Correct radiator cap pressure rating????
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Elder User
Joined: Aug 2003
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From: Houston, TX
Correct radiator cap pressure rating????
A while back I posted a thread about my temp gauge (91 3.0) swinging between a position at 9 o'clock on the gauge and about 10:30. I thought it might be the thermostat and since I was afraid to break the bolts I decided to live with it.
I have recently noticed that the coolant was low. I refilled the radiator (it took about 3/4 gal). The next day it was down the same amount. I then refilled it and didn't check for about 3 or 4 days, and it was down the same 3/4 gal. Also noticed that every now and then the coolant was bubbling into the overflow tank and filling it to overflowing. I figured at that point that I might have a bad radiator cap. Bought a new one, same brand. This one came from O'Reillys and was an 18 lbs cap. I looked at the old one (from the Zone) and it was a 13 lbs cap. Which one is correct? ....and will a lower rated cap cause coolant loss?
Thanks,
Klaus Cook
Houston, Texas
I have recently noticed that the coolant was low. I refilled the radiator (it took about 3/4 gal). The next day it was down the same amount. I then refilled it and didn't check for about 3 or 4 days, and it was down the same 3/4 gal. Also noticed that every now and then the coolant was bubbling into the overflow tank and filling it to overflowing. I figured at that point that I might have a bad radiator cap. Bought a new one, same brand. This one came from O'Reillys and was an 18 lbs cap. I looked at the old one (from the Zone) and it was a 13 lbs cap. Which one is correct? ....and will a lower rated cap cause coolant loss?
Thanks,
Klaus Cook
Houston, Texas
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Joined: Apr 2005
Posts: 5,720
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From: Washington state
no, just lower cooling efficiency, unless the inner neoprene seal is leaking. they do develop hair line tears and splits
time to change that thermostat and find the cause of the frequent boil overs.
full reverse flush time with garden hose backwards thru the block
i would remove radiator and rod the tanks out with long plumbers brush to break the blocking chunks off the core tube ends
be careful flushing heater cores and radiator core, they will only take about 40 psi
Deliverance zombies at quickie car care centers blow them out with water house pressure
with it this bad, i would start with one of the strong alkaline cooling system cleaners. normally, i avoid the stuff like the plague but if your system is scaled and greased up it will remove the worst
how's your timing, static and dynamic with ECU advance?
time to change that thermostat and find the cause of the frequent boil overs.
full reverse flush time with garden hose backwards thru the block
i would remove radiator and rod the tanks out with long plumbers brush to break the blocking chunks off the core tube ends
be careful flushing heater cores and radiator core, they will only take about 40 psi
Deliverance zombies at quickie car care centers blow them out with water house pressure
with it this bad, i would start with one of the strong alkaline cooling system cleaners. normally, i avoid the stuff like the plague but if your system is scaled and greased up it will remove the worst
how's your timing, static and dynamic with ECU advance?
Last edited by 96_4wdr; Jun 16, 2007 at 11:48 AM.
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Gentlemen,
I live in Phoenix, Az and replaced my cap with a 4 lb unit. No heat problems and much less stress on cooling system. 3 years now on Aero, 25 years on many other vehicles. No rad core or heater core problems. I did this on all company trucks for last 20 years. Hard working, trailer towing,city traffic, etc.
The only vehicles this did not work on were 454 chevys which regularly blew their tops with 14 lb caps. That is what 7.5 to 1 compression does for you.
I know there are theorys about local hot spots and whatever. There is theoretical correctness in all of these but I run 4 lb caps in all my vehicles and it works. Nothing succeeds like success.
Ken
This "trick" was told to me by a mechanic in 1969 and has served me well since.
Ken
I live in Phoenix, Az and replaced my cap with a 4 lb unit. No heat problems and much less stress on cooling system. 3 years now on Aero, 25 years on many other vehicles. No rad core or heater core problems. I did this on all company trucks for last 20 years. Hard working, trailer towing,city traffic, etc.
The only vehicles this did not work on were 454 chevys which regularly blew their tops with 14 lb caps. That is what 7.5 to 1 compression does for you.
I know there are theorys about local hot spots and whatever. There is theoretical correctness in all of these but I run 4 lb caps in all my vehicles and it works. Nothing succeeds like success.
Ken
This "trick" was told to me by a mechanic in 1969 and has served me well since.
Ken
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