BMW Thermostat Replacement (E46)

This is a Do-It-Yourself reference for replacing the thermostat on the E46 BMW engines. Mine is a 2002 330Ci Convertible, but this job should apply to all 1999-2005 BMW 3-Series vehicles.

The symptom leading to this repair was that the Service Engine Soon light on my car would come on after driving some distance on the highway, and it would go away after driving some distance on local roads. The error code was P0128 -- "coolant temperature below thermostat regulating temperature."

This job is about $300 at the dealer (some people got a quote for $400). I decided to do it myself and got a thermostat and housing assembly for US$57.70.

Here is how I hooked up a scanner to check the error code. I'm told some shops would do this for free.

This is a closer look at the OBD-II connector, which is standard on all cars manufactured since 1996.

Following the instructions of the scanner, I got the error code P0128, "coolant temperature below thermostat regulating temperature." What it means is that the coolant temperature is too low. One logical reason is that the thermostat opens up too early before the coolant reaches its designed operating temperature. It's probably not stuck open in my case because the light would go away after driving on local roads.

To replace the thermostat, you'll need to drain the coolant, which requires opening the drain plug at the bottom of the radiator, which requires removing the splash guard at the bottom of the car, which requires jacking up the car and putting on stands, at least the front end.

After removing the plastic splash guard, you can see the blue drain plug at the bottom of the radiator.

Open the coolant filler cap at the top of the radiator, and open the bleeding valve with a screwdriver.

Place a pan under the radiator and open up the drain plug.

Drain the coolant.

This is the coolant drained.

There are 4 screws holding the thermostat in place. It is possible to remove the thermostat without removing anything from the radiator. You just need an extender of the right length (a short one) on the socket wrench. In my case, it was a 3/4"-to-1/2" adapter. You'll also need to cut the nylon tie-down of the wiring.

This engine lifting bracket needs to be removed because one of the screws holding the thermostat to the engine also holds this bracket.

There are two hoses connected to the thermostat. Each can be detached by sliding the metal clip and pulling on the hose. This is the upper hose which is easier to detach. The bottom one may require some effort due to lack of working space. Also disconnect the temperature sensor connector. After that, the thermostat is free from the engine. It requires some Tetris skills to take the thermostat out of that space between the engine and the radiator.

Here are the thermostats, old and new, side by side. It appears that my old thermostat is not stuck open. I believe it just opens too early but I didn't test it (by putting it in a pot and heating it up...).

The more difficult part of installing the new thermostat is the bottom hose. There is just not enough space to apply any kind of pressure to push it onto the thermostat. Here I applied a little Vaseline on the o-ring which made it a lot easier.

Once the bottom hose is connected, the rest is easy. This photo shows that the thermostat has been installed onto the engine with the bottom and top hoses attached.

Reinstall the temperature sensor connector, and tie down the wiring which was cut loose when removing the old thermostat.

Now, close all drain plugs and bleeding valves.

The manual says to use 50/50 mixture of long-life ethylene glycol antifreeze and water. I got 100% antifreeze. For the water part, I filled with bottled water. I figure if it's good enough for me, it's good enough for the car.

Lower the car to the ground. Drive some and recheck the coolant level (after the coolant has cooled down, of course). My Check-Engine light came back on once again but went away afterwards and has never returned.

Food Photos from October, 2009

The general term of this kind of seafood is "sushi," a Japanese tradition. I believe sushi is an acquired taste.

Mooncakes are a Chinese tradition. They are usually eaten during the Mid Autumn Festival, which is September 15 on the lunar calendar. On this evening every year, people gather and think of their relatives, living or dead, under the bright moonlight.

Apples are, well, apples.

Lobsters are the favorite seafood for many. Legend has it that the first people to eat them were the prisoners off the coast of Maine. Apparently lobsters do not get old and won't die of old age.

2002 BMW 330Ci Convertible (E46)

This is my 330CiC which I bought new at the end of 2001. This is when it's parked on the driveway. By the way, why do we drive on the parkway but park on the driveway?

Who can resist taking a 360x180 panorama of it?

Here is an interactive view (requires ShockWave).

With only 220 horsepowers, it's not the fastest car in the world by any meaning of the word, but it's always wonderful to drive.

Yup, stick shift is the only way to go on this car.

BMW Lower Control Arm Bushing Replacement (E46)

My car is a 2002 BMW 330Ci Convertible. Yours may be the same or slightly different.

The function of the Lower Control Arms (LCAs) is to hold the wheel in position while allowing it to move up and down following the uneven surface of the road. BMW designed the LCAs to soften the impact of rough roads and harsh acceleration/deceleration. This is accomplished by the LCA bushing, which is filled with fluid apparently.

Unfortunately the LCA bushing can become too soft over time. Mine started around 50K miles. If they are not replaced, the LCA will put too much stress on the ball joint's nylon lining, causing it to fail (developing a play), which leads to uneven wear on the tire and poor handling. In order to replace the ball joint, one usually has to replace the entire LCA, as the ball joint is pressed into it, which requires a power press and removing the LCA from the car. And, LCAs have to be replaced by the pair, which becomes expensive. What it means is that worn LCA bushings should be replaced in time.

Fortunately replacing the LCA bushing is not difficult, and there is no need to remove the LCA from the car. This is written for people who do their car repairs in their own garage, i.e., without access to a lift or specialized tools. My BMW dealer wants $500 for this job, so I decided to do it myself, given this economy. :-)

0. Buy a pair of lower control arm bushings. Mine were Meyle, which I got from Bavarian Autosport for about $100.

1. The most important part is putting the car on stands. On this car, it's not as easy as one would think because there is so little clearance between the frame and the ground. Doing this part correctly is critical to safety, since you'll be working under the car. DO NOT LET THE CAR FALL ON YOU! You'll be hurt seriously, I mean, killed, if 3,600 lbs fall on top of you. Make sure you're on a level and solid surface, like the slab of your garage.

1a. Apply hand brake, and put the transmission in the 1st gear. Choke the rear wheels.

1b. On this car, one cannot simply jack up the side skirt -- there are only 4 jack points that can support the car's weight. Instead, use the jack provided with the car (stored in the trunk) and lift one side of the front just high enough so that you can see the under side of the car and can slide in a hydraulic jack. Find the frame rail (marked by red brush) that runs along the bottom, about one foot from the side skirt.

1c. Use the hydraulic jack under the frame rail to raise the car enough so that you can put a stand to replace the car jack. Make sure you use a stand that can hold the plastic jack point securely. The photo shows the wrong kind of stand. You want to use a stand whose top is shaped like a Y.

1d. Repeat Steps 1b and 1c for the other side. Now you have two stands holding the front up. Because the car has very little clearance (about 4 inches) to begin with, you may need to raise the height of each side alternately and in steps to keep the stands straight.

1e. Jack up the back of the car on the brace (circled in red) just in front of the differential (but NOT on the differential). Again, you may need to use the car's jack to lift one of the back corners to slide in a hydraulic jack. Once you lift the back side of the car, you can use two more stands to support the car. Now you have the car on 4 stands. Rock the car back and forth to make sure it's sitting on the 4 stands securely. No, the car shouldn't fall from the rocking. If it does fall, it's still a thousand times better when you're not under it.

2. Looking at the under side of the car, you'll see the black plastic guard and the big aluminum brace piece (circled with red). You'll need to remove them in order to gain access to the control arm bushings. The plastic guard is held by several screws and 3 retaining nylon clip. The aluminum brace is also easy to remove by undoing the 8 screws (16mm).

3. Once the aluminum brace is removed, there is easy access to the lower control arm bushings. Notice that I put 4 extra stands under the car so that I would feel safer getting under the car. I also considered cinder blocks and lumber.

4. Here is a closer look at the bushing. Remove the two screws (16mm) holding the bushing to the car's frame.

5. Use a puller to remove the old bushing from the lower control arm. I have a puller as shown in the photo, but it didn't work because the hook kept losing its grip as I turned the bolt. Eventually a C-clamp worked. Make sure you wear protective eyewear -- the rubber can store some energy as you turn the puller or C-clamp -- you don't want anything to pop off and hit your eye.

Update: I finally got a picture of using the C-clamp:

6. Here is the end of the lower control arm after the bushing has been removed.

7. Putting the new bushing onto the control arm turned out to be a bigger challenge. I had seen a YouTube video where they simply hammered in an after-market bushing, but it didn't work for me at all because the rubber absorbed all the impact. Using my bare hands, I could push the bushing in about halfway. Eventually I used a steel strip together with the puller to press the bushing into the control arm. Also make sure you wear protective eyewear.

Update: it turns out using some soap eases this part tremendously. You can almost push the bushing in with your bare hands, and it's easily hammered in with a rubber mallet.

8. Attach the bushing back onto the car's frame.

9. Repeat Steps 4 to 8 for the other bushing.
10. Put the car back down on its wheels in the reverse order of putting it on stands.