I am trying to finish my valve adjustment but stuck at replacing the cams. I have both cam lined up with their marks but when I install the cam caps the cam chain bunches up at the intake side and jumps teeth on the exhuast cam sprocket. I think the problem may be the front camchain guide. I noticed something odd when I removed the tensioner - there was no tension on it, did not come out of the bore as I loosened the mounting bolts and after I removed it tthere was still no slack in the chain until I poked my finger in and pushed the guide.
I don't see anything in the manual about checking for wear on the chain guide and at 55,000 miles it should not be worn out. I followed Fred video and the FSM.
Sorry for the blurry pics. Hopefully you can see what I am talking about.
Could the chain be stretched? I see nothinmg about that in the FSM either. I did remove both cams and the crankshaft DID get disturbed with the cams out.
Any ideas appreciated. My options as I see it:
1.torque the caps, install the tensioner and see how things line up
2. remove the cams and try again with possible camchain R&R.
I am trying to finish my valve adjustment but stuck at replacing the cams. I have both cam lined up with their marks but when I install the cam caps the cam chain bunches up at the intake side and jumps teeth on the exhuast cam sprocket. I think the problem may be the front camchain guide. I noticed something odd when I removed the tensioner - there was no tension on it, did not come out of the bore as I loosened the mounting bolts and after I removed it tthere was still no slack in the chain until I poked my finger in and pushed the guide.
I don't see anything in the manual about checking for wear on the chain guide and at 55,000 miles it should not be worn out. I followed Fred video and the FSM.
Sorry for the blurry pics. Hopefully you can see what I am talking about.
<snipped photos>
Could the chain be stretched? I see nothinmg about that in the FSM either. I did remove both cams and the crankshaft DID get disturbed with the cams out.
Any ideas appreciated. My options as I see it:
1.torque the caps, install the tensioner and see how things line up
2. remove the cams and try again with possible camchain R&R.
I have been turning clockwise. I initially attempted to remove only the EX cam as no intake shims are beeing changed. No problem removing only the EX cam but when (FIRST TRY) I tried to re-install the EX I ended up one tooth off after installing the tensioner and roatating the CS. So I then removed both cams and startred over, installing the EX cam first, then the IN. That is when I notice the bunching. It seems to me as if the front chain guide is stuck in the position it was in with the tensioner installed. All seems fine with the cam caps off but once i snug them doen flush with the head, the intake cam seems to pull on the chain and there is no slack. I will check tightness of cam chain sprocket if only to honor the memory of the legendary Haroldo. (And CMA)
OK, after reading your question again, this is my second response and hopefully better than the first:Thanks for your thoughtful second response Brian, it confirmed a lot of what I was thinking. In the morning I will torque the cap bolts and install the tensioner and see if it will pull the chain out of its "bunch".
The intake cam is moving when you tighten the cam bearing caps- this is actually pretty normal and occurs because the cam is not seated against the cam bearing saddles but is hung up on some valves. You will probably see a small air- gap under the cam bearing surfaces before you tighten the caps, this is because the cam is sitting on some cam lobes that are pointed down and hitting the open valves.
Timing the cams is a bit tricky because you have to time them for where they will be when fully seated, not necessarily where they are when you drop them in place. They usually don't move much though and a 'best guess' is close enough to position them. You have to tighten the caps down fully before checking the final timing though. Once everything is in place, move the cam chain so that all the tension is in the back of the engine and the chain is tight in the front of the engine (between the crankshaft and the exhaust cam) and between the cams. Then turn the engine over and see if the timing marks line up. They should be close but may not be perfect. Just make sure it is much closer than moving the cam chain one tooth and all should be well. You cannot move the cam timing just a little bit; it has to be done in one- chain increments so the timing would have to be substantially off to make it incorrect.
As far as the tensioner goes, it should have some spring tension on it in use. Perhaps not enough to drive the CCT back when you remove the bolts though. Quite a bit of the CCT's force comes from hydraulic pressure from the lube system in the engine which is of course zero when it is not running. The CCT will fit in the engine either way but there is a correct direction; if installed incorrectly, the hydraulic ports won't line up and the CCT won't be able to use engine oil pressure to help it extend. The service manual shows the correct orientation and you can look and see the oil hole in the CCT port as well as the CCT body itself and these should align.
Brian
Thanks for your thoughtful second response Brian, it confirmed a lot of what I was thinking. In the morning I will torque the cap bolts and install the tensioner and see if it will pull the chain out of its "bunch".
Didn't we have someone have a similar issue sometime back? I think the consensus at the time was removing only one cam could cause issues with the chain tension or timing and that the only 'fix' was to remove both cams and reinstall. I wish I could find the post but am not having any luck with Google.
I vaguely remembered that thread as I was working and it influenced my decision to give up after the first try and remove both cams instead. I agree with Brian, cannot see why one cam can't be done.
I still wonder if I have a problem with the rear chain guide.
QUESTION: with the CCT removed shouldn't the guide have some free play even with both cams installed..
OK. With Brian's helpful explainations of how stuff works I think I have figured out what was going on. With the CCT out the rear chain guide should be free to pivot and let the backside chain slack drop down and out of the way but for some reason it was not pivoting. (I think this is why the CCT did not back itself out as its mounting bolts were loosened)
Instead the top end of the guide was trapping the chain against a small aluminum protrusion in the head and causing it to bunch up. I was unable to budge the guide using hand pressure through the CCT bore.
However when I re-installed the CCT the chain unbunched and dropped down
as I tightened the CCT mounting bolts. Just to check, I R&Red the CCT again. This time it backed out as it should. Now with everything torqued down the alignment marks all look good. Now to recheck the clearances. I may also take a look at the guide mounting bolts and pivot points.
The rear cam chain guide is held in place with a dowel pin on which it pivots, near the bottom. The pin is closed on the outside end and held in place by a post cast int the inside surface of the timing cover. It will slide in and out with hand pressure and seems to be spring loaded but I don't see a spring in the parts diagram. Anyway I can't see anything abnormal about the dowel pin or guide, they look fine. I pulled the pin half way out and lubed it. Nothing else to do but remove the guide for closer inspections but that requires intake cam and timing rotor removal. I am not motivated to do that. I still have a TB sync to do.