Timing Conversion 1993 to Later Wider Style

[Volvebaker]

I am in the process of attempting to convert my 1993 850 to the later wider timing belt when I dig into some upcoming additional work on it. However, I am still a little confused on a few things and hoping for some clarification.

viewtopic.php?p=369058

In the post here it states that the center bolt for tensioner pulley is an M8 on the block, where as later style is M6 with a Torx head. However in the following:

viewtopic.php?f=2&t=43798

it's stated that the tensioner pulley bolt is a M10 bolt size so, I am a little confused here.

Additionally, it appears recommended, in the first post noted, that you can drill out the sleeve and simply use the original tensioner pulley bolt on the later style roller however, listed in that second link it's stated you need a custom, longer M10 bolt for the later style tensioner pulley.

Lastly, a little confusion on the bolts for the tensioner itself as well. It was stated in this post that you need:

longer 40mm thread size hydraulic tensioner bolts 8mm X 1.25mm from later model 850 or 960 X 2

However, on FCP it shows these https://www.fcpeuro.com/products/volvo- ... 3-5-987498 and are listed as, "fitting all volvos."

I currently already have the later style tensioner installed on my 1993 (had no option at the time) and noticed it was a little offset on the tensioner roller (which is still the original 1993) and it was the original bolts I used simply reinstalled. I assumed this offset was simply due to it not being the correct tensioner roller and would sit proper on a later style tensioner roller. Is this correct or will using the original tensioner bolts continue to cause this issues even on the later style roller?

tl;dr

1) Can I simply drill out the sleeve on later tensioner roller and use my original 1993 tensioner roller bolt, or do I need the custom (from bolt shop etc) longer bolt that listed in linked conversion post?

2) Same with tensioner bolts: Do I need to find and order the bolts you listed in your convert post or will the bolts I linked from FCP work the same (you list 40mm needed theirs appear to be ~53mm). Or alternatively, can I simply re-use the original 1993 tensioner bolts from my vehicle on the later style tensioner (as I am currently already doing) and it will sit/work properly?

I greatly appreciate any further help/clarification you all may be able to provide!

Thanks again!

[afranke]

You’re seeing a few different fasteners get conflated. On the 850 timing setup there are three distinct things:

1. Hydraulic tensioner body bolts (2x): these fasten the hydraulic unit to the block. They’re M8×1.25 and the torque is 25 N·m (18 ft-lb), then +30° per Volvo. The later/wide-belt lever/stack is thicker, so you typically need the longer ~40 mm length here; the early ’93 bolts are ~35 mm and can leave marginal thread engagement. Volvo’s catalog shows both 35 mm and 40 mm lengths for this group (examples: 982797 = 35 mm, 988179 = 40 mm). The “M8×53.5 fits-all-Volvos” bolt (Volvo 987498) that FCP lists is too long on P80/850 unless you shim it; it’s a generic service bolt used on later platforms (see fitment tab: https://www.fcpeuro.com/products/volvo- ... 98#fitment ).
2. Tensioner roller pivot bolt (on the lever): this is the Torx bolt you access from the wheel well (T45 head). It threads into the lever, not the block. Torque spec for the pulley/roller bolt is 40 N·m (30 ft-lb). You reuse this bolt when you swap to the later, wider tensioner roller (Volvo 9135036), no custom M10 needed. The T45 detail is shown in many 850 belt write-ups/videos, and Volvo publishes the 40 N·m pulley-bolt spec.
3. Fixed idler roller bolt (into the block): separate from the tensioner. The idler itself for 850s is 9146258 (various suppliers list it across the early/late break), and Volvo’s parts page shows the breakpoints by engine number (ENG ≤ 131154 for the early kit vs ≥ 131155 for the later/wide-belt kit). That’s why some threads mention different hardware, people are mixing the idler bolt with the tensioner hardware.

You put a later-style hydraulic tensioner on a ’93 but kept the early (narrow-belt) tensioner roller. That will sit off-plane. Fit the later/wide-belt roller (9135036) on the later lever and the belt will track in the middle. Volvo also sells thin distance shims for the hydraulic tensioner stack (1271851/1275047) that are used to fine-tune the offset, a handy sanity check if you need a hair more alignment.

tl;dr

1. Don’t drill anything and don’t chase a custom bolt. Install the later tensioner roller (9135036) on the later lever and reuse the existing T45 pivot bolt. The pivot bolt size isn’t your constraint, the roller/lever offset is. Torque to 40 N·m.
2. Use M8×1.25 with ~40 mm thread length for the later lever/stack (Volvo example 988179). Your original ’93 bolts (~35 mm) can work but often leave poor engagement and can let the unit sit cocked, exactly the “offset” you noticed. The FCP bolt 987498 (M8×53.5) is a generic Volvo service bolt and is too long on an 850 unless you add thick washers; it’s not the correct length for this application. Torque is 25 N·m + 30°.

[Volvebaker]

You’re seeing a few different fasteners get confla.......

Thanks for the response! Just to reiterate and doubly confirm:

The only thing I need to convert my OG 1993 850 to to the later style wider belt, adjusted water pump, tensioner and tensioner roller is:

1) The later model wider belt. (already obtained)
2) The later style, ever so slightly wider/offset tensioner. (already obtained and currently installed)
3) Water pump with the VERY slight position of gear. (already obtained)
4) (2)x 988179 bolts for the later stayer tensioner, I currently have installed with 1993 bolts
5) the LATER style tensioner roller bolt (T45 pivot bolt) will, "plug and play," into my 1993 Volvo despite the roller looking different than the 1993 model as well as and OG bold being a hex head.

Perhaps it was additional changes I was misinterpreting from the 960 conversion I referenced, and it is more simple on a 850 conversion to later style.

Thank you again for the response and further clarification. I have a TON planned for this job so I want to ensure I'm not hung up on something as silly as having incorrect timing related bolts.



tl;dr only thing needed, other than later style components, to convert a 1993 850 to later timing is (2)x 988179 bolts for the tensioner everything else is plug and play from later models to 1993?

[afranke]

Short version: yes, aside from the later-style parts, the only hardware you need to add is two M8×1.25×~40 mm flange bolts for the hydraulic tensioner body (Volvo 988179). The T45 pivot bolt for the tensioner roller is plug-and-play, no custom M10 needed. For best belt tracking, also use the later idler roller that matches the wide-belt setup.

Checklist to confirm:

• Later 23 mm timing beltm you’ve got it. (Most later kits list “from engine #131155”.)
• Later-style hydraulic tensioner + lever – you’ve got it. Torque the two body bolts to 25 N·m + 30°.
• Water pump: if your kit included the pump that pairs with the later setup, you’re covered. (Kits keyed to the later engine # include the right pump.)
• (2) bolts for the hydraulic tensioner body: use M8×1.25×~40 mm (Volvo 988179). Your original ’93 bolts are shorter; the common M8×53.5 (987498) that FCP lists is too long for this location on an 850.
• Tensioner roller pivot bolt: reuse the standard T45 pivot bolt with the later/wide tensioner roller (Volvo 9135036) as it threads right in; no drilling and no custom M10.
• Idler roller: use the later idler that matches the wide-belt setup (9146376 / 8630590) rather than the early 9146258 (which was for engines up to ≈#131154). This prevents the slight “offset” you noticed.

That “offset” you saw came from running the later tensioner with the early (narrow/offset) roller. Once you fit the later roller (and the proper 40 mm M8 bolts on the tensioner body), the belt will track correctly. If you want numbers for the pivot bolt torque, Volvo service info puts the T45 roller bolt around ~30–40 N·m depending on year; I just snug it carefully with a short ratchet given the access.

tl;dr: Later belt + later tensioner/lever + later rollers (tensioner roller 9135036 and idler 9146376/8630590) + two M8×1.25×≈40 mm (988179) bolts for the tensioner body. Everything else is plug-and-play.

[Volvebaker]

Short version: yes, aside from the later-style parts, the only hardware you need to add is two M8×1.25×~40 mm flange bolts for the hydraulic tensioner body (Volvo 988179)......

Can’t thank you enough, friend!! I will get those bolts ordered from FCP (988179) and plan to do all the work when our weather cools a bit more down here!

I plan to also order and replace the inner timing cover with the later style (21435040) as not only is my
original not directly compatible with the later components, it is also cracked and open to elements on the bottom edge.

I also need to replace the radiator, which has a slow leak, with the new one that I’ve had sitting waiting to confirm everything timing before I did that, as I want to
do it all at the same time. Also plan to service the PCV system once again when I have all this torn apart.


Thanks again @afranke !! You’ve finally, and definitively, cleared up the confusion I had concerning this conversion from all the research I’ve done!

[Volvebaker]

The T45 pivot bolt for the tensioner roller is plug-and-play, no custom M10 needed. For best belt tracking, also use the later idler roller that matches the wide-belt setup.

@afranke Unfortunately, I misunderstood what you originally posted. The T45 bolt is NOT plug and play and the new roller’s pivot bolt bearing sleeve appears DOES require to be drilled out and a specialty bolt or thread insert converter for the block to be found.

I guess there was a misunderstanding in what I was referring to as I was referencing the bolt that secured the tensioner pulley to the block. Which, see photo. is a smaller size on later models than the ‘93.

Going to have to let it sit leaned on the jack stands until next weekend and hope this week I find time to get to a machine shop to drill this out, or locate a reducer of some kind. Oh well, so it goes. Hopefully this will at least help people in the future...

UPDATE: Ordered some 20mm m10 to m8 reducer inserts, mentioned on thread linked in OP, and will update on how they work out for future reference. Didn’t really want to go to the hassle of drilling out AND sourcing a proper longer bolt with right shoulder length etc.

[Volvebaker]

Well, the reducer inserts came and worked like a charm to make the later style bolt screw right into my block.

However, when I snug the tensioner pulley down, it does not move freely on the sleeve/bearing. I cannot for the life of me figure it out.

It’s drawing down on the frame of the lever and it doesn’t float like it should, it seems like maybe I’m
missing a piece on the bottom that presses on the sleeve and that pushes on the block to keep the frame from tightening to the block and allow it to float on the bearing as it should.

I stacked a bunch of washers up on the bottom and achieved the floating tensioner pulley, with a tighten bolt to block, but it wants to slide back and forth a hair doing it like this, and I’m sure it’s not proper.

Anyone have any ideas at all? Thanks

[Sveedy]

It's hard to say without seeing exactly what you're dealing with, but would a solid bushing or small piece of pipe do what you want ?

[Volvebaker]

It's hard to say without seeing exactly what you're dealing with, but would a solid bushing or small piece of pipe do what you want ?

Yes that’s exactly what I’m thinking, but I’m trying to understand if I’m indeed missing something on the rear side of the pulley, if it’s just a defective lever frame, or if there IS something different about 1993 that’s causing it not to work.

I just don’t see how else this is supposed to work though, as you’re always going to be tightening against the lever frame and that’s going to cause it to not move freely. By comparison, my original ‘93 lever sleeve goes in on the rear side and sticks out a hair above the lever frame and, as such, the sleeve presses against the block and not the frame and it moves freely even when tightened down.

Hopefully you can see what I’m describing by those photos. It is just not making sense to me how this would work even on a proper later year model. If you’re not pushing on that sleeve you’re going to be pushing on the lever frame and it’s going to tighten against block and not move freely.

Thanks for the response!

[Volvebaker]

UPDATE: Went to a local old school Volvo parts place, a favorite of mine, and was able to confirm: I was sent AFTERMARKET CRAP.

Picked up an OEM Febi lever. The bearing sleeve should come further down and have a lip that sticks out the rear side. On this lip the washer presses so that it does not press against, and tighten on, the lever frame.