So I am tracking down a vacuum leak on my '99 cab and figured I might as well replace the existing 15 year old lines while everything is apart. They are a combination of hard plastic and flexible hoses.

Does anyone happen to know the right size of hose to use (ID/OD)? Also is there any reason not to replace the hard plastic hoses with flexible material? I'm planning on going non-OEM on this one unless there is a really good reason to do otherwise.

Many thanks in advance.

 

I've done that exact thing on many past cars, I typically just measure a few of the fittings for ID then grab some bulk hose from the local auto parts store. A cheap and small caliper comes in handy here for measuring, and most stores stock in standard not metric sizes so measure accordingly. 951 ownership made me paranoid about vacuum leaks, so I also replace barbed tees with brass and zip tie all connections. Vacuum hoses are nothing exotic, it's easy to find what you need locally.

 

Pelican Parts - search for silicone vacuum hose. They have a good selection, black, white, red and blue in the 3.5 mm ID/7.5 mm OD.

 

We offer a good assortment of vac hose, by Contitech, which you may view here. Also, our steps to finding vacuum leaks may be of interest, Finding Vacuum Leaks on the Porsche 911 Carrera.

Hope that helps.
Mark/Pelican Parts

 

If memory serves me correctly the OEMs are 3mm and the aftermarkets are 5/32". I bought mine self-serve & by-the-foot at Pep Boys. The vent hose for the PS pump is 7/32".

 

Thanks guys. Very helpful.