Cooling System Problem?

[dirtrack49]

Took my 66 230sl out the other day for another test drive. After covering some 20 miles, all systems seemed to be fine.
Later that evening, I found a pool of anti-freeze under the car. Looked all over and could not find any leaks. Checked expansion tank and coolant level cold was about two inches below the tang. I had previously added coolant mixture up to the tang. After restarting the vehicle, and driving only a couple of miles, I show no signs of coolant on the ground.

Do these cars have an overflow tube that will send coolant out of the car to the ground if overfilled? Will the coolant level in the tank seek it's own level?

Would having had turned on the heater controls for the first time create a possible air pocket? I had previously renewed the coolant a few months ago but can not remember if I had opened up the heater controls while refilling.

The car shows no signs of coolant in the oil. Oil level has remained approximately the same in the last 200 miles of testing. Vehicle runs dead on at 180F unless climbing a mountainous hill close to home and only goes up to 185f. The engine has 76,850 original miles on it and runs very well. However my concern would be that this vehicle has sat idle for nearly 15 years.

TIA for any and all information on this matter.

[Cees Klumper]

Sounds to me like you overfilled it and upon cooldown it dumped the excess. Deive it like this for a while, multiple warm up and cooldown cycles, and observe the coolant level. My bet is it will stay stable now.

[Jordan]

Tom, there is an overflow on the side of the expansion tank.  Should be on the inside close to the firewall.  You don't say where under the engine you found the coolant, although I know it can travel before dropping to the ground.  You could refill and go for the same 20 mile drive and then go back to the car after 30 minutes to see if it is again dripping coolant.  I think you already know this but the heater controls should be open (set to hot) when draining and refilling the coolant.

[Jonny B]

You should see the telltale stains on the side of the coolant tank from the little stub end overflow pipe on the side of where the pressure cap slots in.

[dirtrack49]

Thanks everyone for the replies.

Took it out again today and everything was fine until I went to park it. Big puddle of coolant coming out of I believe the front of the engine. So, it is not seeking it's own level after all.

My guess, since I can't see where it is coming from, is either the water pump, or maybe if there is one on these cars, a thermostat bypass hose. They sure made it difficult to say the least to see what is going on when there is an air conditioner installed.

Does this mean taking off the hood so that I can make access to all of the stuff up front? Or, can you access most of the coolant items from below? While I am at it, I am thinking I should remove the air conditioner all together. It needs a little more work done to it that I don't really think is worth the effort. And I certainly think that the kuhlmeister box under the dash is rather trashy looking. Anyone with experience on the removal? Any ideas on what to look for next concerning the coolant leak?

TIA

[Jordan]

Before you start taking everything apart I would start with the simple things first.  Check all the rubber coolant lines to make sure none have a crack and check all the clamps to make sure they are tight and secure.  This might also help you identify where the coolant is coming from.  Could your rad be leaking?

[mdsalemi]

You can access all from above and below, including removing fan, radiator and water pump. If you remove the radiator of course you have to get the car up high.
When were the hoses changed? These are wear items, and unless they are fairly new might be a good idea to check/change them all and get the correct clamps if you don't already have them!

[Benz Dr.]

Add a bottle of water wetter to your coolant. It helps to remove air bubbles and makes our coolant more effective.

[ja17]

Long periods of inactivity are hard on old water pumps.

[ctaylor738]

There is a bypass hose, and you would need to remove the AC bracket to access it.  Removing the hood will make this easier.  You also need to remove harmonic balancer to get at the lower bolts that hold the bracket to the engine and the compressor to the bracket.  Not a fun job, good luck!