Strange rattle starting from cold

[drjonts]

So, getting the bulkhead side front cam cover off first thing this morning (with some wiggling and force but needed to see what was happening) revealed a looser-than-I'm happy-with cambelt.

It was possible to see a slight but definite catenary-type droop to the belt run from the pulley down to the water pump. I could just slide the belt back and forth a teeny bit on the front pulley teeth (though the belt is running true and hasn't shifted...yet) - it doesn't seem tight enough when cold.

Bit the bullet and started the car...the run between pulley and water pump was flapping and just touching the cover with the characteristic knock / rattle. Left the car ticking over and the flapping gradually reduced, knocking stopped and eventually once warmed up, seemed to be running true and obviously tighter. Revved the car and of course there were some speeds and during overrun where the belt flaps but that probably happens a bit on all cars when the belt run is in resonance.

So, I am in a quandary with less than 25k miles and 4 years since the full service was done (using Contitech belt - confirmed today) and I believe INA parts (not sure of waterpump). It rather looks like the tensioner is just not doing the job when cold but stepping up to the plate once warm. I do not know if the hydraulic part of the tensioner was done or just the wheel. Could something be up with that? Has it run out of travel for some reason?

1) Do you folks think I will have any checking and work (by an MG specialist that did the service) possibly covered by a part warranty after nearly 4 years or am I looking at simply having to do the belt service again at 25k miles and all the cost involved?

2) How many of you vote for me putting the overalls on and getting in there with a view to a 'Tactical Tippex Timing Technique Trial' and investigate just replacement of the tensioner hydraulics and wheel (but look at how bad all other things are once in there)?

Finally, I was advised not to start or drive it to the garage (about 12 miles) ...and the danger time is initial start-up and cold running. I am feeling OK about it once warm and I have been driving like it for a couple of days.

Thoughts and advice all gratefully received!

Jonty

p.s. Shame that belts and a clutch change aren't something which might be done at the same time! I guess they are a bit mutually exclusive as the engine would be hanging free!

[Salad-Dodger]

If there is slack in the belt its likely that the belt wasn't pre tensioned when the belt was fitted last time it was changed.

Years ago I used to read that the tensioner roller was set up from new and just needed fitting, but this was not correct. You need to undo the allen screw on the back plate and fit the roller, then the tensioner, leaving the pin in position. You then have to have a key both in the back plate and the locking screw. Tension the belt till the slack disappears and tighten the lock screw. Then you can pull the pin.
If the "pre tension" op isn't done the tensioner will be nearly at its end travel sooner, causing the belt to flap. Hope this helps a bit as its quite difficult to explain!

[trikey]

I would check the pulley as well as the tensioner, the pilot is the likely suspect, I am yet to see the hydraulic tensioner fail.


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[Salad-Dodger]

The hydro tensioner doesn't fail but if the belt isn't pre tensioned the hydro tensioner will have a long way to extend before it tensions the belt, then, later on, when it comes to the end of its "useful" travel, the belt will slowly slacken.


I went through this problem years ago. There was all kinds of very strange information to read about the parts and how to use them, some of it printed in Rover manuals. I remember one that gave you a suggested position of the roller in relation to the lock bolt and another that told you that it was all pre set at the factory. All rubbish though. I may have some of it still on my HD. If I find it I'll post it up on here.

[drjonts]

Originally Posted by Salad-Dodger

The hydro tensioner doesn't fail but if the belt isn't pre tensioned the hydro tensioner will have a long way to extend before it tensions the belt, then, later on, when it comes to the end of its "useful" travel, the belt will slowly slacken.

Thanks Steve - I guess this is my real fear to be honest. If that is the case, no warranty on parts would help and it would be up to the chat with the garage eh!

Originally Posted by Salad-Dodger

I went through this problem years ago. There was all kinds of very strange information to read about the parts and how to use them, some of it printed in Rover manuals. I remember one that gave you a suggested position of the roller in relation to the lock bolt and another that told you that it was all pre set at the factory. All rubbish though. I may have some of it still on my HD. If I find it I'll post it up on here.

All info. welcomed - especially if I end up doing this myself. I did some searching on here and found this INA doc. INA Instructions

Cheers.

Jonty

[drjonts]

Originally Posted by trikey

I would check the pulley as well as the tensioner, the pilot is the likely suspect, I am yet to see the hydraulic tensioner fail.

Thanks Andy. By pulley I assume you mean the wheel on the tensioner yes? Idler as well?

I guess I'm worried that something has happened that means the hydraulic tensioner has run out of travel...loose pulley that is rotating away from the correct set position...or not properly tensioned when fitted? There will only be one way to answer this eh!

Cheers,

Jonty

[drjonts]

I did some more hunting on the forum and read Gary's (Lovel) thread with interest where belt tension was thought to be tight but found to be loose.
https://the75andztclub.co.uk/forum/s...d.php?t=288425

I read Gary's words with a mixture of hope (that the flappy belt might be fine and may only need a tensioner / pulley and some effort) and despair (at having to get in there after a shorter time than expected).

Basically lessons learned are the the piston tensioner can fail enough to allow the roller tensioner to back off even further than it should. Even with the piston fully retracted and the roller tensioner butting up against the housing of the piston tensioner, I don’t think the belt would have jumped a tooth thank goodness.

[trikey]

Originally Posted by drjonts

Thanks Andy. By pulley I assume you mean the wheel on the tensioner yes? Idler as well?

I guess I'm worried that something has happened that means the hydraulic tensioner has run out of travel...loose pulley that is rotating away from the correct set position...or not properly tensioned when fitted? There will only be one way to answer this eh!

Cheers,

Jonty

Yes Jonty, the tensioner wheel, and the idler, when I changed the belts on Debs V6 it showed the same symptoms as you describe, the belt was so loose it had won part of the water pump away, not sure of how long it ran like this for but there was about 30k on since the belts were done at a garage!

[drjonts]

Cheers Andy - that is helpful.

Wow...flapping had damaged the pump! Casting or the pulley?

My quandary is ...do I get the garage involved again on this or simply trust in my home-grown spanner-wielding (for which I always thank my Dad - taught me most of what I know on tackling the car jobs)?

From what you say, am I looking at a full belt service then? Not just a tensioner / idler swap but all the bits?

Cheers,

Jonty

[drjonts]

Digging further on the forum after going through Gary's thread again and interest was peaked by Mark's (Sworks) mention of a bung/grommet in the front plate. Found Einar's (Beinet) thread again.



If I pop the front cover rubber bung out (top left of picture) will I be able to see if the tensioner piston is fully pushed out I wonder? I was hoping that it might even be a tensioner tweaking access port for just such eventualities but I'm not sure if it lines up or if you could get in there with allen keys etc.

Jonty