W123 plastic radiator neck
 

The top radiator hose connector has cracked clean off and left the top hose dangling! and throwing up all its coolant!! Left me stranded too! Turned it off before it got too hot and did any damage to the engine it seems...

I gotta say, the Behr radiator in these cars made of plastic seem like a cheap cop-out for MB!!!

So this is how I fixed it and it has held for about 30 miles so far.

I used Devron Plastic Welder available in hardware stores, next to their regular Epoxy glues. It is an epoxy as well as you must push it out the double tube and stir it. What surprised me was its smell-smelled exactly like what the dentist uses when he puts in a porcelin filling!! (note teeth:D ) I roughed up the two broken surfaces after degreasing them with brake cleaner, applied the epoxy quickly after stirring, and used a handy dandy Stanley woodworking clamp (brilliant tool) to keep the pressure on for at least 24 hours.

Still, I saw a metal radiator at the PNP (Pick N Pull) off a '77 which I might just scarf for cheap-test it out and keep in my trunk!

240 Ed

Glad to hear your repair is working. I'll have to keep the epoxy you used in mind next time I need to buy some more and/or do a similar repair.

I would be hesitant to rely on the repair as a permanent fix and continue to use that radiator, however. Over time the epoxy may not hold up and I would be sad to read a post by you that the repair failed at a bad time (like it seems they do), the engine overheated, and now you need info/help to repair the damage. However, you may want to test the epoxy/repair and report back to us that it has lasted for months/years - then others would know how to repair their broken/cracked radiators for little $.

Sounds like the radiator you found at Pick-N-Pull is one of the all brass replacement radiators sold be several manuf. I'd grab that radiator if it looks like it is in good condition, have it reconditioned (if needed), and install it. Keep the repaired radiator as a back up. When I replaced my old Behr radiator I had a choice of the Behr or an all brass replacement - I bought the all brass radiator (plus it was $100 cheaper). Been using it for over five years and I'm very satisfied with it.

My, very cheap, $0.02 worth!
Tom

I have heard successful stories when people insert a metal tube in side the two broken pieces and then chemically weld everything together.

I have personally never done it. Have owned 3 W124 cars and frankly I have had no radiator problem SO FAR (do not break tomorrow, OK.)

I do have a small seep on the little "radiator fitting" on top of the 1991 300E radiator. There is an O-ring inside that connection as I have seen my mechanic repaired the one on my sold 1990 300E. Now I used a small piece of steel wire to tighten that fitting a bit (a hose clamp is too side for that little space) and it has been dry.

Ed:

I would second Tom's advice. Your repair is going to fail sooner or later, as the plastic radiator parts are going to break again somewhere else.

I put at new head and radiator in my sister's Volvo this spring when her's blew on the interstate -- not cheap.

The plastic/aluminum radiator has two advantages -- it is lighter and it works better. Aluminum transfers heat somewhat better than copper or brass. However, not only does the plastic die, but the aluminum is subject to corrosion, especially if you use green coolant. I would personally spring for a copper/brass one because they not only last longer, but are repairable. No way to permanently fix the deteriorated plastic, and even if you can find a new tank (I did for my Volvo TD), the core is usually shot, too. Mine was, still ended up with a new rad.

My brother just lost the rad in his Jeep Sunday -- probably corroded through at the top tank connection, same plastic and aluminum deal. He's getting a new rad put in as soon as he can get it in the shop.

Peter

Thanks for your input folks!

I shall take your combined advice and seek a proper radiator.

Actually I think I found the result of this broken radiator neck, because I just took a compression test on this new to me car, and got 80 psi on #1 !!!

Aparently the PO had just had a rebuilt engine put in (no way, probably a junk yard unknown), but the rad neck was just long enough still to catch the top hose and tighten with a clamp.

So it was probably the cause of the demise of the original engine, what a waste...:(

I had to replace my radiator a few years ago when the top hose connection broke off. I have a great radiator guy who told me that frequently can happen on plastic radiators when someone tightens the hose clamp too much and/or if they use too short a hose and snug it up too much. This is especially true on our cars which can vibrate a lot and may have shot engine mounts. He suggested sticking with OEM hoses (or at least checking to be sure they are the same size) and being careful not to overtighten the hose clamps.

As to the epoxy fix, I once epoxied an hydraulic clutch line fitting with JB Weld and it lasted for about a year. Eventually the temperature changes got to it and it let go.....naturally in bumper-to-bumper traffic. Consider your epoxy fix temporary.