[urq] Vacuum supplyurq urq at pacbell.net
Mon Nov 24 21:05:57 PST 2008
Yes, I see that now too . thanks for the reference to IST Dennis! BTW, the 4kQ Bentley has the information you would need to go to the system that allows locking center or both diffs . I did this to my car YEARS ago. I have to say that now that I know the diff lock is plumbed this way, I'd recommend changing it. If a leak develops in the diff lock system it will cause flow in the lines going to the boost gauge and ECU under vacuum . and under boost should the check valve fail. This means that the ECU's manifold pressure and boost gauge readings will be incorrect. The line coming from the tap on the back of the IM should go to the ECU and the boost gauge. Tee the check valve for the diff lock circuit in to one of the other lines coming from the intake manifold. I'll have to add this to the list of things I need to do when I work the MAC-14 into my car . BTW, there's no need to scan and distribute the IST pages . Martin has them available on his website. I have a link to Martin's website (and many others) on the urquattro yahoo group page: http://autos.groups.yahoo.com/group/urquattro/links Steve B San Jose, CA (USA) -----Original Message----- The IST document showing the vacuum hose diagram shows 1 IM tree hose leading to the ECU that is tee'd to the diff locks and boost gauge. This is white on my car. Another hose from the manifold tree has a check valve (at the firewall I believe) and is then tee'd to the A/C Control and the vacuum reservoir (green). There is a check valve at the console connection for the diff actuator to prevent boost from "unlocking" the diffs. This diagram has been very helpful to me over the years. I can try to scan it if there is interest, and it wouldn't violate copyright. HTH Dennis Graber -----Original Message----- The ECU and boost gauge need actual manifold pressure with as little delay as possible. The diff locks on the other hand are looking to use vacuum as a power source ... and so are connected to a reservoir. Sorry for the long answer to your question, but I thought I'd explain why the answer to your question is no. ISTR the vacuum source for the diff locks on my '83 comes up from under the carpet on the transmission tunnel. On my car there is a vacuum operated recirculation valve for when the AC is on ... if your car is similar you can tee your supply line in there. Steve B -----Original Message----- I got everything for my diff panel swap hooked up. But, I ran a new hose for the boost gauge and left the old one disconnected at both ends. Does the diff lock switch use the factory boost gauge hose for its vacuum source?
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