Noise after cam belt change

[muley]

Sounds like you need a new friend Jim

Now you can plan to do the NC500 clockwise next year in the Fellatio Purple

[HJ2]

[muley]

It's my friend again :slapshead

He's taken the jolly thing apart again (!)

He is finding it necessary to turn the tensioner CLOCKWISE to increase the tension. Allen key hole is at 12 o'clock now. Is that right?

He's got a fancy new 10kg weight and a block of wood all marked up to do the job properly. I'll see if he'll let me take a photo later

[Simon_P]

He is finding it necessary to turn the tensioner CLOCKWISE to increase the tension. Allen key hole is at 12 o'clock now. Is that right?

The jury is out! Iy depends which piece of the manual he believes - not wishing to be controversial let's assume that it is.

He's got a fancy new 10kg weight and a block of wood all marked up to do the job properly. I'll see if he'll let me take a photo later

Splendid! can he balance all that with one hand and take a photo with the other?

Remind him that it is done at 60 degrees ATDC crank. and not to mix up the new and worn belt tensions, as that will make him cross.

[esprit888]

Unfortunately your ‘friend’ has more work to do. When you say its apart is just the top cover off or has ‘he’ removed the crank pulley and bottom cover? If ‘he’ hasn’t ‘he’ needs to , what ‘he’ has done is incorrectly turned the tensioner pulley clockwise until it makes contact with the belt and tightened the lock nut in that position.’ He’ needs to put the spring into the hole in the block and the hole in the tensioner hub then pull the belt out just enough for him to rotate the tensioner clockwise PAST THE BELT which creates substantial tension on the belt when it is moved back in line and the hub released applying pressure to the belt from below the Center line, not above. This spring tension alone would normally be enough for a used belt and simply torque the nut on the tensioner. If it’s a new belt you need to put the Allen wrench in and turn the hub COUNTERCLOCKWISE a very small amount to obtain a tighter tension, turning it clockwise is turning it away from the spring tension which is there so that should the lock nut come loose the tensioner pulley spring will keep tension on the belt. If there is no spring tension using the top of the centreline of the hub then if it comes loose the tensioner will become looser and the belt will jump teeth with the well-known conclusion. It’s actually an identical situation on the Esprit 4 cylinder engine as it can also be installed with the tension rotation in the wrong direction. You can tension the belt, but if it comes loose pistons become very intimate with valves. Your ‘friend’ really needs to read the manual ‘carefully’ (section EC page 16). As mentioned above this is all at 60 ATDC.

[muley]

Thank you very much for that post ; it confirms what I thought - the tensioner is sort of 'upside down'

Thanks Mike (MPx)~ see below




I really appreciate your help with this. Isn,'t LEC great?

[muley]

My friend is really embarrassed. He's changed cambelts on these about 6 times and nary a problem.

I have a new guide for him

1. Re-read the manual
2. Gain access to the cam covers and remove them
3. Re-read the bl****y manual
4. Put engine to TDC
5. Look hard at the f*****g manual
6. Slacken tensioner bolt, turn tensioner slightly clockwise. Nip up the bolt. Mark up belt and
pulleys. Remove belt
7. Have a break ~ read section EC4 of the s***ing manual
8. Mark up new belt, install per manual

[Simon_P]

which creates substantial tension on the belt

That might be described as a little optimistic!

This spring tension alone would normally be enough for a used belt and simply torque the nut on the tensioner.

I believe that Lotus inserted the word "should" as in: "the spring tension alone should be sufficient to meet the tension specification". That suggest that it might not be so you aren't any further on. I suppose that you could try it and see how you get on!

what ‘he’ has done is incorrectly

I've seen very strong arguments for both ways round, and I have tried both with no noticeable difference. In practice the adjustment slips when you tighten the bolt. The only practical difference is if the bolt comes loose and if you want the tensioner to over or under tension... choose your poison.

the tensioner is sort of 'upside down'

or the right way up depending on how you look at it.

If I knew how to I would make a Reel/TikTok.... Nobody's gonna know... They're gonna know... etc

the uploaded file is empty - what? Ah the suspense ... looks like Nobody's gonna know!

[Simon_P]

Muley, that doesn't look much like 60o ATDC Crank - Nice clean engine bay though.

[muley]

Muley, that doesn't look much like 60o ATDC Crank - Nice clean engine bay though.

Fair point. Twas just a demo pic. He has a new spring on the way. Of course, the spring only comes into play when the bolt is undone or if the bolt gets loose / shears off

Weight was GBP13 from Argos.

[muley]

After a third attempt my friend (cough) has finally got the tension correct.

Note : a belt will become +used+ after a few miles only.