Since I purchased the car in April the lock on my tailgate will almost always lock but inconsistently unlocks. Never any problem with any other vacuum-actuated things on the car, all 4 of the door locks work fine, etc.
I'll turn the key and hold it there for a second, watching the rear lock...it will come up and click but stop at about half way and I'm unable to open the hatch, I have to have my wife turn the key while I reach back and "help" it up. My key does not work in the tumbler, either, which leads me to believe that the lock or the entire tailgate may have been replaced at some time.
SO...based on the above criteria, do I have a vacuum problem or a mechanical problem? I've already had all the trim off and sprayed the mechanism down with lubricant thinking that maybe it was just getting tight after all these years but that doesn't seem to have helped.
Thanks in advance for any assistance or guidance in the matter.

I would suspect the linkage or the lock -- if the diaphram was bad, none of the locks would work (this is the old system, operated off of a mechanical switch in the driver's door). If your key doesn't work, its a certainty that either th lock is messed up or it was replaced.

Make sure the linkage is properly adjusted, properly connected, and that none of the rods, etc is bent. You will need to take the liner off the door to do this.

You may also need to lubricate the latch. Also, do you have the electric door closer? If so, and it isn't working, you may have extra mechanical load on the vac motor it can't handle.

Peter

__________________
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!