4106 Engine Trouble? Weird Crunching Noises...

[Jim Eh.]

Is the bolt with the missing lock plate loose?

[luvrbus]

I do hope it is a simple fix Mark have you ruled out the cam followers rollers and push rods ?

[OneLapper]

I do hope it is a simple fix Mark have you ruled out the cam followers and push rods ?

I didn't pull the valve covers off.  Right now it seems that whatever it was is now out of the gear train and hopefully in the oil pan.  The engine starts and runs smoothly.  I'll keep going till I find out what it was, even if I have to remove the tranny and the the rear engine cover.  It may seem odd, but I get some level of peace of mind that my bus is in excellent mechanical condition and is capable of going 5000 miles, if needed, at a moments notice.  I can't ever imagine needing to do that, but IF I needed to, I want it in perfect condition.  Ok, I'll settle for 'very good to excellent' condition, 'perfect' might be a bit out of my budget.

[bevans6]

Thinking on this, I would hazard my guess that one of the 3/8" bolts that hold the engine plate to the block came loose, was sitting on a gear and got jammed in a tooth, backing the engine up 20 degrees made it slip out and get jammed between the gear and the back plate or the engine cover so that the engine would run, but with loud noises and sparks (had to be ferrous for the sparks), and then got spit out so that now the engine runs normally.

As far as the locking plate on the right hand cam bolt is concerned, my January 1978 Detroit manual specifically says that no locking plate is used.  You just torque the bolt and have the special thick washer underneath.  Bolt pre-load stretch keeps it locked.  Now, I have no idea about locks for the bolts that hold the generator drive gear on.  The book doesn't show anything to lock those bolts.

Brian

[seaton@mta]

Good Morning,

Just a little curious.  When did you purchase engine from NYC Transit Authority?  To my knowledge we ran very few.

- Seaton

[luvrbus]

Brian, 1978 is a old manual if you were the original owner DD would send all the releases and updates for manual mine has all up to 1998 then DD stopped supporting it, mine has something like 143 releases each one contains as many as 20 new service bulletins     

[bevans6]

yep, that's why I said the date!  I have no doubt there are updates in the past 36 years!     Just thinking that if that engine is circa 1980's it just may not have had a locking plate so no need to feel bad for leaving one off.

Did the aftercooler come back yet?

Brian

[luvrbus]

No it hasn't Brian I have a call in to Fedx to see where it is at lol those people are getting as bad as our USPS here in the US, I got a notice it was to be here Friday and today is Wed no package yet

[OneLapper]

Thinking on this, I would hazard my guess that one of the 3/8" bolts that hold the engine plate to the block came loose, was sitting on a gear and got jammed in a tooth, backing the engine up 20 degrees made it slip out and get jammed between the gear and the back plate or the engine cover so that the engine would run, but with loud noises and sparks (had to be ferrous for the sparks), and then got spit out so that now the engine runs normally.

Brian

Sounds plausible to me.  I'm going to try and fish it out of the oil pan but if I recall the oil pan has baffles in it so I don't think I can get to the end of pan with a magnet.

[OneLapper]

Good Morning,

Just a little curious.  When did you purchase engine from NYC Transit Authority?  To my knowledge we ran very few.

- Seaton

The engine can from Nimco who purchased it from NY when the last of the 2 strokes were replaced.  My friend works for the company that owns Nimco and told me about this engine after a conversation he had with Jim (at Nimco).  Nimco purchased about 200 buses, most were shipped to central America, the best running had the drive trains removed and the bodies scrapped.

[OneLapper]

Here's the update;

Today the Nor'Easter storm blew thru so the weather was good enough to work on the bus.  I borrowed this very handy tool which worked great!



Inside this hole I found a bent lock washer and a bunch of metal shavings.  I remove a 3/4 JIC pipe fitting and used a magnet to pull out the washer.  I don't believe that hole goes into the rear gear cover, but someone will certainly know what it's purpose is.  This engine had an automatic connected to it and I assumed that this fitting had tranny fluid in it.  If so, maybe the bolt fell out of the clutch area and into this part of the rear cover.



I used the inspection camera and looked at all the gear teeth.  They all look fine.  Inside the clutch housing I found this....





I have used the inspection camera and looked at every single nut and bolt on the or in the clutch housing.  I can't find one missing.  None of the ones I could reach were loose.

Good news is the accessory gears are fine and the problem doesn't appear to be in that part of the engine!  Bad news is the tranny needs to come out to be certain the clutch isn't falling apart.

[Ralph7]

Would those parts  be from the clutch disc?? or  pressure plate?

[OneLapper]

Would those parts  be from the clutch disc?? or  pressure plate?

At this point I don't know where the bolt came from.  All of the bolts that hold the pressure plate to the flywheel are in place. But 'm pretty sure it's a bolt since I found a washer (although it wasn't found near the other part.  The bolt isn't much of a bolt anymore, and it certainly wasn't a "fresh kill". That thing has been banging around for a while.

Does any know what that fitting went to and what was goes in the hole? 

[OneLapper]

Now that I've looked at some engine build photos, I suspect this is the bolt that fell out.  If it loosened up enough it looks like the ring gear teeth can contact the head, wear through that, then the bolt shoulder can hit the ring gear teeth.  The flywheel spins clockwise which would turn the bolt counter-clockwise, effectively backing out what's left of the bolt from it's threaded hole.




The piece of the bolt has a flat spot worn into it, I'm assuming from the ring gear.

Now what?  Pull the transmission, clutch and flywheel to replace this 3/8" bolt and lock washer?  Or?  

[luvrbus]

There shouldn't be a lock washer on the bell housing all those are copper or flat steel washers on a aluminum bell housing that fitting is used where the spacer goes between the bell housing and the V730 a return line