Attention Engine Rebuild Experts: Timing chain idler pics inside
 

All,

I am tearing my engine down to address a broken head stud that I found when I decided to do a valve adjustment while the motor was out for a transmission rebuild.

Head stud:
http://forums.pelicanparts.com/uploa...1426438548.jpg

Engine Drop:
http://forums.pelicanparts.com/uploa...1426438566.jpg

Upon removing the cam gears, tensioner, and idler gear, I inspected them for wear. The left side (1-2-3) idler gear shows some wear on the inside teeth:

http://forums.pelicanparts.com/uploa...1426438849.jpg

http://forums.pelicanparts.com/uploa...1426438909.jpg

http://forums.pelicanparts.com/uploa...1426438954.jpg

http://forums.pelicanparts.com/uploa...1426439060.jpg

The cam gear looked ok:

http://forums.pelicanparts.com/uploa...1426439103.jpg

Neither chain tensioner was extended beyond normal, indicating that the chain isn't terribly stretched after 100,000 miles. (I am assuming the chain is original, but can't be sure. The engine has clearly been apart before, but unfortunately there is no record of what work was performed). I was not planning on splitting the case, as I am on a budget (which was spent on the transmission rebuild), but will if I have to.

What caused this? I am guessing a misaligned timing chain--was the cam not properly set with the appropriate number of washers? was the tensioner somehow off kilter?

So, what do I do now: File the burrs off of the gear and stick it back in, or order a new idler sprocket? There is no lateraly play in the idler sprocket, so the bearing seems to be in good shape.

Thanks in advance,

Put it back together and do a physical alignment of the gears, make the math work out and you're good
Bruce

How many shims where on each side when you took it apart?

3 on each side...