Prechamber Ball Sound?
 

I picked up a '75 w115 300d and was able to get it started after some difficulty. Heard a loud metallic rattling sound that raised as I increased idle and reduced when I lowered idle - sounding like a ball rattling around in a cup! Prechamber ball or vac pump possible? Any opinions? Thanks!

James

Us a Mechanics Stethoscope or my favorite a piece of Broom Stick applied to where you thing the should is coming from to pin point the sound.

Be sure to check the Vacuum Pump. I the Vac Pump is going bad the pieces will drop down into the Timing Gear/Chain and have cause Engine Damage.

Check the Valve Adjustment for Valves that are too tight.

Check the Timing Chain. If there is enough Timing Chain Stretch and Timing Gear Wear the Valves can hit the Pistons.

Look for loose things that could cause the sound during vibration.

If it has an Automatic Transmission maybe the Flex Plate is cracked.

Maybe the Starter Pinion Gear is not retracted enough and making contact with the Ring Gear.

You might pull off the Valve cover and take a look for any Valve train problems.

I have not read of the Ball Pins making noise when they are loose so cannot comment on that. However, I believe it is unlikely that all of the Ball Pins would become loose at the same time.

All good things to think about -all valves were super tight, who knows when they were last adjusted -nothing loose under valve cover anyway, next fire up should be interesting!

If that ball or pintle has dropped into the precombustion chamber you can bet it is affecting your power and or mileage.. might even be contaminating your oil supply and wearing the rings due to fuel washing the oil from the bore.... good to get it checked soon...
The pintle is there to break up the fuel spray from the injector nozzles..
and there are radially drilled holes down there in specific heights and directions to direct the broken up fuel... so anything blocking clear access to those holes is going to produce liquid instead of spray...

once that ball breaks off, it usually destroys the prechamber and sends broken bits into the cylinder. They leave quickly or get pounded into the piston ( no more noise except knocking from combustion on the effected cylinder)

You are more likely hearing a vacuum pump, wrist pins or at wost a rod.

I'd love to see some pictures of this sort of damage if anyone out there has them.

Would removing an injector and turning on the glow plugs create enough light to see inside? (I've never tried it - just a thought)

One particular thread I remember has some good photos... check for one by 'rcounts'.

There are others, though.

And whunter has posted some pretty nasty shots of beaten up pistons (perhaps in the general info section?)

I will be curious when I fire up this engine again to better determine noise after valve adjustment, clean fuel, diesel purge, etc - hope it proves to be a vac pump or other easily curable repair -keeping fingers crossed!

Wouldnt a loose prechamber ball sound like a small ball bearing jumping around in the prechamber cup and create a loud metallic rattle?

In the pic the Red Arrow points at the Ball Pin. Note it is supported on 2 sides.
While the Manual does say to inspect them for looseness there was some amount of clearance (I cannot remember how much) that was OK.

Also, Carbon tends to fill in open recesses that would tend to tighten up stuff.

So I am not seeing how the Prechamber could get excessively loose (Starting Fluid use maybe?).
And, even if it did get loose some I am not seeing that it could easily make the sound you describe.

Several Years ago there was a Thread where a Ball Pin came loose and it evidently fell down into the lower neck of the Prechamber.
When the Fuel Ignited it blew the tip of the Prechamber+ parts of the Ball Pin down between the Piston and Cylinder Head and did damage.

I do not remember the speculated case as to why the Ball Pin broke to begin with.

Great response, thanks!

I've been trying to find the pictures of damage - searching for rcounts - I haven't found them yet but there is a monster thread here that might be pertinent to your problem warmblood58

http://www.peachparts.com/shopforum/diesel-discussion/232743-84-300-cd-suddenly-making-horrible-noises-running-very-rough.html

Thanks! That was one long thread and I am now re educated about the effects of bad diesel/and or gasoline in diesel -think I will be smelling my fuel today -

Yup that sounds about right, either that or autolite glow plugs. DO NOT RUN THE ENGINE ANY MORE. Pull the injector and inspect the prechambe. If the ball is gone it needs to be pulled.

This is what happens with you use autolite glow plugs, ask me how I know :

http://superturbodiesel.com/images/b...rechamber1.jpg