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Timing Gear Notched

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Silent Turtle View Drop Down
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    Posted: 13 Jan. 2021 at 3:44pm
Hi, I am new to the forum.  I searched all over and couldn't find anything on this topic.  I am wonder if this gear was machine notched or if it was rubbing against something in the timing case.  There were no shavings in the case, so I am led to believe this was done for a reason.  I have no idea what that reason may be though.  I tried pulling the gear but she wouldn't budge.  I would rather not go through the headache of replacing if it doesn't need to come off.  Thanks in advance.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Oldpappy Quote  Post ReplyReply Direct Link To This Post Posted: 13 Jan. 2021 at 4:04pm
I just looked at one on an engine I am tearing down for overhaul. It is a high mileage engine and while the gear is worn it does not have such a "notch". 

So, my opinion is yours is a damaged gear and should be replaced. It is lot less of a headache in the garage than it is out on the road or in the woods.

The timing gear has been hitting something.

If you can't see what it was hitting or rubbing against it is possible something got in there, bounced around until it was chewed up by the gears and washed away by the oil flow.

Could have been a piece broke off the edge of one of the teeth which lasted long enough to damage the rest of them. Doesn't take long for that thing to spin many times.

It will come off, it is made out of a fibrous material and may break apart when you try to pull it, but you need to replace it anyway.


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Post Options Post Options   Thanks (0) Thanks(0)   Quote Rus Curtis Quote  Post ReplyReply Direct Link To This Post Posted: 13 Jan. 2021 at 5:26pm
I can speculate for free.  I would first guess that it had been rubbing something.  To me it looks too clean for a loose piece of debris.  Regardless, whether something bouncing around (I would think more damage to other components) or rubbing against something stationary, it shouldn't be there.  It looks like you've disassembled, so whatever it might have been is most likely not there anymore.

Who knows, someone may have noticed a nick on a tooth and came up with that idea to uniformly smooth it out, IDK.  

I agree it should be replaced.  Having had one fail while driving, it will end in either a walk home or a call to someone to come get you.

I haven't been able to get one off until after the fiber part breaks.  I now have a tool designed for this for the next time:

#4

If the cam is out of the engine, it may actually be easier to use a puller on it -or- a machine shop can press it off.
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DMusil View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote DMusil Quote  Post ReplyReply Direct Link To This Post Posted: 13 Jan. 2021 at 5:44pm
Looks like maybe it rubbed on the gear oiler? Is the oiler screwed into the block?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Mark W. Quote  Post ReplyReply Direct Link To This Post Posted: 13 Jan. 2021 at 7:12pm
The most likely thing I see that could have done that would have been if the Gear oiler came loose and traveled up and around the top of the gear wedging between the cover and the gear in the area of the Cover bolt centered where the left side motor mount ear is located. Look inside the cover and see if you see any damage there. As a new Gear oiler jet could have been installed when the oil pressure went to squat and a previous owner went looking for the reason.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Oldpappy Quote  Post ReplyReply Direct Link To This Post Posted: 13 Jan. 2021 at 7:24pm
It does look more like a rub than a break as even and smooth as it is. If the teeth were broken off I think it would be less uniform.

We are only speculating on cause and there may be no way to be sure without a close up inspection before it was disassembled. The suggestions about the oiler are strong possibilities and probably the more likely suspect. 

Another thing which occurs to me is there may be damage to the crankshaft gear, a burr or rough spot, a chipped tooth or just something lodged between two of the teeth. 

You should always inspect it anyway, but pay very close attention to that area of the gear and look at every single tooth for burrs, chips, or debris. 

I almost always replace the timing gear on these if I have the cover off, and I replace the whole timing set on the chain drive engines, unless I know they are pretty fresh. It is cheap insurance.  

It all goes back new on a rebuild. 

These aren't interference engines so if it jumps time it isn't catastrophic, just a break down, but I certainly wouldn't button it up with a questionable part unless I was out in the woods with no other alternative. 



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Post Options Post Options   Thanks (0) Thanks(0)   Quote Bill2A Quote  Post ReplyReply Direct Link To This Post Posted: 13 Jan. 2021 at 8:53pm
Oiler was my first thought, as well.
I have never been a fan of fiber gears in anything.
Dose anyone make a steel or even aluminum cam gear?
That seems like such an obvious longevity upgrade.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Joe DeYoung Quote  Post ReplyReply Direct Link To This Post Posted: 13 Jan. 2021 at 10:27pm
An aluminum cam gear would be a really bad thing as it wears and circulates aluminum particles throughout the engine. A steel cam gear would be be really noisy against the other steel crank gear which is why there is a fiber gear... quieter.
Joe DeYoung
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Bill2A Quote  Post ReplyReply Direct Link To This Post Posted: 14 Jan. 2021 at 10:26am
I have a steel gear in my Volvo.
I was told it would whine.
I've never heard it...but then I've lost much of my high frequency hearing.
Still, I'd take that over wondering if the fiber is about to part company with the rest of the gear.
I've had that happen and it WILL bring you to a stop.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Silent Turtle Quote  Post ReplyReply Direct Link To This Post Posted: 14 Jan. 2021 at 10:26am
Thanks, for the feedback.  The cam is out, so I sat it upright and puddled up some ocean foam lube around where the cam meets the gear.  The lube worked its way down and it slide right off with a puller.  I know these can be really difficult to pull off.  I was not able to get it off when the cam was in the engine.  This technique seemed to work really well, for those having issues pulling it.

Needless to say, I am going to replace it.  And, I still cant find what it was rubbing against or if it was.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Oldpappy Quote  Post ReplyReply Direct Link To This Post Posted: 14 Jan. 2021 at 4:40pm
Possible it could have been installed as a used gear from another engine, but probably no way to know that. 

Check everything closely, including each tooth on the crankshaft gear, and check everything again when re-assembled while turning it a few times.  
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Silent Turtle Quote  Post ReplyReply Direct Link To This Post Posted: 21 Jan. 2021 at 3:54pm
Think I found the problem.  There was not a gear spacer on the end of the rank.  The gear and the thrust washer must have been sliding all over the crank and the notching was most likely from the thrust washer hitting the cam timing gear.
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