SNAP!!

58A - 71E · Post by **58A - 71E** » Fri Jun 01, 2007 10:32 pm

I'm sure many of you will have read with interest James' - (hot66) thread on chain tensioners (and with more than just a passing thought of 'please not mine')
http://www.ddk-online.com/phpBB2/viewtopic.php?t=14373

Well a couple of days ago (bringing my new born son home from hospital) I started to hear a noise and a chain of events unfolded not unlike this....

hot66 wrote:
This time though there was a new noise ... a loud ticking style of noise coming from the rear right of the engine whilst on tick over. The noise sounded like it was a loose tappet.

I quickly checked the valve clearances but the noise was still there. After a good 15 more minutes of listening I decided it sounded like it might be the chain tensioner......

...Whlist proding around the cams Mike also noticed that at some point in my car’s past the cam pulley had been put on back-to-front which in turn has stretched the chain.

The result of all this is Mike is fitting new cam pulleys, new timing chains, new ramps , new 930 style mechanical chain tensioners with safety collars

except mine was on the left, so today I also tried to adjust the valve clearances with no success and thought I'd open 'er up and take a peek at the chain tensioners (with James' thread in the back of my mind) ... well I found this little thing floating around

....

which didnt look good especially when I could see this behind the chain (temporarily removed the tensioner)....

Same thing - looks like someone in the past has installed the left cam pulley on back to front - chain has stretched, jumped off the bottom ramp(after it broke in two) and tried to grind itself back through into the crankcase (the shiny bits of metal behind the bottom ramp)

Now I know where all the metallic sludge and fuzz on my drain plug has come from

Funny thing is this must have sounded terrible when it was first done, maybe enough Italian tune ups ground away the offending metal

and it quitened down, but in my ownership I've never heard a thing, until now.

So looks like I'm also going to need new cam pulleys, new timing chains, new ramps , new 930 style mechanical chain tensioners with safety collars....
I take some concellation though in that...

hot66 wrote:The engine was coming out of the car so why not do some of those other jobs at the same time I thought

So on my shopping list :

New rear back box
New Clutch
Rebuild throttle bodies
Replace damaged CV joint along with all CV boots
Replace leaking engine seals
Repalce leaking gearbox seals
Remove ‘rally timing device’ from gearbox

Got a new stainless back box and heat exchangers,

installed new clutch 3,000 miles ago

and fitted new drive shafts,

already changed all seals on gearbox and filled with magic swepco

,
hmm need to sort a couple of engine seals...

and dont have a rally timing device fitted...

Just hope the throttle bodies and injectors are alright..

hot66 · Post by **hot66** » Fri Jun 01, 2007 11:49 pm

sorry to hear

At least you caught it before any serious damage could occur.

Remember to bleed the tensioners before fitting them. On my car , we couldn't fit the safty collars as the new chains are quite tight and not enough of the tensioners shaft is exposed to clamp them to. As the chains stretch over the years I'll install the collars.

impmad2000 · Post by **impmad2000** » Sat Jun 02, 2007 9:13 am

Looks familiar to me too. The ramp inside the ccrank case lower left side had disappeared altogether !!
look at the state of the pins !!

Is it the pulley on the end of the cam that had been fitted wrong ?
I am going to get the tensioner pivot arms bushed in phosphor bronze bush. Has to be worthwhile if re fitting the old tensioner arms.

Cheers
Tim

Gary71 · Post by **Gary71** » Sat Jun 02, 2007 10:14 am

Must pull my covers off this winter....

This seems to be a recurring theme!

58A - 71E · Post by **58A - 71E** » Sat Jun 02, 2007 12:52 pm

Tim - yes it is the left hand cam pulley that is on back to front - it should have the cup of the socket facing outward - not the same as the right - which mine is. Interesting about the pivot arms, read the same in the Dempsey book, although mine show no signs of wear at all.

James what did you have done with yours?

Tim/James - who did you use for parts?

Cheers

James

hot66 · Post by **hot66** » Sat Jun 02, 2007 1:03 pm

we didn't rebush mine.

For parts I used Mathew @ type911 . Prices are good and I have been extremely happy with the service

impmad2000 · Post by **impmad2000** » Sat Jun 02, 2007 1:10 pm

58A - 71E wrote:Tim/James - who did you use for parts?

I bought the clamp collars from pelican, The Gasket and ramps from Berlyn Services. I've not yet bought the 930 style tensioners, but will probably go to Type 911 for those.
On the pivot bearing , one side had obviously started to pick-up material from one surface to the other. It looked kind of scabby ! dissimilar metals cannot do this, hence the bushing. I reckon this is had started to do this 'cos the tensioner had gone slack and the chain was flapping around and hence moving far more on the pivot, hence the material transfer. It could have siezed, and failure could have snapped the tensioner pulley !
Gary, with your luck I'd recommend you check sooner rather than later !!
Cheers
Tim

Guest · Post by **Guest** » Mon Jun 04, 2007 9:16 am

Hi Guys, I'm a bit confused, are 930 style mechanical chain tensioners with safety collars different to the carrera oil fed tensioner update. I'd like to do the modification for peace of minds sake, but am not completely clear as to the best solution if there is in fact more than one option?

Adam

impmad2000 · Post by **impmad2000** » Mon Jun 04, 2007 11:04 am

Oil fed tensioners was always the way to go. But This solution is not as permanent a fix as previously though, as these too have started to fail. It is now beliecved that the uprated 930 mechanical tensioners offer at least as good a fix as the oil fed ones. And you dont need the new covers and pipework.
The take-up of 930 machanical and Oil fed seems to split on DDK !
Cheers
Tim

hot66 · Post by **hot66** » Mon Jun 04, 2007 11:35 am

the advantage of the 'tradition style' is they are not oil pressure dependant ( remember at low revs the oil pressure in teh engine is not that high & its at low revs when the chain can slap about) and you can fit the safety collars to the traditional style. You can not fit the safety collars to the pressure fed tensioners.

With the safety collars, even in the worse case scenario of the tensioners failing the safety collars will prevent the tensioner colapsing & teh chain jumping off the cam gear. That security for me over rides everything else

All imho

fourteener · Post by **fourteener** » Mon Jun 04, 2007 1:20 pm

The 930 tensioner is very similar in appearance to the 911 tensioner but has the 930 part number cast on the body. I have one 911 + one 930

-but no evidence of a failure

From memory the 930 type has a pin that you remove after fitting and the piston springs into place -the 911 tensioners need a special holding tool (or a cable tie as I have seen elsewhere) to compress the piston whilst fitting.
I have a picture of the 930 tensioner but not at work -I'll post later if no one else has.

-James

Guest · Post by **Guest** » Mon Jun 04, 2007 1:31 pm

Thanks for answering my question guys. So I guess the 930 type with the safety collars would be a safe easier solution and, looking at the price of the Carrera type, hopefully cheaper too. Anyone know where these are readily available as I don't see them listed on type 911, only the oil fed type or mechanical?

Thanks in advance

Adam

Guest · Post by **Guest** » Mon Jun 04, 2007 1:33 pm

Or in fact do I just require the safety collars?

fourteener · Post by **fourteener** » Mon Jun 04, 2007 2:12 pm

You could get a rebuild kit for both your 911 tensioners and then add the safety collars.
How stretched are your chains? I can't see how close the 'pivot arm' is to the chain housing. If the chains are long enough (as mine are) then you may want to replace these to as there's more chain to flap around if anything goes.
I'm in two minds about this as there's some good info on pelican about the new chain rapidly wearing out the original lay-shaft sprockets -there was a line of thought that chains/cam sprockets/lay shaft sprockets should be replaced as one unit because of this (but involves a case split

) -or find some used chains that have less stretch than your own pair

58A - 71E · Post by **58A - 71E** » Mon Jun 04, 2007 3:36 pm

Adam - I totally agree with Tim and James' comments - I went with the 930 tensioner and collar as I am just not convinced that oil fed ones are as bulletproof as some claim - more bits to go wrong etc - and the security with the collar does it for me.

The originals (part number 901 105 519 00) had done over 120,000 miles without a disastrous failure; my problem is more that some idiot has put the left hand cam pulley on back to front hence damaging everything in there and hence my changing the lot.

The mechanical ones listed on type 911 are the 930 ones, I think the 901 is NLA - just ordered mine from them at £120 each
Cheers

James