Replace the Coolant on an E36 (1991-1999) 3 Series BMW

Works For:
1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999 BMW 3 Series Models
BMW 3 Series Includes:  316, 318, 320, 323, 325, 328, 330 and M3 .

Source: BimmerZone

(As usual, Do it at your own risk! Or get a Bentley Service Manual)

Hello fellow bimmerheads,

Last weekend, was time for a coolant change to my Avus Blue beauty. I have to finish up my yearly maintenance on the car, before the North East winter arrives. Well as you probably know, coolant must be changed annually since it breaks down. As ethylene glycol breaks down, it becomes acidic and eats away your head gasket, water pump etc. If you want a high mileage car, you have to start with annual coolant flushing.
The whole procedure takes a couple of hours for the first timers, or half n hour for the old timers.

Anyway, enough with the intro. Here’s what you need for a six cylinder E36 (procedure performed on a M3).

Hardware list:
1 1/2 gallons of distilled water
1 gallon of BMW brand coolant (don’t use the other stuff, BMW has done extensive research on coolant additives for aluminum radiators). If you want strictly 50% mix get another jug of BMW coolant. I forgot the metric sizes of the tools needed -sorry ;( ( I think I used 19mm wrench)
A screwdriver (flathead and Phillips)
A funnel (gotta be neat)
A coolant collector (didn’t really help actually). A flashlight
A pair of gloves for safety.

Procedure:

Warm up the car, with incar heat controls on highest temp.

Remove the radiator cover over the kidney grill (DO NOT OPEN THE RADIATOR SIDE TANK YET). This plastic flat cover has a few screws holding it. On the M3 it also has a RAM air tunnel that cools the alternator. Let the car cool down somewhat. Touch the exposed aluminum radiator. The temp should be lukewarm.

Look for the BLUE plastic plug (about 8mm) at the drivers side bottom of the radiator (note the radiator- not the refill plastic tank)

Use a big sized flathead screwdriver to unscrew the plug. Note: If you have trouble finding it, stick your head between (why do I sound like a sex manual ?) the oil filter container and the airbox. Look straight down (use your flashlight) and the blue plug will shine. Worst case scenario (you are blind) remove the airbox temporarily (2 plugs). For ease of installation do no take the blue plug completely out of its socket. the old coolant will flow easily, while re-installation of the plug at that tight spot will require no time.

Open the radiator refill plastic tank. A couple inches (3-4cm) away (towards the front-middle of the car) there is the air trap valve. It has a long German word next to it. It looks like furhfernugen to me 😉 That black plug can be opened with a flathead screwdriver.

Look underneath the exhaust collector/headers for the engine drain plug (19 or 20mm I think). The plug is almost invisible since it is exactly underneath the 3-to-1 gas collector that is closer to the firewall. I could not see it myself, since I have heat wrapped my headers, and the insulation obstructs my view. You can also feel your way there with your hands. Note: Again if you cant find it, just jack up your car (I parked the front axle on a speed bump; raised the car easily 5 inches-also put stoppers on the wheels) Look under the headers and use your open-ended wrench.

Put the fluid collector under the engine drain plug. It doesn’t really help, since the fluid comes out gushing.

Undo the plug and turn away just before the plug is completely removed (the engine coolant is still kinda warm).

Optional: stick a hose in the radiator fill tank and kinda flush it.

Tighten blue plastic plug by hand (do NOT over torque) and torque the engine plug (I think the manual says 40-50 N-m)

With the Air trap valve (I call it the Favernugen plug) open, pour slowly coolant mix in the plastic radiator fill tank (next to the actual radiator). The quick way for M3 is to pour the whole BMW coolant (1 gallon) and then pour the whole one gallon distilled water. Adjust mix to taste.

As you pour the fluids “massage” the hoses in order to get the trapped air , all the way to the top where the fafernugen valve is. You will notice the air bubbles and fluid coming out of the valve.

Close the radiator fill tank and start the car with heater on. keep massaging the hoses for a couple of minutes.

Tighten (by hand) the favernugen plug, only when bubble free coolant comes out.

Let the car warm up. Once the A/C or radiator fan kicks in (you will hear a click sound) the temp gauge inside the car should point to the middle (normal). Note: If engine keeps heating up past the middle, (very unlikely), turn off engine, let it cool and massage the hoses w/ valve open so more trapped air comes out. Turn engine off, wait until cools off and check fluids.

The whole procedure is a lot simpler than it sounds. I tried to be as descriptive as possible since the M3 engine comp. is more crowded than Rosannes’ bra.

The whole procedure makes the trip to the dealer like an inconvenience. VOB stealer quoted me $200 for a radiator flush and brake flush. The VOB stealer rep
(when asked) revealed the fact the dealerships use the cheap stuff AND NOT THE BMW fluid (customer has to specifically request it and pay for it).

Considering I would be w/o a car (and $200) for a day (well the $200 would be gone for ever), I highly recommend the above procedure as quick and harmless way to save time/money and pump your blood w/ matcho-feeling bragging-right-having hormones .