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Disco 2 Rattle

Discussion in 'Land Rover Discovery' started by Intestinalworm, Oct 14, 2020.

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  1. Intestinalworm

    Intestinalworm Active Member

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    2003 Disco 2 Td5 with A/C and ACE

    Okay, changed serpentine belt - replaced original Contitech belt (17 years old, but perfect when I removed it!). Anyway, new Gates belt popped on - went on without issue; keeping the "Benjamin Button" Contitech as a spare! I didn't change the belt tensioner (original belt tensioner and it seems fine), in fact, all the pulleys looked and felt fine when I checked them, except the A/C clutch pulley - I decided to pop a new bearing in that one. Everything looks fine in operation, but there is a noticeable vibrating "tinny rattle" from somewhere near the front behind the bumper bar it sounds like? Sounds like a piece of sheet metal vibrating a little!

    I was thinking about taking the belt off and maybe the viscous fan as well, and then starting the engine from cold for a minute or so to see if the rattle is still there? That way I can tell if it's a pulley or the tensioner that's causing the noise?

    Any ideas?

    [PS I have removed the acoustic shield and the fan cowling separately and they aren't the cause of the vibrating rattle sound. The turbo heat shield is also well secure.]

    [PPS Noticed the Gates belt is listed as 1888mm long and the original Contitech was 1870mm.]

    Now, thinking a second option might be to put the old Contitech belt back on (18mm shorter) and see if the rattle goes away? If it does, then I probably need a new tensioner??
     
    Last edited: Oct 14, 2020
  2. MJI

    MJI Well-Known Member

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    I would replace tensioner anyway, mine went and took out the alternator.
     
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  3. JUKE179r

    JUKE179r Well-Known Member

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    I agree with @MJI . If the tensioner unit has never been replaced, go ahead and replace it. Preventive maintenance. :D
    On my V8 belt tensioner I found a large crack on the plastic pulley.
    [​IMG]
     
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  4. MJI

    MJI Well-Known Member

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    Mine lost all spring and the slipping screwed the alternator
     
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  5. Hellastony

    Hellastony Active Member

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    +1, replace the tensioner anyway, they fail at about 120k miles generally, and although you can replace the bearing, the spring must be weakened by then.
    I would also ensure you have an original Contitech belt, many others do not have the ridges on the reverse to help them grip and therefore slip. In addition if the extra length is the rattle problem, you will have resolved it. Try replacing with the original Contitech, and see if you still have the rattle. Then buy a genuine Contitech, most others are not as good.
     
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  6. Intestinalworm

    Intestinalworm Active Member

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    Thanks for all the input! Got me worried now! Don't like breakdowns and big unexpected spends!

    Searched and searched for a Contitech belt over here (Australia) - no luck at all. Harder also finding belt of the right size for both A/C and ACE. Dayco or Gates were the options - bought a Gates: good looking belt and highly regarded like the Conti from what I read on forums - really can't tell apart from the Conti really (apart from slight length increase and logos).

    I changed the belt in the first case purely for preventative maintenance - there were no issues (noises or running problems) and the Conti belt itself was surprisingly in great nick when I took it off - no visible faults (small cracks) at all after 13 years!

    The thing I did notice is that the spec for the Gates belt is 18mm longer (almost 2 cm) - this was also visibly noticeable when I stretched them both out alongside one another. With the Gates belt on there is no squeaking or squealing and there is no noticeable difference in play (feels tight), however, I guess the original tensioner is now being asked to pull a little more to keep the belt as tight as it did with the Contitech?

    So, pressed new bearing into A/C clutch pulley and put new Gates belt on. Checked all pulleys - they seemed fine - no lateral play.

    All good apart from the NEW rattle sound (sounds like a flapping piece of metal - but no obvious issues with front panels). Rattle is noticeable in the background and becomes more prominent when the engine is revved a bit; can't say I notice it inside the car when driving though.

    So, reading all the above, maybe:

    - Test with Contitech belt back on again?
    - Test from a cold start with NO BELT ON at all for a minute or so to see if there is a rattle (just in case rattle is not related to belt/tensioner/pulleys)?
    - Buy a new tensioner in any case?

    Might just get a new tensioner either way to be safe (didn't like the look of that crack I saw in a previous reply post!) - probably won't go LR Genuine though - bit pricey for what it is!?

    Any further thoughts?
     
    Last edited: Oct 15, 2020
  7. ronsealdeath

    ronsealdeath Sagging Member

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    If you remove the tensioner, dont lever it off the block or you will snap the dowel on the back. Gentle tapping and penetrating oil between it and mount is the way forward
     
  8. Intestinalworm

    Intestinalworm Active Member

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    Okay, haven't noticed the sound the last several days! No squeaks or squeals at start-up or ignition off, no tinny vibration sound (like rattling piece of sheet metal or unsecured body panel), so happy in that respect. Don't hear, feel, or see any problems with the the pulleys, harmonic balancer or belt: took the new belt (Gates) off again and can't hear any grumbling pulleys or notice any lateral or end play. Conclusion, maybe because the Gates belt is 21mm longer than the original Contitech it took a wee while to "bed in" (1888mm compared with 1867mm for the original Contitech)???

    Inspected the original tensioner (17 years old), takes a bit of effort to move so assuming spring is still good, and couldn't see anything visually (had to use a telescopic mirror) - looks okay to me.

    Didn't want to remove the tensioner in any case as I believe it is held on with a 12pt (bi-hex) bolt and I only have 6pt sockets. (Why use a bolt like that?)

    Might just monitor then before I spend money and time fixing problems that are no longer there?
     
  9. Intestinalworm

    Intestinalworm Active Member

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    2003 Disco 2 Td5 auto

    Okay, confirmed again - no tinny rattle when idling anymore - all good, however, yesterday evening I reversed up a driveway with a little bit of an incline and as the rev's went up there was that tinny rattle from the front of the engine bay again?! As I said before, not loud, but certainly noticeable - sounds like a rattling piece of sheet metal (a sympathetic vibration sound) - seems to be low down somewhere in the front passenger side of the engine bay. I had the original engine mounts replaced with new LR Genuine engine mounts around 7 years ago. Thing is, the vibration sound originally came about when I changed the serpentine belt, but of course it could be totally unconnected? Got a 14mm 12pt socket today so I can remove the tensioner this weekend and inspect. Might replace the tensioner (original) for piece of mind, but the belt tension looks good and there is nothing as yet observable to the eye! Rattle not there (not noticeable) at idle or during driving - only when reversing up the driveway when the revs go up.

    Got me stumped for now.
     
  10. Stanleysteamer

    Stanleysteamer Well-Known Member

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    There are small inspection hatches under each wheel arch. towards the front.
    Could one of them have come a bit loose? Accessed from under the wheel arch.
     
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  11. Intestinalworm

    Intestinalworm Active Member

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    Okay, will have to have a look - sounds like sympathetic vibration. Incidentally I was just reading and someone mentioned a dump valve! Apparently it's under the front passenger wheel arch and just below the air box - not quite sure what it's for, but I might have a look when I'm checking there!
     
  12. Stanleysteamer

    Stanleysteamer Well-Known Member

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    If I am understanding you you may mean the little valve at the bottom of the airbox designed (badly) to allow water to drop out thriough it and it is plastic.
    I had to think a bit there as the normal meaning of "dump valve" is something some people attach to a turbo to help it spool up faster or summat.
    I'll find a link and put it up https://en.wikipedia.org/wiki/Blowoff_valve
    and as you can see they are only used on petrol engines with a turbo.;)
     
  13. Stanleysteamer

    Stanleysteamer Well-Known Member

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    Oh, and while I am at it, I used the inspection hatches to find out and cure a leak caused by chafing. there are loads of pipes, both sides, that need to be protected from one another and it is possible that not only will you be able to use this opportunity to protect stuff, you may even find a metal to metal contact that is causing this rattle.
    I lost steering fluid due to this so it is well worth checking.
     
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  14. Intestinalworm

    Intestinalworm Active Member

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    Didn't even know about this - will check the inspection hatches! Thanks for the tip!
     
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  15. Andy Warren

    Andy Warren Active Member

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    Hi, have you checked the exhaust manifold cover as these are prone to cracking/breaking especially the rear fixing.
     
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  16. Intestinalworm

    Intestinalworm Active Member

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    Thanks for that. Yeah, checked the turbo shroud and had a good look at the exhaust manifold - can't feel/see any (obvious) issues there. Sound is lower down in the engine somewhere at the front. I'm busy with other things now and driving the other car - stripping down the washing machine to install new tub bearings now that I'm an expert at changing bearings!o_O Just got a 12-point socket in the mail to take the tensioner off, so will do that fairly soon. Sound (sympathetic vibration sound, like piece of rattling sheet metal) started straight after I changed the serpentine belt - I kept the original tensioner. There is no rattle when driving out on the road. So, I'll pull the tensioner off and check it and then follow-up on some of the other advice posted here including the inspection ports under the front wheel arches.
     
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  17. Stanleysteamer

    Stanleysteamer Well-Known Member

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    This couldn't be something as simple as a splash guard on a brake calliper could it?
    The obvious thing is that is started immediately after you did something, so that is the obvious place to look.
     
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  18. Intestinalworm

    Intestinalworm Active Member

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    The original Contitech belt is about 2cm shorter than the Gates. Will remove the tensioner first and at least check it visually and then might put the old Contitech belt back on and see what happens? Will also check wheel arches! I did also take the front left wheel off to check brake pad wear, but the mud guard seems firn - can't find anything obviously loose so far? Later this week I'll remove the tensioner, try the old belt and try and eliminate things one by one.
     
  19. Stanleysteamer

    Stanleysteamer Well-Known Member

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    Good move!
     
  20. Intestinalworm

    Intestinalworm Active Member

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    I made a short recording of the intermittent background engine sound (tinny rattle). It was recorded on my phone but is a ".m4a" sound file extension - can't upload here (not a recognised extension?). Any suggestions?

    New Dayco tensioner fitted with the new Gates belt! Guess I'll try and put the old Contitech belt back on again (slightly shorter in length) and see what happens when coupled with the new Dayco tensioner. Could be complete coincidence, but the sound only appeared originally when I put the new Gates belt on with the old LR, 17-year-old tensioner (now replaced with new Dayco). I wanted to change the old tensioner as the bearing was a little scratchy.

    Change gears (1-2-3-D-N-R-P) on auto box while at idle and the background rattle sound remains.

    Will have to persevere.
     
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