E46 M3 Cooling System Refresh

I've owned this 2004 BMW M3 for well over five years now. It had 82,000 miles on it when I bought it in 2009 and at the time of this writing has just over 128,000 on it. I got it completely caught up on maintenance when I first got it, but other than regular periodic maintenance, it's needed very little else in that time. The only unplanned repair it has gone down for was a seized front brake caliper which I replaced. At this mileage, though, I know I've been driving on borrowed time for a while. The E46 does not suffer from the same cooling system weaknesses that the E36 did, but it's still a very critical system on the car and the consequences for poor maintenance are dire. So I decided it was time to completely go through the cooling system and renew everything I touch.

As usual with my blog, this is not a how-to. It's a you-can. There are plenty of forum posts and blog entries elsewhere that will tell you everything you need to know to complete this maintenance.

I started with an order of parts from ECS Tuning.

• Genuine BMW Remanufactured Water pump #11517838118
• Genuine BMW Radiator #17102228941
• Genuine BMW Thermostat #11531318274
• Water pump gasket #11517831099
• Thermostat O-ring #11531318402
• Water pump O-ring #11537830709 (qty 2)
• Coolant pipe O-rings #11537830712 (qty 2)

This order with shipping came to $710.

Thankfully the water pump for the M3 has come down a LOT in price since a few years ago. It used to be over $500. This one was $300 and I've seen a few other cheaper options as well. Shop around. Make sure you get a pump with a polymer impeller. It will last forever. The front bearing of the pump will wear out, not the impeller. If you get a metal impeller I can't say the same will be true. Here's a pic of my removed water pump (right). The impeller is perfect. This pump was not leaking but the bearing is pretty loose. This also shows how well the BMW coolant protects the engine from corrosion. There simply is none.

To start I removed the lower engine shield, fan with clutch, fan shroud, intake filter housing, hoses, belts, and finally the radiator. The lower radiator hose was impossible to get loose from the rad so I left it in place and removed both through the bottom of the car. You have to move the oil cooler out of the way but you can leave it attached. Support it with something so it's not hanging by the oil hoses.

When removing the thermostat housing there's a coolant pipe that runs between the housing and the bigger pipe that runs to the back of the engine. It's about 2 inches long and machined from aluminum. It is sealed with O-rings (#11537830709) on both ends. Mine pulled free from the engine end, not the thermostat housing end, and thus the whole housing was too big to remove from the space it occupies. I had to work for quite a few minutes to get the pipe loose from the housing side so I could remove it. Most write-ups I've seen don't tell you to remove that pipe at all, but there is an o-ring on the engine end that you should replace as well, so it's just as well that it came out that way.

Once the thermostat housing and thermostat are out of the way, you can unbolt the water pump. A firm pull disengages the pipes on the back side and it easily comes out.

At this point I assessed where I was and decided I needed a few more parts to do a more thorough job. Again from ECS, I ordered:

• Radiator Fan Clutch #11527831619
• Aux fan switch O-ring #13621433077S
• Expanding rivet (qty 4) #17111712963
• Heater hose #64216902679
• Heater hose #64216902680
• Hose #64216902678
• Air filter #13721730946
• Cooling fan blade #11521712058

This order came to about $160.

Replacing the heater hoses requires removal of the intake manifold. Due to the M3's six individual throttle body design, there are six individual hose clamps to remove. The factory clamps are Oetiker-style clamps that require a special pair of pliers to remove without destroying them. The Lisle 30500 CV Boot Pliers will do the trick. Using the pliers I was able to remove the clamps without damaging them. The intake manifold, having never been removed before, was very hard to dislodge from the throttle bodies. The throttle body boots are pliable rubber, but were VERY stuck. Rather than risk breaking something, I opted to carefully cut the boots with a knife and pry them loose a bit. After unclipping all of the hoses and wires that run along and around the manifold, it finally came out. This means I had to order new throttle body boots, part #11617830265. About 17 bucks a piece. I also ordered new clamps for the manifold side of the boots (#11617830306). While the throttle-side clamps can be reused, the manifold-side clamps are one-time only. They're a bit over $3 each, and I had to buy a tool to crimp them, the Lisle 30800 CV Boot Clamp which was about $25 at Amazon (photo above). You can use traditional hose clamps, but these are simple and look factory.

Once you have the intake manifold off it's easy to replace the coolant hoses that feed the heater core. There's one other hose that doesn't connect to the core, but rather connects the heater valve to the back of the coolant pipe alongside the cylinder head. I found it rather hard to find the part numbers for these hoses. Even ECS's website doesn't tell whether they fit the E46 M3 or not. They do, and the correct part numbers are in my list above. The photo here shows them fairly well. For what it's worth, my original hoses were still nice and soft, and looked pretty much like new. I think I could have easily gone another 50k miles on them.

Once I had the hoses replaced, everything went back together quite quickly. Access to the cooling system on the M3 is very good and doesn't require many contortions (except for those three hoses under the intake manifold). While I was in there, I also replaced the main serpentine belt tensioner spring and pulley. I had bought them a long time ago so they are not listed in the parts list above. The bolts that hold the water pump to the block should be tightened to 7 lb-ft of torque. That is NOT VERY MUCH. I don't even have a torque wrench that will read that low. I used a 1/4-inch ratchet and very gently torqued these bolts down. The bolts that hold the pulley to the water pump snout are also torqued to 7 lb-ft. Be careful!

BMW M3 Valve Adjustment, S54 Engine

My M3 is way overdue for a valve adjustment. The maintenance schedule calls for doing it at every inpection interval which is roughly every 30,000 miles. I've had this car for 19,000 miles but I have no record of it ever being done. It probably was done at least once, but I'm betting it's way overdue. When I measured the clearances, every valve was out of spec, and all were on the "loose" side of the spec, which is actually better than them being on the "tight" side. They weren't really TOO far out of spec, considering. Just a few hundredths of a millimeter, on average. The worst one was 0.08mm out of spec. The car has 102,000 miles on it now so I want to get it in spec and give everything a good going-over so it will be ready for the next 100,000 miles. As usual with this blog, this is not a "how-to" but rather a "you can". On my difficulty scale of 1 to 10, with 1 being putting air in the tires, and 10 being an engine rebuild, this is about a 3. Seriously, it's not hard. All you need is your basic hand tools, the BMW shim removal tool, and a digital micrometer. I paid about $30 for a cheap-ish micrometer specifically for this job. I paid $30 plus a crazy $20 for shipping for the shim removal tool, and I'm spending about $50 on shims. If you need to get this done in one day you'll need to buy the full shim kit which is about $375 but that includes the removal tool and when you're done you can easily sell it online for most of what you paid. I didn't do that so my car will be down for about a week while I wait for the shims to come from Pelican Parts. So I'm into this for about $130 and maybe 4 hours of labor, probably 5 by the time I'm done. A shop quoted me close to $1000 for this service, so it's a good DIY project. I referred to an excellent video on YouTube that covers the project in good detail. I definitely recommend you watch a couple of those before you start.

Valve cover is off and I'm ready to start measuring clearances and removing shims. It takes about 30 minutes to get to this point.

Here's my spreadsheet where I recorded all the clearances, the thickness of each shim, and do a little math to find out what size shim would give me the exact clearance I want. I calculated the Theoretical Best Shim (TBS), and compared that to the shims I actually have (24 of them) to identify which shim should go in each location. Doing this, I was able to reuse 14 of the 24 shims. I have to buy the remaining 10 because none of the 10 I have left are the right thickness. No way I could have kept all this straight without a spreadsheet. It took me a couple hours working slowly to measure and record all the data.

Here's where I laid out my shims to keep them straight until I did all the math. A few have already been put back in the engine in this photo. Now that I have the exhaust side all done, and none of the remaining shims can be used except two on the intake side, I no longer have need of these shims or this sheet of paper.

Here's the official BMW shim removal tool. I say removal tool because it was far harder to put the shims back than it was to get them out. This little plastic tool was almost $50 with shipping and everything, but it's a necessary evil. I finally got the hang of using it to put shims back in, but not before dropping a few shims. It is IMPERATIVE to block all the little oil passages in the head so that errant shims can't disappear into the engine.  That would be BAD. A magnetic pickup tool helps fish them out from where they fall. God help you if you lose one in the engine.

This is the micrometer I bought for this job. It was in the $30 range at Harbor Freight. It may not be extremely accurate, or it could be that I just had to learn to use it. That thousandth's decimal place should definitely be taken with a grain of salt.

UPDATE: 5/14/2011

The shims I ordered from Pelican Parts on Sunday arrived via USPS on Friday. Perfect timing. So this morning I finished the job. Unfortunately, when I put the new shims in place, most of the clearances turned out tighter than I had calculated them to be with my spreadsheet. A couple were just under the minimum and I wasn't comfortable with that. Upon re-measuring things today, everything was measuring bigger. Checking my technique with the micrometer with the new shims of known thickness, I think I was cranking down too hard on the micrometer last week. You can definitely influence the measurement by how hard you turn down the dial. Once I standardized my technique and got consistent results, I ended up re-measuring all the clearances and moved several shims around to get closer to the clearances I wanted. My main concern was to not leave any valves too tight as that can lead to problems. In the end, I got all the clearances on the lower end of the tolerances. The minimums are 0.18mm on the intake cam, and 0.28 on the exhaust cam, while the maximums are 0.23mm and 0.33mm for the intake and exhaust, respectively.

Most interestingly, and to my surprise, the engine really does feel smoother and a little bit quieter after the adjustment. I swear I can feel and hear the difference. I didn't expect to. The S54 really likes proper maintenance. I also took this job as an opportunity to inspect the bolts on the VANOS system as there have been internet reports of them backing out and causing catastrophic failure of the timing gears and chain. Everything looked absolutely perfect so I didn't touch a thing there. I feel better having had a look at them, though.