help!! Loud engine knocking noise... :(

[TJ 450]

Excellent, Ryan1980. The parts should be here soon.

Tim

[WGB]

Thanks Ryan.

Sounds like a good excuse for a mini WA get together.

Bill

[TJ 450]

I second that.

Tim

[13B]

If everybody brings along a set of vice-grips each you'll have that new chain wound-on in no time!

I.

[Ryan1980]

The parts arrived today!
How long do you guys envision this job will take?
I am working all day tomorrow unfortunately and sunday's my birthday so gotta do the family thing.

Perhaps next weekend whoever wants to come around and give me a hand can come?

Oh by the way, i didnt order a new chain, i figured we'll wait and see how the existing one is first.

[WGB]

What bits have arrived.

Bill

[Ryan1980]

heres my order

1161800084  Cam Oiler; Camshaft Oiler Kit; 8mm  $2.66  2  $5.32 

0001800609  Oil Filter Kit  $5.76  2  $11.52 

1160140522  Oil Pan Gasket; Lower to Upper Pan  $8.63  1  $8.63 

1170520916  Timing Chain Guide/Rail; Cylinder Head Inner, Left/Right; 172mm  $5.90  2  $11.80 

1170520816  Timing Chain Guide/Rail; Left Cylinder Head; 143mm  $4.81  1  $4.81 

1160521616  Timing Chain Guide/Rail; Left Lower; 113mm  $3.90  1  $3.90 

1160502716  Timing Chain Guide/Rail; Right Lower Curved Above Crank Gear; 135mm  $7.95  1  $7.95 

1160501611  Timing Chain Tensioner  $107.47  1  $107.47 

1160160521  Valve Cover Gasket; Left  $5.89  1  $5.89 

1160160621  Valve Cover Gasket; Right  $5.89  1  $5.89 

[CraigS]

Oh by the way, i didnt order a new chain, i figured we'll wait and see how the existing one is first.

Seems like false economy to me when you are going to so much trouble, for the sake of the additional $100.00. At least the tensioner is a reasonable price. The one for my 300b is over US$350 !

[13B]

Once its back up and running with that stuff installed and the jumped tooth(s) corrected, you'll still have a timing chain stretch somewhere in the vacinity of 8-12 degrees.

You'll then need to order the correct offset keys to bring that back to around zero (give or take a couple of degrees).  At least you can pick them up from a MB dealer and they shouldn't cost heaps.  While waiting for them to arrive I wouldn't push that car hard.

I.

[s class]

Over here in South Africa, I paid about $12 each for offset keys.  The 6.9 needed three (one cam takes two), so that's $36, which starts to stack up against the price of a new chain. 

[Ryan1980]

I wasnt aware of any of that. I thought there might be a good chance the chain hadn't stretched.
What are offset keys?

[CraigS]

Mileage on engine ?, last time changed (if known) ? All these things make up enough reasons to change it. It is a cheap investment to know it has been changed. Generally, these should be changed every 100,000 miles (160,000 km) so if you don't know that it has been changed, and when, you should.

[13B]

A quick calculation, assuming you have the original chain, or know how many km since the last time the chain was changed.

MB recommend changing the chain at 160,000km... most people don't change it until its done over 200,000km and find that it has around 10 degrees of stretch.

Like death and taxes, the timing chain will stretch as you use the car.  The only way it won't stretch is if you don't drive the car.  Based on other people's findings, I think its fair to say that the chain will stretch by about 1 degree for every 20,000km driven (200,000 divided by 10 is 20,000).  Therefore in your case its of some considerable importance to determine whether your car has the original chain (no master link) or had one replaced at sometime in its life. 

Just my 2c worth.

Either way: new chain or offset keys should help fix the problem.

I.

[TJ 450]

Getting the car running with the existing chain shouldn't be a problem. A new chain can always be fitted afterwards, providing that chain isn't stretched beyond its limit. It is actually quite a recent chain, as the heads were rebuilt (I've seen it).

Tim

[oscar]

What are offset keys?

Offset keys are pictured below.  A Woodruff Key goes into the camshaft end and locks the chain sprocket onto the camshaft.  I suppose the offset keys should be called Offset Woodruff Keys since they do the same thing as a Woodruff Key except you'll notice the two below have an offset (a lip on one side and depression on the other), this effectively changes the alignment of the chain sprocket in relation to the camshaft compared to using a zero offset key.  A zero offset (or normal Woodruff Key) is flat on both sides.

If the chain is as good as TJ says it is then you should be able to get away with using offset keys to get the camshafts aligned at TDC. 

PS, there's a few different offset keys, 2 degrees, 4 degrees and a few more I can't remember.