The overflow nipple broke off the radiator of my 300D, and I need to repair or replace the radiator now.

I bought a new radiator, but that's going to require a complete flush before I install it, and that's going to result in my leaving the car with a drained cooling system or a system filled with water for at least one night in sub-freezing weather if I can't finish in one day.

Would I be safe leaving the system drained overnight or should I wait until I can get the car in a heated garage to start the series of flushes and the radiator replacement?

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1983 300D

It will not hurt anything to leave it drained overnight. Thats if the small amount of coolant left in the system is your normal anti freeze mixture.

Now flushing it with water and leaving it overnight in freezing conditions is a no no of course. Some water is usually retained in the system as well.

Thanks for the reply Barry.

As I understand the citric acid flush procedure, I won't have any anti-freeze mixture in the car between between the initial drain and the final refill. The car had green coolant in it when I bought it, and that's why I'm forced to do the flush before installing the new radiator.

If I can, I will repair the old radiator using a tire valve as Einyodeler from the Schuman forum did on his...

http://www.schumanautomotive.com/forums/showthread.php?t=6630

That would allow me to hold off on the flush and radiator exchange until Spring. Won't know till I try.

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1983 300D

Search Easy Rad Fix or RadiatorRecovery

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1984 300SD turbo 126
"My true love"

God made me an atheist and who am I to question His wisdom

I've scoured the internet and the archives here concerning plastic radiator repairs, and it is generally believed that the radiator should be replaced. But if draining the block during the flush is still going to leave enough water in the engine to cause damage in sub-freezing weather, then I am screwed for the time being.

If any one else is ever searching the archives for broken overflow nipple repairs, let me offer another possibility. It's a BMW factory repair nipple for their Behr plastic radiator...

Part# 17-11-9-055-593-M9

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1983 300D

I don't want to start a theological argument here but I have weaned both my '85 and my '87 Benz off of green coolant by simply draining the old, doing a thorough flush with tap water, and then refilling with a 50-50 mix of Mercedes coolant and distilled water.

I suppose if a cooling system were all crudded up you would want to do the citric flush anyway, but if not is it really necessary? If you could skip that step you should be able to finish the job in one day and not have to worry about leaving the car to freeze overnight.

Jeremy

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"Buster" in the '95

Our all-Diesel family
1996 E300D (W210) . .338,000 miles Wife's car
2005 E320 CDI . . 113,000 miles My car
Santa Rosa population 176,762 (2022)
Total. . . . . . . . . . . . 627,762
"Oh lord won't you buy me a Mercedes Benz."
-- Janis Joplin, October 1, 1970

Before I install my new $300 radiator I want to do the flush.

If I can repair the old one, I couldn't care less what color coolant it has running through it.

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1983 300D

Now lets don't get too hasty and short sighted here...

Mercedes, not ever allowing anything to be that simple....

has made their cars where if you don't use the right antifreeze.. you take a serious chance on corroding A HOLE in the heater core inside the car.
Naturally they also give you a way to check this all out...
by measuring with a VOM the current flow between the car and the coolant you have in the car... this is all from the FSM .... It is the same as metal plating.. except opposite.

Understood. Any repair I can make to the old radiator will only be buying me time until I can do it right, and that will include a change to the proper coolant.

My mechanic broke the radiator nipple off while doing some other repairs to the car. It had been JB Welded by one of the previous owners, so I couldn't really fault him for it.

He put a bolt in the side of the radiator and told me it might run hot in the summer if I didn't do something about it. Well, it's already wanting to run above normal temperature in traffic, so it's parked until I can sort this out.

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1983 300D

We've had enough good weather for me to pull the radiator, install a brass tire valve, drain the block, flush with water and refill with Zerex G-05 and distilled. I installed a new Behr thermostat as well and my engine temp is now consistent at around 90 C.

The brass tire valve is $4.99 at NAPA, part #NTH90252

http://www.napaonline.com/MasterPages/NOLMaster.aspx?PageId=470&LineCode=NTH&PartNumber=90252&Description=Tire+Valve

Installation requires a 7/16" x 12" drill bit and I used a bench grinder to flatten one side of the flange. Otherwise, just as Einyodeler describes in the link above. I wouldn't throw away an otherwise good radiator without first giving this a try. Thanks Einyodeler.

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1983 300D

If the block or radiator are way cold, ice will form not long after you fill it. If daytime temp is above freezing, come night, cover hood w/ a blanket & leave hair dryer on an extension cord in the engine compartment to heat it. Leave thermometer or a glass of tap water in there as well. Check a few times overnight. If it's <32F of skim ice forms, flush w/ coolant.