Water pump replacement = rough idle 380SL

[Johnny9]

Well it appears I've done it again. To save money, I went after a water pump change on my 83 380SL. What a job. I completed last night and it runs vvvery rough, especially at idle. Anyway a few notes from the shop desk.

1. Removed the crankshaft bolt, realized later was not warranted. Seemed to replace without a problem.
2. In performing above problem step, turned crankshaft backwards about 40-50 degrees.
3. Distributor was marked, removed and replaced.
4. Smokes rather badly.
5. Best running position for the distributor is 10 degrees different than mark as in point 3, and is at the "end" of adjustment.

I am ready to "throw in the towel" on this one because I'm scared on what is the real issue here.
Please don't sugar coat it. Thanks in advance.

[126nut]

Man that is a bummer, maybe too graphic for your ears but sounds to me like maybe the timing chain jumped, any ideas on the condition of the guides?

I had a similar problem after doing a transmission on my old 420SEL, it would run but not very good, turns out I had disassembled and reassembled the flexplate assembly incorrectly and the crank sensor wasn't getting the signals right. Took a while for me to figure that one out.

Oh yeah welcome to the board, too bad you gotta jump in like that with your first post. Hope you get it figured out and get some more input, it might be me but things aren't exactly the same around here since I left back in the mid 2000's.

[tbomachines]

Originally Posted by Johnny9

Well it appears I've done it again. To save money, I went after a water pump change on my 83 380SL. What a job. I completed last night and it runs vvvery rough, especially at idle. Anyway a few notes from the shop desk.

1. Removed the crankshaft bolt, realized later was not warranted. Seemed to replace without a problem.
2. In performing above problem step, turned crankshaft backwards about 40-50 degrees.
3. Distributor was marked, removed and replaced.
4. Smokes rather badly.
5. Best running position for the distributor is 10 degrees different than mark as in point 3, and is at the "end" of adjustment.

I am ready to "throw in the towel" on this one because I'm scared on what is the real issue here.
Please don't sugar coat it. Thanks in advance.

In general, you shouldn't turn the engine backwards, especially with timing chains as you can break the tensioner. I am not familiar enough with that engine to say if the tensioner would break but I would imagine that if you turn the engine backwards, it basically can mess up the timing by screwing with the chain tension, then as you marked the distributor you could have gotten a reading that would have been off. I am just speculating, I hope someone with more experience specific to your engine can chime in.