LT1 15 vs 16 lb radiator cap?
03-20-2013, 01:21 PM
#1
Burning Brakes
Thread Starter
LT1 15 vs 16 lb radiator cap?
I've got a 94 LT1
So I'm replacing my radiator cap.. and I thought it'd be a no brainer. I went to Autozone (because I was near) and picked one up. They sold me a 16 lb cap. I thought it was supposed to be 15 lb, but their system had it as 16 so I went along... when I checked, OEM is indeed 15 lbs. (per the FSM, existing Cap etc..). I thought it was just a typical Autozone error, so I went to another local (more trusted parts shop) and they also showed the "correct" cap as 16lb... they didn't have a 15lb cap that they would say fit...
So the question is: is 1 lb going to make a difference? Did the spec change at some point? I'd rather not pay the dealer in gold just for a cap....
So I'm replacing my radiator cap.. and I thought it'd be a no brainer. I went to Autozone (because I was near) and picked one up. They sold me a 16 lb cap. I thought it was supposed to be 15 lb, but their system had it as 16 so I went along... when I checked, OEM is indeed 15 lbs. (per the FSM, existing Cap etc..). I thought it was just a typical Autozone error, so I went to another local (more trusted parts shop) and they also showed the "correct" cap as 16lb... they didn't have a 15lb cap that they would say fit...
So the question is: is 1 lb going to make a difference? Did the spec change at some point? I'd rather not pay the dealer in gold just for a cap....
03-20-2013, 01:29 PM
#2
Team Owner
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St. Jude Donor '05
Id use the 16 without a second thought. Especially as warm as those like to run
03-21-2013, 08:10 PM
#4
Burning Brakes
Thread Starter
Why are you changing the cap? If the gasket is distorted, or torn,
it is very simple to cut a replacement gasket.
If the 'closed' system is working..... expanded coolant going to the
over-flow bottle when hot, and returning to the surge tank during cool-down..... there is no need to replace the cap.
If coolant is going only one-way, and not returning by siphon to the surge tank, there may be other factors involved..... hose ends cracked or loose, or any break in the cooling system preventing a siphon to occur.
If your cap is ACDELCO and stamped with RC36, don't discard that cap. The cap is no longer in production, and they are going for $50 (+/-) on ebay for classic restorers.
it is very simple to cut a replacement gasket.
If the 'closed' system is working..... expanded coolant going to the
over-flow bottle when hot, and returning to the surge tank during cool-down..... there is no need to replace the cap.
If coolant is going only one-way, and not returning by siphon to the surge tank, there may be other factors involved..... hose ends cracked or loose, or any break in the cooling system preventing a siphon to occur.
If your cap is ACDELCO and stamped with RC36, don't discard that cap. The cap is no longer in production, and they are going for $50 (+/-) on ebay for classic restorers.
We all know our cars run hot... I'm doing a once over on the cooling system since I don't know if it was ever done. Part of it will be replacing the cap. I don't have a cooling system pressure tester so I can't test it or the cap, but for $8, it's worth just replacing.
I don't know if I agree with you on the premise that if coolant is moving to and from the overflow tank the cap is good. It has to hold a certain pressure. If it's opening say at 10 lbs instead of 15, it still will allow coolant to flow into the overflow tank when hot and back when it cools, but the car won't run at the correct temp because the system pressure will be off. The springs in the caps do fatigue and don't always just fail altogether. Besides, my coolant looks like it was changed, so it's still clean and green, but I'm getting some rust off the cap that dripping into the surge tank. Dunno what would rust on the cap (thought it wasn't supposed to rust) but just another reason to replace. I'll be doing my hoses shortly too...