joe shelton (Littlewind) (67.241.230.120)
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Votes: 0 (Vote!) | | Posted on Wednesday, May 29, 2002 - 1:12 am: | |
I talked to a tech at Vehicle Systems today about my Webasto installation. Here is some of the info he gave me. (Vehicle Systems sells the most Webastos in the U.S.A.)
COOLANT HOSE: He described 3 types; Rubber hose, Silicon hose, & Blue stripe hose. Rubber hose was used up into the 70s. Silicon came out when higher temps were generated as a result of emission control. Problems with silicon hose= 1) water permeates out of hose resulting in higher % of glycol in coolant. This is why a silicon hose may feel/look slick. 2) hose puts off odor. 3) hose is susceptible to Electro Chemical Degeneration (ECD).
ECD may not be a big issue for bus applications but here is how I understand it. Dissimilar metals in the coolant path (i.e. alum head & cast iron block) may act as a cathode & anode with the coolant as the electrolyte creating .25 to .3 volts. Carbon tracks that accumulate on the I.D. of silicon hose result in internal cracks and eventual failure.
Blue stripe hose (SAE-J20R1) is not suseptable to ECD, dose not permeate water, and puts off no odor.
HOSE CLAMPS: The hose clamps in my bus are typical and there are doubles in some locations. Last winter I had some leaks and tightened the effected clamps thinking I would need to replace those hoses in the spring. Now I'm told the hose contracts in cold temps resulting in a drip-leak. There is a new clamp on the market that increases it's clamping action as the temp goes down. They probably cost too much but are made by Gates and are called Power Grip Clamps. |