Lister Engine Forum

Lister Engines => Listeroid Engines => Topic started by: Mtour on December 06, 2019, 12:54:31 AM

Title: Idler gear wear pics
Post by: Mtour on December 06, 2019, 12:54:31 AM

Hi
 I have replaced the bearings in the metro, and installed a bronze idler gear. This is a new to me Metro with low hours I believe... I ran it for a few hours with the original steel idler gear and found lots of metal on the magnets,some of the metal looked like small wood shavings.

 Now with the bronze idler gear I am finding lots of suspended bronze in the oil. I have read on the subject and my guess is that the backlash is either too tight on a gear or to loose on another. I can not hear any noise from the gears while running. Any chance you could tell from the pictures whether I should run the engine and let the bronze idler settle in or should I come up with another fix.

Thanks.. Dave..

Title: Re: Idler gear wear pics
Post by: EdDee on December 06, 2019, 10:29:50 AM

Hi Dave,

A brief look at the pics tells me you should either replace the steel gears or spend some long, careful time with a file and emery cloth to dress and clean up the tooth pressure faces... They're chewing up the brass gear quite efficiently...

Mesh looks a little loose, it could be improved upon, but the machining marks on the steel gears are "quite bad" to put it gently....

My not even .0001c worth...

Cheers
Ed

Title: Re: Idler gear wear pics
Post by: 32 coupe on December 06, 2019, 12:32:19 PM

You need an offset idler bolt.

I have made a few for members here.

PM me if interested.

Gary

Title: Re: Idler gear wear pics
Post by: Mtour on December 06, 2019, 01:58:06 PM

Thanks for the replies..

 I put the steel gear that came with the Metro back in, it did not have near the amount of play that the bronze gear had. Maybe these metal gears will polish themselves, I have lots of magnets in the sump..I am going to run it for a few hours and check the magnets..

Thanks..

Title: Re: Idler gear wear pics
Post by: veggie on December 15, 2019, 03:47:13 PM

You say the engine has low hours.
The metal you originally found on the magnets may be from the initial running-in of the engine.
I think you are correct to change the oil and run it for a while and monitor it with the cast idler.
If the lash is somewhat correct on the cast iron idler you may be ok for thousands of hours.
Many people have good life from the iron idler. Others have had them break prematurely.
Most blame goes to poor casting quality and/or excess tooth lash.

Title: Re: Idler gear wear pics
Post by: dkmc on December 20, 2019, 10:54:36 PM

The crank gear has sharp edges, galled buildup on the tooth faces, etc. It's hobbing your bronze gear to death. Some careful de-burring and smoothing will stop the problem.

Title: Re: Idler gear wear pics
Post by: veggie on December 21, 2019, 03:17:22 PM

Quote from: dkmc on December 20, 2019, 10:54:36 PM

The crank gear has sharp edges, galled buildup on the tooth faces, etc. It's hobbing your bronze gear to death. Some careful de-burring and smoothing will stop the problem.

Good point dkmc and edDee,

A close look at those steel teeth reveals an awful finish.
If the whole face of the teeth needs attention (and not just the burs at the end of the tooth),  you may find that you have excessive clearances after de-burring and may require an offset idler to bring it back into tolerance as 32coupe stated.