Join Date: Sep 2007
Although correct clamps are preferred it actually isn't essential. The leak resistance is provided by the liner compound, the burst strength is provided by fibre reinforcement (as for tires) and the external cover is well up to withstanding a bit of penetration by screw type clamps. Remember that the portion of the hose under the clamp is not subject to any line pressure unless the clamp backs off. In that event the pressure leaks out the open end of the hose rather than inducing a rupture in the hose itself.
I do recommend double clamping the hoses though. Until I did that mine seeped fuel chronically. Not enough to wet the hoses but enough to create that unpleasant aroma. The seepage occurred when the engine was very cold and stopped as the coolant heated up.
Correct clamps equalize the pressure around the hard pipe. Worm types have to be overtightened to ensure enough pressure is exerted all around the hard pipe. Double clamping with one clamp offset from the other helps with this deficiency of worm type clamps.
Those worm type clamps are really useless for any automotive function involving restraint of pressure. Euro style spring clips are preferred, if you have the nifty instal/removal tool. Otherwise the pad type band clamps pictured in the link are definitely preferred for sealing pressurized connections, if you have them to hand.
Here's a good explanation of the three common types of high pressure fuel hose clamps in common use. You can see the worm drive is the least desirable. I have them on my car!
1991 Alfa Romeo 164L 5 spd
White on grey leather 230K km, owned from new
Last edited by Michael Smith; 11-22-2017 at 02:33 PM.