One of the two diagonal frame braces at the top of the engine compartment on my 1974 250 sedan (W114) has broken at the weld at the firewall. It is the brace on the driver’s side, which here in Australia is the right.

What is the standard repair procedure? I will not do the welding myself, but I want to make sure the mechanic I bring the car to is giving me a straight story (a history of multiple attempts at various repairs by Mercedes specialists leaves me wary).

What other, possibly-related problems should I look for?

A previous owner seems to have had firewall corrosion attended to. My evidence is the new sound-deadening blanket on the firewall. The car also has an ‘exchange’ engine, a 2.3-litre unit in place of this model’s original 2.8-litre unit. I would not be surprised if the brace got bashed during the engine swap (experience indicates that some mechanics in Australia have a habit of creating new damage while conducting repairs). In addition, when I got the car, the driver’s side door (the right side) had a large shallow dent in it. The car had also had a lot of putty work done on the roof, trunk lid, and hood, and it has small ripples in the topsides of the fenders. My suspicion is hail damage (not rare in this country) rather than collision damage.

I am wondering if this frame break has been causing the funky steering. The steering has always felt rubbery on the highway during my ownership (last six years). The car seems to oversteer on long left-hand sweepers but not right handers. The steering box has been adjusted to have no play in it. Suspension bushings front and rear, rear springs and shocks, and steering bushings have all been replaced.

At this point, I will not even start on the 14-month tale of getting the Weber carbs mounted (38 DGAS’s, which are too large). The engine runs smoothly, but ….

Any insight on the frame repair would be most welcome. Thank you.

Will R.
Sydney, Australia