Do we have hydraulic or mechanical serpentine polyribbed drive belt tensioners?

Originally Posted by bluebee

Luckily, I think 'this' thread has all that anyone would need to answer that question!

That's the good news.

The bad news is that people aren't 'finding' this thread when they order parts. Sigh.

For example, just now I saw this thread from today:
-> E39 (1997 - 2003) > 2003 530i - A/C Tensioner Pulley part number help

The user clearly did his homework - but - sadly - he ended up with the wrong parts.

Originally Posted by rcatank

Hey everyone, need some help finding the actual part # for a A/C Belt Tensioner Pulley on 2003 530i.


According to this forum: http://www.bimmerboard.com/forums/posts/199986


The part # should be 11281748131

But when I bought this part, its actually wrong. No way can it fit sungly as the original.


My full A/C Belt Tensioner Assembly looks like this:

http://www.ecstuning.com/BMW-E39-530...ner/ES2528731/


Can anyone tell me,
Thanks.

Even in 'that' thread, people erroneously suggested that RealOEM will provide the part number (it won't).

To help out, I suggested the following, which I hope people find in the future (which is why I post this here and now).

Originally Posted by bluebee

Go to the bestlinks and do a /tensioner F3.

You'll find the canonical threads for the tensioner.

As you found out, many people will suggest RealOEM or your VIN to look up the part number, but if you actually try (I was also a victim of that advice), you'll find out that RealOEM can NOT help you.

You'll find out that you first have to VISUALLY look to see if you have hydraulic or mechanical tensioners.

In addition, you clearly have the 2003 E39 because, AFAIK, no other E39 has the mechanical tensioner adjustment fulcrum point as a recessed T60 Torx. All other E39s have the mechanical tensioner adjustment fulcrom point as a raised hex 'nut'.

But all this is a repeat of what you'll find in the bestlinks.

For example:
Common questions which need to be answered BEFORE you do an alternator and/or drive belt system overhaul:
- 1st: Physically, determine what type of tensioners you have (1)
- 2nd: Physically, determine exactly what alternator you have (1)
- 3rd: Determine which parts you need to buy for a complete drive belt system overhaul (1)
- 4th: Do the alternator and drive belt system DIY (belts, tensioners, pulleys, rollers, alternator) (1)

Alternator and Belt Drive DIYs:
- Removal instructions for the alternator & drive belt system of a 2002 525i
- Removal instructions for the fan shroud of a 2002 525i
- Alternator and Belt Drive DIY (1) (2)
- How to tell if you have spring-drive or hydraulic belt tensioners or both (1)
- How to diagnose noises coming from the drive belt system (1)
- One users' example of total electrical failure (AAA towed away) alternator repair (1) (2)
- Video of cold idle engine squeal (1)
- Recommended parts list for a complete belt drive system overhaul (1)
- How to make your own BMW special cooling & belt drive system counterhold tools (1)
etc.

If anyone is seeking a hydraulic tensioner assembly for their M54, see this:

http://www.bimmerfest.com/forums/sho...ulic+tensioner

For those who want to convert from mechanical ---> hydraulic, see the attached pdf published by "INA".

Aha! So that's why I couldn't get it to fit. It used a different mounting hole!

Originally Posted by Fudman

It used a different mounting hole!

If the value difference between so-called hydraulic and mechanical tensioners were greater - and - if the replacement were plug and play, I could see us switching to hydraulic by default.

But, seems to me, the cost is greater, the utility is marginally better, and the effort is greater.

Given that, I don't see overall value in the switcheroo.

Originally Posted by bluebee

If the value difference between so-called hydraulic and mechanical tensioners were greater - and - if the replacement were plug and play, I could see us switching to hydraulic by default.

But, seems to me, the cost is greater, the utility is marginally better, and the effort is greater.

Given that, I don't see overall value in the switcheroo.

NOW you tell me! Anyone wanna buy a new hydraulic tensioner?

For cross reference on switching from mechanical to hydraulic tensioners, this thread today has some good information from Fudman and cn90 about the autohauz conversion kit.

Originally Posted by cn90

Originally Posted by Fudman

I bought the Ina hydraulic tensioner and the assorted longer bolts and pulley as an upgrade for my cooling system overhaul last spring. But after taking everything apart, I could not, for the life of me, figure out how to install the hydraulic tensioner. It does NOT fit into the existing mechanical tensioner mounting holes. I ended up reinstalling my mechanical tensioner. After some research, it appears that you must mount the hydraulic into different mounting holes on the block (which I did not find). Bottom line, this is not a simple one for one replacement. Do some research before attempting this. I, for one, will simply replace my mechanical tensioner with another one this spring.

Originally Posted by cn90

Also,

The BMW TSB is attached.

See also:
- How to tell if you have mechanical or hydraulic belt tensioners (1) & how to switch from mechanical to hydraulic (1) and what is the difference between the two types (1) (2) & how to rebuild your hydraulic tensioners (1) & how to re-grease your pulleys and rollers (1) & the answer to the question of adjusting the 540i hydraulic tensioners' belt tension (1) (2)

Bluebee - Thanks for the pics! Thought for sure I had mechanical tensioners as I have a first year e39, but after studying the pics and studying underneath the hood I have hydraulic. saved me from ordering the wrong parts.