any reason to replace tensioner?

[cali-ti]

i was going to replace my belts soon and was wondering if there's any reason to replace the mechanical belt tensioner? i have 206k on her now.

what size hex do i need for the tensioner?

thanks in advance!

[bmw///m3///]

you should probably replace the timing chain tensioner though if you havent done already. it theres play/grinding in tensioner you should replace, I think it may be 19mm but not sure.

[mickd]

If it isn't making any noise I wouldn't worry about it. The post I used to help doing my belts and tensioners is here: http://staff.connect.com.au/lheather/318ti/2000-09/msg00234.html It is a 8 or 10mm, buy a bit to fit a torque wrench, the torque specs are on the post.

[cali-ti]

thanks mick, great link. the bentley manual lists the tensioning gear locking nut at 18 ft-lbs. damn those others are low torques! have to make sure i have 10mm and 12mm hex bits for the ole torque wrench.

btw, what "noise" is common from the mechanical belt tensioner? i have a clicking noise that is most common at start up, usually going away after warm up (although, i'm trying to remember if i've heard it on occasion even after coming to normal operating temp). the clicking is NOT dependent on revs, constant rate regardless. i was thinking it might be the air pump which only operates when the car is cold (if my understanding is correct).

m3, how much work is it to replace the hydraulic timing chain tensioner? #21 in the pic, right? seems like a good deal of work from looking at the bentley manual.

never done any of this stuff myself before so i'm working my way into it. :blink:

[mickd]

The belt tensioners get metallic sounding, pretty noticeable with the car idling sitting still. I thought it was the timing chain at first. And you will hear it from the interior of the car. Not as noticible driving though. I'm kind of messed up here, I was talking about the external belts and tensioners, the timing chain tensioner is pressure fed from oil pressure, never replaced it, but I guess it is pretty easy, you can do it from the outside of the engine.

[cali-ti]

mickd, you aren't messed up. i opened the thread re: belts (serpetine and ac - although i could have made it more clear) and the mechanical tensioner for it. you answered that question (thanks!). m3 just suggested that the timing chain tensioner should probably also be replaced since i have over 200k on it. if memory still serves me after only 5 hours of sleep, you have to remove the belts before getting into the timing chain.

the "metallic sound" ... bearing whine or what kind of thing? if it's gotten slowly worse over time, i may not have noticed so i'd like to listen with more knowledgeable ears :)

thanks guys!

[mickd]

Yeah, bearing whine. It did get worse over time and I didn't notice it until it got so bad. The more I think about it, it was fairly loud and it was higher pitched, sounding like it was on the outside of the engine, not muffled like it would be inside the engine. that was like 5 years ago, around 70K miles, so that's about all I remember. If They haven't ever been replaced, I would say for sure you need both tensioners and the idler. I would guess though you are probably at least on your first replacement set.

[cali-ti]

mmmmmm ... don't bet too much mickd :p

i'm too tired to look at the ETK yet again (you'd think i'd have it memorized by now!), can you shoot me PNs for the tensioners and idler you're talking about. my parts guy must think i'm rebuilding my car from scratch with all the crap i've been getting. he just got a new office, i'm thinking it's because of all the parts i've gotten!

thanks again!

[mickd]

Here is a picture of the main drive belt assy. The tensioner is #2 on the diagram. It is the type that needs no adjustment, spring loaded http://www.realoem.com/bmw/showparts.do?model=CG73&mospid=47506&prod=19960600&btnr=11_1522&hg=11&fg=18&PHPSESSID=aa482615e4b90a1aa6240d184aedc275
Here is a picture of the A/C compessor drive belt assy. The tensioner is #2 on this diagram http://www.realoem.com/bmw/showparts.do?model=CG73&mospid=47506&prod=19960600&btnr=11_3579&hg=11&fg=18&PHPSESSID=aa482615e4b90a1aa6240d184aedc275 I used a 6-96 build date for your car (M44) to get these diagrams. Some of the parts changed over time. To be sure of the #'s I would click on "select another car" at the top of the page and enter your VIN or specific build date, select "engine" (main group), then select "belt drive" (sub group)

[mickd]

Didn't know which system you had for the main drive belt. The one I posted above doesn't have the idler pulley. Here is the one that does. It is #6 in the diagram http://www.realoem.com/bmw/showparts.do?model=CG73&mospid=47506&prod=19960600&btnr=11_1523&hg=11&fg=18&PHPSESSID=aa482615e4b90a1aa6240d184aedc275 As I said, make sure you get the right #'s by selecting your specific car.

[cali-ti]

thanks mike. i have the one with the idler. got pricing and will be placing an order within the next day or so. my belts are cracking and need to be replaced asap. i appreciate everyone's help and recommendations, especially as i'm too tired to think straight now :p haven't decided yet if i'll do the timing chain tensioner or not. probably be smart to just do it ... what's a little more work, right? ;)