Rad Caps??

-
69signetv8

69signetv8

Well-Known Member
Joined
Jun 7, 2005
Messages
2,375
Reaction score
7
Location
Sooke BC
Think I have the right idea..just want too make sure and get some feedback.

I noticed today (after a good ride weekend) that I had a "small" upper seam rad leak. I believe that my cap is rated at 16-18 PSI and that my stat is 180*
I will be looking for a new rad down the road however for the time being I did a quick JB weld job on the seam and will hope for the best.

My Question..
I was thinking of replacing the cap with a lower PSI (for the stress facture of the rad) but this would lower my boiling point...and if so, does this mean that when the stat opens at 180* that the engines/rads high water pressure would just bypass the cap seal...(piss out) then overheat the engine??

Should I just keep the same Cap and hope for the best until I get a different rad?

PS..318 30K over - heads are 360 in 318 cast.

Thanks for keeping me stright.
 
I've got the same issue. After a drive and warm up I get a top seam leak and a thin line runs down the top seam. I too have a new cap (16lb) and still get it. My rad is a cheapo parts store 22" replacement that I have no idea how old it is. I'm going to try a bottle of leak stop I got from Hughes now that my engine's back together and I'll let you know if that works. I was hoping to avoid the JB Weld route myself!

I too am biding my time and living with it until I can get an alluminum rad and electric fan package. It's just annoying to pop the hood and know you need to wipe it down at a cruise night or show!
 
Thanks, :read2: I have read told to stay away from "stop leak" as it can do later damage to engine gaskets or clog important cooling passages. If it's not one thing it seems to be another....Oh crap!!
 
I've ran a weak system cap (6 lbs) due to leaking freeze plugs. It helps slow the leak.
Stop leak products will not fix and upper tank leak. It cant stay up there long enough .
I should add... My brothers 93 Mustang has needed a new radiate for 3 or 4 years now. He is constantly having problems with the car.Battery terminals, starter, etc.. and doesn't comprehend the side effects of a continuous coolant leak.
 
Keep your cap as is, but go get some stop leak pucks from...ahem...GM. They sell excellent tablets that work great, and will not plug up your system. Also, as a side, stay away from extended life antifreeze, as it will open up old seeps that regular antifreeze has plugged. I just change my coolant every fall before storage.
 
Thanks...still looking for the pressure system answer.

Why is the caps PSI important?? I know that it makes your system like a "pressure cooker" and that the higher the PSI cap..will increase the boiling point temp. So why not use a MAX PSI cap and to lower the overall temp as max as possible. Wouldn't a system with a higher boiling point reduce the overall pressure in the system preventing due to less boilover, leaks and high overheating temps?


What don't I understand here about this phyics stuff and why is it standard to have a 16 - 18 PSI Cap..
 
The water pump doesn't really create pressure nor does it create a suction on its incommng side. Its main function is circulation by design. In certain conditions a water pump will spin while moving very little water. The thermostat has effect on minimum operating temp by blocking circulation through the radiater. Bypass hose allows the water to circulate within the engine while T-stat is closed. The system heat and pressure still reaches the radiater since there are no other gates. The rising temp creates system pressure. That pressure pushes water into the pump incomming side which is a good thing. More in equals more out.
The radiater cap is a safety feature since too much pressure would bust something. Lower system pressure only slows a leak. The lost pressure in turn lowers the volume of circulation.
Hope this helps.
 
RedFish said:
The water pump doesn't really create pressure nor does it create a suction on its incommng side. Its main function is circulation by design. In certain conditions a water pump will spin while moving very little water. The thermostat has effect on minimum operating temp by blocking circulation through the radiater. Bypass hose allows the water to circulate within the engine while T-stat is closed. The system heat and pressure still reaches the radiater since there are no other gates. The rising temp creates system pressure. That pressure pushes water into the pump incomming side which is a good thing. More in equals more out.
The radiater cap is a safety feature since too much pressure would bust something. Lower system pressure only slows a leak. The lost pressure in turn lowers the volume of circulation.
Hope this helps.
Click to expand...

Thanks Redfish. It does!
 
I dont know if this will help or not but I'll say it anyway. For every 1 psi that is applied to the coolant system, the boiling point of the liquid will increase 3 degrees. So, If the boiling point of water under no pressure is 212 degrees, using a 10 psi cap would increase this by 30 degrees, or 242 degrees until the liquid boils. I would be a little leary of a lower pressure cap unless it is a pretty mild engine that doesnt make a lot of heat.
 
You must log in or register to reply here.
-

Back
Top