Putting it in line. There is a feed in the 1/2 inch line with a rubber connection and from that connection a bunch of other lines located near the brake booster share the common feed. I will look again but I do not think you can....Just had an idea.

Got it. The system vac reads 19.5" or just a shade below 20". Isn't that remarkable after thirty years. So I am just short the 21" spec.

Good. The pump is working correctly. Was that level with the climate control hooked up? The climate control can be a source of leaks. When my climate control had leaks, I had harsh downshifts.
Can you measure the system level going in to the VCV?

__________________
1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

Do not know about climate control. I unhooked the feed off the 1/2 inch pipe and dead ended the mityvac there and got almost 20". Again engine would not shut off until I hooked the line back in. So that means all those lines which eventually were shunted through the firewall were disconnected when I pulled the vac. I am guessing that unhooked the climate control.

But my shifts are nice and smooth now so I am going to drive it for a while and see how it feels. At least now I know what to do. And all along the guy who installed the tranny has wanted to sell me another vcv - another instance of just throwing in new parts without really understanding what is the problem. It shifted just awful when I picked it up from his shop - and he had kept it for four weeks working on it.

In a previous post I had said my Trans Modulator when tested with a Mighty Vac type Tool would have the Vac pump up but in about 2 seconds would leak down to zero.
When I did the check I used the Vac Line under the Hood.

Opinion is that the Modulator is bad or a problem with the Modulator Cap.

When I was looking up the price of the Modulator I was reminded again that the Modulator Cap could cause a Vacuum Leak and that I sould test for that before ordering a Modulator.

I went back and tested the Modulator with the Mighty Vac hooked direct to the Modulator. I held vacuum Perfectly!

I reconnected Hose/tubing and tested again from under the Hood and found I still had a Vacuum Leak.
It turned out that one of the Vacuum Hose sections fit loose on the Plastic Tubing.

After that was fixed that line that goes down to the Modulator would hold Vacuum like it was supposed to.

__________________
84 300D, 82 Volvo 244Gl Diesel

Yep, Occam's razor ( lex parsimoniae ) - often the simplest and least complicated hypothesis is the correct answer to the problem .

Glad that is all it was.

Boy, has this been an interesting journey. Yesterday the car stopped shifting out of second, leaving me stranded. So I pulled the transmission vac line out of the rubber Y and drove it back home - decent shifts because there was no vacuum but dreadful downshift. Then today I drove it again and it would hardly go over 30 mph.

Looked under the hood and found 1) the bottom rubber Y that goes to the bottom outlet of the proportioning valve (or vcv) was pulled out and 2) the line that goes from the switchover valve to the back of the engine on the passenger side had pulled out.

Stuck both back in and magically I am back in business. I am beginning to feel like I actually know what I am doing. Maybe the worst is behind me. So far the pickup is great again and the shifts (both up and down) are very good.

Saga continues. Have had surging lately and flaring and generally not shifting well. Sometimes if I shower down on the throttle it goes through the gears OK but if I take it easy, the thing just will not shift or I have to get it to shift using a certain touch on the gas pedal.

A week ago to resolve this problem I adjusted the vac modulator just less than a quarter turn CW for sharper shifts. Not good. The cover on the vac modulator was cockeyed when I got under the car so I put it back on correctly after the adjustment. Still not shifting well - maybe I need a new cover because some folks say the cover cannot be removed and reused (I have reused it at least five times now).

So today I move the vac modulator back two clicks CCW (old position and reuse cover again) and check the entire system with the Mityvac again. Nothing leaking but I notice I am getting very little bleed down at WOT - goes down to 10". Not sure what to do and then notice that I have 17-18" vac at the VAV instead of 15" so I pull off the plastic domed cap and loosen the screw a full turn. Check the vac level again and no change; loosening the screw had no effect. Drive it again and still shifts poorly. Drive it with the Mityvac attached (no vac to tranny now but I can pump it up when I need to downshift) and it upshifts somewhat better. When I pump up some vac for the downshift, the downshift clunk goes away. But something just does not feel right.

Go back home; pop the hood and check the transmission fluid level. No fluid touching the dipstick.

Put in four quarts; back to proper level. Test drive and it shifts again.

Moral of the story - check the simple things that can go wrong first.

When will I ever learn??? But at least it is back in service now.

Now I know why it was low on transmission fluid yesterday.

Today I drove around for about ten minutes, having put in quite a bit of transmission fluid yesterday, and the shifting was perfect. Drove back home and checked the fluid level just to be sure. It was down to the second mark. What the heck? Looked inside my garage and saw that about a pint to a quart has leaked over night.

Unfortunately my guarantee expired two weeks ago so I am out of luck. I am just hoping that a cooler line is leaking instead of the front or back seal.

At least I know that the replacement transmission is good; it shifts like a dream.

I do not have a lift so anyone have ideas about the best way to locate the leak?

Drove the SD back and left it at Lagrange today. Did not seem to leak any transmission fluid over the hour trip. The garage that installed it said they would take care of the leak even though it was two weeks past the warranty period.

Will report back.

Going to pick up the SD this morning. The mechanic said that the leak was the transmission pan. He replaced a gasket and says it is ready to go. Good guy - the repair was two weeks out of the 90 day warranty period.

Hope this works.

Follow up 2014. Still running great; still shifting great. Thanks Kerry and JT.

Follow up 2016. Still running great and still shifting great. Thanks Kerry and JT.

Follow up 2018. Still running and shifting great. Thanks to Kerry and JT.

Followup 2020. Running and shifting fine still. Amazing. Thanks to Kerry and JT.