1985 300TDT - I've already disconnected EGR and Air recirc valve. Question - how do I go about disconnecting at the transducer - in case there is a leak (vacuum)? There seems to be a swtchover valve tied into the transducer. What gives?

I took a soldering iron and melted the vacuum lines that run from the egr/air valves shut at the ends that plug into the controller. You could always trace the vacuum lines back from the egr/air controller to the source and plug them there. You have the option of simply plugging the line with a BB and reinserting the vacuum tubing or removing the lines/controller/etc. completely. I chose to leave all in place just in case some future emissions testing requires a visual check. RT

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I have an 85 300tdt and plan on plugging the egr. What and where is the Air recirc valve? Should that be plugged also? If so How? Thanks

Brian 85 300TDT 365K

Recirc valve and EGR are both near turbo, both have vac line (1 EA). I took line off and capped. Or ! read you could put a bb in line. Recently, I've started to investigate transducer (upstream of vac lines to both recirc and EGR), I've read that there could be vac leaks there too.

The transducers control the vac to the EGR and the air recirc -- follow the vac line back and you will find them -- electrical connection and two vac lines on a black box.

Most likely they are both bad by now, and leaking vac -- they will buzz if you apply vac to the supply side (from the main vac system).

Peter

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1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!

Peter - Thanks. How are these disconnected, there looks to be a "feedback" vac line going back toward main vac line from vac pump?

The transducers are actually vacuum switches, electrically operated. Simply switch on and off, possibly control volume, too.

Unplug stopper the supply line, either at the tranducer or at the supply T. Make SURE you plug the side TOWARD the vac pump to keep dirt out of the vac system.

Peter

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1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!