'm going to eventually fabricate one to replace my overflow tank since it's really a bitch to get all of the air out of my system and I'm wondering if any of you have thought about or done this. The article is here: http://www.pirate4x4.com/tech/billavista/Cooling/

74modified

I have a Mercedes pressure surge tank on my 74 with a LS. It is plumbed so that you get constant coolant circulation - so you continuously remove steam/vapor/air. The LS is know to generate a little steam (hence the steam vents in the heads) so this type of system helps. It is also a good system for any other engines.

Illegal Vette

Ahh, so you've already solved this problem! Does your tank mount in the same spot as the overflow tank?

74modified

No, I mounted it high on the passenger side fender well. There is a "T" in the heater hose to the bottom of the bottle, and a small line to the steam vents.

I looked at aluminum tanks, and decided that I would rather be able to see the level. So, I looked at modern plastic tanks. I am cheap and picked up a lightly used tank. You could even use a C5 tank - most all modern cars use a circulating pressure tank. I just picked one that worked for me.

Richard454

That "Billavista" has some good write ups- also did one on AN fittings - worth the read.

Although mines not a LS engine-I do have steam ports and I copied the BMW expansion tank system originally on my engine.

I had a BMW tank laying around but opted for a little more bling and went w/ a Canton one. You can often find somebody on eBay selling one they never used a lot cheaper than new.

For the steam port I used some aluminum tubing- tapped an AN fitting - and used it as a connection between two different size hoses at the highest point in my system.


DSCN5119 by Richard Hayes, on Flickr


DSCN5129 by Richard Hayes, on Flickr

Illegal Vette

I like your thinking with the plastic tank, it's nice to be able to see your coolant level. Do you have a picture of yours? The Canton 80-225 for a Z06 that's pictured in Billavista's article is for a C5, I'm guessing the C5 tank is about the same size? If so I don't think it would fit my car, it's 2 feet long, 11.5 inches wide and 9.5 inches tall! I may go visit the junk yard and see if there's something that would work. Or I could use the stock overflow tank as a model for an aluminum tank and it would fit perfectly.

Illegal Vette

I'll have to look for his other articles, that one taught me more about cooling systems than I've learned anywhere else.

I like your tank, It looks awesome enough to be in your incredible car. I'll look on ebay too, it seems like one of Canton's products would work.

Illegal Vette

There's also this:


Which seems like it could be pretty easily adapted to fit if it isn't too big.

Illegal Vette

I decided to duplicate the original overflow tank and made a mock-up which I sent to Canton Racing Products to build:



And they sent me back a few pictures of what they're building for me:






I'll be plumbing it like this:



I think this is the solution to air in my cooling system, and I'm very impressed with the quality of their work.

74modified

I am very impressed as well. That should be a great solution.
I have mine plumbed the same way, with the exception of the heater hose "T" right off of the bottle. I have a line out of the bottle with the "T" in the heater hose mounted lower. After looking at yours, I think I will change the location of my bottle. It is mounted in the same location, but doesn't wrap around the inner fender.

Illegal Vette

I looked at some of the other ones they made for C5 Corvettes and they had the tee in a similar location so that's where I asked them to put it on mine. It sounds like an easy change to make to yours.

Afterhours

I am a new Z06 owner, so can someone explain Why would you replace the stock unit with an aluminum tank? is there anything special about this unit or can I replace it with a non-z06 unit piece.?

Easy Mike

Z06 was never a C3 option. Are you possibly in the wrong Forum?

PAmotorman

if your rad has a pressure cap that must be replaced with a non pressure cap so the coolant can circulate to the purge tank.

jasper711

De-aeration would seem better served by a tank to slow down the flow within the main coolant circuit, like the old Thunderbird expansion tanks installed halfway down the upper radiator hose. I thought the idea was to provide a larger cross section reservoir allowing the coolant to slow enough for the bubbles to rise and be vented off. (The top of a down-flow radiator would also do this effectively).

Illegal Vette

[QUOTE=jasper711;1593199282]De-aeration would seem better served by a tank to slow down the flow within the main coolant circuit, like the old Thunderbird expansion tanks installed halfway down the upper radiator hose. I thought the idea was to provide a larger cross section reservoir allowing the coolant to slow enough for the bubbles to rise and be vented off. (The top of a down-flow radiator would also do this effectively).


I'd forgotten about that one, a very effective solution.