Pagoda SL Group
W113 Pagoda SL Group => General Discussion => Topic started by: SL113fan on July 19, 2004, 05:30:36
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Does anyone know of the proper torque spec for the engine block bracket to front engine mount bolt (19 mm head)? CD-Rom doesn't reference it, nor do the several archive postings on the subject.
Thx.
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I can't find the torque spec either, but here's a guess: the bolts have the same thread size as the subframe mount bolts, and those have a torque spec of 72 lb-ft.
George Davis
'69 280 SL Euro manual
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Hello,
The subframe mount bolts are a much larger diameter. I fear you will snap these at 72lbs. You need to get a feel for these kind of things. These are non critical hardware, so specs may not be listed for such items. You can find a standard torque table for hardware which will give the torque specs for different hardware according to diameter and hardness. The numbers on each bolt head are the hardness of the fastner. Mercedes stndard hardware is "8g" which is a high strength steel (equivalent to grade 5 SAE). Use this 8g spec on these unmarked studs. Your motor mount support studs are 10mm diameter. Just look up the specs on the chart! If you have not yet developed a feel for tightening things, keep a copy of a torque chart handy for unspecified bolt torques.
Hardware used on such things as flywheels, or headbolts are much harder and may carry a rating of 10g or 12g. Torque specs should be followed closely when listed. Secial "stretch bolts" require a torque then an additional turn of a specified degree! Te stretch action of the bolt locks it into place and provides more lasting tightness with the abiltity to take up some slack.
Now if I can just find my torque table!? I am sure you can find one on line. I will get back asap.
Joe Alexander
Blacklick, Ohio
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Sorry about the bum steer, I recalled them being the same size! I'm glad Joe corrected me. Mustn't rely on failing memory...
George Davis
'69 280 SL Euro manual
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Hello George,
Sorry I may be in the wrong here myself. I thought SL113fan was refering to the engine block to motor support stud (with 17mm nut). The large motor mount bolt does have a 19mm head and larger bolt as you stated (probably a 12mm diameter bolt).
In this case I would still lighten up on the torque, gravity is on your side in this instance. A good hand tightening with a 1/2" ratchet handle or box end wrench will work fine .
Joe Alexander
Blacklick, Ohio
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For "Fastening bolts of engine supports to cylinder crankcase", the MB shop manual specifies 6.5 mkp (which equates to 47 ft-lbs) torque