AC belt/tensioner/assembly....

Okay, I have looked at many diagrams and actual photos of what this whole area should look like when all put together correctly. However, I can't figure out which parts I am still missing. Here are a couple terribly blurry pictures I took from underneath the car.




I know this falls under the category of "horrible post", but I'm not really sure where I need to go from here. Also, where the belt goes on at the compressor, there is some rust and a piece that just sort of hangs there, I assume this isn't supposed to be like that, but like I said, not exactly my area of expertise. Any help or suggestions would be greatly appreciated.

I think you're missing an entire pulley, and that shock absorber-looking thing is a tensioner, but I can't tell where the loose end of it should be attached.

This might help:

I have the pulley that I'm missing, (red A)


Is it supposed to go here?


If so, What does the arm do? it moves around but doesn't connect anywhere but at the bottom, is it supposed to be attached to something at the top too?

The white part in Picture #2 is plastic, and looks like the pulley will fit onto it, but I am missing the bolt that holds it on.

Crystal, it looks like you're missing an entire plate that pivots on that plastic covered stud! Your plastic tensioner pulley would bolt to that pate, and the tensioner spring/shock absorber-looking thingy bolts to the plate below the pulley. The plate with the pulley pivots upward, being pushed by the tensioner, and puts pressure on the belt.

I noticed the posted diagram has what appears to be a hydraulic tensioner on the bottom (compressor) belt and I'm not sure (from the diagram) if the upper tensioner is hydraulic (but I have the same picture on the E39 Bentley).

The blurry pictures provided are clearly of a hydraulic tensioner (which, incidentally, cn90 has found out, isn't really hydraulic either ... but that's an aside).

But, they look totally different in real life - so one may need to be careful until they familiarize themselves with the differences - especially since the mechanical tensioners usually come with the pulley attached while the hydraulic don't:
- How to tell if you have spring-drive or hydraulic belt tensioners or both (1)



In my 525i (M54 engine), I have two mechanical tensioners (yes, I know the use of either tensioner or both tensioners is arbitrary):
- One users' example of total electrical failure (AAA towed away) alternator repair (1) (2)

Here is the equivalent diagram, for my M54 engine from that thread for others reading this for reference:

Originally Posted by hornhospital

Crystal, it looks like you're missing an entire plate

I have mechanical tensioners so I am relatively unfamiliar with the hydraulic (other than to say mechanical tensioners almost always come with pulleys attached while hydraulic tensioners rarely arrive with the pulley attached).

Is the plate that's missing in this picture from the referenced thread?

Oooh I think it is.... There is currently nothing connected to the end that is in the center of that pic ^.

Now I'm wondering if I can just survive my last desert summer with no AC instead of tackling all that... not to mention I don't even know if it will all work if I replace all the missing parts, damn the PO....

according to realOEM it looks like I am missing parts 3, 4, 6, 8, 10, 11 and 13....

Yup. That's the same parts I had circled as an assembly in the Bentley Manual screen capture.

I'd just about bet you your A/C compressor is kaput. That would explain why someone stripped the tensioner pieces off the mount.

that's what i was starting to believe, not worth the effort right now, i won't need to worry until about March, it shouldn't hit the 90's till then

I'm just wondering ... so dismiss this out of hand if you're sure it didn't happen ...

But ... maybe ... do you think someone before you could possibly have replaced a mechanical tensioner with a hydraulic tensioner without adding the conversion kit that apparently you need to convert a mechanical to hydraulic tensioner?

I don't know much about this conversion "kit" but the topic and links to it are covered in the thread I already referenced you to (and in the VERY best of E39 Links).

I can't answer for Crystal, but what she's showed us in the pictures is the back plate for a hydraulic tensioner and the tensioner itself. There is no evidence that any conversion was started that I can see. What's there is what should be there for a '92 2.5l six. What isn't there is the upper pivoting plate and associated pieces, including the pulley itself. The '92 came with a hydraulic tensioner from the factory.

BTW, I searched Pelican Parts for the conversion kit you mentioned, but I can't find said kit on their site. How about a link?

Originally Posted by hornhospital

I searched Pelican Parts for the conversion kit you mentioned, but I can't find said kit on their site. How about a link?

I personally have NOT converted from mechanical to hydraulic (and I don't recommend it for a variety of reasons already covered in this the VERY best of E39 Links thread) so I only know what other people posted about it:
- How to tell if you have spring-drive or hydraulic belt tensioners or both (1)

But the conversion kit is covered in this the VERY best of E39 Links thread:
- Changing from Mechanical tensioner to Hydraulic tensioner for your serpentine belt drive

I just went to that mechanical to hydraulic tensioner conversion-kit thread (which I hadn't read in a long time since I didn't need to do the conversion) ... and here are the important references out of that thread ...

Here is the Hydraulic tensioner from realoem that you will need to buy:
http://www.realoem.com/bmw/showparts...90&hg=11&fg=18

Here is the mechanical tensioner from realoem note: This is just a comparison so dont buy this one)
http://www.realoem.com/bmw/showparts...05&hg=11&fg=18

And, here is a conversion kit from mechanical to hydraulic (although not for the E39) from that thread:
- autohauz mechanical to hydraulic tensioner conversion kit

Here are pictures of these respective links from that reference thread:

Here is the Hydraulic tensioner from realoem that you will need to buy:
http://www.realoem.com/bmw/showparts...90&hg=11&fg=18

Here is the mechanical tensioner from realoem note: This is just a comparison so dont buy this one)
http://www.realoem.com/bmw/showparts...05&hg=11&fg=18

*******>********>

No.	Description	Supplement	Qty	From	Up To	Part Number	Price	Notes
i	Only applies to hydraulic belt tensioner
01	RIBBED V-BELT	6PK X 1538	1			11281706545	$39.18
02	Base plate		1			11281726774	$67.76
03	Bush		1			11281748718	$8.39
04	Pitman arm		1			11281726773	$61.13
05	NEEDLE SLEEVE		2			12311713153	$18.45
06	ADJUSTING PULLEY		1			11281748131	$45.97
07	Fillister-head screw	M10X25	1		07/2007	07119920150		ENDED
07	Fillister-head screw	M10X25	1			07129905534	$1.50
08	Hydraulic belt tensioner		1			11281717188	$112.15
09	Hex bolt	M8X40	1			07119901161		ENDED
09	Hex bolt	M8X40-ZNNIV SI	1			07119905549	$1.05
10	Hex bolt	M8X50	1			07119912652		ENDED
10	Hex bolt	M8X50	1			07119904533	$2.84
11	Hex bolt	M8X105	1			07119901785		ENDED
11	Hex bolt	M8X105	1			07119904532	$1.78
12	Flat washer		3			11281440369		ENDED
13	Hex bolt	M8X35-8.8-ZNS	1			07119913111		ENDED
14	WAVE WASHER	B8	1			07119932121		ENDED
15	Deflection pulley		1		07/2007	11281748130		ENDED
15	Deflection pulley		1			11287841228	$46.81
16	Hex bolt	M10X150	1			07119904677	$3.82
17	PROTECTION CAP		1			11281730349	$2.37
18	PROTECTION CAP ADJUSTING PULLEY		1			11281727159	$2.37
19	PROTECTION CAP		1			12311713143	$0.42
20	Mudguard		1			11281730532	$2.37
21	Complete hydraulic belt tensioner		1			11281722789		ENDED
21	Complete hydraulic belt tensioner		1			11287838797	$69.64

*******>********>

No.	Description	Supplement	Qty	From	Up To	Part Number	Price	Notes
i	Only applies to mechanical belt tensioner
01	RIBBED V-BELT	6PK X 1538	1			11281706545	$39.18
02	MECHANICAL BELT TENSIONER		1			11281427252		ENDED
02	Complete hydraulic belt tensioner		1			11281722789		ENDED
	only in conjunction with
02	Complete hydraulic belt tensioner		1			11287838797	$69.64
	only in conjunction with
--	PROTECTION CAP		1			12311713143	$0.42
--	Flat washer		2			11281440369		ENDED
--	PROTECTION CAP ADJUSTING PULLEY		1			11281727159	$2.37
--	Mudguard		1			11281730532	$2.37
--	ADJUSTING PULLEY		1			11281748131	$45.97
--	Hex bolt with washer	M8X35-Z1-ZNS	1			07119900261		ENDED
--	Hex bolt	M8X105	1			07119901785		ENDED
--	Hex bolt	M10X150	1			07119904677	$3.82
--	Hex bolt	M8X50	1			07119912652		ENDED
--	Fillister-head screw	M10X25	1			07119920150		ENDED
03	Hex bolt with washer	M8X35-Z1-ZNS	2			07119900261		ENDED
03	Hex bolt with washer	M8X35-U1	2			07119905533	$0.44
04	PROTECTION CAP ADJUSTING PULLEY		1			11281435114	$2.37
05	Deflection pulley		1		07/2007	11281748130		ENDED
05	Deflection pulley		1			11287841228	$46.81
06	Hex bolt	M10X150	1			07119904677	$3.82
07	PROTECTION CAP		1			11281730349	$2.37

All the conversion write-up seem to be going FROM a mechanical TO a hydraulic tensioner. Crystal already has part of her original hydraulic tensioner setup. All she needs are the parts she noted in her last posting to put it back together as it was from the factory. She most likely can source those pieces from the pick-and-pull for very little.

Thanks for all the work writing, copying and pasting, bluebee!

I'm pretty sure Ken's right, most of the parts on my car are original.... lol which would be good I suppose if they were all there. It's a 92 (Oct 91) 325i, 6 cylinder. The tensioner is in the same condition as the rest of the engine. I was supposed to be moving before the deathly hot summer hit, so was just trying to be a good PO to whoever would be buying it. However, with a change of plans from the military, it looks like I'll be here, so I want to get the AC working before then. However on closer inspection, (and from the hindsight I've gained in other areas of the car) PO probably broke/removed these parts because they were:
a. making an abnormal noise
b. not working
c. damaged in the crash (front passenger fender was hit)

Thanks for all the info, I'll update (or post a new thread) when I decide to tackle it. Main issue right now is figuring out the MAF issue I have, which isn't something I'm enjoying either.

Crystal whats wrong with your MAF? the new car im getting has a MAF that is included in the deal. a 1992 325i just as yours is.


need a new one?

I have a working one in there it just doesn't fit the plug I have. The plug that connects to the MAF is 6 prong, where most MAFs (and my replacement MAF) are 4 prong

And are you selling Noelle, or just getting a 2nd car?

Im not sure whats in the new car.

But im trading noelle for the new girl.. just dont tell noelle. she will hate me

Originally Posted by night_raven9

I'll update (or post a new thread) when I decide to tackle it.

Update?

BTW, for reference, we finally figured out "why" a hydraulic tensioner "might" be better than a mechanical tensioner:
- WHY would a hydraulic belt tensioner be any quieter than a mechanical belt tensioner?