Chain Tensioner for 1989 300SE
 

I need to reset the chain tensioner. See photo. I have all parts except # 508 which I suspect is in 506/507 (which are together). I need to separate 506 from 507 and cannot see any way to do. Can anyone walk me through it?

The plunger only moves toward the chain. To disassemble it the plunger had to move toward the chain and then out. Put the chain completely in place, put the body of the tensioner with gasket onto the head and snug it in place, lubricate the plunger and install it from the outside of the head into the body of the tensioner, put the spring into the plunger, put the seal on the big nut. STOP and go eat Wheaties and spinach, reinstall the big nut whilst overcoming the spring tension, it's not easy. Done.

510 is threaded in place and uses a large hex bit. A bolt head of the correct size could probably be used with two lock nuts on the other end as a turning point.

Post a picture of the instructions if you can.

I already have the unit totally disassembled and the manual instructs to "disassemble before installing". In the picture I attached I see I have to separate # 506 from 507. I don't see a way to do that. Nor, so I see part 508 unless it it in the assembly?

Picture was attached with first thread. Do you see?

Here are the instructions. Not very detailed. Please advise.

Picture 2 instructions
 

Here's another page.

506 is inside of 507. You can see the tip of 506 sticking out of the end of 507 in your pic. Simply push 506 through 507 by pushing what you see inside of 507 which IS 506. It might feel stuck because 508 is is attached on the outer diameter of 506 which is part of the ratcheting system that holds it in place and won't let it back out, but it will push through. Make sure that when you reinstall it, that you get a couple of clicks from 506 when reassembling it before you reattach to the car.

Appreciate the help. I am going to do tomorrow when I'm fresh. Been a long day with the Benz! Will keep you posted.

X2 Paul...

Can I use a tool to push 506 out? I tried using just my hands & it doesn't move at all.

use a 1/4 drive extension and a small hammer. there's a snap ring you have to over power.

WOW! That was great. Came apart with about 3 light taps of the hammer. I will clean all & reassemble. Any hints on the rebuild? How far do I push in? Counting clicks? Never did this before, so any suggestions would make sure I do correctly.

Ah...looking at the installation instructions, I assemble by putting the components in the area in a specific order as dictated. I do not preassemble. Is that correct?