OM617 Chain Tensioner Torque - PeachParts Mercedes-Benz Forum

masc243 · #1 05-13-2014, 05:04 PM

Had a leak at the chain tensioner following a recent timing chain replacement. Cleaned the surface and installed chain tensioner. Tried to torque the bolts to 59 ft lbs and noticed they just were not getting tight. Best I could I get get was about 35. Finally snapped one off. Luckily it left enough threads to grab on and remove. Pulled the other bolt and noted it was stretching close to the head of the bolt.

Anyone know what the torque value on these bolts should be along with the nut that covers the tensioner and exhaust manifold? A search of this forum says 59 ft lbs; but that is obviously not correct. I did verify the bolts are original and are stamped 8.8; which should be equivalent to a grade 8?

Thanx,
Mike

Diesel911 · #2 05-13-2014, 08:16 PM

The Timing Chain Tensioner is different on the Turbo Engine than the Non-Turbo Engine. Which Engine do you have?

Diesel911 · #3 05-13-2014, 08:58 PM

On the OM617.952 the large Spring Plug is 90Newton meters = 66.38 foot-pounds

I have looked an cannot find a specific Torque for the other Bolts that hold the Housing on.
The 8.8 grade on the head only helps if you know the diamter of the threaded area and the Thread Pitch.
Torque Charts
Metric Bolt Torque Chart
Metric Bolt Torque Table - CNCexpo.com

There is supposed to be a Gasket between the Housing and the Cylinder Head and a Crush Washer between the Spring Plug and the Housing.

Also I had a Craftsman Click Type Torque Wrench that after a few Years use became unreliable when it came to the Click Feature causing overtorqueing. I have also seen where some People are real fast on the Torque Wrench and after the Click they were still moving the Torque Wrench.
Cheapie Click Torque Wrenches like the Harbor Freight ones can be destructive. If someone is going to buy a Cheap Torque Wrench get a Beam Type one.

masc243 · #4 05-13-2014, 10:36 PM

Quote:

Originally Posted by Diesel911

On the OM617.952 the large Spring Plug is 90Newton meters = 66.38 foot-pounds

I have looked an cannot find a specific Torque for the other Bolts that hold the Housing on.
The 8.8 grade on the head only helps if you know the diamter of the threaded area and the Thread Pitch.
Torque Charts
Metric Bolt Torque Chart
Metric Bolt Torque Table - CNCexpo.com

There is supposed to be a Gasket between the Housing and the Cylinder Head and a Crush Washer between the Spring Plug and the Housing.

Size is M8 x 1.25. Decided to go with just under 18nm as this is the highest setting of my 3/8 click type torque wrench. Felt tight; no bolt stretch, and best of all, no oil leak on tensioner and no water leak on thermostat housing.
Thanks for the chart.
Mike

Also I had a Craftsman Click Type Torque Wrench that after a few Years use became unreliable when it came to the Click Feature causing overtorqueing. I have also seen where some People are real fast on the Torque Wrench and after the Click they were still moving the Torque Wrench.
Cheapie Click Torque Wrenches like the Harbor Freight ones can be destructive. If someone is going to buy a Cheap Torque Wrench get a Beam Type one.

Size is M8 x 1.25 (8.8). Decided to go with just under 18nm as this is the highest setting of my 3/8 click type torque wrench. Felt tight; no bolt stretch, and best of all, no oil leak on tensioner and no water leak on thermostat housing.
Thanks for the chart.
Mike