Page 1 of 1
Timing gear shreaded
Posted: January 5th, 2020, 6:54 am
by Cschaff63
Happy New year fellow AAers, Does anyone have any ideas why a fiber timing gear on a freshly rebuilt engine with less than 300 miles on it would shred the teeth off. Cruising along at 30-35 mph and makes a clunking noise and dies. Pulled the timing gear cover and gear teeth are shredded about one third of way around gear! Then, is it advisable to go to an aluminum gear at this point? Thanks in advance for any input.
Re: Timing gear shreaded
Posted: January 5th, 2020, 9:49 am
by emf
I'm going to start something here, but that may be a good thing... Fiber timing gears have been used for many many years without the 'shredding' issue. Maybe the gear that was put in your truck was a cheap one. I think the good ones with brass impregnated are good ones. I, for one, don't like the aluminum gears due to the excess noise. You can hear them from 50 feet away. Check with the rebuilder and see what he says. It could also be that your engine was out of time and it kicked back. Don't just blame the gear, maybe it was something else...
Frank
Re: Timing gear shreaded
Posted: January 5th, 2020, 10:18 am
by BrianT
To shred a timing gear that quickly the most likely cause was lack of backlash between the fiber gear and the crank gear, it should be approximately 3 thousandths measured in 3 places, a common problem is that the crankshaft may have been ground of center, or the main bearings line bored out of alignment.
What ever you chose to replace it with be sure to measure the back lash and inspect the face of the camshaft for any burrs that would cause the gear to wobble, best to take back to the re builder.
Re: Timing gear shreaded
Posted: January 5th, 2020, 10:38 am
by Cschaff63
emf wrote: ↑January 5th, 2020, 9:49 am
I'm going to start something here, but that may be a good thing... Fiber timing gears have been used for many many years without the 'shredding' issue. Maybe the gear that was put in your truck was a cheap one. I think the good ones with brass impregnated are good ones. I, for one, don't like the aluminum gears due to the excess noise. You can hear them from 50 feet away. Check with the rebuilder and see what he says. It could also be that your engine was out of time and it kicked back. Don't just blame the gear, maybe it was something else...
Frank
Thanks for the response, I agree with you. I had the time precisely set with a timing light also, has been running beautifully up to this point, for a little while I was having overheating issues but that is resolved! I do plan on asking engine builder tomorrow what to look for, AER was the engine builder. The motor is built as a touring motor with insert bearings and oversized valves with hardened seats.
Re: Timing gear shreaded
Posted: January 5th, 2020, 7:11 pm
by David R.
I had a rebuilt 6 cylinder in a GM 1 ton in my fleet of bakery trucks years ago. After it stripped the third gear they sent me an aluminum one. Never stripped again but you could hear the truck coming up the alley to the plant three blocks away. Whirred like a space ship on a 1950 sci-fi movie!
Re: Timing gear shreaded
Posted: January 6th, 2020, 8:11 pm
by Cschaff63
Spoke to my engine builder, he thinks it was just a bad gear, sending me a new one and all the gaskets. I hope this is the case, guess we’re gonna find out! But at least he’s standing behind his work!
Re: Timing gear shreaded
Posted: January 7th, 2020, 9:16 am
by David R.
I hear a lot these days about modern replacement parts failures. Let’s hope this fixes you!