I have a timing rattle despite a new chain, chain guides and tensioner. all dealer parts. I even pulled the tensioner out to make sure it was moving freely. It was.

The one part I didn't change is the crankshaft timing gear (the one that is shrink-fit onto the crank). The Bentley says replace it, but I haven't heard anyone mention actually doing that. Mine visually looked fine.

So, thought I would ask --- in the real world, should I replace it to go along with my new chain?

Any other ideas? Will pull it all apart this weekend to inspect again.

 

Has the block/head ever been decked?
Only folks I have heard that had a chain rattle after a timing chain was on the second rebuild...both had been machined TWICE...
Fix was simple one it was realized what was going on...a washer on the tensioner to help make it extended longer...to take up the extra slack.

 

Thanks for the suggestion. I have not had it decked, but perhaps a previous owner. Seems worth a try to put a spacer in. Will update in a day or so....

 

An update -

Took my car up to Helix in Philly for a RMW tuning day (worth every penny!) and Eric immediately focused in on the racket. His mechanic pulled the valve cover off and they noticed the exhaust side rockers weren't pressurizing with oil. Jan was there and suggested that maybe the exhaust side rocker arm shaft ("rocker arm axle" in mini speak) was reversed. Sure enough that shaft is slightly asymmetric and if installed flipped left to right, doesn't pressure with oil the way it should. A very subtle misalignment. In this arrangement, the bolt flats are facing up so the bolts look right and can be torqued correctly. Flipping it other wrong ways (like upside down) should be pretty obvious, but apparently can be forced together (and will result in a racket also).

The other rocker shaft - on the intake side - has notches for the spark plug tubes, and flats for the bolts, so more visual ques about which way it should go.

So, my clatter is gone. Thanks to Eric and Jan. Chalk this up as one of the few that wasn't a bad chain tensioner.

 

That's awesome.

It's too bad Jan isn't on nam anymore

 

This was a new one for me. I had never noticed that the rocker shaft oil journal was slightly offset and thus wouldn't pressurize if reversed. We once had one come in rattling like a sonofoab#tch with the shaft on upside down.

Oh, and David.R53, I'll send your dyno sheet today.

 

Good to hear it was something simple. What are your impressions after the RMW tune?