540it alternator replacement

[BlackBMWs]

proactive maintenance. I have replaced the VC gaskets and the VANOS solenoid seals then I did my timing chain guides. Changed all seals and gaskets. No leaks.

[DaveCashmen540i]

this is fantastic thank you. My alternator recently failed on me and I plan on doing this soon. Quick question for you.
my indi mechanic friend said my 98 540i uses the water cooled alternator. He changed my radiator for me last month. I called O'reily auto and their computer has it as air cool alternator. Is it possible my car is late 1998 model or something putting it with 1999up categories?

love the info thanks everyone

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update.
I can clearly see it's the air alternator. He must have been confused. The air alt is much cheaper so this is a good thing.

[bin01123]

I just installed a new alternator and a new battery. I plan on a long road trip and I call myself being proactive. I got a new battery (mine was on its way out) and a new alternator because my car is at 120K miles so I didn't want the alternator failing on me on the road. I tried an MPA alternator. It ran for less then 10 minutes then failed. I just tried a Pep Boys Alternator today. It ran 15 minutes then failed. Do I really need to get a Bosh unit at this point? Me trying to be proactive has me down a car for the past few days now. About to bite the bullet and get a Bosh from FCPEuro were I see it the cheapest.

[yersole]

I just installed a new alternator and a new battery. I plan on a long road trip and I call myself being proactive. I got a new battery (mine was on its way out) and a new alternator because my car is at 120K miles so I didn't want the alternator failing on me on the road. I tried an MPA alternator. It ran for less then 10 minutes then failed. I just tried a Pep Boys Alternator today. It ran 15 minutes then failed. Do I really need to get a Bosh unit at this point? Me trying to be proactive has me down a car for the past few days now. About to bite the bullet and get a Bosh from FCPEuro were I see it the cheapest.

I just replaced mine with a Bosch Reman last week and paid a little more than the FCPEuro price which is the cheapest I have seen.
I put the Bosch on and battery light stayed on. Turned out it was faulty. They shipped me another one and no problems with that so far.

[ImTheDevil]

Just finished buttoning up the car from this job. Turned the key and it ran for 5 seconds and shut down - not enough juice. Jumped it off the wife's Odyssey and all through high idle it ran fine, but my nav screen was flashing. When it came out of high idle, it stumbled a bit and the coolant needle suddenly slammed from cold to the hot peg. I'm assuming that the battery still needs more charge as it's below 12.6 with the car off. Assuming also that since the cooling system needs bleeding and topping off, that's why the needle slammed over. I'm trickle-charging the car now, so I can run it and burp it. Can't do test 9 because my display is pixelated so I'm going on these hunches. No coolant leaks, pulley wobbles, or bad noises - she just purrs nicely. I'll update once it's done and running. Meantime, anyone with any feedback to confirm or contradict my assumptions would be great to hear from.

[ViolinARC]

Just finished this exercise for a good friend. Since I had never worked on a 540 before, this tutorial was essential, but I would have breezed through it if I had known:
1. there are two fasteners at the very top of the radiator shroud. No one tells you how they should be removed. Since we couldn't figure out the correct way, I ended up snapping off the end, then drilling out the middle to pry it out. You need to pull the post directly out toward the engine such that the prongs of the fastener are no longer pushed out. It's the same type of principle I've seen used in wallboard plastic fasteners that use a nail to push apart the two prongs to hold it in. Anyway, I had never seen these on any BMW before, so we destroyed them to get them removed. Maybe BMW mechanics do the same thing since they can just grab two more and pop them in. They should be available for a couple bucks. We spent more time then we had to on this. Hopefully this saves you some if and when you run into them.
2. The expansion tank needs to be removed to get the fan shroud out. This is essential to the process. You need to disconnect the hose below to the expansion tank, along with pulling out a temperature probe and disconnecting the harness to the probe. The tank slides into two slots for it on the fan shroud. The hose clamp fastener will have the hex nut / screwdriver release in a difficult spot, but after playing with a few angles it is reachable and removable. There is another hose to the bleeder screw valve that is threaded through the fan shroud. You don't need to disconnect this. Once you remove the lower hose, probe, and electrical connection, you can work the tank and shroud out to rest on the left side of the engine with the bleed hose still attached.
3. There are cap covers on each of the tensioner pulleys that can be snapped out with a small screwdriver to reveal the torx bolt, and yes, you need to remove the lowest tensioner next to the alternator, or you won't be able to get to the last lower bolt to remove the alternator, aside from the fact that you can't remove the alternator with this tensioner pulley in place.

Aside from these items, the rest of the instructions were spot on and very helpful. Thank you.

Failure at 197k+, which finally forced me to address this issue.

1. The pop rivets are used in quite a few places so get used to them.

2. The expansion take does NOT need to be removed. It just takes a little finessing and you can angle it out the driver's side. Just remember to disconnect the plastic shield around the bleed screw and the small hose at the inlet nipple. Also remember to disconnect the wire to the expansion tank sensor as you remove the fan shroud.

3. Yup...most of us are also aware of this. I noticed the OP's were already removed. You are correct that the tensioner pulley overhangs the alt so yes, it must be freed.

Special thanks to BlackBMW for having the balls to tackle this daunting task and document it. Also thanks for posting all the additional info guys, it really does give one the confidence to march on and attack the failure. This task took me about two hours and it was my first attempt. On first start, the batt light was non-existent and there wasn't a single squeal from the belt so I'm not sure what you guys did but maybe the tensioner wasn't fully torqued? I now have a coolant warning but I KNOW that it is full so I prolly have to burp my baby now.

[Skitzo91]

Have the light blinking on my dash but my test 9 has a better voltage than yours after the change, battery checked out fine aswell as alt from Advanced auto test.

Should i ride it until it leaves me stranded?

[540imtech]

I wanted to post a Thank You to BlackBMW for posting this excellent DIY. "Thank You!"

Had the red battery light illuminate recently and, with no particular mechanical skills, but a decent set of tools, was able to tackle this job on my car this past weekend. Start to finish was about 3 hours. Car started right up, red battery light off and everything tests out perfectly.

Saved me the (reasonable) $220 in labor quoted by my indy shop. They'd also quoted me an outrageous $825 for a remanufactured Bosch water cooled alternator which I found online for about $370 after core deposit refund.

More importantly.....this DIY repair gave me the satisfaction of having successfully tackled this myself!

Good Stuff! So, Thanks Again!

[BlackBMWs]

I wanted to post a Thank You to BlackBMW for posting this excellent DIY. "Thank You!"

You are very welcome! In retrospect, I am glad this DIY has helped many of my Bimmer Brethren. Regards, Rich

[ndz]

Thanks OP. Just completed my water cooled Alt replacement on my 99 540iT (128k mi). Not a bad job. I went with a Bosch reman 150v from FCP.

A couple suggestions. If you don't have the fan removal tools, buy them now. It makes fan removal take seconds.

I didn't have to remove the fan shroud. It's a tight fit but you can wiggle the alternator past it.

[E0339]

Thanks for this DIY. I particularly liked you mentioning how the M50 bolt might be tight, and some tricks to help get it off. What is the "Why" behind putting grease on the o-ring?