Digging around and saw this from awhile ago… https://forums.jag-lovers.com/t/v12-engine-suplamental-air-valve-hose/125832
I’m replacing my old hard EAC 4096 and was wondering if silicone vacuum hose would work or if it needed to be fuel or coolant line. Thanks!
Crap - I had no idea there was a whole forum for V12, so this question is duplicated in the V12 forum also…
I have replaced ALL my vacuum hoses with silicone vacuum hoses…lasts much longer and is better suited for heat. If it only deals with intake vacuum air, then it’s fine. The Supplemental air valve is pure intake air, mine is now silicone. It’s a big hose though, so you may not use that size anywhere else, so don’t buy too much. (Silicone hose can be expensive)
Only time I do not use silicone hose is when fuel or oil vapor will be present. There are also silicone hoses I have used for coolant and turbo intake, but they are special reinforced just for coolant and turbos.
Greg do you think silicon is ok for the distributor vent ? I just changed most of the vacuum lines to silicon.
sure, I did. Yes, some of these hoses ‘may’ see a bit of oil vapor, but very rare. If they do see a lot of oil vapor, there is something wrong.
Rubber is great, but dries and cracks with heat and age. Silicone lasts much longer and can handle heat better (and looks cooler with color choices), but becomes soft like a noodle if it sees oil vapor or other contaminants regularly.
The funny thing is that if that vacuum hose gets really soft the vacuum pressure will collapse it and cause the car’s idle to surge and drop, as the hose collapses the engine almost stalls so the hose opens back up then the vacuum goes up and the hose collapses, and so on and so on.
