I never see any threads on timing chain or belt issues. Is ther no scheduled timing belt replacement on the 840ci ?

The 840 has a chain with no scheduled replacement interval.

The M60 has a double row chain and the M62 has a single row.

I have never heard of a timing chain failure on either of those motors. Regardless, I like the added security of dual chains on the M60.

I have never heard of a timing chain failure on either of those motors. Regardless, I like the added security of dual chains on the M60.

I like the extra power and security of four extra cylinders in the M70 and two extra gears in the Getrag... ;-)

You have no shame...... take all the cheapies......:stickoutt

I have never heard of a timing chain failure on either of those motors. Regardless, I like the added security of dual chains on the M60.

No chain failures BUT--

I have seen failures of the chain guide of the M62 engine. The chain, when going from the left bank to the right bank, goes down in the valley between the heads, on the M60 there is a gear at the bottom of the that "V", on the M62 there is just the guide where the chain goes around and slides on. This point has to absorb all the torque and tension of the chain as it pulls the right cam thru its rotation. Definitely a cost reduction scheme but one that has and will cause problems in higher mileage M62 engines.

I have never heard of a timing chain failure on either of those motors. Regardless, I like the added security of dual chains on the M60.

Mr. Cradick, so from my understanding, the V12's don't have the dual chains, but are they compatible (the ones from the M60) for the V12 for the added security as you were saying? Better to be safe than sorry :(

Nope, nothing is compatible from the M60 to the M70!

As the man said above apples to oranges and not even worth a second thought. For my money in the E31 V8 department it's hard to beat an alusil (for resale purposes only) M60 in the 94/early 95 cars. You have the beefier timing drive(s) larger intake plenum and chipable DME. As a base motor to start throwing money at it's the most bang for the buck IMO. It wouldn't take much to surpass the small torque advantage of the M62 and keep on goin'.

I never see any threads on timing chain or belt issues. Is ther no scheduled timing belt replacement on the 840ci ?

BMW say's that they don't need replacement. A few months ago, i put some new valve seals in my M60-motor. And diagnosed that my chains where a little bit worn. It is like a chain on a motorbike. They also need replacement after a couple of miles. I changed them! And put my cam-timing on time. Now it's fluying again:D!!

PS: BMW also says that the transmission oil is lifetime oil, yeah right!!

M70 chains are durable, never heard of having to replace them. I did have a broken upper chain guide on mine, but that was an easy fix while doing the valve stem seals and cam timing.

how hard is it to do the value seal, and cam timing

Valve Stem Seals require removal of intakes, valave covers, upper timing case cover, distributors, and about 100 other little parts. The valve stem seals themselves can be done with the engine in place - takes about 8-10 hours (with cleaning and debris removal). The timing takes literally 2 minutes

always a great help:buttrock

anything else i should replace when i do this

check the lifters while there and banjo bolts on the oil spray bar. If you find that they are loose, make sure you get new aluminuim crush washers and use locktite on them. Also, you will need new paper gaskets for everything you take apart. Valve Cover gaskets are also a good idea. Alot of mission-creep here...

You can also get drilled banjos with aircraft safety wire from Don Gale in NM. Click http://www.nmia.com/~dgnrg/page_2.htm (http://www.nmia.com/%7Edgnrg/page_2.htm)