1969 Rad/Heater Hose Clamps and Nipple Fittings

[MJFUR]

1969 Chrysler 440/505, everything is new, overhauled or rebuilt. I've put about 2000 miles on the car since May and now the rad/heater hoses are starting to seep/drip.

1. Noticed a few drips on the lower radiator hose coming from the water pump side. Tightened screw type band clamp, worked for about a week, clamp loose again.

2. Heater hose nipple fittings seeping, 1/2" and 5/8". These were fresh install in May. What type sealant and/or thread tape are you using?

At initial rebuild I tried using the squeeze type clamps that require pliers to install. They ended up leaking. Tore everything apart and installed screw type steel band clamps, but they are now working their way loose. Is there a Mopar Kit with correct size clamps?

Additionally, Ive seen some cars with the 5/8" nipple fitting about 6"-8" tall. Where do I get one of those? P/N # ?

Because the heater hose clamps are buried, every little leak requires a semi-big tear down to get in there and work on them. I just want to fix this correctly and be done. Thx

 

[CBODY67]

All of the clamps you have pictured worked in their respective locations when the cars were new, fwiw.

BUT there is a correct way to position the hose and the clamp on the tube the hose is attached to. I never had considered this until I ran across a Chevrolet Tech publication on such, about 20 years ago. Key thing, regardless of the clamp type is to position the clamp just under the lip on the fitting, NOT at the end of the hose. AND, from my own experiences/learning curve, always have the end location of the clamp positioned such that it can be accessed easily without any disassembly or similar.

For example, on the larger Corbin-style clamp (the thicker wire clamps) on a radiator hose fitting. As you push the hose over the lip on that fitting, you will notice a bulge where the lip is in the hose. You can push the hose on as far as you might desire, but put the Corbin clamp just as the bulge in the hose goes flat. That maximizes the "clamping area", so to speak, on the flat portion of the fitting and also on the curved area too.

Should you be using a worm-drive stainless steel band clamp, position the edge of the band on the flat portion of the hose, just after the bulge. Which will help pull the bulged area downward and also seal against the flat portion of the fitting. BUT do not put that band clamp on the bulge! Too much torque can end up cutting the hose in that area.

The flat band clamps were usually only used on fuel lines, at the fuel filter, for example. With the Corbin-style clamps being on the rearward sections of the fuel line, pre-fuel pump locations.

On my own cars, I usually use the stainless steel worm-drive clamps. If the fitting might have some pitting or roughness in the sealing area (after cleaning and such), I'll apply some high-heat black silicone sealer to the fitting, let it cure overnight, and then install the hose on top of it the next day. I ALSO position the ending position of the clamps such that I can reach them (if needed) with a long screwdriver or a socket with an extension on a 3/8" drive ratchet.

Do not over-tighten, but use enough torque to ensure a tight seal on fresh rubber hoses.

Many times, a new hose and clamp might seep a bit after the first few hot/cold engine cycles. In that case, a re-torque is needed. But past that with quality worm-drive stainless steel band clamps, I've not had any of the issues you mention. Just good practice to check new hoses/clamps anyway, until you determine they will reliably seal.

Just my experiences,
CBODY67

 

[MJFUR]

Thanks for the info, unfortunately there isn't any access to the clamps with every thing back together. Upper radiator hose covers the top access, alt belts cover the side access, metal belt guard blocks front access. So every attempt to repair is a chore.

I'm using Permatex Thread Sealant with PTFE for the fittings, is there a better product? Not sure why they are leaking after 2K miles?
https://www.autozone.com/sealants-g...68097b0191841435d0f2185386c92d65&gclsrc=3p.ds

Any P/N # for the tall 5/8" fitting?

 

[Justin Plant]

You might just replace the rusty nipples the hoses are being clamped to, there seems to be more pitting there than should be. I would wager, if you changed those your problem would be gone.

 

[Big_John]

Any P/N # for the tall 5/8" fitting?

MOPAR 1960-69 Big Block Heater Hose Tip Set BB Nipple Nipples 383 440 426 HEMI | eBay

 

[Big_John]

Some of those gold Corbin clamps in the foreground look like they've been over stretched during installation or removal. Once they lose that tension, they won't seal.

You would be better using a smaller clamp that's closer in the correct diameter. When you get into the smaller hose and corresponding clamps, the clamps get a little narrower. The narrower clamps will squeeze the hose just a little more and help prevent leaks. They'll also conform to the outside diameter of the hose better. Then there's quality... The Ideal (trade name) are a little harder to find, but they are better than most of the offshore cheap clamps that you can buy in bulk for pennies. I tend to use brand new clamps, sized correctly, when I change hoses. Tighten properly, but not so tight it bites into the hose. Be sure the clamp falls into the recessed area on the pipe nipple for best results.

One other thing I haven't seen addressed and that is to verify you are using the correct size heater hoses. One thing I often see on old cars is a heater hose that's too big and just squeezed down to the correct size.

 

[MJFUR]

MOPAR 1960-69 Big Block Heater Hose Tip Set BB Nipple Nipples 383 440 426 HEMI | eBay

Hi, Thx, but that isn't the Tall 5/8's. The Tall one is more like 6" or so, it actually looks kind of out of place on the car.