Need new tensioner/idler/timing gear backplate bolts... from where??

Technical Area Engine, Transmission, Exhaust etc
2

Hi all,

I’m doing a timing kit on a 2000 Mk2 1.8. When reinstalling idler I found that I could get to about 44Nm (short of the 46Nm spec) but then the bolt just kept turning without holding more torque… so I quickly stopped as I definitely know what comes next from experience…

So I’m after a new tensioner and idler bolt set. Autolink list the two bolts as 997961060 and 997961045, but only sell used ones, which seems to negate the issue I’m up against. I will trying going to Mazda directly (how expensive can they make two bolts… )

Any ideas? I’m thinking of getting busy with a vernier and ordering something from Westfield Fastners, but I have a sneaky suspicion that the flat collar on the tensioner bolt is slightly different to the size one would expect on a typical bolt…?

Oddly I had the same problem with the 6 bolts that go into the backplate behind the camshaft timing gears (that covers the point where the thermostat housing meets the block). One of these actually split inside the block (!!) but luckily I don’t think it’s one that really needed since the plate still has 5 screws, but they all felt mightily soft and none could properly hold torque!

I cannot find these three bolt types on any of my typical parts websites.

Thanks!

3

The two timing belt bolt are around £4 each from Mazda with the VAT added. Similar price to Autolink when the VAT and carriage is added.

I would have no issue with the bolts from Autolink.

It appears a coincidence that you have had similar issues with different bolts on that engine.

Either someone has been ham fisted prior to this or your Torque wrench is faulty or your previous tightening has been an issue.

I have worked on this area before many times and have never had this issue!!!

4

It is a little suspect isn’t it… although what I felt was roughly what I’d expect to feel, and thinking about it each was done with a different torque wrench (one being only 22Nm and one being 46Nm, top of my small one and bottom of my big one!). I do suspect either ham-fistedness by some previous interfering person, or just bolts having not shifted in nearly two decades undergoing who-knows how many thermal cycles…!

I’m also a bit suspicious of the water pump; as I remember it, the idler bolt is actually threaded into the pump rather than the block, and it was this one that felt stretchy (didn’t dare try the tensioner bolt!). So it could actually be the water pump (which was brand new) causing issues (but not for the timing back-plate bolts!).