How to change coolant on '99 E300 Turbodiesel? - PeachParts Mercedes-Benz Forum

LightMan · #1 04-27-2004, 04:49 PM

Well, I do most of the other basic maintenances - oil, filters, change brake fluid, etc, but haven't ever tackled the coolant change. How do you do it? Thanks in advance.

Dave

LightMan · #2 04-27-2004, 10:26 PM

anyone???

md21722 · #3 04-28-2004, 12:59 PM

I would remove the lower radiator hose, drain, & refill with 50/50 MB coolant and clean tap water. There is a plug on the passenger side of the head that can be loosend and more coolant will come out of that.

A more complete way to do it would be to remove the upper and lower radiator hoses and thermostat and run a garden hose thru the entire system until clear water comes out. Remove hoses off the heater coil and run water thru that.

LightMan · #4 04-28-2004, 01:18 PM

Is that pretty much it? Just remove a hose low in the system and allow gravity to drain it, and refill?

shoe · #5 04-28-2004, 04:23 PM

There actually should ba a drain valve on the radiator that should drain the entire system. At least that is the way it worked on my 96 E300.

md21722 · #6 04-28-2004, 09:30 PM

Yes, there is a drain valve. On my rads they have always been right near the lower rad hose & the valve is a red thumscrew that takes a long flatblade screwdriver to turn. Sometimes they get stuck or don't drain so well. Recently I had to remove the rad hose. Removing the rad hose also seems to get a little more out and you can shine a light inside to see if the hose is scaled up or not.

Regards,

Gilly · #7 04-28-2004, 09:42 PM

Radiator drain screw and there is a block drain. I wouldn't touch the hoses. You need to remove the front apron under the front bumper to get to the radiator drain. It'll pour out pretty good once the radiator cap is removed.
When refilling, I'd keep topping it up for 1/2 hour to an hour, just keep topping it up with 50:50 mix, use the MB coolant though. You don't want to take the chance of overheating that engine, with the popcan head. After refilling and on the first test drive, watch the temp gauge like a hawk, first sign of trouble SHUT IT DOWN! Let it cool off, and bring extra coolant with you so you can add more after it burps, which usually is only a few minutes after shut down.

Gilly

LightMan · #8 04-28-2004, 10:07 PM

Thanks much Gilly. Any idea where on the block the drain is, and is that necessary or should I just do the radiator?

Ive been noticing my car is warming up to temp a lot faster lately than it used to, and that its been getting slightly hotter than usual for this time of year. Think my coolant is just getting old or I have another prob? THanks!

Gilly · #9 04-28-2004, 10:30 PM

Definitely pull the block drain also. It's on the passengers side of the engine block. As I recall it's easier to get to on the diesel than on any of the V engines, about as easy as a 104 in a 210.
Now that I'm writing this I can't look at your profile, it's about a '99, right?
This coolant flush is due every 3 years, i'd base whether to do it or not on the interval, not any particular problem, I don't really think it'll create problems if replaced on schedule.
OK, there's the thermostat, for one thing; who knows? Could be that.
On the earlier year 210's, and I believe even the 99 300 Diesels, there is this really strange (for an MB) system for the aux fans you should look at. What's weird is that there are dual fans, but only ONE fan motor. The motor, you can tell by looking, is on the drivers side. Along the perimeter of the fan hub there is a very thin belt which drives the right-side fan. So one thing you should do is spin the drivers side fan (by the front of the fan, which sticks through the fan grille) and see if the right fan also spins with it. If NOT, the belt has come off, or worse there is a problem with one of the fans.
That's a common problem.
Another fairly common problem is the fan controller being bad. You can idle the car for awhile and run the AC, and the fans should either run constantly or at least cycle on and off, so you can at least check that yourself, and if they never seem to run, you may want to seek "professional help". The fan controller is a few hundred bucks, so you don't want to just "try it" without a few tests. I could tell you how to jump B+ to the fan motor, then you can assume if the fans run strong when jumped that it MUST be the controller, but it's a gamble.
Also have had a few bad fan motors (which can lead to burned-out fan controllers, kind of a double-whammy).
Also of course the "outside" of the radiator or AC condenser could be plugged up with dirt/dust/leaves/etc. If the fan unit needs to be removed for repair or replacement, that's an excellent time to clean up the outside of the radiator and condenser.

Gilly

Ockman · #10 04-29-2004, 06:09 AM

How difficult is it to R&R the front apron to get to the drain screw?
Any special tools/tips to getting it off and back on?

Gilly · #11 04-29-2004, 07:30 AM

Pretty easy. Just remove the panel under the engine (the one you'd remove to drain the oil out of the oilpan), then you'll see 2 of the same type of screws that the panel under the engine uses, up towards the front of the apron panel, so remove those two, and inside the front wheel wells you'll also see 3 on each side. If you are doing this on the ground you'll want to turn the wheels left/right to give yourself some room to work. With the wheels straight ahead you won't have room.
After the total of 8 screws are removed (plus the ones on the engine panel) you can pull the panel down out of the bumper, then pull it forward and remove it.
A guy at the shop I used to work at just LOVED using a large hole saw and chopping an access hole for the radiator drain (and before the oil extractor, he'd do this for the oil drainplug too (without asking the owner if it was OK, of course). To me it was kind of a "butcher job", I wouldn't do it on my own vehicle that way.

Gilly

LightMan · #12 04-29-2004, 09:16 AM

Gilly - I've turned the right fan by hand and the left one moves with it perfectly, so I think my fans may be ok. Whats a sign of a bad thermostat?

Also, any more tips on what the drain plug on the block looks like? There are a few plugs, NPT style plugs, but they look like oil ports

Thanks!

P.S. Ockman - if getting the belly pan off is a challenge, I might reconsider wrenching on your car

Gilly · #13 04-29-2004, 09:30 AM

As far as I remember (which could be wrong) it is forward of the starter and slightly higher than the starter. I believe it looks like a big brake bleeder screw-hollow in the center and you loosen it and the fluid comes out of the middle. It may require a hex or "allen" socket be used in the center hole, as there is no hex on the outside of it.

Sign of a bad thermostat is incorrect temp readings, usually too high, but could be too low and gradually increasing to an overheat. Don't just order up a thermostat right away, check things out first.

Try the idle thing I mentioned, (idling with AC on and watch for the fans to run). You could try this after getting up to operating temp, that'd speed things up. Edit: Just because the fans are interconnected (the small belt is OK) doesn't mean the fan motor and fan controller are good, this is a bit of a leap to say you think the fan is OK.

Gilly

md21722 · #14 04-29-2004, 09:35 AM

LightMan,

I have not seen it on a 606, but on all the previous 60x diesels, its on the passenger side in the block. Has a nipple on the end where you could attach a hose if you wanted.

I have since decided its just not worth the effort to deal with. 100% of the coolant is not recovered by draining the block.

LightMan · #15 04-29-2004, 09:37 AM

I am one who likes to do a job as completely as possible IF possible. I'll take a look for the block drain.

Gilly, I will try those other things you mentioned, you're right, I shouldn't rule out the fans yet.

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