Radiator hoses; how tight is too tight?

[Dave R.]

This may seem like a stupid question but, how do you know when you've tightened your hose clamps enough? I recently changed the anti-freeze in my '69 Corvette and changed all of the hoses while I was at it. Just last week I noticed that I had anti-freeze dripping from my lower radiator hose after stopping the car during a drive.
I quickly returned the car home and tried to see where the fluid was coming from; the car had never leaked anything prior to the anti-freeze flush and hose change.
Feeling around the lower radiator flange it seems like there is a small flat in it and I think that this is where the fluid is seeping by. Is it possible that I tightened the hose clamp too much and caused the lower radiator flange to start to crumple?
What are the suggestions for fixing this and how do I prevent it from happening in the future?

[Patrick H.]

Re: Radiator hoses; how tight is too tight?

Dave,

Does your car have a cooper/brass radiator in it?
If so, the lower outlet has a built-in flat spot so that it won't hit the front stabilizer bar.

I would suggest that you actually might not have tightened the hose enough at this point. I often find that with a heat cycle or two I need to re-tighten my hose clamps after installing a new hose.

See the picture below (borrowed from DeWitt's) that shows the kink in the lower outlet.

Patrick

[Dave R.]

Re: Radiator hoses; how tight is too tight?

Whew, that makes me feel a little better since that looks like the same dimple that I am feeling on my radiator. I am concerned about the leaking though since it's not just a little drip; I have a puddle under the car when I stop and turn the engine off.
Should I drain the coolant and put some sort of sealer on the flange or sand the flange for better sealing? Did I make a mistake when I sprayed the flange with WD-40 so I could get the hose to slip all the way onto the radiator?

[Terry M.]

Re: Radiator hoses; how tight is too tight?

There is a drawing in the front of the Assembly Instruction Manual (AIM) on how to install clamps on hoses. I'll try words, but a drawing would make all the difference.

There is a raised bead on the radiator outlet. The clamp should be installed next to that bead, so that if the hose were pulled off the bead would prevent the clamp from sliding off with the hose.

I believe there is a torque specification for the clamp in the AIM, although the chances of getting a torque wrench in there are slim.

I use silicone grease on hoses, and have had no issues. One of the old-timers I learned from used gasket sealant -- the old Indian stuff -- to essentially glue the hoses on. I prefer to think that some day I will be removing the hoses, so I prefer the silicone.

BTW: Which style of clamp -- tower or worm type? Early or late 1969?

The theory is that the tower type clamp will provide more even clamping force around the circumference of the hose. If using the worm type clamp, a small amount of silicone grease on the inside of the clamp will promote more even clamping. Without lubricant the worm clamp binds on the rubber of the hose and fails to provide clamping force all around the hose.

[Dave R.]

Re: Radiator hoses; how tight is too tight?

I bought reproduction tower clamps for the car along with the reproduction hoses. I will have to look at my AIM when I get home; hopefully it's a simple matter of adjusting the clamps or hose position.
As far as how tight to make the clamps would it be safe to say that it's doubtful that I could tighten them too much if using a nut driver on the clamp?

[Duke W.]

Re: Radiator hoses; how tight is too tight?

I recommend using the THIN (and I emphasize THIN) film of silicone grease. This will allow the hose to slip easily over the nipple and also make hose removal easier when that day arrives.

WD-40 has a petroleum distallate carrier, which may attack polymer hose materials, and I'm not sure about the active ingrediant - whether or not it will attack hose materials.

Silicone grease will not attack polymer hose materials.

Also the clamp should be positioned right at the base of the "upset" on the nipple.

Duke

[John H.]

Re: Radiator hoses; how tight is too tight?

You'll know if you over-tighten the repro tower clamps - either the screw will break, or the clamp will come apart.

[Terry M.]

[John H.]

Re: Radiator hoses; how tight is too tight?

I'm original owner of a 1972. I had a leak years ago and it was fixed by
tightening the clamp a little more.
On a slightly different note I tried to catch my overflow with a plastic
drink bottle. BIG MISTAKE. One thing lead to another, the final result was
a law suit and a burnt up interior. 2003-2005
1.Bottle was duct taped completely sealed, pressure built up and caused
heater core to leak.
2.Core was replaced at Corvette shop. First core tube was completely bent
loose by shop upon installation, they tried 2 others and said cores had
pin hole leaks. I supplied core no.1 from Paragon. Since have letters
from Paragon with no previous problems. I believe Paragon.
3. Core no.4 finally installed by shop. They called me to tell me my
car's interior caught on fire. Shop claimed my radio shorted out.
After my collector's insurance viewed car, I brought the car home.
Shop refused to have his insurance look at car. completely stoned walled
me.
4.After my insurance settled with me, I filed a small claims in civil
court aganist the shop. I had started to disassemble the burnt duct work
under the dash and discovered that the pilot bolt for the core assembly
had pinched a hot 20 amp orange wire on the firewall. This wire grounded
out to the temperature control cables and toasted the wiring under the
console and radio. I hired a insurance adjuster to testify as my expert
on car fires, however at the pre-trial hearing with judge it was discovered
that my expert adjuster had NO fire investigation experience. He wouldn't
be able to testify. Luckly the shop's lawyer offered a settlement and we
split the baby.
5. The bottle is gone...gone...gone.
6. I learned a lot about the good and bad people that make up our hobby.