w126 tensioner
 

Hi, there,

just changed guides and timing tensioner (1991 420SEL) on right hand side (all MB parts).
I did not fill tensioner with oil, and turned the crank by hand. I felt that every little bit the tensioner would release pressure and chain would slack, then I turn again and it becomes tight again.

I would like to know if this is a usual behavior from a tensioner. I recall my old one did something like that where every other turn it would give slack and the re-tighten.

I am thinking because there is not enough oil pressure, the tensioner is loosening up and then re-tightening.

Anyways I removed the new tensioner, filled it with oil, it is better, the behavior is still there but the slack is better. and once it gets tight, it is really tight.
Ok then I checked the car again, the tensioner has some slack after not turning the crank manually for 2 hours, as soon as I moved the ratchet to turn the crank, it put more pressure on the chain and it became tight. Is this normal?

If the tensioner has a one way valve, does it relase oil and pressure (in the pin on top)? and when?

Thanks everyone

1) As viewed from the front, which direction are you turning the crankshaft? CW or CCW?
2) How many degrees are you turning the crankshaft at each try for chain tension?
3) Where on the chain are you checking for tension/slack?

1) CW
2)about 1/4 turn with ratchet, not sure how many degrees
3) on the RHS and LHS chain under the sprocket.
I can feel it is loose a bit, but again as soon as I start turning the crank again it gets tight again. Is this normal?

If the checks for chain tension are being done under the right side cam sprocket (cylinders 1-4), then the chain towards the center of the engine (along the straight slide rail) will become tight when the crank is turned, and the chain outboards of the sprocket (along the tensioner rail) will be slack.