So when should timing chains be replaced?
 

One of the boxes is getting up in mileage. When should the chains be replaced? Probably should replace the followers too at that time.

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Internal engine parts should be throughly inspected anytime you have access to do so & replaced if excessively worn or will be before you have access again. the chain wear pads are the only exception to this rule I can think of.

When you pull your engine to bits. At 120k my engine (one case) was completely clean inside, spanking new, and completely worn out. If your thinking of changing the chains, think about the mains. <Any poor poor rhyming in this post was completely unintentional, and no iambic pentameters were injured in its writing>.

the mains?

Oh the main bearings?

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Yes, the main bearings. You'll need to split the case to replace the chains. If you go that far you might as well replace the main and rod bearings.

sounds like fun but I don't want to get too carried away.

To replace the chains, you are going to have to split the cases anyway, so why not update everything while you are in there?

Ah okay then... that's the answer I was looking for!

I thought the chains was maintainace free, is have been told...??
Or?

Everything wears out. I happened to have my engine split so I replaced the chains. I would not recommend changing them as a maintenence item.

They are maintenance free. You dont have to change them under normal circumstances for the lifetime of the engine. However, they do stretch and affect the cam timing a few degrees by the time the mileage is over 100k.

Obviously, you'd never be able to replace the intermediate shaft to crank chain without opening up the block. Mercedes sells their timing chains open so that you can attach it to the old chain, rotate the engine, install the removable link and replace the chain without removing the timing cover. I wonder if you could do the same thing in a M96?

In reality, replacing the chain guides should be more than enough!

No....................................

We have had master linked chains made in the past for our preventive procedures. The source that made these for me passed away a few years ago and I have not been able to source them.

We are now working with SSF Auto Parts and Iwis (tier 1 supplier for Porsche timing chains) to develop a mass produced version of these chains for the M96/ M97. This comes on the heels of a year where we had as many as 4 engines with chain failures here at one time to be repaired, all of them requiring full disassembly, repair and reassembly- about 11K worth of expenditure.

Currently there are no master linked chains, so the only chains that can be replaced without full teardown of the engine are the 4th and 5th chains found only on the 5 chain M96 engines, 2002 and earlier. All main timing chains require full tear down.

I am awaiting samples of the master linked chains now, once they arrive here we will develop a procedure for their installation on a fully assembled engine and begin torture testing them. These chains are not just master linked, they will be superior in other ways as well, as Iwis has different levels of timing chain quality.

Once these chains are tested I will mandate their replacement on every engine that we carry out an IMS Retrofit or other procedure on. It just makes sense to do this and I develop things to have them for ourselves, primarily.

SSF has become the leading distributor of our components to shops worldwide, they are great to work with and they are more than willing to work with us to have anything made to supply the needs of these engines. Recently this included having a new run of IMS assemblies made :-)

So yes, once developed and tested your local shop will be able to buy these from SSF and install them with my procedure. :-)

Thank you, Im looking forward to ordering some!

I also found some master links from FEBI that worked on some BMW engines, which saved us at least a dozen hours in labor. Customers will definitely appreciate saving money on timing chain replacements!

The chains used in these engines are odd in roller diameter and spacing, as well as width.. I tried everything available and nothing currently available is sized appropriately.