long tranny shifts and vac problem

[Red Rover]

I have a question .... I've been having a vac prob with engine not shutting off unless a door is open for the past few months. This happened before but "fixed itself" in a few days.

Just today noticing longer shifts in the tranny esp going from 2nd into 3rd. I've been unable to get a basic vac tester to try and find an obvious leak but am still trying. Now that the tranny is effected I'm getting more concerned about the issue and wondering if it's more than just a leak.

Should I stop driving her until I get this fixed? She is my daily driver.
I've read so much about vac failure ruining the engine and I'm not sure if it's just a leak or the pump failing. I'm not sure how "bad" is bad when it comes to this.
I have read the previous threads but "serious" situation wasn't really described. Am I there?
Thanks!

[Maxbumpo]

Jeff,

Vacuum pump on your car is NOT one that can fail and destroy the engine.

You've definitely got a leak in the central locking system, may be affecting transmission which depends on vacuum for shifting quality (not timing). You may want to consider isolating that system to see if the shifting improves.

Continueing to drive a poorly shifting transmission can cause increased wear/tear.

[pch2021]

These little transmission issues can cause quite a few issues.

Lets see if we can sort some of them out.

1. Is your main vac line healthy and not cracked or damaged? is the rubber line coming off of it healthy?

Is the car shutting off, and are the brakes working well? you may have a weak vacuum pump.

ARE THERE ANY NOTICEABLEY BROKEN VAC LINES UNDER THE HOOD? LOOK CAREFULLY! EVEN a small rubber line can tear.

The supply lines to the locks/shut off and transmission should not be on the same feed off the main line [on an '81 turbodiesel]. If they are , something may be wrong. This leads me suspect an issue in the main vacuum supply. With the engine running, check for vacuum at the 19mm brake booster connection. If it feels inconsistent, the check vavle at the top of the pump might be dying, or the pump itself may be calling it quits.

[Red Rover]

ok update time ... shifting is still running high, still within range but high. I have been backing off the accelerator to get it to shift within range and not do too much tranny damage. I checked pretty carefully under the hood and couldn't find any lines cracked or split (81 non turbo, by the way). When either door is open she shuts right off. No brake issues or anything else I have noticed. I'm pretty sensitive about how she runs and can notice the slightest of changes. Keep in mind I'm not trying to neglect her, but just dropped 500 on 5 new diesel injectors and trying not to find myself another 500 bill if at all possible.
Maxbumpo ... how do I "isolate" the central locking system to see if shifting improves??

[MB88SL]

Mercedessource.com sells several vac trouble shooting guides you may want to take a look at. The vac issues can be maddening. The open door solving the shut off problem is something I have never heard. This would seem to suggest to me that opening the door is pitching a line and stopping a leak in a door. If this is correct it may help you locate which door the leak is in. Pulling the inner door panels off and replacing the door lock vac unit is not that difficult or expensive if you do it yourself. I had a leak in my climate control valves that would come and go until I finally had the dash pulled to get at the leak. When it would act up I just pulled the vac line to the climate control under the hood and plugged it with a golf tee. The valves opening the different vents didn't change the air flow with different settings but it solved the shut off (and door lock) problem immediately. You might try pluggging of the line to the door locks and see what that does. The tranny shift may also suggest the need to adjust the tranny modulator valve. You may have leaks in more than one area. As thees cars age the rubber goes and my experience is leaks pop up all over. I am with my 1983 basically at the pont when anything new is opened up, eg door panel, dash etc, that is difficult to reach, I just replace all the vac parts and rubber while I am in there. Good luck.