How do you know when a wire hose clamp is tight?

[TJ Hopland]

The subject I think says it all.   I'm talking about the wire and screw type of hose clamps that I believe were OE on things like radiator hoses in the 70's (and likely other years too).    Unlike the worm drive ones these never really seem to tighten up as far as torque on the screw goes.   On this last project I just went a couple turns past where I could not wiggle the hose anymore and it seems to be working but not sure if that is correct or not. 

[Jon S]

If it's a new hose, make it good and snug - no hose wiggle allowed.  After a good drive and cool down, probably a 1/2 to full turn of the screw for good luck.  You don't want to over-tighten them as they can destroy the hose.

[Dr. John T. Welch]

The answer is: you don't!!

Over time the elasticity  of the hose polymer changes, and  hose material under the clamp compresses .  These combine to reduce the effective clamping force of a clamp.  It's a crap shoot as to  whether and for how long a seal remains after  initial installation torque  is applied to a clamp.  These clamps were used when necks and nipples were new and not contaminated and pitted from decades of use and exposure to water and coolants. Dirty little secret:  the OEM  spec composition for radiator and heater hose contains a  very thin ID layer of heat activated vinyl that bonds to  smooth new necks and nipples in a way that replacement aftermarket hose does not and never will. This is why wire and worm clamps seemed to work well for new cars but can be troublesome years later when performing hose replacement.

Modern coolants do not tolerate any exposure to oxygen and degrade quickly when this happens.  (Hello orange Dexcool!)  To be effective over their long lives, today's cooling systems must remain anerobic beneath the pressure cap. No leaks are allowed over the life of the powertrain and emissions warranty. To help insure this, we now have OEM universal use of the constant force spring  ring clamp design by Mubea, Rotor Clip and others. Why use anything else?

Beware: judges deduct points for progress.

     

[TJ Hopland]

So aftermarket figured with the corroded necks it was not worth the extra expense to the vinyl thing?   I suppose without it you buy more hoses too since the hose gets blamed before the necks do?