Adding Antifreeze???
 

What is the easyest way to add a gallon ($26.00 Gallon from MB dealer) to my radiator,
I want to add it to the radiator not just into the overfolw holding tank.
Starting to approach freezeing here in seattle in the mornings, wont be long till we get a good freeze.
Is one gallon enough for my 91' 300e 3.0L.
Thanks!!!

The reservoir in the engine bay is not an overflow tank. It is part of the pressurized system. If you notice, there is no cap on the radiator so there's no convenient way to fill the cooling system except through the reservoir.

If there is a hose from the reservoir that disappears into the fender then perhaps there's an overflow tank behind the inner and outer fenders.

Sixto
87 300SDL

You really should drain the system and refill with the proper concentration of antifreeze rather than fudge the existing concentration. You probably don't know what the existing concentration is so throwing in a gallon could result not enough or too much of an antifreeze concentration.

Sixto
87 300SDL

Yeah, follow the above advise. Just drain the whole thing and refill with a 50/50 concentration of antifreeze and water. There are two drain plugs, one on the bottom of the radiator and one on the engine block.

If you are trying to increase the concentrion of antifreeze, is it that the car only has water in it right now?

un-known mixture in radiator, just purchased last summer.
looks to be just watter.

You can get one of those little devices that measures the antifreeze concentration from an auto parts store for a few dollars. You don't want the mixture to be a lot more than 50% antifreeze because then its ability to aborb and transfer heat will be reduced. i.e. if the mixture was 100% antifreeze it would abosrb less heat from the head and not cool as much during its run in the radiator.

If you want to take a little time, your best bet would be to drain and refill the system or just test the mixture.

Cheers. -Ali

Will a prestone branded antifreeze "meter" work with the unique MB fluid???.
A have a common prestone tester.

Yes it will. It works properly with any glycol based fluid. The MB fluid may have have a slightly different formulation that some other fluids, but it is still glycol based and thus the prestone antifreeze tester will work correctly.

If you have one, use it and see what it says.

just water

I used to have an 89 W124 that would give this gurgling sound somewhere inside the dash area when the system is running. Apparently MB issued a kit that would fix this. On my 95 W124, this has not been a problem so maybe MB updated the design.

So back to older W124s, is it just drain & fill the coolant? Would there be any 'air pockets' that need to be purged, and how to do this?

For the M103, on the horizontal surface of the head near the #1 and #2 injectors there are a couple of 13mm bolt heads. Some cars have one bolt head and one sensor. Remove a bolt then pour coolant into the reservoir. Keep filling until coolant leaks out of the hole. Cap the hole, top off the reservoir and you should be good to go. Check the reservoir over the next few trips.

Sixto
87 300SDL

Ah, but how do you know if it's distilled water?

https://www.mbwholesaleparts.com/StarTuned/pdfs/AntiFreeDec04.pdf

Check conductivity?

Sixto
87 300SDL

If you're running only water at the moment, this is my suggestion:

1. First get the coolant capacity (qts) of your system.
2. Drain all the water you can using the radiator drain and engine block drain.
3. Close drains.
4. Add 50% of the capacity with antifreeze, the remaining charge with water.

This is just the bare minimum that should be done. There are many other steps that can be added to this procedure - some of them can get anal - but this should get you started.

Running only water is never appropriate for a cooling system for many reasons.

If you want to read more archived information on cooling system maintenence, search using keywords "demineralized", "distilled water", "coolant flush".

Can I replace the expansion plastic tank with a bigger one on my 300E86? What is compatible?