chip_962

If you are the proud owner of a late 964 please help. I am updating the throttle assembly on my 1990 and have no model for comparison.

SOS! Please help with photos if possible.

I want to know how the factory routed the vacuum line off the throttle body and the routing of the fuel recovery line just behind the throttle springs.


The early inductions have a vacuum "y" right at the throttle. The later ones have a single vacuum line that disappears somewhere and then has to split for the fuel regulator and another vacuum valve, I believe. Where is the split? Where does it go first?

The fuel recovery hose is also different in late 964's in how it mates to the resonance housing. Reusing the 1990 hose makes clearance problems for the throttle lever.

Photos of the first couple legs of each system, denoted by arrows, would be greatly appreciated. PET CD is useless for this. Even Adrian's book misses these images.

JasonAndreas

I've tried to make the arrows point to both ends of a connection. There is no Y-junction coming off the throttle body, just a straight connection to the check valve (blue arrow). Using images from Adrian's book and PET you can piece together the vacuum lines and where they are supposed to go. If you need me to color code/tint the actual vacuum lines (which would probably be a lot more intuitive than arrows) just ask.

Red Arrow: upper intake manifold cross-over tube to fuel pressure regulator.

Green arrow: T-Junction from vacuum solenoid(1) to vacuum canister attached to air filter housing.

Blue Arrow: Throttle body housing to check valve

Purple Arrow: Vacuum solenoid(1) on upper intake manifold crossover to resonance valve.

Yellow Arrow: Vacuum solenoid(2) to check valve

chip_962

Jason, You have gone above and beyond the call...

Thank you very much; This is a huge asset to the community. The microfiche does not show the difference between the early and late cars in terms of vacuum lines. Adrian's book does not have the detail.

I will have to see if the fiche has a separate page for the fuel vapor recovery line which I circled. This is the only remaining mystery--the first eight inches. My hunch is that the first 8 inches and the first adaptor at that point is different. The 1990 line is larger than the nipple on the resonance assembly. You can see a bracket on your photo, which is also unique, that fends the line away from the throttle springs. I circled the mystery in white.
https://rennlist.com/forums/attachme...id=39584&stc=1

chip_962

Oops, that which is circled in white may actually be an extra oil breather hose. The late cars may have one piece all the way to the firewall. My 1990 has two-- one short run off the resonance housing into a stepped jag then a longer one to the firewall.

JasonAndreas

The hose you have circled in white has two 90 degree bends and then heads for the oil tank. In the following photo there is a red arrow pointing to it, the hose at the bottom of the image.

JasonAndreas

Here is a closeup of the bracket and oil breather hose attached to the upper intake manifold cross-over, routed around the throttle cable. If you have cruise control (i don't) there is an additional support bracket that you'll probably need, #964-110-219-02. The bracket in the photo below is #964-110-229-00 and the two M5 x 10 screws are #N-014-129-12. I think the breather hose itself changed for MY91, the original part was #964-207-315-00 and for MY91+ it is #964-207-316-00. The newer version doesn't use any clamps or adapters and is just one piece.

chip_962

Many thanks Jason! In 1990 the oilbreather is segmented with a small 10 " section that increases in diameter to mate to the cast throttle housing. I will probably find a male-to-male jag and a piece of similar hose and replace the 1990 part with hose of the 1991 caliber. This will be less troublesome then running the solid piece to the oil tank as in 1991. I really appreciate the help. Currently putting the hole thing back together Do you by chance know the torque specs on the crankcase breather and temp sender housings? I hate running to the library to use the fiche readers!!

Goughary

Since its 1 degree at the moment in lovely sunny chicago - with wind chill in the -20 range - I'm sitting here looking into vacuum system refresh for the 964...

Came across this old thread as well as many others -


Anyone want to chime in on typical vacuum leak culprits and places to look to refurb?