radiator tank leaks - PeachParts Mercedes-Benz Forum

vtmbz · #1 09-19-2014, 07:51 AM

I'm seeing a small amount of weeping on the top of my Behr radiator tank; where the aluminum and the plastic side tank join. This is original radiator I feel certain.

Im in a cool climate with little stop and go driving; wondering if I can replace the radiator cap with a lower pressure one instead of buying a new radiator.

The car runs around 90c all the time, with long hills going to 100c.

Would less pressure make any difference?

leathermang · #2 09-19-2014, 10:20 AM

You need to fix the leak...
the engine needs to run at a certain temperature .... your system can not meet that cooling task under the range of conditions you might expect your car to function correctly under.... unless it has the ability to refrain from boiling during the extremes it encounters.

jay_bob · #3 09-19-2014, 10:46 AM

What he said. Your aluminum head engine is very unforgiving of coolant loss.

Unfortunately this is a common problem with these radiators, this is a typical failure point. It will only get worse. It will at best just leave you stranded, and at worst will leave you stranded with the HG blown or head cracked.

funola · #4 09-19-2014, 11:40 AM

Clean the crimps well then goop it with RTV all around. It was a permanent repair when I did this to leaky plastic radiator tank.

leathermang · #5 09-19-2014, 11:52 AM

RTV's are not all created equal....
Mercedes specifies a glue for this purpose...
it needs to be compatible with the plastic to stick to it well enough to hold pressure...and vibration, heat, over the years...

vtmbz · #6 09-19-2014, 02:40 PM

New radiator for me I guess!

vstech · #7 09-20-2014, 10:02 AM

Go to auto parts store, rent the radiator pump up tool, then clean the top of the tank where it's weeping, with soap and water, inside and out. Gently re crimp the aluminum I have used a socket extension. It just takes a slight tap. There is a large o-ring under it, and more clamping force generally fixes the weeping syndrome. Then fill the cooling system back up, and pump up the radiator to 18 psi and see if it's still weeping...

Total cost of repair: 2 hours of your life... No parts.

funola · #8 09-20-2014, 10:35 AM

Quote:

Originally Posted by vtmbz

New radiator for me I guess!

You're not going to try to fix it? Try Vstech's recrimping, that may just do it. If it doesn't, paint it with 2 coats of POR15 (after cleaning /degreasing/ drying), then RTV over it. I guaranty that will stop the leak. POR 15 is amazingly tenacious stuff. I spilled a few drops on some plastic and could not scrape it off easily with a screwdriver.

vtmbz · #9 09-20-2014, 11:02 AM

I see it this way: 250.00 once every three months or so is well within tolerance to keep a car on the road. Its running hot away, and I know it had prestone in it for the last 30 years. So the radiator is compromised if not due for a total failure. I definitely drive it hard, so it makes sense to have confidence in my cooling system.

Wifey likes the car, but she'd change that soon enough if we had to walk home from the dance some night...

I'm also going into the water pump soon for an inspection of the impeller.

So anyone want to buy a BEHR oem with some slight weeping issues? Cheap?

leathermang · #10 09-20-2014, 11:03 AM

Quote:

Originally Posted by funola

....... POR 15 is amazingly tenacious stuff. .

IF YOU CAREFULLY follow the specific instructions for application .

ALSO POR 15 name covers several products.. research to see which you need to use...