K Series alternator torque settings

[john milner]

What should I torque the three bolts that hold an alternator on a K Series? Main swingy one and each end of the bracket.

Haynes suggest 25Nm for all of them but the Rover manual says 45Nm for a clamp (aka main swingy one) and 25Nm for a bracket.

My money is on Rover but I would rather get it right and someone has made a typo.

[SM25T]

Having adjusted alternator belts on tours . .. they are generally FT !! Never torqued them on the roadside .. . just as tight as can be achieved with a spanner.

[Jonathan Kay]

DVA's advice.

Jonathan

[revilla]

Yes I looked these up just now and found exactly the same as you - widely differing answers depending on where you look! I think SM25Ts advice is more like what I've always done in practice, a good hard pull on a spanner. None of them have given problems. Don't under-tighten them though or they will shear the bolts. I've seen two where the inner bolt for the adjuster arm (where it bolts into the front of the block with a spacer bush) had sheared off flush with the block (one on a block I bought from Oily that came with half a bolt pre-installed, one on a friend's recently). I was watching a video of my spare engine when I revved it up rapidly and every now and again the camera caught a frame where the top run of the belt was so slack it formed a clear S-shape; the bottom run must have stretched by the corresponding amount and the tension load taken up by the adjuster arm must be enormous. I was very surprised, but it explains the sheared ones.

[revilla]

You can just about see it bowing out

but it's not the clearest.

[john milner]

I'm not keen on guessing tightness any more as I have had too many problems with sheared bolts. I'll go with 25Nm for the bracket and see what 45Nm feels like for the clamp.

For years I tightened wheel nuts by feel but when I tried torqueing them I was very surprised at how little they need.

 

Shearing to date:

Sump plug stripped sump thread. Now tapped to 15mm (no metric washer available. I'll try 9/16" next oil change unless I get lucky and find a 19/32").

Alternator bracket bolt found to be snapped about a year ago flush with the block. I had to drill out the centre with a Dremel and ram a Torx bit in to get it out.

Alternator adjuster bolt head fell off when trying to undo it a couple of days ago. Stud is now solid in the alternator and will not budge so I have to adjust by pulling on the alternator.

Upper timing cover/water pump pillar bolt found to be sheared. (Thanks again for the replacement Andrew).

[Piers300]

 

 

I over tightened the top alternator bolt a number of years ago on my K R300 and cracked the mounting bracket. It sounded like the little ends had gone. 

 

Piers

 

 

 

 

 

 

[john milner]

45Nm for the main bolt felt right but if it is right is another matter.

[revilla]

There should be a sliding bush in the front of the alternator top mount - the bracket itself shouldn't be taking the strain as you tighten it, the bush should slide through the bracket until the bolt is just pressing the bush against the alternator. I guess if it was stuck or something the tension would go onto the bracket.