I have this persistent problem with one of my power valves blowing exhaust past the seals and up into the cable and out through the servo,been doing it for a few years now.I've changed the seal in the power valve tower to no avail and I'm still not sure what's causing this.There is a funny looking wear pattern around the upper part of one of the valves,not gouged or scratched it just looks like the valve was stuck against the seal at some point but surely the rubber seal would not wear a low spot into an aluminum valve would it?
I'm kind of stumped here,what I think I will do is change the valves around and see if the blow by changes to another cable.
I'm kind of stumped here,what I think I will do is change the valves around and see if the blow by changes to another cable.
fourbarrel said:
According to some chemist/meterial handling friends, natural rubber is white so most black rubber has other fillers (i.e. taulk, carbon black) so it is possible for a black rubber seal to wear away aluminum even if it's anodized.
I've seen this first hand with black vinyl vapor line (which got me thinking to ask some experts). The vapor line ran across an AC evap core inlet tube and wore a hole into the aluminum tube. At the time I was told the vinyl vapor line consisted of maybe 2-5% carbon black and was enough to make it hard enough to abrade the aluminum.
Talking with the experts this morning, most black colored rubber has considerably more carbon than 2-5% so I asked them flat out about your concern and they agreed that it is very possible.
What does adding carbon do to steel?
Can you feel the percieved low spot with a thumb nail?
Also, I've seen rear main kits that come with a sleave that fits over the seal surface to avoid replacing the crankskaft due to the seal wearing a groove. Granted the seal wear takes a long time but perhaps the seal in this application has less carbon.
If you can feel a low spot I'd guess that's your problem. Maybe take a set of calipers to it to confirm.
If you can feel a low spot I'd guess that's your problem. Maybe take a set of calipers to it to confirm.