Hey folks

Quick question. What is the name of the metal (on my 1997 XK8) cylindrical part on the top middle of the engine, closest to the cabin, with the vacuum hose coming out of it.
What does it do?

Thanks
Nick

 

picture would help

 

Car is in the shop till Monday-Tuesday and I don't have access to it

 

Sounds like the cruise control servo doodad on top of the TB, which, I believe, was metal rather than plastic on the early cars. Is this what you mean?:



Described as a 'vacuum actuator', but not shown as a separate part in JEPC.

Part of the cruise control if you have it, otherwise it does nothing.

 

If your vacuum actuator is not the later black plastic unit and it is still functioning properly, you have a RARE first edition AJ26 throttle assy. Congrats on the accomplishment!!!

I replaced DOZENS in the late 1990s and early 2000s. Many never made it through the RECALL era.

bob

 

That's the part! And it is the rare AJ26 throttle assembly. Still purring...

 

Nick, you may find interesting /file for future. My 1998 has same device.

I was driving, set cruise, started to go uphill - Restricted Performance amber alert came up.

What could that be, I wondered. Then noticed no cruise control at all! Well sure enough when I pulled over, turned ignition off, then restarted her, all was OK. That's until I engaged cruise and got to a hill which forced cruise to try to apply accelerator.

Got home and took a look at things. That vacuum hose was disconnected from the device you asked about. Then it all made sense- when cruise control needs to accelerate vehicle, it relies on the vacuum signal , since it was disconnected nothing happened as it applied vacuum to accelerate. This resulted in the car disabling the cruise control, and putting me into restricted performance mode.

Of course I was so happy to have "solved the mystery that I never bothered to ask how the hose could have become disconnected.

Turns out motor mounts were shot. Each time I accelerated the engine would over extend its normal movements, a twist in this case, and mm by mm it loosened the vacuum tube until it eventually fell off the port.

Figured that while on this topic you might want to file that away for future troubleshooting.

John

 

Thanks Johnken
I will file that away in my enormous data bank of what can go wrong with these cars. Kinda makes me long for the simple days when you could open up your hood and see the driveway underneath...

 

Wrong thinking !!!!!
Be happy that you have a cruise control that depends on something as simple as engine vacuum, rather than on a computer which can throw it's toys out of the pram because the battery only has 12.6 volts instead of 12.7. (Later cars have an electronic CC system)