... and the head smacking begins.

My cooling system woes kept growing and it was probably all my fault. I limped the 300D on distilled water for about 4 days til the new overflow tank arrived. My guess at the end it was about 25% coolant, 75% water. Filled it up and the water pump immediately began leaking.

Replaced that and the next day I'm driving along, happy as a clam and I got a large rush of antifreeze smell. Maybe that gap in the firewall around the steering column I haven't fixed yet is not so bad after all. I was right by a gas station, pulled into their air-up station, got out and saw a large coolant trail behind me. It was a large coolant system leak. Really large.



Why in the F did I cinch down on the hose clamp so hard the night before? Oh yeah, I'll make sure it doesn't leak. OTOH, the guy from Kent, WA says that the upper neck is a weak spot with age - brittle. He offers a repair kit. If I was a thousand miles from home mayby I'd have found the fight copper piping and given it a shot. The neck left on the radiator was sort of maybe long enough. But I'm thinking, no, I'm at home, go deluxe, doesn't cost that much and OEM is still available.

I bought a new Behr from some geeks for $181 for everything.

When I attach the hoses I'm going to tighten til it starts to get snug, maybe go an eighth or quarter more and then run it and see if it leaks at the low torquing. If not, easy enough to fix, easy does it.

No need to show the coolant tank in the vid but that's what I saw after opening the hood. Coolant was still coming out of the radiator, lot of steam everywhere. I caught it in time, was about 3 miles from my shop, Triple A was there in about 10 minutes.

Don't know why my video won't display. If you hit quote and copy and paste it into a new window it will play. I snapped the upper inlet tube in a rough circle completely off. Now I done ruined the dramatic tension.

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1986 300SDL, 362K
1984 300D, 138K

That's what's commonly referred to as PPM - poor maintenance.

Tough crowd. Sorry to hear of your troubles Carl.

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

I concur.

No usefulness in doing so. Self-compassion would likely be more helpful. Mistakes resulting from good intentions are part of being human and learning.

That's the key success.

Decades ago when I first tentatively started non-professional wrenching, a friend who owned his own independent M-B & BMW shop and took care of my M-Bs gave me some excellent advice that I still remember (and use):
Easy does it. Avoid too much wrench (tightening).

There is a repair for the little snapped upper inlet tube. Find the thread for the specifics. What I can remember is you pick your direction to go and thread a wire through the upper tube hole and you slide I believe it is a metal valve stem with out the valve in it. They you thread a nut down the body of the stem.
I would use the slow 4 hour curing JB Weld epoxy coated on it be fore you install it so you are sure it seals and holds well. The JB Weld slow curing epoxy can take the heat. There is other companies that make similar epoxy but be sure to read what amount of heat it can take. Duro is one of the companies that makes it.
Anyway find the thread or wiki on the repair as there is also other choices instead of the valve stem.

A common reason hose clamps get over tightened when you try to stop a leak is that the Hoses are old and have lost elasticity.

I have the same URO upper and lower radiator hoses on my Car since around 2007. I would not surprise me if I had to replace them now.

Another reason for coolant system leaks is corrosion of the aluminum parts under the hoses. I had that also. I wire brushed out all of the white corrosion degreased and filled the large and small pits in with JB Weld Epoxy and wrapped tape around them so it followed the contour of the hose nipples.
After it hardened I removed the tape and filled in any voids. Followed that with sanding it down to match the original contour. Have had no issues in those areas since around 2007.

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84 300D, 82 Volvo 244Gl Diesel

An excellent and empirically-based counterpoint to the assertion along the lines of: But the hoses on my (30+ year old) M-B engine look fine.
Yeah, well...

A condition that supports the wisdom of the cooling system maintenance regimen as outlined in the applicable Factory Service Manual.

Although it is probably too late now but I have learned tinkering with my W123 it is faster, better, and easier in the long run to replace everything in a system versus a part here or there. I try to tackle by part grouping or components or what is accessible in the cluster of parts. The entire cooling system on a W123 cannot cost more than $500 to replace new. I would do a 48 hour flush and just replace everything. Radiator, water pump , thermostat, all hoses, clamps , correct coolant , belts, sensors, and whatever correct fasteners you need. This way , it’s a long day or even a weekend but it should be good for a decade. I learned this a while ago when tinkering with my W123 and it is the approach which I try to take. May not be for everyone but time is my most valuable asset.

Thanks guys. This last month was hectic beyond words. Normally I do better. I'm really careful when tightening bolts with a wrench. When installing the water pump I was pretty gentle with the small bolts holding the pump to the aluminum housing. I guess I never considered that even without the leverage of a wrench you can over-torque a hose clamp. I used the screwdriver type socket holder. Most of my vehicles have had brass or alum radiators so the danger of overtightening was not as apparent.

I take solace that I now have a cooling system in line with this car's mileage (138K) rather than its age. I think Kent is right. This was almost certainly the original radiator. Though the miles are low it was a daily driver for much of it's life in Eugene, a not large town. 10 miles a day over 35 years would yield that mileage. Any sort of plastic heated to those temps that often is going to get weak. This might be a blessing in disguise.

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1986 300SDL, 362K
1984 300D, 138K

If this car was near on its last legs, I might have tried the radiator patch. The kit I saw had 2 pieces of copper piping that looked about the inner diameter of the radiator neck. But his car is a low miles cherry with good compression. I replaced the thermostat several months ago.

The original owner, deceased as of a few years ago, was a career VW mechanic, trained in Germany his daughter told me. Then she had it for 10 years, he still doing much of the maintenance. The hoses look like they were renewed not that long ago, certainly not 36 year old looking. No signs of age.

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1986 300SDL, 362K
1984 300D, 138K

This gave me a laugh. Why? Because from time-to-time, I say the same thing when I inadvertently over-tighten something. I think: Wait a minute, I'm so careful, how the heck did I do that?! LOL. Life is practice.

I don't always have the patients to read each and every thread closely.

However, it is similar to the stripped valve cover nuts or threads issue and the aluminum under the nuts being deformed from attempts to tighten the Nuts and stop a Valve Cover Gasket leak when what is needed is a new Valve Cover Gasket or otherwise using sealant with the old Valve Cover Gasket. (And in fact my Valve Cover Gasket is leaking a tiny bit. So Far procrastination is winning. It will have to wait till I do a valve adjustment.)

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84 300D, 82 Volvo 244Gl Diesel

I think everyone has over tightened stuff. My thing used to be stripping worm gear clamps that had been on the Equipment for years and years.

The other issue is if you bought the car and are working on that area for the fist time was it the former owner that actually overnighted it and you simply gave it a little push over the edge.

I remember about 8 years back there was quite a few people that had bought W123 and when the did an Oil Change one of the Oil Filter Lid Studs snapped off or stripped out and the previously mentioned Valve cover Nut and Stripped Stud issues. There was like a 3 year period where several times a year someone had one or the other of those issues.

Former Owners did it or in the case of the Oil Filter Cap it could have been those Oil Change Places that over tightened.

About that same time there was also frequent stripped threads on the Oil Pan.

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84 300D, 82 Volvo 244Gl Diesel

You can feel when good snugness is reached. I then go just a tad more. I use torque wrenches for the big stuff but I've been burned trying to use them for small torque specifications.

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1986 300SDL, 362K
1984 300D, 138K

At first I didn't get what you were saying but I read it again and saw "little snapped upper inlet tube." That could well be a safe repair.

I'm almost glad it happened. My 300SDL radiator failure took place about 400 miles from home, it had more miles but 2 less years on it that this one.

I filled it and fired it today, when it got to operating pressure I checked the hose connections, no leaks, and I had not torqued them very hard at all.

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1986 300SDL, 362K
1984 300D, 138K

I've been running a Nissens radiator for the past five years with absolutely no problems. Of course, I bought gates brand radiator hoses so that might have something to do with it.