john milner Posted November 25, 2015 Share Posted November 25, 2015 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. Link to comment Share on other sites More sharing options...
SM25T Posted November 25, 2015 Share Posted November 25, 2015 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. Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted November 25, 2015 Member Share Posted November 25, 2015 DVA's advice.Jonathan Link to comment Share on other sites More sharing options...
revilla Posted November 25, 2015 Share Posted November 25, 2015 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. Link to comment Share on other sites More sharing options...
revilla Posted November 25, 2015 Share Posted November 25, 2015 You can just about see it bowing out but it's not the clearest. Link to comment Share on other sites More sharing options...
john milner Posted November 26, 2015 Author Share Posted November 26, 2015 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). Link to comment Share on other sites More sharing options...
Area Representative Piers300 Posted November 27, 2015 Area Representative Share Posted November 27, 2015 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 Link to comment Share on other sites More sharing options...
john milner Posted November 27, 2015 Author Share Posted November 27, 2015 45Nm for the main bolt felt right but if it is right is another matter. Link to comment Share on other sites More sharing options...
revilla Posted November 27, 2015 Share Posted November 27, 2015 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. Link to comment Share on other sites More sharing options...
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