Hey guys,
New menber here, I'm working on refreshing the cooling system in my 2003 M3. I did a little writeup and put it up on Reddit to try and help others looking to do the same, thought I'd post it here as well. I am curious if I'm missing anything obvious while I've got things apart for this work, so if you notice something please chime in.
So I spent the past couple of days reading up on various components of the e46 M3 cooling system. My car is at 128k miles and as far as I know, all the cooling system parts are original. I'm doing a refresh, and here's what I decided to go with. I figure this might help some others out a bit, tons of info is available online but it's scattered.
It's a mixture of genuine BMW, OEM, and aftermarket components. All together it came out right at $2,000 in parts, which seems pricey but hopefully it'll get me through another 20+ years. It's certainly possible to come out cheaper by going with more aftermarket parts, or simply not replacing everything I have listed.
Water Pump $463 - Genuine BMW, 11517838118. Quite pricey, but this isn't one you want to skimp on. GPM makes the OE water pump and it's only available as the BMW part. It's the only one you'll find with the original composite impeller, a metal impeller is actually a downgrade here and flows less than the genuine part.
Water pump gasket $6 - Rein 703670600, couldn't find a lot of info on this, the genuine BMW gasket is \~$35.
Radiator $560 - I went with a Koyo HH422675, which is a 2 row radiator like the original, but in all aluminum. I couldn't find a single bad review on these, but do note that not all aluminum radiators are considered an upgrade. Zionsville is the gold standard here, but it's double the Koyo price. The genuine BMW radiator is \~$700 and the original manufacturer (Modine) is no longer making radiators for BMW. The Koyo all aluminum construction should be an upgrade durability wise. ~~I also got the Koyo KOYO-SK-C13 1.3 bar cap, as it's not included with the radiator.~~ (Don't do this, the M3 radiators do not use a radiator cap. The cap is on the expansion tank, should be obvious but I missed this part)
Thermostat $57 - Wahler 11531318274. I believe they make the BMW part, reviews are solid and it's about $100 cheaper than the genuine BMW part.
Upper and lower hoses $112 total - Genuine BMW, 11537830715 and 11537830716. You can get Rein hoses for about $45 total, but the o-rings reportedly don't hold up near as well. Might be fine if you replace the o-rings.
Auxiliary fan switch $25 - VNE-49090. I believe VNE is the OEM for this part, a genuine BMW switch is about $50. If you want to save some money and reuse your old switch, definitely get a replacement o-ring.
Expansion tank $200 - Genuine BMW, 17112283344. I'm not sure it was completely necessary to replace this but they do have issues, especially if the system ever overheats. Turner and Moroso both make aluminum models for about double the price, they look nice but add a little weight.
Expansion tank connecting hose $85 - Genuine BMW, 17112229053. This one hurt the most, it seems like such a simple part and mine looked great. They reportedly get brittle over time and often break when replacing the radiator, so I opted to replace it.
Expansion tank to water pipe hose $58 - Genuine BMW, BMW-11537830713. Probably not a high priority to replace, I had mine off for a header install so I figured I might as well swap it.
Coolant bleeder screw $5 - Genuine BMW, 17111712788. I didn't put much thought into this one due to the low price, ECS has an aluminum one for $20 but it doesn't seem necessary. Some folks say these act as sort of pressure relief valve, sacrificing and failing if the cooling system pressure ever gets too high.
Fan shroud rivets $1 each - Genuine BMW, 17111712963. I got 6 of these along with other model rivets (51471919209, 51498237075, 51498237075) not sure what they're all used for but they're cheap enough and I figure I'll use them eventually.
O-rings $50 - Instead of figuring out exactly which o-rings I needed to get, I went with the "Wolfn8tr" high temperature kit. It's a mixture of viton and high temperature silicone, depending on the application. There's cheaper kits available, but I've read nothing but good things about this one. It should cover everything I'll be touching and then some, 19 o-rings in total. If you don't go with a kit, at a minimum you'll need to purchase o-rings associated with the water pump replacement.
Viscous fan clutch $160 - Mahle Behr, MAH-CFC75000P. I actually opted NOT to replace this, as I'm going to try removing the mechanical fan altogether. This is reportedly the OEM, a genuine BMW clutch is \~$380. If you're in a hot climate or drive in traffic often then you want to retain this or go with an electric fan. The downside to having the mechanical fan is that if the clutch ever fails and locks up, it'll overspin the fan blades and send daggers flying in your engine bay. I did buy the BMW fan delete nut for $12, 11511310640. It covers the exposed threads after removing the fan, not necessary but it looks a little nicer.
Accessory drive belt kit $220 - KIT-11287837898KT from FCP Euro. Not directly related to the cooling system, but it's a good time to consider this while you've got everything apart. Includes belts, tensioners, idlers, and bolts for the main serpentine and AC belts. A similar genuine BMW kit is \~$800. I didn't do a lot of research here and haven't noticed any strange noises from my belts, but I figure this is a good "while you're in there" kit for peace of mind. A shredded belt can get sucked in around the crankshaft seal and cause major damage. There are guards available for \~$80 to protect against this, probably not necessary if you keep an eye on things and check your belts regularly.
As far as specialty tools, I did pick up a 32mm fan clutch wrench and a cheap radiator hose spoon kit. The fan clutch wrench is required, I figure the radiator hose spoons will make hose removal a bit easier. I don't believe any other specialy tools are required for this work. Also, I didn't order any replacement bolts, other than what came with the accessory belt kit. I did order some replacement plastic rivets for the fan shroud
So there it is folks, if anyone sees anything glaring that I'm omitting then please chime in. I'm hoping this info might help other folks that are looking to overhaul their cooling system. S54 engines are quite solid, but things can go south quite quickly if a leak occurs and you're not staring at the temperature gauge.
New menber here, I'm working on refreshing the cooling system in my 2003 M3. I did a little writeup and put it up on Reddit to try and help others looking to do the same, thought I'd post it here as well. I am curious if I'm missing anything obvious while I've got things apart for this work, so if you notice something please chime in.
So I spent the past couple of days reading up on various components of the e46 M3 cooling system. My car is at 128k miles and as far as I know, all the cooling system parts are original. I'm doing a refresh, and here's what I decided to go with. I figure this might help some others out a bit, tons of info is available online but it's scattered.
It's a mixture of genuine BMW, OEM, and aftermarket components. All together it came out right at $2,000 in parts, which seems pricey but hopefully it'll get me through another 20+ years. It's certainly possible to come out cheaper by going with more aftermarket parts, or simply not replacing everything I have listed.
Water Pump $463 - Genuine BMW, 11517838118. Quite pricey, but this isn't one you want to skimp on. GPM makes the OE water pump and it's only available as the BMW part. It's the only one you'll find with the original composite impeller, a metal impeller is actually a downgrade here and flows less than the genuine part.
Water pump gasket $6 - Rein 703670600, couldn't find a lot of info on this, the genuine BMW gasket is \~$35.
Radiator $560 - I went with a Koyo HH422675, which is a 2 row radiator like the original, but in all aluminum. I couldn't find a single bad review on these, but do note that not all aluminum radiators are considered an upgrade. Zionsville is the gold standard here, but it's double the Koyo price. The genuine BMW radiator is \~$700 and the original manufacturer (Modine) is no longer making radiators for BMW. The Koyo all aluminum construction should be an upgrade durability wise. ~~I also got the Koyo KOYO-SK-C13 1.3 bar cap, as it's not included with the radiator.~~ (Don't do this, the M3 radiators do not use a radiator cap. The cap is on the expansion tank, should be obvious but I missed this part)
Thermostat $57 - Wahler 11531318274. I believe they make the BMW part, reviews are solid and it's about $100 cheaper than the genuine BMW part.
Upper and lower hoses $112 total - Genuine BMW, 11537830715 and 11537830716. You can get Rein hoses for about $45 total, but the o-rings reportedly don't hold up near as well. Might be fine if you replace the o-rings.
Auxiliary fan switch $25 - VNE-49090. I believe VNE is the OEM for this part, a genuine BMW switch is about $50. If you want to save some money and reuse your old switch, definitely get a replacement o-ring.
Expansion tank $200 - Genuine BMW, 17112283344. I'm not sure it was completely necessary to replace this but they do have issues, especially if the system ever overheats. Turner and Moroso both make aluminum models for about double the price, they look nice but add a little weight.
Expansion tank connecting hose $85 - Genuine BMW, 17112229053. This one hurt the most, it seems like such a simple part and mine looked great. They reportedly get brittle over time and often break when replacing the radiator, so I opted to replace it.
Expansion tank to water pipe hose $58 - Genuine BMW, BMW-11537830713. Probably not a high priority to replace, I had mine off for a header install so I figured I might as well swap it.
Coolant bleeder screw $5 - Genuine BMW, 17111712788. I didn't put much thought into this one due to the low price, ECS has an aluminum one for $20 but it doesn't seem necessary. Some folks say these act as sort of pressure relief valve, sacrificing and failing if the cooling system pressure ever gets too high.
Fan shroud rivets $1 each - Genuine BMW, 17111712963. I got 6 of these along with other model rivets (51471919209, 51498237075, 51498237075) not sure what they're all used for but they're cheap enough and I figure I'll use them eventually.
O-rings $50 - Instead of figuring out exactly which o-rings I needed to get, I went with the "Wolfn8tr" high temperature kit. It's a mixture of viton and high temperature silicone, depending on the application. There's cheaper kits available, but I've read nothing but good things about this one. It should cover everything I'll be touching and then some, 19 o-rings in total. If you don't go with a kit, at a minimum you'll need to purchase o-rings associated with the water pump replacement.
Viscous fan clutch $160 - Mahle Behr, MAH-CFC75000P. I actually opted NOT to replace this, as I'm going to try removing the mechanical fan altogether. This is reportedly the OEM, a genuine BMW clutch is \~$380. If you're in a hot climate or drive in traffic often then you want to retain this or go with an electric fan. The downside to having the mechanical fan is that if the clutch ever fails and locks up, it'll overspin the fan blades and send daggers flying in your engine bay. I did buy the BMW fan delete nut for $12, 11511310640. It covers the exposed threads after removing the fan, not necessary but it looks a little nicer.
Accessory drive belt kit $220 - KIT-11287837898KT from FCP Euro. Not directly related to the cooling system, but it's a good time to consider this while you've got everything apart. Includes belts, tensioners, idlers, and bolts for the main serpentine and AC belts. A similar genuine BMW kit is \~$800. I didn't do a lot of research here and haven't noticed any strange noises from my belts, but I figure this is a good "while you're in there" kit for peace of mind. A shredded belt can get sucked in around the crankshaft seal and cause major damage. There are guards available for \~$80 to protect against this, probably not necessary if you keep an eye on things and check your belts regularly.
As far as specialty tools, I did pick up a 32mm fan clutch wrench and a cheap radiator hose spoon kit. The fan clutch wrench is required, I figure the radiator hose spoons will make hose removal a bit easier. I don't believe any other specialy tools are required for this work. Also, I didn't order any replacement bolts, other than what came with the accessory belt kit. I did order some replacement plastic rivets for the fan shroud
So there it is folks, if anyone sees anything glaring that I'm omitting then please chime in. I'm hoping this info might help other folks that are looking to overhaul their cooling system. S54 engines are quite solid, but things can go south quite quickly if a leak occurs and you're not staring at the temperature gauge.
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