W126 Radiator Life Span - PeachParts Mercedes-Benz Forum

nyko46 · #1 11-25-2010, 04:28 PM

My 1984 MB 300 SD has a radiator leaking at the upper hose connection because there is a big crack in the neck where the hose is clamped on.
I was trying to buy an used radiator to replace mine but I heard from few sellers that the MB Behr radiators have a life spam and when certain mileage is reached it is no longer good. "You must" they say "buy a new one".
If that is true, how old a radiator must be to not longer be good?
Thanks.
Nyck

Aquaticedge · #2 11-25-2010, 05:10 PM

My dealings with Spam say that it's never good, that being said, a radiator can last 12 years or 12 minutes (I used 12 years as a reference only) Plasticy bits can fail, metal bits can erode, Ad far as milage on a radiator, I've never heard of that if you reach X amount of miles your radiator is shot or is unsuitable for reuse.

chasinthesun · #3 11-25-2010, 06:41 PM

Take it to a good radiator shop ,theyll pull the plastice tanks off ,rod it out giving better flow then reaply the tanks.The plastic top hose I always fix with an epoxy and a small metal pipe that fits the reservior hose ,after drilling a hole to the size of the pipe ,Ill rest the radiator somewhat side was so when Ill poor on the epoxy mix it will settle as a puddle on the pipe and area around the fitting.This works with about 4 onces of epoxy and stays as a permanent fix to a rather weak point of the whole radiator.I find that when mechanics get their paws on one of these cars they tend to rest their hands right on that hose thus breaking the piece for future leaks.

Wodnek · #4 11-25-2010, 06:55 PM

The radiators in my two 87 124 diesels lasted 23 years. They failed within two months of each other. On my sedan, the neck where the upper hose attaches sheared off. On the wagon, it sprung a leak where the plastic tank attaches to the core on the bottom. about a 8-10 inch split.

Sev · #5 11-25-2010, 10:32 PM

you don't have to replace the rad if the only problem is hairline cracking on the neck. reinforce the inside of the neck tube with a copper fitting from the plumbing departmnet of your local hardware store, then use plumbers goop over the outside of the neck. voila, fixed radiator

DieselPaul · #6 11-26-2010, 12:46 AM

Sev! Buddy! Good to see you're contributing. Why spend money on ghetto fixes when you get free money online with no repercussions?

On topic, I put a used 23 year old Behr in my 87 from my parts car when my fan ate up my radiator. I notice the car doesn't run as cool as it used to. The get clogged up and corrode over time.

charmalu · #7 11-26-2010, 01:21 AM

When the plastic starts to crack, break etc... it is time to just replace it. I know they are pricy new, but so is an engine if the plastic tank gave way and you didn`t notice it right away.

I don`t think it is the age but the heating and cooling over the years that take a toll on the plastic.

when I replaced the engine in 07, the radiator was replaced also i didn`t want to trust the old one, and didn`t want to dump any crud into the new engine if there was any.

Red necking a rad to keep it going is ok if you are just going to be putzing around town. but for a DD and for long distance trips, I want as many things in my favor as I can.

Use distilled water with the coolant, and you won`t have the radiators plugging up. also flush the system every couple yrs when replacing the coolant.

I have 463K miles on the radiator in my datsun PU. I have always used distilled water and antifreeze. so that is a good testamony on using distilled water. the tubes look clean when the cap is removed.
This radiator really amazes me, I have been driving this thing 29 yrs w/o any real radiator problems. except for the mounting bracket on the side that bolts it to the body needing soldered back on a couple times.

Charlie

t walgamuth · #8 11-26-2010, 07:19 AM

I would not hesitate to use epoxy to make a temporary repair but if plastic parts crack one place they probably will crack another soon.

I would not hesitate to use a junkyard rad either if it looked good. These cars are old enough if you find a recently junked running car there is an excellent chance the rad has been replaced.

mach0415 · #9 11-26-2010, 08:52 AM

I tried the repair procedure over the summer, but she was too far gone. I had a local rad shop retank it and rod it out. I never had a overheat concern. It has been fine since then. I drive 80 miles a day and the repair was $88 for everything. So, to each his own. If I had the money I would have treated her to a new Behr.

funola · #10 11-26-2010, 09:11 AM

Mark,

What exactly is "rodding" out?

micalk · #11 11-26-2010, 09:46 AM

Rodding out: Removing the top and bottom tank and snaking rods through the radiator's tubes to clear any obstructions. Once this is done, new seals are installed and the top/bottom tanks are put back.

brainlair · #12 11-26-2010, 10:14 AM

Quote:

Originally Posted by charmalu

Use distilled water with the coolant, and you won`t have the radiators plugging up. also flush the system every couple yrs when replacing the coolant.

+1

I bet that if the green stuff was NEVER TOUCHED and one always used distilled water, the only concern would be the plastic above and below the metal. Proper coolant inhibits corrosion, and if you never put hard water in there from which deposits can form, what is there to clog the radiator?

pawoSD · #13 11-26-2010, 10:51 AM

My original lasted about 22 years then began to seep at the upper tank seam. I replaced it promptly with a new Behr, been fine for 5+ years. Original was clean inside, but the seals on the tanks had degraded. (I surgically disassembled it to look inside)

New expansion tank:

New lines:

I am rather obsessive about new parts.

Can't complain, as I've driven my car 100k in the past 7.5 years without a single breakdown....not even a flat tire.

vstech · #14 11-26-2010, 11:04 AM

Quote:

Originally Posted by pawoSD

My original lasted about 22 years then began to seep at the upper tank seam. I replaced it promptly with a new Behr, been fine for 5+ years. Original was clean inside, but the seals on the tanks had degraded. (I surgically disassembled it to look inside)

New expansion tank:

New lines:

I am rather obsessive about new parts.

Can't complain, as I've driven my car 100k in the past 7.5 years without a single breakdown....not even a flat tire.

the new parts look good, I'd have been a touch more obsessive, and cleaned everything before taking off the old parts... to each his own!

no a/c eh? that'll keep the cooling system cooler too...

mach0415 · #15 11-26-2010, 12:20 PM

Quote:

Originally Posted by micalk

Rodding out: Removing the top and bottom tank and snaking rods through the radiator's tubes to clear any obstructions. Once this is done, new seals are installed and the top/bottom tanks are put back.

X2 I looked at the flues when the tanks were off and was pleasantly surprised for an original rad. When he was done, it was pressure tested also. The engine always has run under 80 C. But this is a good testimony to proper service/maintenance.