Coolant drips when it's cold out - PeachParts Mercedes-Benz Forum

toddro · #1 01-19-2004, 10:25 AM

Seems to be alot of coolant leaks posted lately...

I have a few drips under my '92 190e 2.6 that ONLY appear when it is cold out (less than 35deg or so) If it warms up, they go away for a few days until the temp drops again.

They all seem to be happening at hose junctions: Bypass hose on the thermostat side, upper and lower radiator hoses where they connect to the radiator, overflow tank outlet, aux. water pump connection, and somehwere further back under the engine that causes a drip near the ATF pan (heater core connections?)

I have a new (7 months old) water pump, thermostat housing, tensioner etc. So for now I'm taking the water pump out of the equation and focusing on the hoses.

Is this an indication that I just need new hoses? Or should I be looking at another culprit? I have tried tightening the clamps I can get to, but don't want to crank down on them too much..

Any input would be much appreciated.

Thanks,

Todd

savagetom · #2 01-19-2004, 01:56 PM

I'd be tempted to tighten each connection a little. Maybe a 1/4 turn if they don't seem too tight now.

On my'87 190D, I removed the aux water pump and replaced it with a brass connector. The heater worked fine and seal leak was gone. I also had a leak from the heater control valve. It is located betweeen the fire walls near the battery. It is an easy relatively inexpensive repair. On my car I was seeing coolant leak out near the transmission, also. I, too, feared a heater core issue, but it turned out to be much simpler.

Good luck. YMMV

MikeTangas · #3 01-19-2004, 05:42 PM

Shortly after arriving in Michigan the temps drop to near and below zero. Until then I had no coolant leaks, but soon as the temps got low I developed a slow steady drip. While changing the oil I checked and tightened the hose clamps at the radiator. Cured the steady drip, drip, drip and didn't even need any penicillin.

The key here is to tighten gently. In the cold I'm sure the plastic is somewhat more brittle and these necks are fragile to begin with, especially if this is an original or unmodified radiator. I think it took about 1/4 to 1/2 a turn to be sufficiently tightened.

toddro · #4 01-19-2004, 05:43 PM

Thanks Tom,

Did fixing the leak at the heater control valve take car of the leak that you thought was the heater core?

This sounds like what I'm dealing with, so I will check this valve out.

Thanks,

Todd

toddro · #5 01-19-2004, 05:47 PM

Thanks Mike,

Seems to be my problem exactly. I didn't see any sign of a drip until we got down into the 20's here (a warm winter day in Michigan probably!!!)

Those radiator hose clamps on my 190 are a bear to get to, but I'm trying to get everything tightened up - otherwise I'll wait 'til spring and quit worrying about it...

-Todd

Glick · #6 01-19-2004, 07:26 PM

Mine did the exact same thing when it got to 5 degrees. The radiator hose clamps were tight but the hoses were kinda soft. Replaced both upper and lower, leaks are gone even in cold weather. In cold temps, the hoses skrink and expose possible pin holes and as the motor warms, the hoses swell and close the holes as was the case in my particular situation. Hope this helps....

toddro · #7 01-20-2004, 09:53 AM

An update,

I seem to have helped the radiator hoses by tightening them a bit; however, this morning I have an even larger leak then before underneath the car. The puddle is centered underneath the car about even with the front edge of the front doors. I have the car up on stands, but I cant find the source anywhere...

Does this point towrds the heater core, or is there another leak that could manifest itself in this area?

thanks for all the input...

Todd

Kestas · #8 01-20-2004, 11:16 AM

Interesting thread!

My Mercury Marquis also developed a leak during the cold weather at the water pump/lower radiator hose junction! I tightened the clamp and the problem went away. Perhaps it has something to do with aluminum's high rate of thermal expansion (or contraction), but you people also report it happens at the plastic radiator necks.

This phenomenon makes a case for the old-style spring clamps that people remove in favor for screw clamps. There are some mechanics that actually favor spring clamps for cooling systems. For one, it prevents over-tightening the joint. And now we know that it can compensate for thermal shrinkage/expansion.

psfred · #9 01-20-2004, 01:36 PM

look for the condesate drain under the car. Usually above the transmission on later models. If there is coolant there, the heater core is leaking. May come dripping off the transmission. Otherwise, look at the heater hoses up by the firewall, they may be leaking.

Peter

savagetom · #10 01-21-2004, 08:49 PM

Hi, Todd.

Yes, fixing the valve cured the leak I thought was the heater core. A heater core leak and a valve leak will appear at the same spot under the car. In my case, I could see a drop of coolant at the valve so I was pretty confident that a new valve would fix it.