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1937 Cadillac fluid through the overflow

Started by VooDoo, March 11, 2023, 07:55:38 PM

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VooDoo

I just had my 1937 radiator recored. And have a new RC four radiator cap. My issue is I am continually losing fluid out of the overflow. Even when the fluid is at a correct level after driving for sometime when parked, I notice a puddle coming from the overflow. I recently pulled out the shutter thermostat section because I have been starting to overheat and wanted to check and replace the thermostat. Apparently that's not where it's at? At any rate, there was no fluid in that top container portion, and it was filled up correctly prior to my 30 minute drive. I'm wondering if maybe my new cap is not sealing correctly allowing pressure to build up an escape? Somebody suggested maybe increasing the To a 7 pound pressure cap might help?
Andy Fulenwider
1937 75 Series Convertible
1947 62 Series Custom Project

VooDoo

Also, when I put in my radiator cap, I don't actually have to to push it down very much for it to get in there and turn so maybe it's just not sealing correctly?
Andy Fulenwider
1937 75 Series Convertible
1947 62 Series Custom Project

Ohjai

VooDoo I  got my 38 6019S back from an engine overhaul.  Coolant was coming out of the overflow and I hunted all over for the proper cap. Did not find one.  What I did was put a fat o-ring in the neck, then a thin aluminum washer over that.  The 4# cap now seals and coolant does not flow out the overflow.

Jim
'38 Cadillac Series 60 S
'41 Cadillac Series 60 S
2017 Cadillac CT6
'62 Buick Skyhawk Conv
'49 Bentley MK-VI  Sold
'53 Bentley R-Type  Sold
'66 Ford Thunderbird
'64 Rolls-Royce Silver Cloud III
'75 Rolls-Royce Silver Shad Sold
'78 Rolls-Royce Silver Shad II
'80 Rolls-Royce Silver Wraith II  Sold
'81 Rolls-Royce Camargue  Sold
'88 Rolls-Royce Corniche II
'89 Rolls-Royce Silver Spur
2020 Ford Escape

VooDoo

Quote from: Ohjai on March 11, 2023, 10:01:58 PMVooDoo I  got my 38 6019S back from an engine overhaul.  Coolant was coming out of the overflow and I hunted all over for the proper cap. Did not find one.  What I did was put a fat o-ring in the neck, then a thin aluminum washer over that.  The 4# cap now seals and coolant does not flow out the overflow.

Jim

Something like this? Or should the opening of the washer be bigger?
Andy Fulenwider
1937 75 Series Convertible
1947 62 Series Custom Project

VooDoo

I put the washer in there just to check it out and it does make a difference when putting it in. It actually feels like it's sealing to something. But I still need a O ring between the filler neck and the added washer?
Andy Fulenwider
1937 75 Series Convertible
1947 62 Series Custom Project

VooDoo

This particular washer is not aluminum though, so it might rust
Andy Fulenwider
1937 75 Series Convertible
1947 62 Series Custom Project

VooDoo

I was able to modify what amounts to be an 1/8th inch rubber washer to fit inside the filler neck on the little flange and now the capSecurely fits. I'm planning on driving it tomorrow so I'll let you guys know the prognosis. Thanks again.
Andy Fulenwider
1937 75 Series Convertible
1947 62 Series Custom Project

harry s

Sounds like the plunger of the cap is not long enough to reach the lip of the radiator filler neck. I had the same problem with my '37 & '41. It is almost impossible to find the proper Delco cap. NAPA has a 7# cap with a longer plunger that works. The part number is 703-1411.     Harry
Harry Scott 4195
1941 6733
1948 6267X
2011 DTS Platinum

VooDoo

Quote from: harry s on March 12, 2023, 12:13:56 PMSounds like the plunger of the cap is not long enough to reach the lip of the radiator filler neck. I had the same problem with my '37 & '41. It is almost impossible to find the proper Delco cap. NAPA has a 7# cap with a longer plunger that works. The part number is 703-1411.     Harry

Any issue with added pounds per pressure with a 7lbcap? I believe originally called for a 4lb cap.
Andy Fulenwider
1937 75 Series Convertible
1947 62 Series Custom Project

VooDoo

Gasket seem to work. Didn't lose fluid out of the radiator overflow. Hopefully that solves the issue. I drove it for about 30 minutes on the freeway today going about 55 to 60 mph. And didn't lose any fluid out of the overflow.
Andy Fulenwider
1937 75 Series Convertible
1947 62 Series Custom Project

harry s

Glad the gasket worked. To answer your question about the higher pressure cap, I never had a problem with it.     Harry
Harry Scott 4195
1941 6733
1948 6267X
2011 DTS Platinum

DaveZ

The radiator cap needs to be the correct one. If they used the original neck you need to find the correct cap which was a bit deeper and had a seal on the end of it that seals up against the seat in the neck. I believe they were also 4pd caps. I will see if I can find the number and post later. If there is not a sufficient seal it will go out the overflow.
Regards,
David Zitzmann
1932 345B

VooDoo

Quote from: DaveZ on March 14, 2023, 02:55:03 PMThe radiator cap needs to be the correct one. If they used the original neck you need to find the correct cap which was a bit deeper and had a seal on the end of it that seals up against the seat in the neck. I believe they were also 4pd caps. I will see if I can find the number and post later. If there is not a sufficient seal it will go out the overflow.

 I did purchase what it called out to be original RC 4 cap but seems it's about an 1/8 short
Andy Fulenwider
1937 75 Series Convertible
1947 62 Series Custom Project

DaveZ

Let me go see if i can find the darn thing:-) Anyway that is your problem.
Regards,
David Zitzmann
1932 345B

DaveZ

Can't find it so I must have given it to someone. Looking at your picture it doesn't like like the right one. Let me ask they chap that has a 37 if he can get the AC part number.
Regards,
David Zitzmann
1932 345B

harvey b

be careful as to how high the level is,there should be a small plate about an inch from the top with a small hole in it,only fill to the top of it,if it is too full it will oveflow.On my 37 it will overflow if too full.I was able to get the right cap from Coopers in california,but i think he is closed,havent seen anything from them in a while. harveyb
Harvey Bowness

DaveZ

Quote from: DaveZ on March 14, 2023, 03:19:03 PMLet me go see if i can find the darn thing:-) Anyway that is your problem.

I asked and he didn't have it:-(
Regards,
David Zitzmann
1932 345B