Knock, Knock (Sensors)!

(Sorry about that subject line.)

I am ordering the (long list of) parts for the upcoming valley pan gasket project on my 2001 540iA. By the way, thanks for the feedback on my recent posting regarding the valley pan project. (Are you out there, Moosehead?)

I would appreciate anyone's comments on whether or not I should plan to replace the knock sensors on my E39 while I am doing the valley pan gasket. My car has 100k miles on it. The cost of the 4 replacement knock sensors would effectively double the cost of the parts for this project, but I also don't want to do the valley pan R&R, then have a knock sensor fail in 3 months and have to re-do all of the labor to get back down to the knock sensors.

Thanks in advance for any insights.

Well, I will say that the knock sensor wiring is definitely better on the newer sensors than on the old ones, so maybe they used better insulation after the initial problems.

Thanks.

So I am thinking I will NOT order the sensors and just see how the old ones look once we get the manifold removed. Hopefully the insulation looks good and we can just leave the old sensors in place. (At least I think that's what you were saying. I am hoping the "initial problems" you reference were pre-2001.)

THe initial problems definitely occur with the M60, but unsure when in the life of the M62 the insulation got better. The last 01 540 I did seemed to have decent insulation and the owner opted out of buying sensors, so you can do the same and just take a look see at how the insulation is doing.

Got it. Thanks again.

FWIW... I did the VP job and I moved two knock sensors to get the VP on. I got knock sensor faults because I had failed to put them in exactly the same orientation at exactly the correct torque. This gave me the opportunity to redo the intake manifold. Redoing the intake manifold caused a vacuum leak (failed to seat a gasket correctly) which gave me the chance to redo the intake manifold. I got really, really, really good at installing/deinstalling.

Bottomline - when you move the knock sensors, put them back correctly. Also, the plastic insulation on the knock sensors will fall apart and fall in your intakes. Plan on a small pair of needle nose to carefully pull it all out. Amazing amount of debris down there... (YMMV)

Yikes! Thanks for the warnings. I appreciate all of this info.

Good info and great warnings to keep others from experiencing the same issues when doing the work!! How's she running now and isn't it nice to get rid of those pesky leaks???

BTW, I got really good at removing/installing my lighting...LOL!