Bill Ball

Yeah, sorry. The picture is from the WSM while the text is from the MY tech guide. I'll see if I can fix that. The main part that was added to provide the fluid damping was the valve part 13 in the WSM exploded view.

Edit - OK, the original post is fixed.

Vilhuer

I find factory document Bill posted somewhat confusing. Original adjuster version needs oil into it also, see WSM 15-20 and 15-21. Later version added channels for oil to flow more easily to different parts of system. It didn't introduce oil at first time.

From '86 model year technical documents:

"Tensioning Roller Console (All Engines)
The center of the tensioning roller is displaced toward the engaging point of the push rod by 8.5 mm. Pressure point and roller center are now on one line, so that bending and inclining of the console are Prevented. The tensioning roller itself has an improved bearing.

Tensioning Roller Housing (All Engines)
The tensioning roller housing is adapted to the tensioning roller console modified by 8.5 mm. Brake bleeder valves are used instead of the former hexagon head bolts to make it easier to add oil and bleed the housing. Filling and bleeding is now very easy by turning both valves counterclockwise by about one turn, and pouring in oil from a plastic bottle and a suitable piece of hose."

So centerline was changed for '86 model year. AFAIK there should be 3 major differences to tensioner housing:

'78-82
- Without outside filling possibility
- Without oil flow channels at the back

'83-85
- With bolt covered outside fillers
- With oil flow channels at the back
- '85 with tension warning system

'86-95
- Centerly (to roller) aligned pushrod
- With brake bleeder valve covered outside fillers
- Not sure if tension warning system changed to later style '87 or already in '86

In '86 32V engine was available in Europe (Germany at least) and came with catalytic converter. It's not exact same version as '85-86½ US engine. Compression ratio is 9.3:1 because of not so good availability of high octane unleaded fuel in here at the time.

All '86 model year Euros have later S4 style suspension and brakes. '86½ (from VIN 1000 forward) is US model thing. I would call US '85-early '86 as S3 and US '86½ as S3.5. If 310hp Euro is S2 then what is Euro '86 S with S4 suspension, S2.5? What about Euro '86 32V, S2.75?

Garth S

Erkka,
A good summary: the only other point of interest that comes to mind is that from '83 on, the tensioner body had a cylinder sleeve ( like a 'wet' liner) with oil passages surrounding it to further improve heat transfer: this cylinder, IIRC, was teflon lined at some point.
In addition, the lower piston of this evolution incorporated the check valve and O-ring seal - presumably in an effort to better dampen the "harmonic flutter" of the TB.
Opps - I was in error by 0.5mm when discussing the improved tensioner body centerline.

FlyingDog

Can brake bleeder type valves be added to earlier tensioners (84) and is it worth it?

Bill Ball

Errka:

Yeah, ALL of the tensioner models are oil-filled for heat transfer to the bimetallic washers. From 83 on the oil also serves a vibration damping purpose. Sorry if I or the documents were unclear. The WSM shows the pieces-parts while the MY83 on subsequent years technical service guides provide the operational nuts and bolts. I tried to pull in various other sources to try to get all the MY changes, as you did, but it strained my little brain too much. Good summary.

H2

I'm still in the market for a used '85S or 86 tensioner system for the 32V engine...the whole kit and kaboodle for a more modern changeover. Or maybe even an S4 system if priced reasonable.

Harvey

heinrich

Keith I admit I am a 32V man so I am not 100% sure which but I do know POST-83 engines are interference. And some 83 and lower ones also. Post-83 means after 83

Anyway my 1985 Euro with something like 11:1 compression ratio has no 45deg mark on the balancer. But it is definitely a 16V and it is definitely an interference engine.

heinrich

Harv I'm not sure about this. I think there was the old system and then there was the interim '84 - '86 system and then there is the '86+ system.

You had the oiled system, right? That means you had the appropriate system for your car. You could go to '86.5+ (I call it S4 system) system. Beefier tensioner and arm. Straighter path. The one thing that continues to bother me about all of them is that the big roller never rolls has the belt aligned properly, rather at the front edge. I have been considering spacing it and will likely do it soon. A nice thick washer should do.

FlyingDog

Heinrich, according to PET5 1985/86 16V and 32V engines had different tensioners and tensioner arms. The 32V tensioner is the same as an S4, and the tensioner arm is a different variant of the same part (928 105 489 00 vs 928 105 489 02).

Anybody know what the tensioner pushrod for an 84 Euro S should look like? Mine doesn't look like the PET picture. It looks more like the pushrod and guide sleave for a tensioner with the sensor.

heinrich

Hmmm ... My 1985 US has a tensioner and arm that are 1 inch closer (than S4) to the block and tensioner uses allen screws for the filler. 1985 Euro had an arm that was exactly like the US '85's, which to me means it must have had the same tensioner as the US car, before the geniuses replaced it with the wrong part.

So US '85 == Euro '85

H2

Harv I'm not sure about this. I think
'there was the old system and then there
was the interim '84 - '86 system and then
there is the '86+ system.

Heinrich, I'm a bit confused on the whole tensioner issue. I just know that I ordered a couple of '85 year tensioner arms that didn't fit my '85S because the tensioner and the arm were offset and incompatible. After some considerable head scratching, I had them send me the earlier (pre-85) arm and it lined up perfectly with my tensioner (with oil filler/bleed holes). The arm was dated 12/84 so I assumed that the tensioner on my car either was an '84 version that the factory fit at the beginning of the '85 production year...or some previous mechanic changed it out for the earlier model. But to change the tensioner or the arm...you have to change both since they will not line up. The newer tensioner arm sticks out a bit closer to the radiator by 1/4 or so. Enough to throw a belt if you used the wrong part. While the tensioner setup on my car seems to be working OK, I still want to fit a later model.

Harvey

Shane

My 86 and 86.5 have identical tensioners!

Nice avatar Harvey, I would bet that I have been there too!

PorKen

Now here's a tensioner design I can truck with:

(Mini Cooper S supercharger tensioner.)

heinrich

Truck with it Ken ... please I think a simple design like that makes a lot of sense. Especially since the overcomplicated one we have, is in 80% of cars, not fully functional anyway.

SHANE:
How do you know? They look identical unles you know what to look for and you're thousands of miles away from your cars for the past 4 months already

HARV:
I think you have the right setup, that is what is on my '85's.

Garth S

Almost anything can be improved, the last generation tensioner included; however, the one thing we are highly unlikely to change is the length of the TB. At issue is the taming of the operational harmonics of an eighty some inch long belt that drives two critical accessories in addition to 'normal' timing belt duties - a tough job!
Harv, if you wish to go to the S4 gen. tensioner, almost everything must be changed ( except the carrier arm bushings). My first post here has a rough parts list.