DIY: Engine Coolant Change for E46 M3

[jaym3smg]

I posted this on M3Forum as well but thought I'd add it in here too.

One thing that I had a helluva time finding was a DIY for an E46 M3 engine coolant change so I put one together. It's a compilation of a number of 3 series DIY's, some tips for the M3, the Bentley manual, as well as my own personal experience on this.

This isn't a difficult job HOWEVER it is MESSY. You will take a coolant shower so don't wear anything you can't get soaked in poison. Be careful, on that note. This stuff is extremely toxic especially to pets so don't let your dog help you with this. And try not to drink any of the coolant when you get soaked in it.

Also, do this on a cold engine. You have to stick your hand in places where, if the engine is hot, you could get well cooked.

Alright let's do this thing.

Parts List:

1 x Engine Coolant Drain Plug Washer (P/N: 07-11-9-963-200)
2 x BMW Antifreeze (P/N: 82-14-1-467-704)
2 x Distilled Water (3.75L jug)

Tools you need:

Torque wrench(es) capable of 18-43 ft-lbs
Ratchet
8mm socket
13mm socket
16mm socket
Socket extension (3" does the trick, 2" might work too)
Phillips screwdriver
Flathead screwdriver
Pliers
A few pails to catch the fluid
A jug to mix the new fluid in

Handy but not required:

Impact wrench (to take out the 12 16mm bolts)


1) Get yourself set up. Get all the tools, supplies, parts and everything together. You don't want to be running around here looking for things because you're going to have your heater running the whole time which will eventually suck the life out of your battery.


2) Jack the car up and set it on jack stands as per the Madrussian DIY (http://m3.madrussian.net/diy_jacking.shtml).


3) Go under the car and remove the front plastic splash guard using the 8mm socket to remove the 7 screws holding it in. Drop it down and pull it to the front of the car, out of the way.


4) Remove the suspension reinforcement plate using your 8mm socket on the back screws and then the16mm socket and a ratchet (or an impact gun, VERY handy). There are 12 of these 16mm bolts, an impact gun will save you time.


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5) Remove the top plastic cowl from the engine bay as well as the small plastic intake channel. Use your pliers to pull up on the small plastic knob on the top of each plug and pull out the plug. This will give you access to the radiator bleed screw.


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[jaym3smg]

6) Go in your car, turn the ignition to position 2 (do NOT start the car!) and set the heat to the highest setting and leave the fan on the lowest setting. Let it keep running while you go through the rest of these steps.


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7) Place a bucket underneath the car's radiator towards the drivers side and unscrew the bleed screw with a phillips screwdriver. It's gonna pour out. Let the mess commence. Strategically place your bucket to catch as much fluid as it can, but you won't catch it all.


8) While that's happening, unscrew the radiator reservoir cap and leave it open.


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9) Now let the fun begin. The M3 is a very special car. Special in that it is much harder to do even the most basic tasks. The 3 series owners were granted a drain plug on the bottom of the radiator.... we were not. You need to remove the hose on the bottom of the radiator on the passengers side in order to drain the remaining coolant in the radiator and the hose. Lovely. This is where you will get wet.


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So first, place a plastic bag around the belt that is right next to the hose. This will keep it from getting soaked in coolant when the spray occurs. Also, keep a bucket handy!!!

10) Now the hose has a metal clip around it which keeps it on and prevents you from pulling it off. This is NOT the metal ring around the hose, but a metal clip around the plastic part. All you need to do is reach around the back of the plastic part of the hose and pull up. Don't pull it off, just pull it up to unclip it. I found it easier to push up on the sides of the clip than on the back, but either way.

11) The hose is still on pretty tight. You can't twist it because of the plastic guides but you can wiggle it back and forth a little and even jam a small screwdriver in between the gap and twist.


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Keep working it and working it and eventually it will come off and you will get a coolant shower. Get that bucket you have handy (or the one under the radiator if the coolant from the bleed screw is done pouring out) and get it under there. Let it drain.

[jaym3smg]

12) Now it gets even more fun. The engine coolant drain bolt is located at cylinder 2 along the exhaust side of the engine.

Just reach up there, over that black cylinder and towards the engine block and you'll feel it. The top of that black cylinder has a bolt at the top, if you guide your hand along that bolt towards the engine you will hit it.


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You need to remove this 13mm bolt. Use your 13mm socket and an extension. Some DIY's said to set the extension and socket on the bolt then attach the ratchet, I found that didn't work well for me so I just managed to get the assembled ratchet and socket / extension up there and lined everything up. Once it was on it wasn't hard to get the bolt off, it's not torqued on too much. A few short turns and then I used my hand to unscrew it the rest of the way. NOTE: As soon as that plug comes out the second shower will begin! Get a bucket under it! You will probably get soaked even more than before, so be ready for it.


13) Let the coolant drain from the engine. Once it's all drained, replace the washer on the drain bolt and screw it back on the engine block. Torque it to 18 ft-lbs. Some DIY's I saw said if you can't get a torque wrench up there then just screw it on until its nice and tight, but this is your engine block. Make the effort to torque it correctly. If you got the bolt off with a ratchet, you sure can torque it back on with a torque wrench. I had NO problem.


14) Reattach the hose to the radiator. I found I needed to put a screwdriver on the end of the plastic part and give it a few good whacks with the back of my ratchet to get it to be snug along the guides. Once it's back on firmly, pull the metal clip back down until it snaps in.


15) Get off your back out of the pools of coolant on the ground and start mixing your elixir. Get your plastic jug and make a 50/50 mix of coolant and distilled (deionized) water. Pour this into the coolant reservoir SLOWLY. Repeat until the coolant starts coming out of the bleed screw.


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16) Now we're gonna get all the air out. Place a bucket underneath the radiator on the drivers side and start pouring coolant into the reservoir. What you want to do is get all the air bubbles out, so keep pouring coolant in until air bubbles stop coming out of the bleed screw hole. Once they do, put the bleed screw back on BY HAND and once it's too snug to turn further by hand do a 1/4 turn with the screwdriver. It is REALLY easy to strip / break this thing so 1/4 turn is plenty.


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17) Go under the car and see if there are any leaks. If you torqued the bolt correctly and the hose is back on right, you should be good to go!


18) At this point you can turn your heater off / turn the ignition to off.


19) Reinstall the suspension reinforcement plate as well as the front plastic splash guard. Torque the 16mm bolts to 43 ft-lbs.


20) Put the top plastic cowl and intake channel back on and reinstall the plastic plugs. Put the radiator cap back on.


21) Lower the car back down and take it for a rip. Drive it until the engine is at full operating temperature then drive home / wherever and park it. Let the engine cool COMPLETELY. It will cool faster if you pop the hood. Might take a few hours. I ran some errands and then parked it overnight in my garage.


22) Once the engine is completely cool, check your coolant level in the reservoir. Fill it with the 50/50 mix until it is at MAX.


23) Put the cap back on the reservoir. You are finished. Apply beer liberally.

-J

[Yorgi]

Nice write-up Jay. What a PITA though, I wonder why M3s don't get a drain plug at the bottom of the rad? Crazy.

[jaym3smg]

Thanks! I have no idea why that is... maybe in a car that is designed for track use, a plastic plug on the bottom of the rad could be prone to some sort of damage causing a coolant leak? Although there is a protective plate there... I am not sure...

-J

[Mclovin]

+ 1 on this diy being messy and pita! Draining coolant from expansion tank and from rad was easy and clean. Now bolt on the engine block..when it was undone, the coolant was pouring everywhere. I was able to catch maybe 50% of it due to locationg of it.