Rad hose blows off

9

91A-77B

Senior Member
I installed a new aluminum rad in my 37 with 284 cid blown 59A. When I first fired it up, the driver's side upper rad hose attached to Navarro head outlet (without sealant) blew off after a few minutes. I got scalded with deionized water I'm using for coolant. I then coated inside of hose part that attaches to the head and placed a weight over it so it wouldn't try to walk up & off, and left it for about 16 hours. I then put the hose clamp on, and tightened it. Started the engine, it lasted about 5 minutes, blew off and got me again.
I realized afterwards, I hadn't remembered to put a thermostat in that outlet, but had, in the passenger side, which hasn't blown. Is my problem that simple, or is it the taper of the outlet that's allowing the hose to walk up & out? My idea is to drill & tap holes in head neck at 4 & 8 o'clock, then run screws through hose to hold it in place.
A buddy suggests grinding a negative taper in the neck, and/or using JB Weld for radiators as sealant. We both agreed that throwing the problem out to The Barners would also be a good idea. What do you think? Anyone else ever have this problem?
I don't want to get scalded again, and I want my iron on the road!
Thanks, guys
 
Try two hose clamps separately slightly. I use constant tension hose clamps for some connections. With this type you may be able to use just one.

"Full contact radiator hose clamps, also known as constant tension or spring-loaded clamps, are designed to apply uniform pressure around the entire circumference of the hose, unlike worm-drive clamps which exert uneven pressure. They are widely considered superior for modern vehicles because they self-adjust to thermal expansion and contraction, preventing leaks and avoiding damage to plastic radiator fittings that can occur with screw-type clamps."

589690
 
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Is the hose blowing off the head or the radiator?
I had a similar problem with 59A style Navarro head. But only on one side. The neck was too big and oval, and slightly tapered. I filed it to make it a little better but ended up using silicone hose as it stretches easier. I've never had a hose blow off. 4 pound cap.
 
I think there is an underlying problem. The neck is undersize or tapered.
I have never had a problem fitting rubber radiator hoses. If the receiving surface is clean, perhaps hot water with a little dish detergent in it. I've never had a radiator hose come off.
Getting them off can be difficult!
I'm also a Shellac user, the brand I've used is Heldite.
Any oil or oil based products act as a solvent on rubber designed for hot water.
Also you can't use rubber hoses that are purposed for oil on hot water systems, they will dry out and crack.
 
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There obviously is a physical mismatch (the other side doesn't blow of). In my world, we find out what it is and fix it.

"Indian Head" shellac is a good product, but probably not the ultimate solution in this case.
 
I would be tempted to file some grooves around the neck to give the hose something to grip on.
 
Thanks again, guys. I'm going to insert thermostat, use rad hose gasket sealant, use same clamp as before, and fire it up. My thought is, the upward water pressure will be greatly reduced with the addition of the thermostat, and may prevent hose from blowing off again.
Theory being, try the simplest solution first, then more difficult ones if that fails. I'll report results.
 
Thanks again, guys. I'm going to insert thermostat, use rad hose gasket sealant, use same clamp as before, and fire it up. My thought is, the upward water pressure will be greatly reduced with the addition of the thermostat, and may prevent hose from blowing off again.
Theory being, try the simplest solution first, then more difficult ones if that fails. I'll report results.
 
Regular hose clamps bite where the worm tightening holes are. Use two rotated 180 degrees apart. The constant tension types have a smooth SS liner around the whole circumference
 
Mart said:
I would be tempted to file some grooves around the neck to give the hose something to grip on.
Click to expand...


You could also "dimple" the outside surface circumference of the thermostat housing with a center punch to give the hose something to "bite" into when you tighten the clamps. I use that technique on my water pump hoses. Notice, I use 2 hose clamps on the water pump inlet hose and 1 clamp of the custom made lower hose. This has been on the car for 30 years.

I did not have to "dimple" the radiator hose inlets on the heads. Just used 4 clamps.
Not running thermostats.

The aluminum coil bracket on left side of photoois homemade and held in place by the water pump bolt.
 

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19Fordy said:
You could also "dimple" the outside surface circumference of the thermostat housing with a center punch to give the hose something to "bite" into when you tighten the clamps. I use that technique on my water pump hoses. Notice, I use 2 hose clamps on the water pump inlet hose and 1 clamp of the custom made lower hose. This has been on the car for 30 years.

I did not have to "dimple" the radiator hose inlets on the heads. Just used 4 clamps.
Not running thermostats.

The aluminum coil bracket on left side of photoois homemade and held in place by the water pump bolt.
Click to expand...
589837
 
Well, inserting thermostat didn't work. Hose blew off again. Question: rad cap is stamped 1.3. Is this metric for pressure rating? What is this in pounds? Thinking cap has too much. I'm also change clamps to constant-pressure type. More to follow.
Thanks again.
 
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