Is the missing chunk still in your hose? If it was my car I'd probably replace it if it wouldn't cause immense financial hardship to do so. It is the cooling system and if it goes bad and your a long way from home it could cost a lot more than the rad.... I'd replace it.

However everyone's situation is different, if you don't travel far from home, and need it to hold together for a little longer then rough up the area and create a lip with some JB weld, may also be worth reenforcing it like many do on the om617 rads by JB welding a piece of metal pipe on the inside of the neck.

__________________
2004 F150 4.6L -My Daily
2007 Volvo XC70 -Wife's Daily
1998 Ford F150 -Rear ended
1989 J-spec 420SEL -passed onto its new keeper
1982 BMW 733i -fixed and traded for the 420SEL
2003 Volvo V70 5 Speed -scrapped
1997 E290 Turbo Diesel Wagon -traded for above
1992 BMW 525i -traded in
1990 Silver 300TE -hated the M103
1985 Grey 380SE Diesel Conversion, 2.47 rear end, ABS -Sold, really should have kept this one
1979 Silver 300D "The Silver Slug" -Sold

I got a discount radiator on Amazon (a mistake, but it worked) and replaced it. Took less effort than I thought it would, actually.

I also took the opportunity to flush out the coolant system and refill with 50/50 Zerex G05, which has been on my to-do list for a very long time.

__________________
Lots of diesel W126s in the past
Current: 1991 Toyota 4Runner with an OM603

These two pictures are examples of necks breaking because of a worm drive clamp. A Constant Tension Clamp would help prevent this.



Over tightening the worm drive clamp is one reason to breaking the neck.

The other reason is plastic necks tend to expand and contract ever so slightly during normal engine operations. With a fixed clamping worm drive clamp, the plastic neck cannot expand or contract, which will lead to stress and fatigue of the plastic.

With the constant tension clamp, it will allow for this expansion and contraction while providing enough clamping force for the hose. Constant tension clamps hardly wear out and can be reused many times, unless damage from the removal process.

I've installed a set on my radiator.
[/QUOTE]

The problem is getting them and matching them up properly. I found a 44mm constant tension band works best on the w123, w124 & w126 diesel radiators. I found my at the salvage yard. You can get them at a dealership if you match them up.

__________________
1983 123.133 California
- GreaseCar Veg System

Huh. Good advice, DeliveryValve. I wouldn't have thought about the clamp. I'll add replacing it with the correct type to my list. Thank you.

__________________
Lots of diesel W126s in the past
Current: 1991 Toyota 4Runner with an OM603

I am not sure the clamp size is for your w140. But my hunch it is 44mm. Again, the problem is acquiring these, if you ever run across them, they will have a "44" on the tab.

Attached Thumbnails

 

__________________
1983 123.133 California
- GreaseCar Veg System

Constant tension clamps are available from industrial supply houses, better to use new.

If I had to repair a broken radiator neck, I would try to find a copper pipe with an OD the same as the ID of the neck. Epoxy it into the broken radiator, then epoxy the broken piece to the pipe. I've repaired vacuum fittings this way and it works. Truth is, you're best off replacing the radiator, because you won't know if it works until it lets you down.