Replace coolant overflow tank with surge tank. (Page 1/1)
1MontanaFiero SEP 29, 09:50 PM
I would like to see about replacing my coolant overflow tank with the pressurized surge tank pictured below. It’s from a 1999 Grand Am, and I just happen to have a brand new one.

Why? Well I have a hood that I’ve had for years, with an inverted scoop that I mismeasured, and the scoop interferes with the overflow tank.

I figure it can go in the engine bay, perhaps, but I will need some guidance. Has anyone done this?

theogre SEP 30, 12:48 AM
Fiero and many other GM vehicle use the Cap on the overflow tank as Vent for normal operation and as overflow path when the car is "boiling over."
Many others have a separate vent for same reasons like black tube at the top in above pic.

Fiero and a lot of others use an "overflow tank."
It does 2 things...
1. Stops spilling coolant when people over fill the radiator until ~ 1980 when most have them. Most "Old School" vehicles did not have anything to tell you the rad is Full like now but Before O-tank the Radiators would puke the extra coolant on the ground and worse leaving Poison Ethylene Glycol coolant in puddles.
2. Purge all Air out of the cooling system. See my Cave, Coolant Fill under "burping."
In short: System get hot force air in the system out then cools off sucking coolant in. If you fill the system right and it not leaking anywhere even Fiero will self purge in only a few heat cycles.

You can move and/or change the O-tank but watch out for Volume it can take. Fiero O-tank is much larger from Total Empty to Add or Full marks "hidden" on side toward HL assembly. look at Jeggs, Summit, etc.

Most pressured aux/surge tank system still use an "overflow tank" to do same thing, purge All air out of the system.
Is mostly used on a vehicle where the radiator in low and very hard to get at, even worse the Fiero radiator setup, and they don't "radiator caps" in the system but the aux tank.

------------------
Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)

The Ogre's Fiero Cave

jelly2m8 SEP 30, 05:32 AM
Ogre always has some great advice.... Ask your self..... Several hundreds of thousands Fiero's have been on the road for almost 40 years now, sure some ill maintained shitboxes have issues but the majority left still run just fine. Why are you trying to change something that just works????
1MontanaFiero SEP 30, 11:12 AM

quote
Originally posted by jelly2m8:

Ogre always has some great advice.... Ask your self..... Several hundreds of thousands Fiero's have been on the road for almost 40 years now, sure some ill maintained shitboxes have issues but the majority left still run just fine. Why are you trying to change something that just works????




He sure does have amazing advice, and secretly, I was hoping to attract his wisdom with this. The WHY of my enquiry is related to the Hood with the inverted vent that I would like to install. I did this hood 16 years ago and it hits the overflow tank when it is closed. The WHAT of my enquiry is-- I happened to have this part from a grand am project I abandoned. So I figured I would ask, and I got my answer. It certainly doesn't hold as much volume, for one thing.
1MontanaFiero SEP 30, 11:36 AM

quote
Originally posted by theogre:

Fiero and many other GM vehicle use the Cap on the overflow tank as Vent for normal operation and as overflow path when the car is "boiling over."
Many others have a separate vent for same reasons like black tube at the top in above pic.

Fiero and a lot of others use an "overflow tank."

You can move and/or change the O-tank but watch out for Volume it can take. Fiero O-tank is much larger from Total Empty to Add or Full marks "hidden" on side toward HL assembly. look at Jeggs, Summit, etc.





So, Ogre, that leads me to a related question:

Way back when... I did a 3.4 conversion with a low mileage motor. Cooling system performed well until I decided to install this hood I mentioned, with the inverted vent. I mismeasured for its location and it would hit the O-tank when I closed the hood. So I simply moved the tank down. From that point forward, the system purged all of its coolant at highway speeds. That car has been parked for a decade now.

I attributed the issue to having moved the tank, but from what I am learning or havre learned just now, is that the tank's position doesn't matter because it isn't dependent on being level with the radiator? Am I reading this correctly? Could it just be coincidence, and maybe a bad head gasket or a hairline crack in a head? Maybe it is time to pull this car out of its hibernation and do a bit of investigating.

Picture not mine, (credit: Angel on earth) but similar.
theogre SEP 30, 06:58 PM
Check the Radiator Cap.
Wrong Cap and Leak(s) in the system can dump coolant on the floor thru the O-tank even at stock location.
See my Cave, Radiator Caps