stevep2000

I've got a problem with no vacuum to my heating system / HCV etc. Found diagrams posted previously, but seems to be different on an S2, e.g. the vac is taken from the manifold rather than the Brake booster? In particular, have the check valve between the after the FPR / Damper and before feeding in to the HVAC in the cabin, but on diagrams this seems to be earlier in the system, at the brake booster end - anyone help please?

joes

I'm not sure if or how the S2 is different than eairlier cars but the principals are the same. There is a vacuum storage canister and a check valve to hold that vacuum under low manifold pressure (WOT) conditions.There is, at the fire wall a vacuum "in" port and a heater control valve "out " port. Get a vacuum gauge and check if you have a vacuum source in (from somewhere) if you don't, try to find a broken line from the manifold. If you have vacuum "in" OK you probably have a leak or a bad diaphragm under the dash that is causing vacuum loss.

krahmlow

I've got an "S," so I can't just look at my car, but looking at the manual, there shouldn't be any difference between the 16V engines, as far as vacuum line routing goes (the fig. is labeled "'16-Valve engines, 87 Models Onward"). According to Clark's, the vacuum line routing for the climate control stuff is similar for all 944s. It sounds like someone got creative when replacing your lines at some point. Maybe he was running short of tubing. That line from the brake booster to the firewall is a long one. If you have the connector coming off the brake booster, then that's where the line should go. If it's open to the air, then you've got a very large vacuum leak. Having said that, if the line is coming off the manifold, then you should be getting vacuum. Is your check valve installed the wrong way around?

jgporsche

i was about to make te same point.....