93 K75S - One-time hose clamps

[ghyber]

I want to check the vacuum integrity of my cooling system water hose from the filler cap to the expansion tank. The water hose linking the coolant filler cap assembly (BMW calls it the container) with the expansion tank (the reservoir behind your right leg) is secured via one-time hose 10mm - 12.3mm clamps crimped by a special tool. The tool costs $35 in Canada.

Are one-time hose clamps preferred for small hose diameters? The hose clamp connection from the fuel tank to the fuel injection pipe is only 13mm and it is of the worm drive type on my bike. Maybe one-time hose connectors are less practical for connections requiring regular removal for scheduled maintenance as in the case of the fuel tank?

So, why does BMW use one-time hose clamps versus worm drive type reuseable clamps on certain connections and not on others?

Can I replace these with worm drive type clamps?

 

[hhshort]

no hose clamps

I use 5/16 (13mm) fuel hose in that application and no need for clamps Harold in Kansas

 

[98lee]

So, why does BMW use one-time hose clamps versus worm drive type reuseable clamps on certain connections and not on others?

Can I replace these with worm drive type clamps?

Cheaper and quicker to install at the factory.

Yes.

 

[98lee]

I use 5/16 (13mm) fuel hose in that application and no need for clamps Harold in Kansas

If you ever have that hose blow off on a very hot day at a stop sign (I've seen it happen on cars) you'll wish you'd put a clamp on it. Might never happen, but it could.

 

[42906]

The hose clamps use a simple CV boot plier to crimp. Any auto parts store has the tool. It is a reliable way to achieve a consistent and accurate clamping pressure. Home mechanics too often over tighten things (who, me ?)

 

[98lee]

The hose clamps use a simple CV boot plier to crimp. Any auto parts store has the tool. It is a reliable way to achieve a consistent and accurate clamping pressure. Home mechanics too often over tighten things (who, me ?)

Exactly


I use these. Works perfect. http://www.summitracing.com/parts/WMR-W83013/

 

[deilenberger]

If you ever have that hose blow off on a very hot day at a stop sign (I've seen it happen on cars) you'll wish you'd put a clamp on it. Might never happen, but it could.

Lee - won't happen on that hose. It's not under any pressure. A tie-wrap works just fine for that one..

 

[98lee]

Don,

What is the pressure of the cooling system? When that gets released by the cap, it is under pressure isn't it?

 

[ghyber]

I suspect there is a little pressure for sure. I would also expect the turbulent air in the area of the expansion tank to splash and spray the rider with hot coolant.

 

[deilenberger]

Don,

What is the pressure of the cooling system? When that gets released by the cap, it is under pressure isn't it?

NO pressure. The reservoir is vented.

In order to have pressure on that hose the reservoir would have to be sealed (and it wouldn't return fluid to the radiator if it was sealed..) That's also why coolant can go down the hose, and never be sucked back up if there is a small crack in the hose near the top neck fitting.

There is pressure behind the radiator cap, but the overflow hose is on the other side - vented nicely to atmosphere by the vent in the reservoir. The only possible pressure (and I somehow doubt if you could measure it) would be from the weight of the coolant in the overflow reservoir.

Had a tie-wrap on the K75S for many years, AFAIK, it's still there (a friend now owns the bike.) And it just looks nice and tidy (use a black one, and put the fastener toward the inside of the bike..)

 

[98lee]

As long as the radiator cap only vents at a volume less than the flow of the pinhole sized vent hole on the cap of the overflow tank, I would agree with you, but I believe the cap is capable of venting a much higher rate than the flow of that pinhole. I have heard of several occasions of the rubber cap being blown off off the overflow bottle on bikes that had their fan malfunction. If the hose was not clamped and the hose was not a very tight fit, it would give a less desirable path for coolant to exit.

Very low chance of happening, but possible. My suggestion is to clamp it. Others may do as they wish.

 

[lkchris]

So, why does BMW use one-time hose clamps versus worm drive type reuseable clamps on certain connections and not on others?

Because with what you call "one-time" hose clamps the tightness of the clamp is guaranteed at the designed value, whereas use of a worm-type almost always comes nowhere close and zero/zip/nada can be specified let alone guaranteed.

This assumes installation using the proper pliers, of course, a problem greatly eliminated by CLIC clamps, which BMW doesn't use.

Another thing guaranteeing proper installation is the the requirement that removed clamps always be replaced with new ones. Nice fresh metal, that is.

Clearly specified tightness is not always required, hence some uses of screw-type clamps.

There's a whole world of automotive knowledge out there that supercedes the Model T and high school shop.