Namely - on a PD TDI, what generates the vacuum that all the valves (N18/N75/N239) rely on to operate ?
Is it the tandem fuel pump ?
Is it the tandem fuel pump ?
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Another vacuum system question...
- Thread starter muddyboots
- Start date
Ta !
Al -> 'Spose I should read a bit more closely
Actually that diagram is seriously useful, have just printed it out and am trying to work it all out. There's masses of joints & long pipe runs, so many opportunities for leaks !
Al -> 'Spose I should read a bit more closely
Actually that diagram is seriously useful, have just printed it out and am trying to work it all out. There's masses of joints & long pipe runs, so many opportunities for leaks !
The vac system is driven off the air pump for the brake servo.
At the rear of the motor, near the driver's side bulkhead, you can see the large-diameter tube that goes into the bulkhead for the brake servo.
On mine, the vac line for the EGR and VNT branches off this large tube, goes up to a t-piece. One end of the t-piece points to the N18, the other end goes to a small cylindrical (black & white) check valve which (I think) only allows flow one-way -- i.e. toward the pump. Then it goes onto the VNT actuator and the anti-shudder solenoid, and tees into the airbox too.
I've suspected that the check valve could leak where the black and white halves meet, so I wrapped it round with a layer of insulating tape to make sure.
I did a 2-stage treatment on all the vac connections that I could get at -- first a tiny drop of "seek & seal" silicon sealant on each joint, which you can get from Halfords. It's a thin liquid which never sets, stays tacky so it finds & seals any leaks. Then a couple of turns of plumbers PTFE tape on each joint.
Anal retentive? Me?
At the rear of the motor, near the driver's side bulkhead, you can see the large-diameter tube that goes into the bulkhead for the brake servo.
On mine, the vac line for the EGR and VNT branches off this large tube, goes up to a t-piece. One end of the t-piece points to the N18, the other end goes to a small cylindrical (black & white) check valve which (I think) only allows flow one-way -- i.e. toward the pump. Then it goes onto the VNT actuator and the anti-shudder solenoid, and tees into the airbox too.
I've suspected that the check valve could leak where the black and white halves meet, so I wrapped it round with a layer of insulating tape to make sure.
I did a 2-stage treatment on all the vac connections that I could get at -- first a tiny drop of "seek & seal" silicon sealant on each joint, which you can get from Halfords. It's a thin liquid which never sets, stays tacky so it finds & seals any leaks. Then a couple of turns of plumbers PTFE tape on each joint.
Anal retentive? Me?
Had a good look round the other day, think I've found where all the pipes go now - lots of them, and lots of joints !craig-pd130 said:
Impossible to know which (if any) are leaking, think I might just buy some decent lengths of vac tube and begin replacing them a bit at a time, see when the hissing stops
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