I have a D6C LGP ser.#90 B1849 engine#44V8821 The engine just started to have a knocking noise at startup. I made a recording so you can listen to it. Funny thing. It seems to be really only there at startup as soon as the engine runs, it disappears and I cannot hear it any more, so my feeling is it has something to do with the starter but maybe you guys know more if it also could be related to the engine or not; just to hear an opinion before I take off the starter thanks. D6C knocking noise
Is there an ether injector on it that may be misbehaving ?
No there is no ether hooked up, no need in our climate.
Yep; took off the starter and found these chips on the ring gear. I guess that's where the noise is coming from. Lots of fun to change that gear And the real sucker is, we changed that gear exactly 10 years ago when we rebuilt the whole engine. Since then I only put a little over 500 hours on the machine. Not enough for a ring gear to go bad prematurely. Guess it was made in China.
The last Cat ring gear I bought was made in India. I think there is a youtube video of them being made from old bicycles.
Way back in the day, I would dress up those teeth with a die grinder equipped with a pointed carbide bit. With a new starter drive it worked for a long time.
I have repaired many like Vetech63 said, and they worked fine after. I would never pull that torque to fix something like that. Stuff lots of rags around to help catch filings from die grinder. Simon C
I wasn't planing to pull that off now, not before starting up the engine would fail. But I will follow your and Vetech63 fix and grind it down. With our usage I think it will serve us for still for some years. Thanks a lot.
How are the teeth on the starter drive? You may want to replace the drive
The starter drive actually looks good, I was expecting to find some damage on it as well but it is not necessary. Sorry can't send some pics, put the starter already back on for now.
Just my opinion, Really strange knock, i found it dificult to belive the starter pinion is beating up that ring gear. But it might... Anyway the the ring tooth still has a lot of material in it, smooth it out with a grinder would be my bet. watch shavings. But i also would take a good look on the ring gear fitment and the starter reducer gear arrangment. on other words , since u have the starter out, overhaul it.
I agree. For what the damage looks like it is a really loud noise; but the fact that it is gone once the engine runs... I couldn't think of anything else. I will also do a in depth starter inspection. Thanks Mquinista
Could the starter drive gear be not fully engaging the ring gear teeth? Maybe the battery is a little weak?
Knock sounds deep to me. Hope it’s not the bottom end for your sake. By all means, grind ring gear and rebuild starter. But i would also check front balancer/pully. Also pull the belts and start it.
Is your engine a 3306 PC?
To me starter drive looked ok. I was waiting for the die grinder bits I ordered and then take the starter off again, I can make some pics then. The batteries are not new but I had never any issues starting her up; I don't think they're weak.
I will do that and see if It changes anything at startup. I was running the dozer about 2 hours today without any issues; just the knock at startup.
It's a 3306 I am not sure about the PC? When we tried to replace it with a aftermarket 10 years ago, the dealer said it is a 3306 DP engine.
Another thought, converter drive shaft universal joints might be shot. Pull the floor plate and check in there.
Will do so, thanks.
The die grinder bits arrived and today I had time to work on this: First pulled the belts and looked at the front balancer which is ok, knocking without belts still there. Checked the U-joints and they are also good. So I took of the starter (made some pics from starter gears in different positions) and prepared for grinding. Put a bunch of rags around the area to be worked and also a welder magnet to catch as much filings as possible. Worked first the single damaged tooth and then went on to the area with the larger damage. While I was grinding I noticed that actually a piece from the first damaged tooth was still stuck in the groove between this and former tooth (see pics). After removing this and grinding everything smooth, cleaned up and put the starter back on and... no more knocking Dropbox www.dropbox.com This led me to the conclusion: This chip which was wedged between the two teeth, must have made the starter gear "jump" whenever it was going over it, that's why the 3 next teeth also got damaged from the hits. Amazing. What such a small little chip can do. Well, learned something new today. Thanks fellows for all the help.