Changed Timing Chain - Can't Crank Engine by Hand
 

I changed the Timing chain on the 300SD, but now when I try to turn the crank the engine by hand, using the crankshaft nut, it just stops. It doesn't feel like the compression is too high because I've been able to turn it by hand before and the feeling is different this time. It feels like there's a jam somewhere.

Did I jump a sprocket? I've been able to join the chain together.

Thanks,
bigmaq

How close to the TDC mark can you get your damper? If close enough I would try to compare That mark with the cam mark. Or if you can get the cam mark on compare the balancer mark. Do not force anything to try this.

Remember the crankshaft turns twice for one revolution of the cam gear. If you are trying to estimate the positions. Of course somehow or other getting the relationship off can happen. Right now from your description it is the best guess. I can think of nothing else yet someone else may.

Ok, I got it to move. The tensioner was pushing it really tight, so I released the tensioner bolts and loosened up the chain.

Thanks,
bigmaq

Replaced Chain - Is My Timing Off?
 

I replaced the chain and have lined up the timing marks on the camshaft. Pic #1 shows the marks lining up, but please look at pic#2. Is something really off here??

Thanks,
Dennis

Seriously off.

You're looking for 0°. It's far past that.

The real question is where it was prior to chain replacement?

You can guess the answer.

'Nother question... Is the damper supposed to have a big chunk out of it like that???

Yes.

Yeah, I thought it was off too. Didn't check timing before replacing the chain. So, what's my first step to correct this? Is this a standard "set to correct timing" job or is this more involved? Let's put it this way: If you were getting paid to fix this, would you tell your customer this is a 1-hour job or a 3-hour job, or, <gulp> a whole day?

The problem is that you are getting into a situation where you have no prior knowledge..........you don't know if you made an error with the chain.........or if some moron didn't install the chain properly during a past servicing.

You can take two approaches:

1) Assume the IP is in time with the crankshaft and adjust the camshaft accordingly. This won't take more than a couple of hours.

2) Assume nothing. Pull the IP and set IP, and camshaft to proper positions relative to the crankshaft. This will take all day.........maybe more.


In the first approach, the crank and cam will be timed correctly but you won't be sure of IP timing until you do a proper drip test...........and, if it's way off, you'll get yourself lost in a big hurry..........necessitating the second approach.

This happened to me, too--Brian probably remembers. I took the option #1 listed above--I assumed ip and crank were still in line and repositioned the cam. Easy to do--remove the tensioner and walk the cam sprocket over a tooth or two at a time. You're probably in a little better shape than I was--I wasn't even certain at one point if I was on the compression stroke--yeah, it was bad. But if you aren't aware of where the marks were before you started the chain replacement, it's a little bit of a gamble. But it's certainly the easiest approach for now. Good luck!

PS: whichever way you go, I would crank the motor over with a wrench at least two revolutions just to be sure you don't have any valve interference.

Seems like approach 1 is a subset of approach 2 anyway... I think I'd proceed to set the cam properly and then check the IP timing. Perhaps running the car is enough? If the chain lost time during the installation, it has to be off by a multiple of a crank tooth spacing. If it is off by one crank tooth (I think that would be 9 degrees?) would the incorrect IP timing be readily apparent? Conversely, if the engine runs properly, one could "assume" that the IP has not skipped time by a tooth? It could still be off because of other prior work, but that would be the case if the chain had been rolled in uneventfully -- and the IP timing would probably not be questioned then.

I'm thinking set the cam then see how the car runs. There is no extra work involved (I don't think) if the IP still has to be retimed.

does it turn and then stop? If so, it sounds like you're hitting a valve.

Take the glow plugs out.

Took Option 1 - Repositioned Cam
 

Ok, so I took the easiest approach first and repositioned the cam. Moved the chain back 1/2 link but still at 15 degrees. Moved back another 1/2 link and I'm about 1 degree (?) before 0. Turned the crank over a couple of times to make sure I'm not binding on a valve. Am I ready to put everything together and fire her up or is there anything else to check.

Thanks,
bigmaq