Timing Chain Oops / Fixing jumped chain links

[jkford13]

To respond again to Barri and Strife...
Thanks again for your suggestions.

Unfortunately, both LH, RH cam cogs, and the crankshaft were out of sync. The result was that we could only rotate the crankshaft CW or CCW ~25 deg before we felt resistance.

Our solution:
We tried rotating counter clockwise to get back to the beginning. Our intent was to pull out the ~14 links of new chain and get the LH, RH cam cogs, and crankshaft all synchronized at TDC.

Rotating CCW, once we felt resistance, we backed of a couple degrees. By looking at the cam lobes, we identified which valves were opened. Using a wire coat hanger, we gently inserted into the sparkplug hole to determine if the pistons in the same cylinders as the open valves were at the top of their movement, and if they were traveling up or down as the crank was rotated CCW.

In our case, the RH cam was causing interference as we rotated CCW. we allowed a few links of slack on the inside of the RH sprocket. using the chain, we pulled this cam cog CCW (independent of the rest of the system due to the slack), then locked it in place with the vice grips, and tried again to rotate the crank. This allowed a few more degrees of rotation before experiencing interference again. We repeated the steps of identifying the valves that were engaged and the piston at the top of its travel, backing off of the interference by rotating the crank in the opposite direction. Then we rotated the appropriate cog in the direction allowing the valves to close. I believe all our movements were primarily in the CCW direction (in terms of adding slack and rotating the cam cogs independently).

It took an hour or more, but we got everything back on track, and using the DIY procedure, installed the new chain in another hour or so.

Thanks!
Justin

[Strife]

Have you got it started again? If not...

1. I wasn't clear if you had also replaced the guides. Hopefully, you did.
2. This is a great time to replace the oil tube fittings. Cheap to replace; potentially expensive to ignore. The PO of my 85 380 ate a cam and a few followers because one of these got old and popped out.
3. On the tensioner, older MB manuals say fill with oil first; newer ones don't . I filled mine (both cars, took a little pumping and a little mess) and pushed the arm of the tensioner in while installing (DEFINITELY keep many threads engaged in the block while doing this!), and the instant my car turned and started with the new chain, I had full tension. I bring this up because my tensioners were in bags of oil and in boxes marked "this side up", ha ha - like anyone's actually been adhering to that...all the oil leaks out!
4. It is a really good idea to turn the engine completely over twice (at least 720 degrees) before firing up, and get to the point where you should see the cam marks, the harmonic balancer timing mark, and the distributor mark at all 0. Gives you a great feeling of confidence before turning the key.

[jkford13]

Strife,

Started with the Oiler clips, and when they showed no signs of damage, I decided to do the guides and the chain (based on the assumption that one of the guides was causing the clacking noise). The inner rail on the LH side was broken at the lower pivot pin. So I had a 1.5" long piece of plastic that kept hitting the chain when I started it (not all the time, but periodically). Could see the visible damage on the broken piece: rounded corners, gouges in the sides.

I got her running on Sunday night around 10pm...HOORAY!! Replaced the plugs, bought a timing light, and after some experimenting she is running better than when I got her over 2 years ago.

Good advice on the tensioner. Mine too was shipped in a bag full of oil. So it sounds like I should back it out several turns, oil the tensioner, and reinstall again. Can i fill it with whatever engine oil i am using (in my case 10W-50 Castrol High Mileage)? I guess another question is, can i remove the tensioner without removing the valve covers and alternator. I had to celebrate when i finally got her all buttoned up after 3 weeks of parts everywhere!

Thanks again!
Justin

[ptoro01]

One thing I would like to add, if you ever mess up during this process of rolling in the chain, you can save the engine by not turning it back and forth anymore and removing the cams to close all valves and set the crank back to tdc, once you do that, the cams are marked to be installed at tdc. You just have to keep the chain tight on the sprockets so it doesn't bind on any of the hidden cogs.

[Strife]

I'm not sure if you inspected, removed and inspected, or actually replaced the oil tube fittings. The act of removing them for inspection renders them unusable for reinstallation (as per the MB shop manual). The barbs won't hold as well as they did before removal and they might pop out later, which is very bad.
The oil tube fittings are sneaky, make sure that the tube part of each fitting is touching the seat that holds it on top of the cam tower. A rubber mallet may be needed. Obviously, use minimal force to do it.

If its started and is OK, the tensioner is already good and filled with oil as much as it can be. It's just that very first start after replacement and until the oil pressure returns that matters.