M42 timing components: 266k and counting

[shEck3lls0]

Couldn't you technically use all the stock stuff, just run a single chain?

[bwawuz02]

Couldn't you technically use all the stock stuff, just run a single chain?

yup. the only thing not stock on mine is the cam gears (which are just stock gears with the outer row of teeth machined off), which is all but pointless really.

[M42Technik]

Shameless plug:

http://www.r3vlimited.com/board/showthread.php?t=229432

Got all the timing parts needed if anyone's looking to refresh their M42 a bit, need it to get another motor to me!

[flying_violin]

I heard a dreaded rattling coming from the front of my M42 recently, so I tore into the front of the engine recently to see about doing the chain. As it turns out, didn't quite have the tools I needed, so I just put everything back in place with new gaskets and called it a day. But I noticed the alternator was extremely loose in it's bracket and the belt was worn. So after a new alternator belt and tighter mounting, the rattle is gone and the engine is quiet and smooth! I think I'll hold off on the chain for a few more miles... By the way, my cam sprockets looked fantastic with minimal wear on them.

[Ryann]

221k

[Jboss12]

why do some cam gears last so much longer than others? Is it just how hard the person drives their car or what?

[Ryann]

It's all about the faulty e30 tensioner piston imo.

[KenC]

It's all about the faulty e30 tensioner piston imo.

Yup!

The part was even updated.

[kwill22]

Got a question. When I was checking out my can gears I found that the exhaust gear is rotated 180 degrees. So at TDC the intake cam arrow points up like it should but the exhaust one is on the complete opposite side. Would this affect the timing of spark or fuel any in a negative way?

Timing between the head and crank is dead on though and everything's true to TDC. Only thing is that gear.

[KenC]

The cam position sensor only uses the intake cam. You're fine.

[bmwman91]

I have developed a new hatred of the M42's timing chain assembly. In the past year, I have been in the timing case 4 times, today being the fourth. It is a lame design, honestly. I founded M42Club, and at this point I am pretty irritated with the motor. In many ways it is great, but the timing chain assembly is absolutely one of the worst parts of the motor. The other major flaw is in the crank thrust bearing since it is only 180 degrees, not 360 and is prone to wearing badly (when you start your car, do NOT push the clutch in since there is no oil pressure & there is a lot of force on that bearing). Anyway...

If you have the opportunity to swap to a single-row chain, do it. The double chain is overkill, and its relatively large mass leads to a lot of issues on motors that are driven hard. Mainly, it will lead to a dead deflector wheel (idler sprocket), and more and more commonly, the timing case casting that the sprocket attaches to snaps off. I just opened up the motor today because I could hear pistons hitting valves at idle, and the culprit was a busted timing case, and the little deflector wheel was just floating around.

Last May the original deflector wheel's bearing blew out & I had to go in there to replace it ($160 for that stupid little thing). I pull the timing case & cleaned the hell out of EVERYTHING and replaced all the leaky gaskets. I change my oil every 10000 miles with Mobil 1 20W-50 religiously, and I replaced ALL timing components about 75000 miles ago (at 145000). They all look like new still, and the tensioner piston has been replaced every 35k miles or so because I am paranoid. So, the failure in the timing system certainly wasn't due to neglect on my part. The PO didn't take great care of the motor, but I actually had to replace the timing case when the oil pump blew up in 2006 as a result of the PO's shitty maintenance & my not thinking to check the oil pan for debris. It was a used one, so who knows what it was subjected to!

Anyway...
a) The M42's timing assembly is sort of a POS design
b) Convert to a single row chain if you have the chance, it will reduce the wear & tear on your motor. If you get some mystery bargain chain though, don't cry if it snaps.
c) Maybe the design isn't THAT bad. Most of us drive our little motors pretty damn hard, and doing that to a 21+ year old motor is more or less a recipe for expensive unplanned maintenance.

I'll get some pictures up in my "Little Motor That Keeps Breaking" thread a little later. I am not the first guy to have the timing case casting where the deflector wheel mounts just snap right off. I am SO done with this particular motor...as of now, I am trying to decide if I should drop $10k on a Metric Mechanic rebuild (if I keep the car, ONLY a fully rebuilt one goes in), or $24k on a new Jetta TDI. No more timing case rebuilds for me, three times over 12 years is more than enough!