1998 v70 xc changing to hydraulic tensioner. Bolt sizes?

superfeed · Post by **superfeed** » 25 Dec 2014, 19:30

Good People,
Merry Christmas!
I've been blessed with a couple of days off and thought I would get back to the engine swap in my 98 V70 xc. The replacement engine was due for a timing belt change and I decided to use the older style hydraulic tensioner as I've read it is more reliable and easier to install. I forgot to order bolts for it and the mechanical tensioner setup uses different fasteners.
Could any of you kind souls tell me what size those two bolts are?
Thanks,
John Gregory - Portage, MI

superfeed · Post by **superfeed** » 25 Dec 2014, 20:26

I found 2 different part numbers listed (alternate?) for the engine 982797 (M8 x 35mm) and 982798 (M8 x 40 mm) They are called flange bolts. Will check NAPA tomorrow. Is there a good reason for me to go to the dealer for this fastener?

Thanks,
John

Post by **mecheng** » 26 Dec 2014, 09:05

Who said it is more reliable. The mech tensioner has the pulley and tensioner all in one. Easier to replace, cheaper. My tensioner started to make noise when cold and I replaced it but it didn't completely fail

Post by **JRL** » 26 Dec 2014, 10:03

You can't just put what you want in, it must match the one that's in there now

Post by **precopster** » 26 Dec 2014, 14:09

Belt size differs 142 tooth for mechanical vs 148 tooth for hydraulic. Also the inner cover is a different part number. The steel belt protector will also need to be sourced.

I adapted an 850 block to mechanical for a 99 V70 application 3 years ago and all I did was tap a thread for the mech tensioner and swap the inner and outer timing covers. I used the 99 head. You should find all the threads there for the conversion.

However if you use OEM Volvo parts in mechanical setup it is far more reliable with increased service life (105K miles vs 80 k miles) between changes. Also with hydraulic you must use an Aisin tensioner which doubles your cost per timing service.

superfeed · Post by **superfeed** » 26 Dec 2014, 16:23

Thank you all for your input.
I purchased two M8 40mm bolts at the local auto store.

I had to fabricate a pliable spacer for under the bottom bolt of the tensioner to keep the back cover from rattling. There was a placeholder flange bolt (with the mechanical setup) that took the place of the bottom hydraulic tensioner bolt. the only purpose was to secure the inside cover from rattling.

The belt is the one that came with the kit I ordered and the timing seems to match up quite well.

All of the threaded holes were already there on the front of the block for either tensioner setup. It looks like all the covers will work.

There was much previous discussion on this site and several others which I read regarding the tensioners. The published Volvo guidelines for replacement intervals didn't seem to correlate with what is happening in the field. I suspect it was simply cheaper to make the mechanical tensioner, which I assume is why Volvo changed in the middle of the model year for 1998. I know the hydraulic system seems much more robust (physically) in comparison.

Now to try and remove the passenger's side front drive shaft.

Thank you everyone!!!

Post by **precopster** » 26 Dec 2014, 16:30

Mechanical tensioner system takes a TB331 belt with 142 teeth. Mechanical takes a TB252 belt with 148 teeth.

You may have lucked out with the combinations of timing system on an older head however do your research on belt sizes. It should be VERY hard to get a belt on if it's the correct belt for your setup. Many 98s had mechanical even if they didn't have the newer heads so your setup may be exactly what the factory did during transition.

The older heads are actually taller so this may be why the longer belt works