Go Back   The Ford Barn > General Discussion > Early V8 (1932-53)

Sponsored Links (Register now to hide all advertisements)

Reply
 
Thread Tools Display Modes
Old 07-18-2018, 09:53 AM   #1
J Witt
Senior Member
 
J Witt's Avatar
 
Join Date: Mar 2015
Location: Acworth GA
Posts: 534
Default Leaking Radiator Cap

My '36 has had a leaking radiator cap since I bought the car. It came with a cap, without the wire bail, plus one of the, I think, Drake caps that has the bail. Both leak around the seal surface of the radiator neck. The leakage appears to occur mostly when the car is driven faster than 30-35 mph. Leakage has occurred with the original radiator and its replacement which is a new Brassworks radiator. The system has a Haney 3 psi valve on the overflow tube. I normally filll the header tank until fluid is about 1 inch or so down from the filler neck. Fluid is 50/50 antifreeze, engine temp about 190F.



Does anyone have suggestions about getting the caps to seal, or a replacement cap that works well.


Thanks to all,


John
__________________
Houston, Tranquility base here. The Eagle has landed.
J Witt is offline   Reply With Quote
Old 07-18-2018, 12:31 PM   #2
1931 flamingo
Senior Member
 
1931 flamingo's Avatar
 
Join Date: May 2010
Location: new britain,ct 06052
Posts: 8,978
Default Re: Leaking Radiator Cap

Increase the size of the gasket.......................
Paul in CT
1931 flamingo is offline   Reply With Quote
Sponsored Links (Register now to hide all advertisements)
Old 07-19-2018, 08:16 AM   #3
Kube
Senior Member
 
Kube's Avatar
 
Join Date: May 2010
Location: Wisconsin, USA
Posts: 6,921
Default Re: Leaking Radiator Cap

Quote:
Originally Posted by J Witt View Post
My '36 has had a leaking radiator cap since I bought the car. It came with a cap, without the wire bail, plus one of the, I think, Drake caps that has the bail. Both leak around the seal surface of the radiator neck. The leakage appears to occur mostly when the car is driven faster than 30-35 mph. Leakage has occurred with the original radiator and its replacement which is a new Brassworks radiator. The system has a Haney 3 psi valve on the overflow tube. I normally filll the header tank until fluid is about 1 inch or so down from the filler neck. Fluid is 50/50 antifreeze, engine temp about 190F.



Does anyone have suggestions about getting the caps to seal, or a replacement cap that works well.


Thanks to all,


John
Typically the fluid will be fine just above the top core plate. I'd start there - reduce the amount of coolant a bit and see what happens.
__________________
"I can explain it for you. However, I can't understand it for you".

Last edited by Kube; 07-19-2018 at 08:47 AM.
Kube is offline   Reply With Quote
Old 07-19-2018, 08:24 AM   #4
Steve Kennedy
Senior Member
 
Steve Kennedy's Avatar
 
Join Date: May 2017
Posts: 294
Default Re: Leaking Radiator Cap

Don't put such a tight cap on it that you keep it from breathing. These are non-pressurized systems. I had a 7 pound cap on mine and blew the seam at the bottom of the reservoir. Does anyone know of a correct aftermarket radiator?
Steve Kennedy is offline   Reply With Quote
Old 07-19-2018, 08:41 AM   #5
V12Bill
Senior Member
 
V12Bill's Avatar
 
Join Date: May 2010
Location: Mt. Holly,NJ
Posts: 1,822
Default Re: Leaking Radiator Cap

X2 # 3 You have too much coolant in the radiator. Increased speed means increased flow of water and backing up of coolant in the upper tank
V12Bill is offline   Reply With Quote
Old 07-19-2018, 02:59 PM   #6
Henry Hopper
Senior Member
 
Henry Hopper's Avatar
 
Join Date: May 2010
Location: N.W.England
Posts: 419
Default Re: Leaking Radiator Cap

Sponsored Links (Register now to hide all advertisements)
Quote:
Originally Posted by V12Bill View Post
X2 # 3 You have too much coolant in the radiator. Increased speed means increased flow of water and backing up of coolant in the upper tank
Interesting....I have similar problem with my 36.Would fitting thermostats help, ie slow the flow rate down?
Henry Hopper is offline   Reply With Quote
Old 07-19-2018, 03:42 PM   #7
Reconnoiter
Member
 
Join Date: Feb 2016
Posts: 43
Default Re: Leaking Radiator Cap

FWIW i had a similar problem with my ‘34, would puke coolant from the cap and overflow once I hit about 50 mph, no overheating. Installed 180 thermostats in my hoses and that brought it immediately under control. Runs great, and no more drooling....
Reconnoiter is offline   Reply With Quote
Old 07-20-2018, 01:12 PM   #8
J Witt
Senior Member
 
J Witt's Avatar
 
Join Date: Mar 2015
Location: Acworth GA
Posts: 534
Default Re: Leaking Radiator Cap

I do have a pair of 165 thermostats in the outlets from the heads (59AB heads). If driven very briskly, these t'stats appear to be wide open, but of course they still have a relatively small flow area. This is in Georgia summertime 90-95 degrees. The problem may go away in the fall when it cools off some.


I have one more parade to do in a couple of weeks and it will barely stay below boiling running 1-2 mph with frequent stops. Hoping for a little cooler weather for that, or may pass it up.


As I mentioned the overflow has a pressure valve that opens at 3 psi. Coolant isn't coming out the overflow, but around the seal on the cap. Appears not to be a pressure issue, but one of high flow velocity.


I'll drop the fluid level some and test again.
__________________
Houston, Tranquility base here. The Eagle has landed.
J Witt is offline   Reply With Quote
Old 07-20-2018, 01:26 PM   #9
petehoovie
BANNED
 
Join Date: May 2015
Posts: 3,336
Default Re: Leaking Radiator Cap

Quote:
Originally Posted by J Witt View Post
As I mentioned the overflow has a pressure valve that opens at 3 psi. Coolant isn't coming out the overflow, but around the seal on the cap. Appears not to be a pressure issue, but one of high flow velocity.

Seems to me that if it's leaking around the cap you are not only losing coolant but pressure as well - the pressure valve will not work under this scenario. Do as 1931 flamingo said in his #2 response above....
__________________
The only thing nice about being imperfect is the joy it brings to others....

"Silver rings, your butt! Them's washers!"
"We shot our way out of that town for a dollar's worth of steel holes!" - from 'The Wild Bunch' - 1969

https://www.youtube.com/watch?v=7NReUd2_0u0
petehoovie is offline   Reply With Quote
Old 07-20-2018, 01:39 PM   #10
J Witt
Senior Member
 
J Witt's Avatar
 
Join Date: Mar 2015
Location: Acworth GA
Posts: 534
Default Re: Leaking Radiator Cap

Steve, I have installed a Brassworks radiator my car. It fits the mounting holes and has more fin area than stock. The header tank is shaped approximately the same as stock, but doesn't have some of the small features such as stamped in ribs that are on the stock unit.


My original radiator core just got too thin to patch the fins anymore. It was springing pinholes as fast as they could be fixed and I finally got tired of taking it out of the car
__________________
Houston, Tranquility base here. The Eagle has landed.
J Witt is offline   Reply With Quote
Old 07-21-2018, 11:31 AM   #11
G.M.
Senior Member
 
Join Date: May 2010
Location: Florida and Penna.
Posts: 4,451
Default Re: Leaking Radiator Cap

Quote:
Originally Posted by J Witt View Post
I do have a pair of 165 thermostats in the outlets from the heads (59AB heads). If driven very briskly, these t'stats appear to be wide open, but of course they still have a relatively small flow area. This is in Georgia summertime 90-95 degrees. The problem may go away in the fall when it cools off some.


I have one more parade to do in a couple of weeks and it will barely stay below boiling running 1-2 mph with frequent stops. Hoping for a little cooler weather for that, or may pass it up.


As I mentioned the overflow has a pressure valve that opens at 3 psi. Coolant isn't coming out the overflow, but around the seal on the cap. Appears not to be a pressure issue, but one of high flow velocity.


I'll drop the fluid level some and test again.


Don't drop the coolant level you had it where it should be. Go to the plumbing section in the hardware store and get a sheet of the red rubber
gasket material which is about 1/8" or more thick. Drill the rivet out
of your cap with a 1/4" drill. Get a round head slotted SS 1/4-20 screw
1/2 or 5/8" long, flat washer, lock washer and nut. Cut the round gasket
to fit and install. Use a little Loctite on the screw and it won't leak. G.M.
__________________
www.fordcollector.com
G.M. is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Sponsored Links (Register now to hide all advertisements)


All times are GMT -5. The time now is 06:57 AM.