Not exactly.

Not true. The IP just needs to relocated so the adjustment slots allow for more travel in the required direction. Chain stretch has no impact on the internal timing of the IP, which is the only thing indicated by the alignment marks on the drive.

I'll admit, I'm pretty stoned right now, but I'm seriously enjoying the dialogue going on between you two. If I understand Brian correctly, he is saying that excessive chain stretch between the crank and the cam sprocket, and the cam sprocket to the IP would mean you would not have sufficient travel in the oblong holes of the IP mounting brackets to end up with proper time if you have the wide tooth of the IP drive set on the alignment mark (10o clock position of the IP drive if you're facing it.)

Tangofox is saying... Well, um, actually I only understand Brians point.

Exactly....

However, the only length that matters is the length between the crankshaft and the IP timer. If this becomes too long, the IP cannot rotate sufficiently toward the engine due the insufficient travel in the oblong holes.

Like I said, I'm pretty stoned and covered in a blossoming carpet of interestingly shaped bruises of various color. I'm hitting the sack now, and I'm seriously looking forward to driving my w126 again tomorrow. Did I forget to mention that I first pulled the old IP in April and the poor old diesel was up on jack stands in my shop until Just the other day when I finally put the new IP in?

I was sidetracked by my little brown /8 280. 16 mpg of carbureted oh-my-god-herecomethe SECONDARIES has never been so much fun.

That is correct. But it has nothing to do with the IP alignment marks. The IP marks are to the IP exactly what the balancer markings are to the crank. The crankshaft angle doesn't become erroneous because the chain stretches; neither do the IP marks.

I believe you are a bit confused between "IP marks" and "IP spline teeth".

My reference is to the teeth on the IP versus the teeth on the timer. Nothing in my comments refers to the marks on the housing of the IP versus the marks on the block.

I now see your confusion.

The "original marks" that I referred are not the housing marks. They are the matching teeth spacing on the shaft of the IP and the timer.

That is highly unlikely. You need to look in a different direction. I am 100% certain that I am not confused. Seems like we had this conversation once before. And you eventually saw the light.

Nor do mine. I am talking about the missing spline on the IP shaft and the associated dot, which, when aligned, indicate SOD for injector #1.

I am 100% certain that you are confused and are simply parsing words again.

My comments stand.

No. You are insisting that chain stretch causes a problem with IP timing relative to the IP itself, such that the IP alignment marks are no longer accurate. I am saying that any inaccuracy of the marks has to be from a problem with the IP, not the chain.

If you think I am confused, kindly explain why the balancer marking are not affected by chain stretch in a similar manner as you believe the IP markings are affected. It's exactly the same concept.

Absolutely not correct. If the IP is aligned to the start-of-delivery position, then mounted with the adjustment slots centered on the studs, there should be plenty of travel for adjustment. There is absolutely no need to install it off the marks to accomodate any prior chain stretch.

I am insisting that the chain stretch causes a problem with the IP timing relative to the crankshaft...........not to the "IP itself". The IP may be absolutely perfect, but cannot be installed per the manual due to chain stretch. You have agreed with this in the above posts.

The balancer markings are the datum. They cannot, by definition, be affected by chain stretch. Only the camshaft and the IP can be affected.

At no time have I agreed with that.

If the IP is perfect, there is no reason that it cannot be installed per the manual. Reinstalling it per the manual will re-establish the correct IP/crankshaft relationship, accounting for any prior chain elongation, with absolutely no need to fudge the IP alignment in any way.

If the IP markings are wrong, it isn't because of chain elongation. And if they are not wrong, there is no reason they can not be used.

I'm a bit done with this. I can't tell if you're being deliberately obtuse or actually have a differing opinion.

I'm going to sleep.

If there is no problem with the IP, then there is no problem using the IP alignment markings. Aligning the marks sets the IP to start-of-delivery for the #1 injector. Set the crank to the desired angle and install the IP in the center of the adjustment range. The proper IP/crankshaft relationship is now established with no need to offset the IP drive by any amount. This procedure compensates for any existing chain elongation.

Here is your initial statement that got my attention. "Two teeth off" is an IP problem and nothing but an IP problem. It has nothing to do with chain elongation. Nothing. If the "new" IP was two splines off, it was that way when it came out of the box. Install a brand new chain, and it will still be two splines off.

This is agreed. The key words in the statement are "install the IP in the center of the adjustment range". This might result in the missing spline on the IP shaft not being in alignment with the associated dot.


This cannot be correct. If the chain has elongated, it is entirely possible that the IP must be installed "one tooth off" to allow sufficient range to meet the specification. (I will agree that two teeth seems a bit unlikely to be caused by chain stretch).

As the chain elongates, if everything else remains constant, the IP must rotate toward the engine to maintain IP timing. Eventually, the IP runs out of range with that chain. The mechanic then needs to pull the IP and install it "one tooth off" to return it to the middle of the range and allow proper timing.

If a replacement IP is installed, the phenomenon doesn't go away. A chain with extended length could cause the identical issue.