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How to remove an alternator on an SLK320

3K views 29 replies 7 participants last post by  Dave2302 
#1 ·
I'm trying to remove the alternator but I haven't got very far. I have both bolts undone, and the electrical connector disconnected. I can't reach the main connector, but I maybe I can get to it when I get the alternator moving.
Does the alternator comes out from below? If so, there are two pipes in the way These are rigid pipes and even with short lengths of rubber pipes in the line, they don't move. See attached; the pipes with orange and yellow marks.

I can't get it out through the top/front without taking the water pump off (which provides the mounting bracket for the alternator). Not a huge job, but best to ask for advice before I do that.

Search shows nothing in our DIY section, and I can't find anything on Youtube. Benzworld has one post that simply says "remove a bracket, and lower the alternator downwards and out". Lack of information suggests it should be obvious, but it's not to me.

Can anyone provide some guidance please.
 

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#3 ·
This was one of the first things I did when I got my 230 about 7 years ago. It definitely comes out from underneath. I don't recall any issue with those pipes. Is it an original alternator or maybe its been replaced at some point with a physically bigger unit.? Or maybe one or both pipes have been replaced and rerouted.

The biggest issue I recall was getting the new one in place and holding it there to get the bolts back in.

Good luck in sorting it.

Sent from my SM-T290 using Tapatalk
 
#8 ·
The reason the 4 Cylinder is easier is because it is longer, so Alternator is further forward, see my comment re my V8 R170 .................

No magic tricks involved, they never will be a 15 minute Alternator swap ;) Have a look at a twin turbo V12 W220 S Class or a C215 CL, Alternator is Coolant Cooled and same location, absolute Bas errrm Bear of a job, a whole day on yer first one, I can do those V12's in about 5 hours now having done a few.

A Halfrauds Socket set isn't gonna cut the mustard either, a good selection of quality tools is essential too, round one bolt and it could cost you hours ;)
What I mean is, Deep Sockets, half Deep, regular, loads of different length extensions and other tools, short medium and long spanners, including ratcheting ones etc etc etc ;)

I pull 'em using a combination of access from above and underneath, not an easy job, except on my V8, which is because the Engine is identical but "2 cylinders" longer, a lot of stuff on that Car is much easier ;)

Many cars including V6's you just gotta rattle a load of bits outta the way until access around Alternator is better ;)
 
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#9 ·
Oh btw no need to remove Water Pump !! That opens up a whole new Rabbit Warren, once bolts are out ya just gotta twist it and turn it a bit to manouvre it out ;)

"J j j j jiggle it about Nurse Gladys" 🤣 .............. "Open All Hours" TV series for our friends afar ;)
 
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#11 ·
So if you got both bolts out what's the issue ...................

If it wont come outta the bracket it's just stuck because there is a sliding collar in one of the mounting bolt holes, carefully pry it outwards from the Engines mount brackets ;)
 
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#12 ·
It's out and rattling around. It's out of the brackets. It's supposed to come out of the car downwards but there's two pipes in the way (transmission fluid by the looks of things). Despite having short lengths of rubber hose, these pipes are largely rigid and don't move even when I remove some fixing clamps. There is a photo in post #1.
 
#14 ·
Try undo the bolt through Chassis to Engine mount and lift the engine a bit on that side ;) I've done a few but normally managed to get them out by doing Alternator acrobatics, but perhaps lifting that side of engine would help, it's only one bolt and easy to undo that mount from underneath ;)
 
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#15 ·
Thanks. I did think that's what a professional might do, but I don't have the facilities to get both ends of the car in the air at the same time. Raising the engine of a sloping car doesn't appeal. :) . I wish I'd had the job done when I got my engine mounts done a few years ago, but I didn't think of it.
 
#16 ·
#17 ·
Hi, Its a while ago that I did the alternator change but I seem to remember I had to rotate the alternator anti clockwise so the mounting lugs clear the water pump brackets then pulled it forward past the water pump bracket, I think I also put my trolley jack under the alternator side of the engine and jacked it up to get a bit more clearance. Was easier than changing the crackshaft sensor.
Still have the 320, nice cars.
 
#19 ·
steps might be the same in some form or another perhaps
 
#23 ·
you might have ATF pipes in the way to get it out from underneath
Now you've said that, although my memory isn't what it was, that makes perfect sense ;)
That is why I mentioned undoing and jacking the Engine ......... Of the handful I've done on R170 some of those customers had Manuals, and some had Autos, (none have 4 Cylinder cars), therefore I would be willing to bet the ones I did without undoing the Mount were Manual Trans Cars ;)
 
#21 ·
#22 ·
Oh, that's a good write-up. I should've thought to look on the crossfire forum. Mind you, I found it impossible to rotate the alternator more than about 5 degrees, never mind 45 degrees. The bottom mount is held between two jaws of the engine casting (as alternators are) and it's held really tight. I managed to push the bush of the upper mount back, so that one was very loose, but I couldn't get enough room to do the lower mount, and even if I had, that would only have retreated half a mm or so.

So I took the water pump out today. LOADS o' room now! New alternator will be here early to mid next week, as well as a new water pump gasket. I wish I'd done that first. I've done the water pump before, so no learning curve, easy job. No stress and frustration.
 
#25 ·
Yes, I think the consensus here is Auto Transmission is a real beast and Manual G/Box is a bit of a beast 🤣
 
#28 ·
The biggest issue with Pump removal is the Coolant passage Sealing between Timing Case and Block, IIRC Pump removal entails removing 2 off longer bolts that go through the Case either side of that seal and I know for a fact that at least 2 folks on forums have ended up with Coolant getting into their Oil ...............

I know not whether hammers and pry bars etc were also involved, but whilst, as @Australian correctly says, it is not a bad job to R & I a Pump, i would only risk it if the Pump actually needs replaced, because if you then have to remove Timing Case to reseal the bugger, as Petri found out, that is a bloody nightmare of a job ;)
 
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#30 ·
The one I had to sort out for the local tight fisted git who declined my quote, FIY'd it and screwed his V6 C class up wasn't ;)
 
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