6.5 td knocking

[farmerson]

I have a 93 chevy 3500 with a 6.5 td that has a knock. It is not in the bottom end and all of the valves are still there. I pulled the injectors and found two bad but the guy that tested them said they were not bad enough to make it knock. So am i looking at a busted crank? There is maybe a quarter inch delay between the flywheel and front pully when you hold the flywheel and turn the pully. Thanks for any help.

[Robyn]

First off

Welcome to TDP :D:D

Now
I am thinking that if this little creature is still running and there is only about 1/4 inch of play that the issue may be the serp drive pulley on the crank.

These have a bearing piloted hub that is rubber mounted. When the rubber gives up these things can make a HELLUVA noise.

Get the fan sroud and fan out of the way so you can see good. Get the serp belt off and check that crank pulley out well.

My bet is that your pulley has gone south and allowing the stops on the four spokes of the hub to bang, resulting in the noise.



Running the engine with the pulley removed (4 bolts that go into the damper) will tell the story real quick.

Broken cranks generally cause a catastrophic crash and destruction of the engine.

If you can wiggle the outer ring of that pulley back and forth, there in lies the trouble.

Let us know.


Missy Robyn

[farmerson]

Thanks for the info but sadly that is not the problem. It has a rod knocking. oh well keep my bed rear end and cab and i aint out nothing i only gave 475 bucks for the truck the way it sits and figured it was junk. now i am looking at a Chevy with a Cummins conversion. :D

[DmaxMaverick]

I wouldn't throw it out, just yet.

Robyn got it right. If a crank is broken, and has that much "play", it will scatter in a hurry. Faster than you can shut it down. If the crank is broken, that ain't the indicator. Your problem is the pulley, and probably some injector knock (there is no "not bad enough"....they do or they don't). Sounds just like a rod letting go, believe it or not.

[farmerson]

Ok ill have to try and get the pully off and see but when we turned it over after i put the injectors back trying to bleed the lines it had a patern whenever that cyl got compression. it sounded like it was at the back on the bottom you could heafr it more an the right side than on the left.