Radiator overflow tank - The 1947 - Present Chevrolet & GMC Truck Message Board Network

/<eystroke · 08-20-2003, 11:37 AM

I recently bought a '69 with a 350/400 combo. The PO had installed twin
electric fans on a new Heavy Duty 4 core radiator and also installed a
overflow tank. My question is does the overflow tank have to be at the
same level as the radiator cap to allow the fluid to siphon back into
the radiator? Right now it is below the cap and the overflow tank stays
full but the fluid level in the radiator is rather low. Thanks.

tom hand · 08-20-2003, 11:44 AM

No vacuum that the radiator creates as it cools pulls it back. Most likey you have the wrong radiator cap on it...a system with an overflow tank require a cap with second seal to create the vacuum.... or there is a leak in the system allowing it to suck air

/<eystroke · 08-20-2003, 01:21 PM

I'll check the cap and for leaks. Thanks!

71Chev · 08-20-2003, 03:42 PM

Get a radiatior cap for an 85 chevy truck.

nate68 · 08-20-2003, 04:50 PM

anybody have any part #'s? cuz i need one of those radiator caps also

71Chev · 08-20-2003, 05:21 PM

Just go to any parts store and ask for a radiator cap for an 85 chevy pickup. Don't need the part number. Heck Walmart might even have one.
I just checked the one I have on my 71 and there isn't a part number on it. I just bought one for an 85 chevy.

nate68 · 08-20-2003, 05:29 PM

there were 2 diff part #s and they looked exactly the same

71Chev · 08-20-2003, 05:57 PM

I made a phone call. One part number should be for a cap with the pressure release lever, the other part# doesn't have a pressure release lever. Both are 16# and either will work.
STANT w/PRESSURE RELEASE 10331
STANT REGULAR 10231

nate68 · 08-20-2003, 07:15 PM

i'm running a 80's big block radiator

08-20-2003, 11:37 AM	#1
/<eystroke Registered User Join Date: Jul 2003 Location: North Texas Posts: 265	Radiator overflow tank I recently bought a '69 with a 350/400 combo. The PO had installed twin electric fans on a new Heavy Duty 4 core radiator and also installed a overflow tank. My question is does the overflow tank have to be at the same level as the radiator cap to allow the fluid to siphon back into the radiator? Right now it is below the cap and the overflow tank stays full but the fluid level in the radiator is rather low. Thanks. __________________ '69 C/10 Short Wide 350/400/AC/Tilt/Tach

08-20-2003, 11:44 AM	#2
tom hand CCRider Join Date: Feb 2000 Location: Olive Branch,MS,USA Posts: 2,232	No vacuum that the radiator creates as it cools pulls it back. Most likey you have the wrong radiator cap on it...a system with an overflow tank require a cap with second seal to create the vacuum.... or there is a leak in the system allowing it to suck air __________________ 72 GMC Sierra SWB almost finished---- 84 Softail Olive Branch MS

08-20-2003, 01:21 PM	#3
/<eystroke Registered User Join Date: Jul 2003 Location: North Texas Posts: 265	I'll check the cap and for leaks. Thanks! __________________ '69 C/10 Short Wide 350/400/AC/Tilt/Tach

08-20-2003, 03:42 PM	#4
71Chev Senior Member Join Date: Dec 2000 Location: Indiana Posts: 3,074	Get a radiatior cap for an 85 chevy truck. __________________ 71 Chevy CST Long Fleet 350/350/3.07 leaf rear.

08-20-2003, 04:50 PM	#5
nate68 Registered User Join Date: Jan 2000 Location: ca Posts: 1,110	anybody have any part #'s? cuz i need one of those radiator caps also __________________ 68 short step, 406/700r4, 9" w/discs.

08-20-2003, 05:21 PM	#6
71Chev Senior Member Join Date: Dec 2000 Location: Indiana Posts: 3,074	Just go to any parts store and ask for a radiator cap for an 85 chevy pickup. Don't need the part number. Heck Walmart might even have one. I just checked the one I have on my 71 and there isn't a part number on it. I just bought one for an 85 chevy. __________________ 71 Chevy CST Long Fleet 350/350/3.07 leaf rear.

08-20-2003, 05:29 PM	#7
nate68 Registered User Join Date: Jan 2000 Location: ca Posts: 1,110	there were 2 diff part #s and they looked exactly the same __________________ 68 short step, 406/700r4, 9" w/discs.

08-20-2003, 05:57 PM	#8
71Chev Senior Member Join Date: Dec 2000 Location: Indiana Posts: 3,074	I made a phone call. One part number should be for a cap with the pressure release lever, the other part# doesn't have a pressure release lever. Both are 16# and either will work. STANT w/PRESSURE RELEASE 10331 STANT REGULAR 10231 __________________ 71 Chevy CST Long Fleet 350/350/3.07 leaf rear.

08-20-2003, 07:15 PM	#9
nate68 Registered User Join Date: Jan 2000 Location: ca Posts: 1,110	i'm running a 80's big block radiator __________________ 68 short step, 406/700r4, 9" w/discs.



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