Is this rod knock?

[CruiserTrash]

That's an very odd sound for a end bearing to make, but I suppose it's possible. They call it a 'Rod Knock' for a reason 'cuz there's a rod involved with the ignition thrust.

Can you carefully put the stethoscope rod on one or the other of the rod cap bolts while the engine is running?


Isn't # 3 the end cap ?


View attachment 3331723

You’re right, it’s #3. I had it oriented wrong in my head. I don’t think I can get the steth on there with the flywheel spinning - the cap is sloped towards the flywheel. I’m using a long screwdriver and it’s going to slide right into the spinny stuff. Maybe I’ll try to get it on one of the bolts.

 

[CruiserTrash]

Is there another bearing inside all the flywheel/clutch stuff? Like a roller or needle bearing? Maybe something in there isn’t right and the rotating stuff has just enough wiggle room to slap around.

 

[Spike Strip]

Harbor Freight $7

Saved my ass diagnosing sooooo many times. The ear/screwdriver thing is ok but in your situation, hazardous.

 

[CruiserTrash]

@Spike Strip I just lose or break them. Didn’t have time to stop and grab another today haha. But yeah, a far more elegant solution.

 

[Spike Strip]

Yeah, I understand. I have 3 or 4 cuz I can never find the one I have so I just go to HF and get another

 

[CruiserTrash]

Made a safer steth. Works pretty well. Noise is most audible in that rear cap, and especially in the bell housing.

So am I good for a simple remove/replace of that cap as long as I put everything back exactly? I did check that the cap bolts were torqued to their minimum of 91.

 

[Spike Strip]

I've never removed one with the flywheel still on, so I don't know how tight the cap is in there, but "should" be able to wiggle it out....

Someone who has done this should chime it at this point.

 

[Spike Strip]

Is there another bearing inside all the flywheel/clutch stuff? Like a roller or needle bearing? Maybe something in there isn’t right and the rotating stuff has just enough wiggle room to slap around.

Yes, there's a pilot bearing at the end of the Crankshaft for the trans input shaft snout. Not uncommon for those to go bad after many miles.

 

[CruiserTrash]

I gotta pack it in for the night. Thanks for the help this far. I’ve at least narrowed down a couple culprits.

 

[Spike Strip]

Me too. Good luck!

 

[fjc-man]

There is no easy way to inspect that bearing. First, the oil pan has to come off because it sits on it. Second, the flywheel has to come off to replace the rear crankseal. I guess the upside is you could check more than one bearing and you could have a look at the pilot bearing.

 

[LandoNick]

I am super interested in this. I have the same noise, in the same location. for years I thought it was an exhaust leak. Mine does quite down after warm up. so everyone told me it must be exhaust. replace manifold with machined ones, all new gaskets, block of plates, removed EGR. I back pressured the exhaust. NO LEAKS! But still have the noise. Took it LCNW they did my H55 swap. we opened up the Oil filter. no metal. no change with clutch in or out. I want to start ruling things out but it is tough.

 

[CruiserTrash]

@fjc-man thanks Bill, you're always a font of knowledge. I figured pulling that was a can-o-worms. I have a rebuilt H42 sitting here so maybe later this year I'll swap that in, and "while I'm in there" do the oil pan gasket, rear main bearing & seal, pilot bearing, clutch, and throwout bearing.

@LandoNick Interesting that yours goes away when the engine warms up. Mine does not, it's pretty consistent no matter what. Maybe, maybe it gets a little more intermittent than warm. Maybe not, hard to tell. I think the way I'll be able to figure it out is the work that I mentioned to Bill above. OR - long shot here - there's a loose bolt on the bellhousing and either it's slapping the block ever so slightly or the transmission is doing that to the bell housing. Another long shot I thought of was maybe since my body bushings are pretty rotten, the top of the transmission is vibrating against the bottom of the transmission hump. I don't hear the sound very well inside the cab though. I dunno, I'm trying to lay every idea on the table at this point.

I guess if you've been running with that sound for years that's kind of a relief for me to hear!

 

[CruiserTrash]

Here is another video of the noise, this time underneath the truck with the flywheel inspection cover removed. Notice that when the phone mic gets adjacent to the edge of the bellhousing the sound increases in volume. When I used my homemade stethoscope I found that the sound was loudest through the bellhousing. Correlation? Possibly.

 

[jayp2]

There is no easy way to inspect that bearing. First, the oil pan has to come off because it sits on it. Second, the flywheel has to come off to replace the rear crankseal. I guess the upside is you could check more than one bearing and you could have a look at the pilot bearing.

If you're that far in the rear engine seal and pilot bearing should just be replaced

Super easy and super cheap to do, heck, I'd also replace the throwout bearing and consider a new clutch while you're in there and save yourself labor down the road

 

[LandoNick]

@fjc-man thanks Bill, you're always a font of knowledge. I figured pulling that was a can-o-worms. I have a rebuilt H42 sitting here so maybe later this year I'll swap that in, and "while I'm in there" do the oil pan gasket, rear main bearing & seal, pilot bearing, clutch, and throwout bearing.

@LandoNick Interesting that yours goes away when the engine warms up. Mine does not, it's pretty consistent no matter what. Maybe, maybe it gets a little more intermittent than warm. Maybe not, hard to tell. I think the way I'll be able to figure it out is the work that I mentioned to Bill above. OR - long shot here - there's a loose bolt on the bellhousing and either it's slapping the block ever so slightly or the transmission is doing that to the bell housing. Another long shot I thought of was maybe since my body bushings are pretty rotten, the top of the transmission is vibrating against the bottom of the transmission hump. I don't hear the sound very well inside the cab though. I dunno, I'm trying to lay every idea on the table at this point.

I guess if you've been running with that sound for years that's kind of a relief for me to hear!

Mine is very prevalent Cold and at about 1K rpm. LCNW said if it was the rear main bearing that you could see movement on the fan up front under load. not sure if that eliminates that or not and with the "NO METAL" in the oil filter.

 

[fjc-man]

Jim, have you checked your valve clearances lately? Maybe a lobe on the camshaft wore off making that a valve speed noise.

 

[BGarcia88FJ62]

Sounds a little gentle compared to known rod knocks I've heard. Possibly a sticky lifter and Pushrod in the valve train?
I'd pull the valve cover and inspect the valve train look for a damaged push rod and also check your valve clearances.
You'll need to pull the valve train to inspect the pushrods completely. Best of luck.

 

[CruiserTrash]

@fjc-man I set valve lash two weeks ago as part of the variable elimination process on this. Most were spot on and a couple were a touch wide, but overall nothing horrible. No mushrooming. The valvetrain looked good in action with the engine running. @BGarcia88FJ62 Last summer I had the side cover off and none of the pushrods were bent. Obviously things can change, and I didn't get at the lifters. The noise is definitely in the area I mentioned above though - bottom side, near flywheel.

@LandoNick I see what your shop was saying about movement in the fan up front, but just the torque of the motor itself under load is enough to make the fan appear to move slightly. My engine mounts are all good and the motor still shows a little lift & twist when you goose the throttle. I'm talking just a little bit - with something like a broken motor mount it looks like it's trying to jump out of the engine bay.

 

[Spike Strip]

If sound is increasing when you're on the Bellhousing, it seems like sound is traveling through the block. BGarcia beat me to it, but I too would check the valve train, particularly the lifter/pushrods before tearing anything apart.

FWIW, if/when you get to that point of replacing the Pilot bearing, JimC sells a super-duper one I've been itching to try:

Pilot bearing, 1F/2F/3F series engines

There's nothing worse than having to drop the transmission & transfer case and pull off the clutch to change a dried out pilot bearing. That's a lot of backbreaking labor that could have been saved by installing this top quality made in EU by SKF aerospace bearing filled with synthetic grease...

tlcperformance.com