'96 E320 Coolant Flush and Change
 

:confused: Would appreciate any sage advice offered. I would like to drain, flush and replace the antifreeze/coolant in my '96 E320. I've always had MB dealer do this for me ... but now that I am retired I would like to tackle some of the easier preventive maitenance jobs myself, i.e., oil/filter changes, air filter changes, spark plugs and the like.

Can anyone provide a step-by-step procedure for draining the coolant, flushing and replacing same? I am a novice, so I need location of drain plugs and how to flush the system -- real basic stuff. Also, can you suggest how what kind and how much antifreeze I should add and whether there is any anti-corrosive additive that I ought to be adding? The car has nearly 52,000 miles on it. The last time the coolant was changed was about 2 years ago -- when I look in the pressurized overflow tank, the antifreze looks "spent" to me and there seems to be gunk in the little plastic tank. MB recommends a three year cycle, but I think the antifreeze is ready for change. The hoses look fine, i.e, no cracks or leaks, and they feel firm, but pliable. The hoses have never been changed -- should I change them when I do the coolant replacement? Thanks for any help.

There are two drains. One at the bottom of the radiator and then other on the engine block. The block drain plug is located just under the middle part of the exhaust manifold. Let it all drain out of those two and then refill.

I always change the thermostat as preventitive maintenance at the time of coolant change. Also make sure all the air is purged out when you refill. To do this fill the expansion tank all the way to the top and let it run and keep refilling if necessary. This will bleed any trapped air out of the system. Additionally, I fill the block up through the thermostat housing to make sure no air gets trapped in there, but this is probably not necessary.

As far as which coolant to use, if you do a search this has been debated almost as much as the topic of oil changes. I use MB coolant and distilled water.

Overall it is an easy procedure.

Good luck.

My oldest car is 42 and the youngest is 14 (all bought new and maintained by me). They all have their original thermostats and pressure caps, and they all work as new.

Page down and find a recent thread on M103 coolant change. It's basically the same procedure.

Duke

Every time I have had to do a coolant change on my C280, I find the thermostat opening a little too early and the engine running too cold. For example, after 3 years the engine will run at a solid 80C on the highway. New thermostat brings it back up to the 85C to 90C range on the highway. Thermostat is supposed to start to open at 85C-87C.

I always like to add a flush to the drain and refill. After draining, it's just a matter of removing the thermostat, reinstalling the top hose, removing the hose at the radiator, and running a garden hose down the upper radiator hose. It hopefully stirs up any sediment and carries it out, plus removes any residual coolant.

It's a lot easier to flush through the heater circuit supply (back LH side of the head on M103). You remove the hose and flush both the engine and heater circuit and you don't have to remove the thermostat and get a new gasket.

Duke

I remember the good old days of the garden hose flush.
Can't bring myself to do it anymore.

I know what you mean. I now try to drain as much as I can and put it down the sanitary line of the house (toilet). The diluted flush just goes on the ground.

Thanks
 

All - thanks, I think I've got it from here. cp

In my city it's okay for home owners to dump antifreeze down sanitary drains. The sewage treatment process breaks down the glycol and traps heavy metal ions.

I just place bucks under the car with hoses attached to the block drain and radiator drain nipples. I can drain and flush the system without spilling a drop on the ground.

Duke

One more question ....
 

Is there a gasket that needs to be replaced when I pop the thermostat back in? Is there any sealant that needs to be used to seal the thermostant housing? thanks again All ... cp

Yes, there is a gasket. I reused mine the last time I serviced it. It's rather beefy.