OVERHEATING PROBLEM

[fordhealey]

OK.. I know i'm not going to get any simpathy
from some of you guys because i'm running a
289 in my BT7. the stock healey radiator
cap looses just enough water over time that i
eventually overheat ( i'm in Key West) i tried a
NAPA cap# that somebody had posted on the Modified Healey site and SLIGHTLY balooned the top
tank of my radiator.(rebuilt stock healey radiator larger core). there has to be a middle ground as far as caps go. my engine is only running at 218 which is accepable for a 289.
new motor.. still tight..i need a number for a slightly heavier cap the one i'm using is
a stock one from Moss> HELP !! gregg

 

[John Loftus]

Anyway to hook up an overflow tank so that water you lose is returned each time?

Also, check out the following discussion. You might need to go to an uprated core for your radiator to handle your motor

https://www.britishcarforum.com/cgi-bin/ultimatebb.cgi?ubb=get_topic&f=1&t=001468

Cheers,
John

[ 01-10-2004: Message edited by: John Loftus ]</p>

 

[Dave Russell]

Hi Gregg,
You may very well need a higher pressure cap. What some folks don't realize is that in addition to the static cooling system pressure of 7 psi or what ever the cap is rated at, the cap has to resist the dynamic pressure of the water pump. The pump pushing against the flow resistance of the radiator tubes.

If the radiator flow rate is too low in relation to the water pump output volume, There is additional dynamic pressure on the cap which the cap must also hold. This situation is made worse by your V8 having a higher capacity water pump than the original cooling system was designed for.

There are several solutions;

1- Put on a higher pressure cap. Not easy to find a higher pressure cap for the long, small diameter original filler neck. Replace the filler neck with a shorter standard neck & use one of the many standard higher pressure caps which are available.

2- Replace the radiator core with one that can flow more volume. Larger or more tubes. This will create less pump back pressure on the cap. A flow rate similar to the original 289 radiator would be needed,probably with a cap having the same pressure as the 289.

3- Possibly install a restrictor in the top hose (thermostat housing) which will allow less volume to be pushed through the radiator & reduce the pump pressure against the cap.May or may not work.

4- Install a larger water pump pulley to reduce the pump flow rate. Might create other problems.
D

[ 01-10-2004: Message edited by: Dave Russell ]

[ 01-10-2004: Message edited by: Dave Russell ]</p>

 

[ThomP]

Er Dave, I think you mean a larger water pump pulley to reduce the flow don't you?

 

[Dave Russell]

Thanks Thom, I corrected it. My "old folks confusion" is extensive, inner-outer, larger-smaller, up-down, I even have to carry a rock in my right hand to remember which is which & then I have to mark the rock with an R.
D

 

[fordhealey]

Sorry! i responded before i read all of the posts, a different neck on the radiator may be
a solution, as the napa cap did not seat properly on the healey tank. I CAN DO THAT!
have a local radiator guy that cored my healey radiator. never thought of changing the neck.
GOOD IDEA!
THANKS
GREGG
i'll also try the water wetter'

 

[fordhealey]

RESPONDED TO THIS IN THE OTHER MESSAGE, BUT THE
14# CAP SEEMS TO HAVE SOLVED THE PROBLEM
THANKS
GREGG