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Author Topic: Oh oh.. Timing chain  (Read 617 times)

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April 11, 2018, 07:44:19 AM

themoog

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Oh oh.. Timing chain
« on: April 11, 2018, 07:44:19 AM »
This morning my wife got in her 4.4  to go off to the office. When she started the engine I heard - for the first time on hers- the timing chain slapping against the guides for a second.
Having shelled out 2K on mine a couple of years ago I'm not keen on doing that again.. Mine broke at 150k but hers is only on 90k with fsh too.
Is there a way to prevent the initial slack in the tensioner on start up as that is when the guides get broken? I seem to recall an updated tensioner somewhere ( I'll have a search in a while) and if so, has anyone installed one?
What else can I do to prevent /delay a catastrophe..

April 11, 2018, 09:02:27 AM
Reply #1

IanP

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Re: Oh oh.. Timing chain
« Reply #1 on: April 11, 2018, 09:02:27 AM »
Someone on here has a pre lube system fitted which should help,  cant remember who it is though.
My chain tensioners snapped while chasing a Porsche, up till that point they had been fine on start up....

April 11, 2018, 09:58:21 AM
Reply #2

themoog

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Re: Oh oh.. Timing chain
« Reply #2 on: April 11, 2018, 09:58:21 AM »
Just ordered a new tensioner from BMW at £80. I remember mine had very little spring travel in it but a new one has a longer spring to prevent slack before oil gets in it.

April 11, 2018, 03:12:08 PM
Reply #3

V8 00USH

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Re: Oh oh.. Timing chain
« Reply #3 on: April 11, 2018, 03:12:08 PM »
It's not just about any potential slack in the chain that needs to be taken up - it's more about the fact that the guides become brittle with age and just fall to pieces, admittedly the chain slapping on it isn't going to help but if they are brittle then there's no going back and it's just a matter of time before they fail.

Now that you have heard it you will save yourself a fortune if you just go ahead and get the guides replaced now. If you want to do it 'cheaply' then you can just literally replace the chain guides and nothing else. I reckon you'll be able to do this for under £500.

Anyway....you're lucky.....the only warning I had that there was a problem was when a strange scraping noise started coming from the left hand bank which turned out to be a piece of tensioner wedged between the sprocket and the guide cover. 100 miles (2 days) after I first heard this they all fell apart and it was clatter city!

April 11, 2018, 03:32:44 PM
Reply #4

Greydog

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Re: Oh oh.. Timing chain
« Reply #4 on: April 11, 2018, 03:32:44 PM »
Totally agree with V8 0ooush The heat cycles the engine goes through bakes the plastic guide making them brittle it also make most of the cooling system brittle as well which is why header tanks fail. The same heat cycles anneal the spring in the tensioner softening it, at cold start with no oil pressure and a soft spring you get the rattle. Your new tensioner spring will look longer but in fact your original started out looking like that.

After I had my engine rebuilt I fitted a pre-lube system to give oil pressure in the tensioner prior to starting, my effort to try and extend its life.
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April 16, 2018, 06:31:04 PM
Reply #5

themoog

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Re: Oh oh.. Timing chain
« Reply #5 on: April 16, 2018, 06:31:04 PM »
Ive just put the new tensioner in. The spring travel in the old one is considerably less than the new one.
When i started it it clattered like the like mad for a second-I thought the guides would break until oil got to it and shut it up. Phew..
Now i just need Sudacrem on all the grazes on my arm from trying to reach the chuffing thing..

April 18, 2018, 10:50:15 AM
Reply #6

lezmtaylor

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Re: Oh oh.. Timing chain
« Reply #6 on: April 18, 2018, 10:50:15 AM »
I put a new tensioner in my 94000 mile 4.4, when I compared old with new there was a lot of length difference between old and new.
HOWEVER do not attempt to unlock the new tensioner to check the length. you will not be able to lock it back in again.
I did it , and had one hell of a job refitting it as you are trying to compress the spring to engage the threads and screw in.

Silly me.

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April 18, 2018, 01:37:46 PM
Reply #7

V8 00USH

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Re: Oh oh.. Timing chain
« Reply #7 on: April 18, 2018, 01:37:46 PM »
Ive just put the new tensioner in.

I hope this achieves what you wanted it to mate and it prolongs the life of your guides. I'd still seriously consider replacing them though if funds allow at some point in the near future.

April 19, 2018, 03:58:27 PM
Reply #8

themoog

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Re: Oh oh.. Timing chain
« Reply #8 on: April 19, 2018, 03:58:27 PM »
Its definitely made a difference. The engine is totally silent when starting from cold now.