E420 Coolant Drains?????

[y2kimmel]

I tried to change the coolant in my new (to me) 1995 E420 tonight. I have the service CDs, and the location of the crankcase drains (I was able to find the radiator drain) was indicated as "next to the engine mounts". I think that I found them, but am totally unable to access the passenger side drain - it's really a tight fit. Am i better off going to an indy to have this done? I can't even see how a drain hose could snake up through from underneath the car.

Thanks in advance,
Troy

[TimFreeh]

Welcome to the wonderful world of M119 V8 engines in the W124 chassis.....

Its pretty obvious that the W124 was never designed for a V8 - I've never worked on a car that was as tight for space under the hood as my 93 400E.

When I changed the coolant on my car I did not remove the block drain plugs - as I recall there was about 1.5 quarts of old coolant that I just left in the block.

I strongly suspect that if you took the car to a dealer or independent shop they would NOT remove the block drain plugs. I remember thinking if I wanted to remove the block drain plugs I would have had to remove the starter, motor mount support and the exhaust system before I could get a good solid look at the drain plug. This would require an engine lift and at least a day of RR to accomplish.

Tim

[DR.DIESEL]

It takes some small 1/4 drive tools and u-joints to get to that
drain. If you have access to a lift, it is pretty easy.
However, if you drained the radiator and the L cyl head, you
got about 90% of the coolant out.
Just flush the coolant again in 14,000 miles and call it good.
Dr.D

[y2kimmel]

The car current has the wrong coolant in it (the green stuff!). I'd like to be sure to get as much of the old coolant out of the car as possible.

Would it be OK to drain from the radiator and left drain plug, then refill the cooling system with just water, run until warm, and then drain it again, refilling with the proper coolant / water mix? I'm not sure if running just water for 5 minutes would be bad for the engine.

Thanks,
Troy
1995 E420

[carman850]

Reminds me the nightmare I had when I flashed the coolant from my 92 400E(M119) 1 year ago.

It took me 6 hours!! I had to use the car the next morning so I almost fell into sleep underneath the car at 2 AM, I was virtually soaked with coolant, made me want to kill the guy who designed the cooling system 3 times.

There is no trick, you definitely need an u-joint, and a lot of patience and brutal force.

Would it be OK to drain from the radiator and left drain plug, then refill the cooling system with just water, run until warm, and then drain it again, refilling with the proper coolant / water mix?

This sounds like a good idea if you do if many times, at least much much... easier than draining it from engine.

[apb]

I just put on one of those flush kits from Prestone that you can buy at the autoparts store.
It flushes the coolant from your heater core hose out the radiator.
Then just put in a replacement hose that you get from the dealer.
No reason to mess with the plugs just b/c a german engineer thought it would be a cool thing to put in.