I looked through many posts, but was not able to find what I needed in the detail I need.

This is for a 1991 350SD. I am trying to get the transmission vacuum control adjusted properly.

I have seen some posts for the older 300SDL cars (maybe it would be the same?) that suggested that the initial adjustment needs to be made at the transmission modulator before setting the Vacuum Control Valve. I guess if I do that I need to jury rig a banjo bolt to check the pressure?

On the 1991, the adjustment to the VCV is made by rotating the VCV. The thing I was wondering about is that most adjustments seem to say to check the vacuum on the line going to the transmission, but that is after the blue vacuum valve that is between the VCV and the transmission.

I could have sworn that the VCV is to be adjusted prior to the blue vacuum valve. I think there is supposed to be some sort of drop in vacuum as the throttle is depressed and you have to check the output of the VCV. The output of the VCV is a three pronged connector with the vacuum pump on one connection, the interior climate control system on one connector and the output to the blue transmission valve as the third. At least that is what I can tell.

So I assume you have to plug the connector going to the climate control to get a good reading. The other thing I was trying to think through was trying to give it full throttle. I read somewhere that you needed to disconnect the throttle linkage, but isn't the part that drives the VCV also the part of the linkage that is on the Injection pump and so would also inject more fuel? In other words, if I move the disconnected linkage on the pump, won't it rev the engine anyway?

Also, I think there are some measurements for the vacuum I need to adjust to I think?

Probably making this more complex than it is, but I want to understand it in my head before I start messing with it.

The symptom is that the transmission is doing like what feels like a double shift. It shifts up (2-3 I think) and then seems to shift right back down. Not sure if it is down or up, but it's like one shift and then another back to back. Not sure what it could be so I'm trying to be sure the pressures are right.

The transmission shop had way overfilled it and I already fixed that.

The attachments are from the Superior shift improvement kit.

It says all 722.3 and 722.4 transmissions. It also says up to 1990. I understand you have a 722.361.

They may be of help.

Attached Thumbnails

   

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83 SD

84 CD

You should check the service manual, it describes how to set the valve.

Sent from my KFTHWI using Tapatalk 2

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1991 350SDL. 230,000 miles (new motor @ 150,000). Blown head gasket

Tesla Model 3. 205,000 miles. Been to 48 states!
Past: A fleet of VW TDIs.... including a V10,a Dieselgate Passat, and 2 ECOdiesels.
2014 Cadillac ELR
2013 Fiat 500E.

I am unable to locate ^ that, would you be kind enough to provide the FSM number?

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83 SD

84 CD

Loosen the two 10 mm bolts on the vcv

Have a friend get in the car and put the accelerator pedal to the floor

Turn the VCV clockwise until you feel resistance.

Tighten the 10mm's


what you initially posted only applies to 617s and 616s. No 60X has that style VCV that I've ever seen.

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68 280SL - 70 280SL - 70 300SEL 3.5 - 72 350SL - 72 280SEL 4.5 - 72 220 - 72 220D - 73 450SL - 84 230GE - 87 200TD - 90 190E 2.0 - 03 G500

Nissan GTR - Nissan Skyline GTS25T - Toyota GTFour - Rover Mini - Toyota Land Cruiser HJ60 - Cadillac Eldorado - BMW E30 - BMW 135i

Either the VCV is hooked up backwards or you're viewing it backwards. The VCV supply side tees into the ACC supply line from the vacuum pump. The outlet goes through a green damper to the BFS if you have one or directly to the modulator. Adjustment is one sentence - loosen the VCV bolts, set the IP linkage to WOT, turn the VCV clockwise just until resistance is felt, tighten VCV bolts. It's in section 07.1-1826 of the 124 FSM. I don't have a 126 FSM handy for the section number. The same section gives the spec as 385+/-25mbar (11-12" Hg) at idle and 0 at WOT. You need an external continuous vacuum source because a hand actuated MityVac will never keep up.

FWIW, I don't think the shift issues you describe are caused by an incorrectly set or improperly functioning VCV. Sounds more like something in the valve body is gummed up or broken. But definitely look into external adjustments first. Check the control pressure (Bowden) cable too.

Sixto
87 300D

^ Ah, I was looking at my car instead.

Attached Files

	VCV 350SD:07.1-170.pdf (79.6 KB, 387 views)
	control 350SD:30-300.pdf (458.8 KB, 368 views)

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83 SD

84 CD