timing gear whine

John (AR)

Member
TO30. I just replaced both the crank and cam timing gears (new ones were Tisco and A&I brand respectively). There appeared to be "some" backlash between them but very little (I did not actually measure it with a feeler, but turning the crank did show a wee bit of delay in the cam gear turning). There is a loud whine when running the engine which is worse at lower speed. Does this indicate too little timing gear lash?
I replaced the old gears (which had a huge backlash) to try to get a minor clucking sound under control. Now I have a bad whine. The crankcase has an "S" stamped on it and I assume I used standard gears because they were not otherwise designated. So I thought the lash would be about right. Could the gears manufactured by different companies be incompatible?
I could put one of the old gears back in to increase the lash...or...could I just run it and hope the gears wear into each other?
Has anyone had this issue? Any suggestions would be very much appreciated.
 
Loose gears rattle, tight gears whine. Just tell everyone you have a Pete Jackson gear drive! LOL. Seriously, when I worked at the MF dealer we always looked for the block stamp like you did as MF Continental had over and undersized crank and cam gears when needed. Not sure if Agco still has them available. I have a Cockshutt 30 Buda that had really loose gear noise, replaced both and it's better but still there. Did you find size marks on the original gears? Any markings on the new gears too?
 
Dieseltech, thanks for the quick reply.
I did not see any size marks on any of the gears, new or old. I think you answered my question...I have too little gear lash. Can I live with it without doing damage or should I tear it down...again...and put one of the old gears back in? It's pretty loud.
 
My concern would be they are so tight the cam gear is shedding metal. If you find aluminum in the pan, definitely go back in!

As far as going back with an old gear, not a good idea. Don't want to mismatch a new gear with a worn one. If you go back in, look at the wear pattern. That will tell if they are simply too tight (the pattern is straight across the gear) or the angle is off on one gear (wear on opposite ends of the teeth). Or possibly something else is wrong, a misalignment? Something rubbing?
 
Might be best to see if you can get the gears from one supplier. Continental never had aluminum gears originally, not sure about aftermarket, never saw any aluminum years ago anyway. I would ask about over/undersize available too. If you do take it apart I would set up a dial indicator and recheck the lash in 3 or 4 places to see what you actually have now. Also recheck the crank end play shim pack, that's critical too.
 
(quoted from post at 00:40:13 12/14/14) Dieseltech, thanks for the quick reply.
I did not see any size marks on any of the gears, new or old. I think you answered my question...I have too little gear lash. Can I live with it without doing damage or should I tear it down...again...and put one of the old gears back in? It's pretty loud.

There should also be a stamp on the block in the cam gear area showing the size estimate. Either an S or a + or - plus the number under or oversize. Me personally I would rather have gears on the loose side rather than running tight and in a bind.
 
I will need to go back in and check things. Ugh! Hopefully no shredding going on. Crank end play is correct but timing gear lash may be tight.
Also the ends of the teeth on the cam gear were sharp where the machining meets the cast faces. The teeth could be rubbing the oil slinger.
Dieseltech, it does sound like a Pete Jackson gear drive! (I had to look at a u-tube video for that one!) or like a power steering pump low on fluid.
I was trying to save a few bucks getting gears from two different suppliers. The Tisco crank gear from here was machined with teeth edges slightly chamfered rather than just sharp.
OK, enough of this whining.
Thanks to all for the suggestions.
 
(quoted from post at 04:50:17 12/14/14) I will need to go back in and check things. Ugh! Hopefully no shredding going on. Crank end play is correct but timing gear lash may be tight.
Also the ends of the teeth on the cam gear were sharp where the machining meets the cast faces. The teeth could be rubbing the oil slinger.
Dieseltech, it does sound like a Pete Jackson gear drive! (I had to look at a u-tube video for that one!) or like a power steering pump low on fluid.
I was trying to save a few bucks getting gears from two different suppliers. The Tisco crank gear from here was machined with teeth edges slightly chamfered rather than just sharp.
OK, enough of this whining.
Thanks to all for the suggestions.

Your only other option is to take some valve grinding compound and put on the teeth of both gears and then turn them by hand for a long time. The compound will lap the gears together. Only downside is you will have to make sure you get it all removed from the gears afterwards.
 
I was asked to investigate a NOISE from a speed increaser. Yes high speed whine. After acquiring all of the facts I was able to ascertain that a new 8" diam. pinion gear was installed being driven by an 80" diam. bull gear. I was able to conclude that the GEAR SET was made by two different machine shops. The BACK LASH,RUNNING CLEARANCE,was incorrect (insufficient) as the gear blanks were not identically machined. There was an error in the corresponding "Diametrical Pitch". As per the CHEIFS direct orders the load was placed back on the gear train. At some point around 168 hours of load the top shaft stopped!......$%^%$#% .
Same scenario with a 150 HP 6 cylinder WAUKESHAW.Crank Gear...*&^%. I would not run a gear train with mixed gearing if I was intending on using the application that will require the rated HP. The last engine I viewed after a CAM GEAR failure (failure for what reason?)the valves and several pistons were not serviceable.
Ultimately the MAN who pays the piper gets to call the Tune.....so you shall make the call
Hope you call it right.
 
One source of noise is having tip interference with the gear tooth profile. The lowest point of active profile is usually spec'd on the drawing. The master gear is designed to touch this point as they are rolled together. If there is interference, it will show up. Quite possibly, the tip chamfer on either or both gears is too small. Off course, I'm talking about ancient gear technology. We had women in our shop hand-grinding the chamfers (tip breaks). They also ground tooth side chamfers and root side chamfers to resist cracking, but this is more important before case-hardening the gears.

Modern people save money by not checking the result, they just input the machine settings and assume it all turns out okay. A form of "lean manufacturing".

Someone with a signal analyzer could pick up whether the frequency matches the number of crank gear teeth or cam gear teeth.

Another thing to consider, is that at higher temperatures, the aluminum gear expands and fits tighter. The iron crank gear is much less sensitive. Perhaps the cam gear worked well at
room temperature testing, but not when heated.
If the aluminum gear was made from the drawing for the OEM iron gear, that would be risky.
Gear Chamfering
 
OK. This is my follow-up to the original post. Thanks to everyone who offered information and advice.
I opened the front up again and measured the gap between the timing gear teeth at several spots in the rotation. Two beer can feeler gauges (total .008") passed easily between the teeth all the way front to back. There did not seem to be any tight places and what little "wear" I saw looked even along the teeth. By the way, the gears are steel; an aluminum cam gear was mentioned in the discussion...not so. Plenty of oil getting to things, good crank end play. Standard "S" stamped on block and presumably the new gears were also standard. I did notice that the oil slinger had been rubbing lightly on the timing cover, so I put in an extra gasket on when I put the timing cover back on to give it slightly more clearance.
Well, the same whine is still present. I ran it for an hour and it did not get better or worse. I am going to conclude that it is due to the geometry of the gear teeth not matching up correctly (tip interference) as suggested by cdmn and others, even though there appears to be sufficient lash (between .009 and .011). It is worse at low RPMs and almost goes away at higher revs.
I have decided it is probably not going to self destruct and I will just live with it. As Boss Hog suggested, it has a blower, right? The tractor gets only light duty and my neighbors are not close enough to be bothered by the extra noise. Maybe it will quiet down over time.
The bottom line to this is DO NOT INSTALL TIMING GEARS FROM DIFFERENT MANUFACTURERS. They should be matched. I hope this thread is helpful to someone else down the road.
Thanks again for all the information and helpful suggestions.
 
(quoted from post at 23:32:36 12/13/14) TO30. I just replaced both the crank and cam timing gears (new ones were Tisco and A&I brand respectively). There appeared to be "some" backlash between them but very little (I did not actually measure it with a feeler, but turning the crank did show a wee bit of delay in the cam gear turning). There is a loud whine when running the engine which is worse at lower speed. Does this indicate too little timing gear lash?
I replaced the old gears (which had a huge backlash) to try to get a minor clucking sound under control. Now I have a bad whine. The crankcase has an "S" stamped on it and I assume I used standard gears because they were not otherwise designated. So I thought the lash would be about right. Could the gears manufactured by different companies be incompatible?
I could put one of the old gears back in to increase the lash...or...could I just run it and hope the gears wear into each other?
Has anyone had this issue? Any suggestions would be very much appreciated.

I was going thru the Napa catalog earlier today and they sell a matched crank and camshaft gear set. You might want to check into that.
 

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