Seized alternator

[Welly]

I saw Ed China repair an alternator bearing on Wheeler Dealers, it looked easy but then everything her does looks easy

[mjb]

John, you ever done one of these water-cooled V8 alternators (E39 540, E38 740, X5, Range Rover) - http://www.meeknet.co.uk/e38/Alternator ... cement.htm ?

I've got everything out the way and unbolted it, but I can't get the bloody thing out of the housing no matter how hard I hit things, and there's nothing to lever against!

[jasper5]

Sorry, never changed one before.

Looks like you might squirt WD40 round the back of the alternator mounting bolt and let it soak then bash it all round the mountings and hit it where the wires come out....looks like somewhere to hit it there....obviously be careful not to damage it.
Looks like you need a good, solid chunk of metal and a good hammer to shock it free.

My mate recons these, just had a quick mention of it to him, didn't ask for a price or how to replace the bearings, but I can ask if required.

[Doggy]

If you look at this pic



It looks like the cap head screw in the left-most of the 3 holes is used to clamp the alternator assembly together. Note that in the picture below, (which shows the opposite end of the same screw), the rear half of the casing is threaded, but it goes all the way through, (i.e. it's not a blind hole).



You may be able to withdraw these cap-head screws, them screw in some longer ones, to carefully jack the alternator out of its housing. You need to try this very carefully, so you don't damage the housing with excess force, or flare the ends of the jacking screws, so they can't be withdrawn. (Normally, we would turn the last couple of threads off, to ensure they can be unscrewed, but these are so small already, you don't want to put a point on them).

[mjb]

nice spot! I'll give that a try if I'm still stuck tomorrow.

I've been out and got some WD40 on the job (for some reason all 500 of my cans have gone missing so needed to buy more) and it looks like some of it's seeped in, which is a cracking sign I should be having an easier job tomorrow after the new alternator gets here.

What I need is a 6"x1"x1" bit of steel welded to an impact socket and attached to my impact wrench could be used to apply some nice shock/vibration treatment to stuff like this without needing to resort to my shiny new 4lb 'ammer and a hole in the radiator

[mjb]

4lb 'ammer and a pry bar to transmit the shock. Job's a good 'un

4 bloody hours to finish off the job ain't good though, but I had to get rid of the sealant(?) (solidified white powder) on the replacement part and do a rubber gasket transplant, then there was a load of time spent trying to bleed the thing. So far, it seems you don't need to bleed past the first few turns of the engine if you've got the front on ramps? Took ages to get up to temperature (110c) and then it just spewed coolant all over the garage - d'oh. Re-filled, took it for a drive and it seems good. Put some ready-mixed in the boot though, just in case

Have to admit, once you know how, working on this bmw is really quite nice. Take the undertray for example. Completely protects the engine bay unlike 406 ones, and the screws holding it on are really easy to use, and more like clips than screws (hard to explain - only 1 turn required then it locks in place). No dicking about with zip ties like the 406...

[Welly]

Nice work, that'd cost a pretty penny in Labour by the sounds of it.

[mjb]

Nice work, that'd cost a pretty penny in Labour by the sounds of it.

Actually, apart from getting the new alternator into a usable state, I reckon the whole thing could be done in under 2 hours now I've got the tools and know-how. I think my problem getting the alt off was due to the tension of the sitting coolant behind it sucking it in.

Having said that, it does seem that bleeding one of these things is a process which takes several days - fill, run engine for a minute, fill, get hot (thermostat opens at 105c , but the fan won't let it go over 100c idling), wait for it too cool (long long time) then repeat a few times

[Welly]

I hope you're not missing anything with the bleeding bleeding procedure, I'd hate to see the thing get too hot, there's no 'secret' bleed nippule hiding somewhere? to be fair other than the level settling a tad car coolant filling shouldn't really be a mammoth task?

[mjb]

No, there's just the expansion tank and the bleed screw on the top of the radiator. It's not really a mammoth task, it's just that the thermostat opens at such a high temperature you can't open up the system without getting a face full of scalding antifreeze so it needs to be done over a lot of time to let the car cool down in-between top-ups

[Welly]

105 degs? must be some kinda warm-up-quick emissions bollocks.

[jasper5]

Good result

BMW are easy to bleed with that screw on the radiator, just fill the system with the screw open and let the air bubble out.

[mjb]

BMW are easy to bleed with that screw on the radiator, just fill the system with the screw open and let the air bubble out.

Aye. It does suck a load down during the first minute or two, and this morning I checked before setting off and the level was fine, but 20 yards down the road it needed a top up. After that it's kept at the right level, even after some extended hard urban driving