on critical things like inside the engine and suspension and brake parts I use a torque wrench. on other things that have a spec like 25Nm I go by feel. Then there's places like manifolds where it's difficult to use a torque wrench.

Sixto
93 300SD 3.0

This may open up a can of worms, but, generally if there is a specified torque and you have a torque wrench, go ahead and use it. But be aware of how the engine was or is intended to be assembled.

Someone already mentioned that lubricating the threads and the bearing surface under the bolt head can make a big difference in the closing force the bolt applies to the mechanical joint members (usually metal part, gasket, metal part for sealing applications and just metal parts in brakes/mechanical assemblies that transmit torque). So, you have to know whether or not the assembly is intended to be lubricated or not. In general there are relatively few unlubricated assemblies. Typically those involving the use of a thread sealant/locking compound (LocTite or the like) are not lubricated, and the wheel lug nuts/bolts are not lubricated. I presume all others are intended to be lubricated.

So, if you have a torque wrench, use it. If you don't, well, either get one or just live with what happens.

By the way, what kind of stuff seems to be falling apart? I have not seen a reasonably well maintained 240D just "fall apart" before, regardless of miles on the odo. Jim

__________________
Own:
1986 Euro 190E 2.3-16 (291,000 miles),
1998 E300D TurboDiesel, 231,000 miles -purchased with 45,000,
1988 300E 5-speed 252,000 miles,
1983 240D 4-speed, purchased w/136,000, now with 222,000 miles.
2009 ML320CDI Bluetec, 89,000 miles

Owned:
1971 220D (250,000 miles plus, sold to father-in-law),
1975 240D (245,000 miles - died of body rot),
1991 350SD (176,560 miles, weakest Benz I have owned),
1999 C230 Sport (45,400 miles),
1982 240D (321,000 miles, put to sleep)