distributor not turning

[Dave]

Car suddenly died while driving.  Engine just stopped running. Was running fine up until then.  Crank crank crank no hit not even once.  Towed home and checking for spark.  No spark.  Then i pulled distributor cap to see if all in order or if distributor loose.   As i cranked the engine i noticed that  after i took the cap off the rotor is not turning.  I took off the rotor and the shaft is not turning at all.  Any help is much appreciated!
67 230

[jameshoward]

Easy first thing to check is to see if you can turn the dissy housing. It may have popped up if the collar has become lose. There's an 5mm (I think) allen head bolt that keeps the dissy locked in place once you've set the timing. There's a bit of spring there, and if the collar wasn't tight then the dissy could disengage. I hope that's what you find.

[Flim]

Dave,

Try to pinpoint the cause for the fault by first inspecting the distributor. See if the distributor is tight. If it is I would inspect the distributor next, as there may be a problem with it's shaft. Pull out the distributor to check it's shaft but set engine timing mark to TDC with number 1 piston at compression stroke first - (check by remove spark plug).

If the distributor seems to be in order then I would inspect the timing chain/gears. The distributor shaft runs off the auxiliary shaft which drives the fuel injection pump & distributor shaft by a gear on the timing chain. Remove the distributor housing next and inspect this gear and timing chain.

Let us know what you find….

Charles

[stickandrudderman]

Remove the oil filler cap and observe if the camshaft is turning when cranking.
If so, then you have a local distributor drive problem. If it isn't then you have some rather large problems as a result of a failed timing chain.

[Dave]

 Distributor is tight.
Cam turns -  Thank God.
Now what ?

[awolff280sl]

pull out the distributor and see if manually turning drive dog will turn the rotor; check if its "ears" are not damaged somehow

[ja17]

Check to see if you can turn the rotor with your hand. If so your distributor may have elevated itself and dis-engaged. If not the "ears" or timing gears may be damaged, as mentioned.

[Dave]

Pulled distributor.  The ears are fine and the distributor turns ok once out of the car.  I opened the oil fill and I see the cam turning when I crank the starter.  When I look into the hole that the distributor goes into, at the bottom- the slot that the ears on the distributor shaft fits into spins with the distributor out and looking into the hole, but when I insert and fit the distributor in place and press down to make sure it engaged then the distributor doesn't spin.
 Thanks for any help and insight, I would not have gotten this far without the great folks on the forum.

[ja17]

Possibly your vertical timing gear has failed. Unscrew the tachometer cable at the engine. Have someone crank the engine while you closely watch the tachometer drive. If it does not turn, then the timing gears are probably the issue.

[Dave]

Thanks Joe
I'm sure your diagnosis is right.  How difficult is it to repair if that's the case?  Gear pull and replacement possible thru front, or pull or diassemble engine and it gets really $$ painful?

[ctaylor738]

Are you sure that the ears on the bottom of the distributor shaft are engaged in the slots on the top of the drive gear?  Maybe I'm missing something, but if if the distributor drive is turning, then the distributor has to turn if the shaft is engaged.

[Dave]

I swear that I pushed down and had the thing engaged but I have been wrong before.  I leaned down hard while somebody cranked

[ctaylor738]

I hear you.  This just seems very strange to me.

Suggest you put the shaft in the hole with the rotor on, then press the body down and turn the rotor.  You should feel the ears engage and the whole thing go down the last 1/8" or so.  At that point, you can tighten the clamp and try the starter.

[andyburns]

I had something like this happen to me a few years back.  The cause was entirely my fault.  During a refurbishment of my distributor I left off one tiny washer underneath a grub screw that secured the condensor to the side of the distributor housing. 

The lack of that one washer allowed the grub screw to penetrate just a few mm extra into the innards of the unit just enough to interfere with the centrifugal plate.  This in turn loaded up the distributor quill enough to cause catastrophic damage to the timing gear. 

Ripped the entire hub out of the main timing gear and at the same time stripped all the teeth on the quill.  Unbelievable amount of damage from such a tiny screw.   

The real kicker is that at the time I dropped the washer down the side of the engine and said to myself... 'mmmm thats not to important, will be ok without it'.  After the damage was done I hunted around and found the washer sitting on the bottom ledge of the engine block.  If I had only taken the five minutes to find it in the first place.

I priced the part new through Mercedes but they were astronomically expensive so I  ended up stripping the parts from a wrecking yard for 80 dollars.  It didn't take too long to fit up, probably only a couple of hours.  This was a lesson I will never forget.

[glenn]

Aren't the ears on the bottom of the dizzie off-center?   Push the rotor down, turn until the ears drop in, then tighten the hold down clamp while ears are engaged.  The receiver shaft below the dizzie should be synced to the crank/cam shafts to have TDC synced to rotor pointing to #1 plug wire mark.  Amazing how well it works when everything is in snyc......

[ja17]

Check to see if the tach drive is turning.  Also be aware the set up cogs on the bottom of the distributor are not symetrical but very slightly off-set to one side (same with the drive gear). You can force it in a 180 degrees off. But it fits in easily the correct way.

[Dave]

It runs!  Thanks Gents.  The distributor had slipped out and wasn't engaged.  Thanks for the education on the off center drive.  I feared the worst and now it is almost nothing.  I had been in there end of last year installing pertronix and setting the timing.  Drove fine for a few days then died suddenly.  Towed it home.  Next day plenty of battery but completely dead.  Figured I killed the starter doing so much cranking when it died on the road  That turned out to be neutral safety switch - (thanks Joe.).  Then no spark.  Then no distributor spin.  Now all I need to do is set the timing and start  driving again.
Thanks to all !!!!!

[kftca]

Folks: I experienced the very same thing on my 70 280 last weekend. The car just died like I turned off the ignition while I was running at 65 mph down the highway.  I never suspected this after I concluded Ihad no spark, but sure enough , the distributor rotor was not turning. I looked the oil filler cap while cranking the engine and confirmed cam turning and no bad mechanical noises. I pulled the distributor and rengaged the drive and rotor started turning just like it should. I put it all back together and it started right up and ran perfect.
So , recommend you check distributor clamp and ensure the distributor is properly seated to ensure full dog engagement.
Again, kudos to this forum, tremendously helpful!

[ja17]

Yes, there is a small spring between the distributor cog and it's drive gear. The spring will push the distributor up and did-engage it if you do not have the distributor down all the way and tight!