: Timing chain issue, not lining up? stretched chain possibly?



devill.dude
12-09-12, 11:00 AM
Nearing the end of my 2000 Deville Headgasket job. Car has 84kmi.
The RH bank cams just dont seem to be right at 12 0'clock but just a tad off center(midway between 11-12). The chain also has some slack in it on the topside(non-adjuster side) between the intake cam and the idler sprocket.
I tried moving chain over on idler sprocket one tooth to attempt to take up slack and the cam marks fall at 1 0'clock so that clearly isn't right. I tried moving the cam sprcoekt over one tooth to correct but then I end up with the same situation as before. There's clearly slack in the chain.

Anyone ever come accross or know if it's typical for there to be some slack on the opposite sid of the tensioner? The LH side is perfect and taught on bith sides.

I was thinking I may have a stretched chain:rolleyes:
Everything is in great shape. Hardly any wear on the guides and zero wear on sprocket teeth.

I bolted things up, but think I'm gonna take the balancer back off and go through it again to be sure. I would appreciate some input. This is a tedious job.

bigtone
12-09-12, 11:20 AM
I remember when I did mine, the side opposite the tensioner needs to be tight. Did you lock you cams or mark anything before you removed the chains? It sounds to me that if the right bank is between 11 to 12 o clock with slack in the leading edge of the chain, then with the slack out of the chain it will be more like 11 o clock (one tooth off). I would try advancing the cams just a hair and try to get the sprockets on with no slack on the leading side of the chain.

devill.dude
12-09-12, 11:46 AM
Thanks for the response.
I pulled the heads with the cams in 12 position or so I thought. I marked cam gears and chain with paint because I didn't plan on removing front cover to save some time and a $45 gasket.
Timing grooves were perfectly aligned when I removed front cover. LH cam chain side is perfect.
I did try to advance the RH cams and pretty sure they ended up at 1 0'clock, but I'll pull the cover again and double check. The Exhaust cam wants to spring forward on me and it's a PIA.
I'll post back later with my results.

Submariner409
12-09-12, 12:00 PM
Double check that the sprockets are on correctly and that the tensioners are unpinned. The "pull" side of each chain should be pretty tight with little slack and all 4 sprocket marks at exactly - no fudging - 12 o'clock.

devill.dude
12-09-12, 03:10 PM
Thanks guys. I actually bought the newer revised Dealer Service Manual 3-book set. Picked them up online for $55shipped. They appear to never have been used. Too good of a buy to pass up.

Pulled everything back off and started over. Looks like I was one tooth off the idler pulley. Once I got everything all set, I used a wrench to relieve cam pressure CCW until the tensioner clicked. Everything is snug and tight as it should be. Glad I took it back apart or else it woulda sounded like, well, a loose chain inside there...haha prob woulda been missing and running very choppy as well.

Submariner409
12-09-12, 04:26 PM
Choppy ???? The Northstar is an interference engine: one or two cam sprocket teeth off and the thing starts eating valves. Those piston crown valve reliefs are there for good reason.

devill.dude
12-09-12, 11:48 PM
Choppy ???? The Northstar is an interference engine: one or two cam sprocket teeth off and the thing starts eating valves. Those piston crown valve reliefs are there for good reason.
It's a 2000 Deville with flat tops. 10:1 compression ratio. I believe the 99's prior had the reliefs with 10:3 ratio.
I don't even think the 2000 DTS even had reliefs, just a higher profile grind in the intake.
Eitherway, the flattops would still be at the same height as the reliefs, so if valve would hit the bottom of the reliefs they would hit the flat tops.
I didnt rotate the engine but maybe 45* to see if alignment was good. No binding, but I know that isnt enough.