Need help re-installing distributor on 450SL - PeachParts Mercedes-Benz Forum

winecountryone · #1 11-19-2008, 08:09 PM

I removed the distributor to replace the oil seal that has caused fouling of both the ignition and trigger points 3-4 times over last 2500 miles or so on my 1974 450 SL.I thought I had marked the distributor so I could put it back in same position but was apparently off somehow as the car now refuses to start.
I need to find/verify the proper procedure for finding #1 TDC so I can then re-install my distributor.I haven't had to go through this on any car for a VERY long time.This is what I did:
#1: removed the #1 plug and rotated until I could see/tap the piston through the plug hole.
#2 I then lined up the TDC mark on the crank pulley.
When viewing the cam lobe through the oil filler hole at this position,it appears that the intake valve lobe is pointing "down",thus depressing the intake valve.If the valve is open,then I'm obviously not at TDC on the intake stroke am I??
My mechanic is 60 miles away and doesn't do "house calls".Any help from forum members who could help get me back on the road would be greatly appreciated.

ctaylor738 · #2 11-19-2008, 08:48 PM

You have it at the end of the exhaust stroke. Crank it another 360 and you should observe that the intake lobe is pointing up. That's TDC on #1. Align the distributor so the rotor points at the mark on the side of the housing. You should be able to start it and do the final timing adjustment.

Graham · #3 11-20-2008, 11:07 PM

Quote:

Originally Posted by winecountryone

I removed the distributor to replace the oil seal that has caused fouling of both the ignition and trigger points 3-4 times over last 2500 miles or so on my 1974 450 SL.I thought I had marked the distributor so I could put it back in same position but was apparently off somehow as the car now refuses to start.
I need to find/verify the proper procedure for finding #1 TDC so I can then re-install my distributor.I haven't had to go through this on any car for a VERY long time.This is what I did:
#1: removed the #1 plug and rotated until I could see/tap the piston through the plug hole.
#2 I then lined up the TDC mark on the crank pulley.
When viewing the cam lobe through the oil filler hole at this position,it appears that the intake valve lobe is pointing "down",thus depressing the intake valve.If the valve is open,then I'm obviously not at TDC on the intake stroke am I??
My mechanic is 60 miles away and doesn't do "house calls".Any help from forum members who could help get me back on the road would be greatly appreciated.

As Chuck said - just rotate it one more time. Believe me, I did exactly the same thing. You could also take the valve cover off and line up the marks. Check chain stretch at same time.

By the way, that distributor seal - did you have to cut it out? Does the new one go in easily?

230/8 · #4 11-21-2008, 10:52 AM

Checking with the valve cover off also allows you to confirm you are at the correct TDC point by observing that both the intake and exhaust valves on #1 cylinder are closed.

230/8

winecountryone · #5 11-22-2008, 02:02 AM

I believe the seal was original.It was rock hard,and cracked into 2-3 pieces upon pulling out the distributor.
I got the new one from my local mercedes "stealer" on overnight express for the paltry sum of 4.85$.I could have probably used a generic O ring but I am tired of cleaning trigger points every few hundred miles so I opted to do it right.
Thanks to all who replied!!!

ctaylor738 · #6 11-22-2008, 07:35 AM

So does the car run now?

winecountryone · #7 11-22-2008, 07:03 PM

Car runs fine now.Only time/mileage will tell if new seal solved oil fouling problems.
THANKS AGAIN to all who helped!!!!