Timing is out but deviation is steady: set timing or major overhaul

[steved0x]

Make sure the engine is nice and hot or else you mat get false readings that show higher deviation than actual. That said, -10 and -7 are quite a lot, and I am surprised you don't have a check engine light from the -10 reading, as I think the threshold is either -8 or -9. The spec is +-6 degrees. I personally am at -5.xx (very close to -6) and holding steady so I am just watching and waiting, if it ever makes a significant jump or over time gets much higher I plan to have the chain guides (or whichever the name of it is, the pieces that wear that cause the deviations)

I don't know if timing being off can cause readings like this - it seems like timing off would cause bad running.

Steve

[IanHall]

Thanks for the feedback, very helpful!

Originally Posted by steved0x

Make sure the engine is nice and hot or else you mat get false readings that show higher deviation than actual.

Engine had been running at idle for maybe 5 or 10 min when I took the readings, but given the balmy Canadian climate (sub freezing at time of test), it's possible it hadn't reached full operating temperature. Will re-run after a serious warm up and see if the deviations drop.

For future reference, anyone have any sense for how much adjustment CAN be done via fine tuning (i.e. via the camshaft sprocket)? Are we talking a degree or two only or several degrees?

[JFP in PA]

Originally Posted by IanHall

Thanks for the feedback, very helpful!



Engine had been running at idle for maybe 5 or 10 min when I took the readings, but given the balmy Canadian climate (sub freezing at time of test), it's possible it hadn't reached full operating temperature. Will re-run after a serious warm up and see if the deviations drop.

For future reference, anyone have any sense for how much adjustment CAN be done via fine tuning (i.e. via the camshaft sprocket)? Are we talking a degree or two only or several degrees?

Take the car out and drive it for 20-30 min., then check the deviation values. Letting it idle for 10 min. ain't going to do it.

Again, you are not going to adjust your way out of being 10 degrees out; one tooth on the gear is about 12 degrees, and you can only adjust the cam timing slightly with the adjustment system. You have a tensioner wear pad wear issue, and if the values repeat after driving the car, you need to replace some parts.

[IanHall]

Thanks JFP, will retest after good 20min drive. Regardless of results, I will definitely be replacing the internal chain ramps / whatever else shows signs of ware.

Assuming the re-test under hot engine condition yields the same or slightly better results, am I risking any damage continuing to run the car until the clutch starts to show some signs of ware (current clutch drives like new - prior owner did almost all highway miles)?

I would prefer to do the clutch, IMSB and timing rebuild all at once, but of course if I'm hurting anything having the timing this far out, not the end of the world to write-off the current clutch and do it all now.

Thanks again