One for the experts on vacuum systems!

[Doug Huffman]

Originally Posted by mobilejo

Yeah, I downloaded it here: http://www.kaross-chip.lv/m_download...ommon-Rail.pdf

Thank you very much.

[mobilejo]

Originally Posted by Doug Huffman

Thank you very much.

But from what i'm learning, the e70 system works in reverse to what is explained in this document (which was for the older M57 engines) - in our cars, higher revs activates vac which puts them in the hard setting!

[mobilejo]

Okay, I just realised that the vacuum solenoid I have been messing with - thinking it was for the mounts - is actually the EGR solenoid at the front top of the engine right by the egr cooler DUHHHH!

So where is the engine mount solenoid located? From the bottom of the car I follow the vacuum line up from the mounts as far as I can, and it feels like it goes behind something on the engine and I lose it. Can't figure this out for the life of me

I did notice that when I use a piece of my own vac hose and connect direct to a vac pipe at the top of the engine and run that down and connect direct to the mounts, the car is much much much smoother at anything but idle. Normally I get vibrations upto around 1400-1500rpm, but with the constant source of vac going to the mounts it only vibrates in idle.

[ninja_zx11]

Originally Posted by mobilejo

Also, can you remember the following: when I put my thumb over the nozzle on the mount itself (i e the nozzle that the vac pipe would go onto), I feel fluttering air coming out of the mount, this suggests that while idling the spring in the mount is bouncing up and down a little. Hastens in both mounts.

Did you ever check if your mounts did this?

If this bouncing of the spring is basically allowing fluid to move into and out of the chamber that controls soft/hard setting, then surely this is a problem on idle? Would this fluttering not occur if the vacuum system after the mounts is air tight?

Yes i remember same fluttering air coming out of the mounts with no vac hose connected.I got my both mounts replaced under warranty but it didn't help much.May be i am too sensitive.

Have you started feeling vibrations just now or was it like that from day one?Are you too feeling on the steering wheel and on the floor?
The only thing left is transmission mount which is easy to replace and not that expensive.You can try that.What year your X5 is?

The vacuum solenoid for mounts is hidden under the intake manifold by the glow plug controller.Very hard to access.So have you driven the car with supplying vacuum to the mounts continuously in hard mode?

[mobilejo]

Yes I have, it was much better except for in idle where it was maybe a little worse than normal.

My vibrations are on the steering wheel and floor, exactly as you describe.

Did you ever fix yours? Did you check your egr to make sure it wasn't stick open and this putting exhaust into the intake at idle? That's a common problem we have on older diesel cars with the old egr system but not sure if it applies to the new electronic egr found in these cars.

[mobilejo]

Oh mine is 2011 LCI. Vibrations since I got it but it's under warranty and being looked at next week. I wanted to diagnose it myself because dealers can never find vibrations and just say it's normal.

[mobilejo]

Originally Posted by ninja_zx11

So do one test.Unplug your vacuum hose from the mount and rev the engine past 1000~1500 rpm and check if vacuum is applied to the mounts.If it is ,means your pressure converter solenoid valve is working correctly and your system is working properly.

Hope it will help you...

Did this test and vacuum is applied when revved so solenoid is working.

I also disconnected the EGR feed pipe from the intake so I could test it's operation - on idle there is no exhaust gas escape, then at low revs it opens and then closes again at higher revs so it is working as it should and not open on idle.

I still maintain that with constant vac to the mounts, it drove extremely well at any speeds above idle. It is not so smooth when the mounts are connected to the control solenoid...

They will have to change the engine mounts and take it from there.

So bad or faint are your vibrations - do you feel them in the floor and dash on both sides of the car? I do, but easiest to feel in the wheel as that is where hands are.

Do yours feel like a misfire (inconsistent judder) or is it a totally consistent vibration/rumble?

I expect some vibration from a diesel but I tested an identical age/mileage car and it had much much less than mine.

[ninja_zx11]

Yes I do feel vibrations on both sides on the floor.Its more like a shudder but it occurs only at certain RPMs while accelerating.Vibrations come and go while accelerating and more pronounced at speeds under 60 ~70 km/hr.If I drive in DS mode,it feels much better.After changing mounts ,dealer started saying 'totally normal' and I just gave up but it's annoying.I had a jetta TDI and it didn't have that kind of vibrations.My X5 at idle is not bad but I feel vibrations only while driving at certain RPMs.
That's why I wanted to diagnose it myself but eventually gave up.
I think I read it somewhere in the repair documents that there should be certain amount of vacuum at the mounts inlet in a certain time when you activate mounts manually through ISTA.So in our case it could be sticky or slow moving solenoid.Another thing I suspect is transmission mount because it can transfer the vibrations to the body as well.I will try to find that vacuum spec document.

[jfoj]

Front driveshaft??? Even at idle, front axles and front driveshaft slop can cause vibrations on some model vehicles.

[mobilejo]

Originally Posted by jfoj

Front driveshaft??? Even at idle, front axles and front driveshaft slop can cause vibrations on some model vehicles.

Would that not go away in N or P? Because there is no change in mine in any gear at idle.