Please see the picture which I hope I have attached. This is taken from the front of the engine with the engine breather cover removed from the timing gear cover. Also the nut, washer and chain adjusting plate have been removed from the shaft of the idler gear/eccentric shaft I have two separate questions:
-note the circular piece with a lob sticking up just to the right of vertical. Both the circular piece and the lob are part of the “front bracket” mounting the timing gear and do not move or rotate. The " chain adjusting plate" sits on the circular piece But what is the purpose of the lob?
-I have been able to rotate the idler gear/eccentric adjuster by hand by twisting the chain adjuster plate to tighten or loosen the upper chain. But for some reason the idler gear shaft will hardly turn even with force. Why is that and what have I done wrong?
The ‘Lob’ is the retaining spigot that the seated plate locks into place once you have the tension on the chain. It needs to be depressed to allow the adjuster plate to rotate.
I think Phillip is referring to the horn on the casting that points to 1 o’clock. I can think of its purpose. Maybe just to stabilize the circular plate.
I’m not seeing anything amiss there. If something is interfering with the rotation it would have to be deeper in, assuming the plunger mechanism is working correctly.
As above there looks nothing wrong …but i dont follow what you are saying…“i can move the adjuster by hand…but the idler gear shaft will hardly turn even with force”…what are you trying to do…if just tensioning the chain…then reassemble the parts…press in the plunger and useing a 2 prong tool rotate anticlockwise to add tension to chain…have a close look at the toothed adjuster…sometimes the locating “flat” gets very worn and it can turn without moveing the gear…Steve
Not sure I understand what you are asking as if you are able to adjust the chain tension then the idler gear shaft must be turning.
maybe you could trying removing the spring loaded locking device (shown in the photo at the 11 o’clock position) then reinstate your serrated adjusting plate and ascertain if the idler is in fact moving. please also stuff some rags in the timing chest so you don’t drop anything into the Bowles of the chain area.
in my experience it is quite difficult to rotate the serrated plate by hand so I wonder if I am understanding your references correctly?
normally to get the serrated plate to move you need either the jaguar tool or a pair of needle nose pliers.
best regards
Is the idler sprocket seized to the adjuster eccentric? Why did you take this apart? Did the idler sprocket rotate freely? If not, you will have to pull the head to get at the bushing inside the idler sprocket…
Let me make 2 clarifications/supplemental comments:
- Erica is correct that the “lobe” (better spelling) I mentioned is the protrusion sticking up at about 1 o’ clock. It seems to have a definite purpose but I can’t understand what that may be. Is it a carry over from an earlier version of this engine, with a different gear adjustment mechanism? Or does it have some connection to the apparent seizing of my idler gear shaft?
- Further to last sentence above, I took off the idler gear adjustment plate because I could no longer turn the adjuster by hand or even with a self made tool. I was looking for a reason it had seized.
As Erica suggests, I.Will take off the head to better inspect the idler gear mechanism.
But if anyone can explain the seizure before the work to remove the head, I will be greatly appreciative.
I would soak it in PB blaster and apply heat. Work it back-and-forth it may break free. If not off with her head.
A self made tool may be the problem…someone recently gave me an adjuster tool he had just made and had started selling…the 2 pins were a fraction too long and were actually catching on the lobe you mention and prevented the adjuster from turning…also the adjuster dosnt turn much…when the chain is tight it stops…was your chains still lose?..Steve
Unfortunately out of dozens of photos of my rebuild I can’t find one showing the front of that aluminum cage without the serrated adjuster plate attached and I can’t recall what it looked like.
Here is one of the front of the tensioner gear with the cage removed though so you can see what is happening when you rotate it.
As you see, it is simple. That inner eccentric shaft rotates and the lobe on it drags the gear down. Note however, how much mass is there and how many friction points there are. It can be especially stiff if it’s been sitting around and the oil coating has dried up along the shaft.
Plus you’re working against the chain. I’m not sure what your homemade tool looks like but if it doesn’t have a lever on it and simultaneously push in the locking pin so that you can use both hands to rotate, then you’re probably just not getting it where it needs to be. A repro factory tool isn’t that expensive and it makes it easier and more predictable.
If you notice above the gear, built into the aluminum cage there is a little hopper. There is no forced lubrication for this mechanism. The hopper just catches oil that is flying around and it drips onto the gear and flows inside to lubricate the shaft. You might do well to fill that hopper up to get the part lubed.
edit: I just noticed the suggestion about the pins being too long and recalled a problem someone had not long ago with a repro factory tool with too long pins. They will collide with the aluminum and stop travel prematurely. So do verify that while you have the plate off.
Hmm I don’t thinks its as simple as just removing the head. you need the timing cover off and for me that needs the sump off. all rather difficult with the engine in the car. I would have thought that with careful application of PB blaster etc and a decent tool you will get it to move. in my experience these adjusters are a bit ‘jerky’ when you try and move them. so if you have adjusted it so the chains are tight it might feel a bit reluctant to move. but if it did move once then it should move again.
I wasn’t suggesting removing anything, just showing the mechanism. As I don’t think he’s seen the parts exposed. I’m pretty sure the problem is him not having the right adjuster tool.
Erica
I’m a rare case, I think you have missed. As another tool, I’m took off the adjuster plate and put the nut back on the idler gear shaft and using a socket wrench turning clockwise, the nut does not turn after twisting it right against the axle shaft. I stopped trying to turn it just before stripping the treads.
So.now I will.follow your suggestion to.remove the head and hope to have better access to inject some penetrating liquid
The nut only locks the adjuster in place, it does not turn the cam from memory.
Hi Phillip…as i mentioned in a post above…the gear only has limited movement either way becaus it is connected to the chain…clockwise losens the chain counter clockwise tightens it…so you cant move it anymore clockwise…how about anti clockwise removing the head it totally unnecessary at this point…Steve