Radiator Neck Fix/Preventive Maintenance - PeachParts Mercedes-Benz Forum

EricSilver · #1 05-01-2002, 08:17 PM

I have the radiator with the all-plastic neck in my 89 260E. While trying to stop what I thought was a persistently leaky hose -- losing about 2 quarts of water a day -- I over-tightend the hose clamp and crushed and crumbled the outer-lip portion of the neck.

It turns out that the hose connection was fine and there was actually a hairline crack in the inner part of the "L" of the neck.

My remedy (which is holding up so far):

From Home Depot I bought a 1" copper pipe bushing, some putty epoxy, and some JB Weld. The bushing -- a rather substantial piece of metal -- fit perfectly and tightly into the radiator neck, and was exposed only where the plasitc had broken off. I filled the exposed areas with the putty epoxy then, after it hardened, covered it, and the area around the hairline crack, with the JB Weld.

After drying and curing overnight (plus a few extra hours) I rough sanded it, and reattached the hose, turning the clamp as tight as I wanted since there is no way I'll damage that copper fitting. So far, the car is dry as dust with no leaks, and running noticeably cooler.

Just thought I'd share this cheap and easy fix -- or preventive measure -- for a common problem.

Eric Silver
1989 260E
165,000 miles

Mike Murrell · #2 05-02-2002, 12:08 AM

Sounds impressive, but I'd keep an eye on it. The crack is in the plastic and it could move closer to the radiator. Summers on the way. Temps will rise and pressure will increase. It could go at an inopportune time. Thanks for the tip. At the very least, this could suffice until a new Behr arrives.

EricSilver · #3 05-02-2002, 07:10 AM

Hi Mike,

That's my thinking as well. I know it is a temporary fix and eventually some other (plastic) element will fail.

I feel more comfortable knowing that I reinforced the weakest link of the radiator, rendering any further degradation in that area impossible. For the next few months it should hold, but I'll certainly be replacing the radiator and/or the car within that time.

mbtjc · #4 05-02-2002, 07:40 AM

Going along with that, what do you guys think about doing that to a non-broken radiator? Couldn't one find a small piece of piping similar to what comes in the new reinforced neck styles and slip it in there with a little epoxy or JB Weld or whatnot, then preventing you from having to buy a whole new radiator just because of this flaw?

EricSilver · #5 05-02-2002, 07:51 AM

mbtjc,

I wish I had thought to do that a long time ago.

The copper bushing I described could probably be inserted without any adhesive at all -- that's how snugly it fits -- and will protect the horizontal part of the neck from coolant corrosion, but not so much from heat.

It's also one of those "fun" and relatively quick and effortless repairs/fixes that give great satisfaction when completed.

#6 05-02-2002, 08:45 AM

I had a similar failure, but the neck broke about 3/4 inch from the end of the pipe. I refitted the hose as there was enough pipe left for a good fit - 3 summer weeks now and it still holds.

i digress

using copper inside the neck of the radiator will be problematic in the long run as copper expands rather nicely and may cause extra stress on the pipe. AFAIK a thin aluminium 'pipe' is used in the new radiator to strengthen the neck ....

Also, remember that the coolant might corrode the copper fairly quickly, or that introducing copper into the cooling systems might react with the steel (block) and aluminium (head, pump and radiator) the coolant comes into contact with.

maybe some chemical expert might come up with accurate answers ...

Arthur Dalton · #7 05-02-2002, 09:38 AM

I did mine with aluminum tubing as preventive maint.

EricSilver · #8 05-02-2002, 10:14 AM

Louis --

Good points. I wondered about copper expansion at first, but this bushing is considerably thicker than standard copper pipe and I don't think it will expand a great deal.

The coolant corrosion issue is one of interest, and I hope some chemical expert (or near expert) here might offer an opinion.

#9 05-02-2002, 11:17 AM

in just that way about 6 years ago, and it's still holding.

But my wildest JBWeld story concerns a '69 Mercedes 220D. Fully qualified M-B Techs should avert their eyes and read no further, lest they suffer permanent emotional trauma:

About 15 years ago, a friend phoned from Frankfurt (he was a Captain on the then-new 767 route from Charlotte to Frankfurt) to say that his wife had a transmission failure of some sort with her diesel in a shopping center parking lot near our town, and he asked me to see what I could do to help. I found that the nut which holds the flange (to which the flex-joint bolts) onto the output shaft of the transmission had worked loose, probably long before, and that the wobbling flange had moved rearward about 6 mm and worn away the splines on the output shaft. After staring at the mess for some time, I decided that that last 6 mm of splines might have some strength left, so I filled the remnants of the splines in the flange with JBWeld and then slid it back into place and torqued the nut up properly. I then sent the lady home in one of our cars and told her to come back in 24 hours when the JBWeld had time to harden and we would take a test drive to see if there was any hope of her making it home with this temporary repair. Next day, it seemed to be holding, and having confidence in her smooth shifting ability (she learned to drive in a '64 Sprite!), I told her to drive very gently home and park the M-B until her husband got back and could get the transmission output shaft replaced.

Five years later, he told me he had sold the car because it was getting too rusty (only 450,000 miles) and I asked him how much it had cost him to fix or replace the transmission problem; he then admitted that he had forgotten all about my "temporary" repair job. In the meantime, 3 of his teen-aged sons had learned stick-shift driving on that car!

EricSilver · #10 05-02-2002, 12:52 PM

That's an incredible story. I was doubtful about the product, but it seems to be super strong. I'm becoming a believer.

Ashman · #11 05-02-2002, 07:29 PM

For my friend computer retorfit I had a chassis for a computer cut to size. some of the holes for the mainboard mounting bolts were cut in half. I JB welded the mounting nuts which normall screw into the threaded hole that was cut, and it is solid. so slid in fact, that I am pleased with how strong JB weld actually is.

Years ago my father had a 1969 rolls cornice. The intake manifold cracked. We bought some JB weld, and Took off the manifold and JB welded it back together. The repair was excellent and lasted quite some time. My father and I did not actually do that repair, but we had a mechanic do it, as were were on a road trip and just needed to band aid it.

We drove home, no problems. My father took it to the mechanic at home, and well he looked at it and said no need to repair or replace it, the JB Weld has fixed it. We were surprised, but we never had a problemw with that car again. my father sold it a few years later while in the middle of restoring it to someone. The person to this day still has no issues with that intake manifold. We happened to bump into the guy randomly, and the car is still going strong.

The Rolls was alsoa right hand drive. Funny story on how my dad bought it. We were having a garage sale, and this lady pulled up in the car to look at what we had at the garage sale, and well my dad bought it from her.

LOL

Alon

#12 05-02-2002, 09:57 PM

If you put it on exhaust manifolds, it will just burn off right away, and even on cooling systems, if someone runs the car out of coolant completely and really overheats it to head cracking temperatures, the JBWeld will disappear, but by then you'll have a long list of other things to fix, too.

I wonder how many people who bought high mileage '69 220D cars or used transmissions in the last decade went out tonight to check for traces of JBWeld on their transmission output flange?

renok7 · #13 05-03-2002, 09:54 PM

"Good points. I wondered about copper expansion at first, but this bushing is considerably thicker than standard copper pipe and I don't think it will expand a great deal."

- The expansion coefficient of copper is the same regardless of its thickness. It is the temperature differential that controls the degree of expansion. It doesn't really matter anyway since the expansion coefficient of plastic is greater than that of copper.

"The coolant corrosion issue is one of interest, and I hope some chemical expert (or near expert) here might offer an opinion."

- Until the early 80's radiators used to be made out of... copper.

- The best way to maximize the lifespan of an original radiator is to leave it alone. Over time plastic hardens and becomes brittle. Messing with it can only lead to premature failure.

David C Klasse · #14 05-04-2002, 12:56 AM

I once left a gas station in my C280 in too big of a hurrey. I hit hard on the dip out.

I cracked my oil pan... They JBWelded it the crack, and it's been over a year and about 40k miles later, and hasn't leaked a drop since!

EricSilver · #15 10-03-2002, 08:31 PM

After 5 months and 7,000 miles, I re-did part of the repair in my first post in this thread.

I apparently did not mix and apply the epoxy putty as throughly as I should have, and also used teflon tape, which was causing the material to crack and seep coolant and steam. (I was replacing about a quart or water per week.)

The epoxy putty was used around the copper bushing. The JB Weld surrounded and reinforced the "L" part of the radiator neck. (Not surprisingly, the JB Weld part of the repair is still holding up strong.)

This time around, I used only the putty, after gently tapping the copper bushing more deeply and snugly into the radiator neck. This second repair was fast and easy, using materials left over from the first repair. So far, I have not lost any coolant. (The reservoir is still topped-off after a week.)

What I find curious is that now with the coolant system completely air-tight, my engine is running hotter than it did when it was leaky

I thought the opposite was supposed to happen.

Interestingly, on my last visit to my mechanic's, he had a nice collection of broken-neck radiators -- all of them with the new metal inserts! So no matter what, these things are destined to fail at some point, and I am glad I chose to spend $5.00 and about an hour to fix mine rather than $300.00 to replace it.