71406

During hot weather, I keep loosing anti-freeze to the pavement when I stop the car during hot weather and ac blasting. Other cars have an overflow tank to accept the expanded anti-freeze and then the system sucks it back in when it cools off. Has anyone installed one on their car vette? And if yes where did you mount it? What kind did you buy? My car looks stock under the hood and I want to keep it that way of possible. Don't understand why the GM didn't install one when new???

standup

I don't think an overflow tank is going to solve your problem of losing fluid.....what's your operating temp on hot days?????.......if it's over 180 it could be thermostat, fan clutch or the radiator needs a flush or recored, maybe the water pump.....or a vacuum leak in the combustion process can lead to overheating.......perhaps you need to change your PCV valve????

The aluminum tank you would want was for big blocks without AC and base 4 speed 350's and if you want to keep your immaculate looking '71 (I've checked your photo :thumbs: ) original, then you aren't "allowed" an expansion tank.....but if you insist........

The tank is located on the passenger firewall just near and above the wiper washer bag.....a new tank will cost you around $130 (undated) and the bracket, which is riveted to the firewall, $15.....and the straps holding the tank to the bracket is $12 for the pair.....other than additional routing of new hoses, I think that's all you'd need........

I'd advise you check your existing cooling system first.....I'm 99% positive that GM had it together when they designed it.....

BTW.....why do you have a big block hood??? Do you own a rare LT1 Vert or what???

Larry B.

This come up a lot. One thing overlooked is the upper hose routing and shape. This is more common with big blocks because they are taller, but the same principle applies.. Here's the idea... The stock upper hose with a "U" (on BB's) MUST be install with the U shape down in front of the alternator and the hose goes around the alternator. If the hose goes over the alternator then the highest point of the system will be at the hose instead of at the pressure cap. Air (always) goes to the highest point. As the pressure builds the air expands and forces water out of the cap. Now when the car cools, it sucks in more are.. More air expands more, forcing more water out... viscious circle... If the highest point of the system is at the cap, you fill the tank 1/2 full. Now when the system get under pressure .. air will vent . The pressure cap MUST be the high point of the system. Only under extremes will you loose water. You just don't want to fill the tank more than half. Mine never vents any coolant even with the A/C on here in Florida.

Matt Gruber

have one on my 72.
click on link in sig/profile.
click on OVERHEATING?
i stuffed it in the rt. corner near the rad.

71406

Standup...thanks for the reply. Everything is new in the cooling system, radiator, fan clutch, 160 thermostat, cap. And it typically doesn't overheat, but if it looses water to the ground due to normal expansion, eventually it will overheat. I looked in Jegs and they have a few tanks that I might be able to hide. The big block hood on my car is not original...neither is the motor. I took out the 350/270 and installed a 400 too keep an original look. The original motor is in a crate in the garage.

zwede

Do you have the stock expansion tank? For a BB with AC it is a copper/brass unit painted black and mounted infront of the evaporator box.

The expansion tank should not be filled up or it will leak when hot.

On my 71 I never liked the expansion tank design and swapped it out for a 78-82 overflow plastic tank ($15 from a Chevy dealer. Still available). You would need a radiator with a cap though (BB radiators had no cap).

With the overflow tank I never loose a drop and car runs cool.

If you want an original expansion tank for a BB/AC, you're out of luck. Not reproduced ad the aluminum one won't fit.

71406

Zwede, I have a small block so your suggestion of a GM overflow tank sounds like a great solution. Where did you mount yours? And if I go into GM to order an overflow tank, do you have the part number or can you tell me what 78-82 models used this tank? Was it the 78-82 vette? Thanks.

zwede

It's for a 78-82 Corvette. I mounted it in the stock location which is in the pass side inner fender. Had to make new holes as it didn't use the earlier mounting holes. It was total hell to get in there as with the big compressor there is very little room. I finally did manage to get it in without removing the compressor (just tilted it towards the engine).

Don't forget to also get the cap. Doesn't come with the tank.

PRNDL

I picked up a cheap but ugly plastic overflow/recovery tank at my local autoparts store. I attached it with one screw to the passengerside inner fender. It works great - prevents coolant spillage to the ground, driveway or garage, and coolant gets sucked back into the radiator when the engine cools off. (Plastic overflow hose from radiator cap attaches to BOTTOM of the recovery tank) MJ


[Modified by MNJack, 4:51 PM 7/5/2003]

zwede

I just took a picture of the tank. I like the factory look.

69stingray

:lurk: I have the same issue. Fill the tank...after a good drive, it is all over the ground...

PRNDL

There is no excuse for that!! You can go first rate, like Markus (as he always does) or you can go Bubba, like me! :lol: But for less than 10 bucks at the aoutoparts store you really shouldnt be spewing coolant in your driveway. 1 pint looks like nothing in the recovery tank, but it's quite a mess in your garage!!!!



And I know I am not supposed to have an expansion tank at all, and if you have an expansion tank there should be no cap on the radiator, but this is how it came to me - I added the red-capped recovery tank. :)

71406

Sweet. Thanks for the photo...it does look factory. I ordered the same setup today from the good doctor.