Inexpensive alternative alternator for a Mercedes OM636?

[geegrrl]

Hi, this is my first time posting to this board and I am a novice to boating. Cash is tight right now and raising the £180 for the replacement alternator offered by Westfield is a bit difficult. I wonder if any Mercedes OM 636 owner has successfully replaced their Mercedes OM636 alternator with something like the more reasonably priced Lucas A127? If so was it a straightforward slot in replacement or did it require modifications?

Or perhaps there are other alternator models which are common enough to find reconditioned?

Would be more than grateful for any tips...sitting in my cold, wet boat trying to charge my batteries.

 

[lynall]

Stick up a pic of your alternator and I am sure someone will advise you.
If you cant load a pic, stick one onto photobucket then a link to the pic.
Has it got a removable brush box?

 

[pcatterall]

Can you fid and take it to a 'back street' ( old fashioned) auto repair shop ? They may be able to repair it or advise and procure a cheaper alternative.

 

[lw395]

You might find a car alternator from a breakers yard will do.
The key is usually the dimensions of the bracket, in terms of distance from the line of the belt.
You can do a certain amount with spacers, but there are limits.
I simply took the old alt to a car breakers that had shelves of alternators and found the most likely candidate.
I had to shim the pulley a few mm and make a spacer.
It is worth getting the old one looked at, if the windings are sound a fix can be very cheap.

 

[geegrrl]

Here are the pix of the faulty OM636's alternator.

 

[geegrrl]

Can anyone suggest a large breakers yard in North/East London? All the online breaker sites I've found require a car registration number.

 

[vyv_cox]

As suggested by others, it's definitely worth having an automotive electrical workshop look at it. The problem may be as simple as worn brushes, very cheap to fix. Yellow Pages usually lists a few.

 

[lw395]

Here are the pix of the faulty OM636's alternator. View attachment 38462View attachment 38463View attachment 38464

That looks like it mounts differently from a typical car alternator?

What were the symptoms of it failing?
Did the light fail to come on or flicker? That is likely to be brushes...
Good Luck!

 

[2nd_apprentice]

Google came up with old Ford Fiesta alternators fitted as replacement on Unimogs. Seemed to require some machining to make them fit but apparently not too difficult.

Edit:

K1-14V23/55A (BOSCH K1 14V 45A 20).
BOSCH 0120488182
BOSCH 0120488177
BOSCH 0120488176

I'd take my old one and compare them just in case!

 

[Skylark]

A quick Google search found this, among many:-

http://www.jcrsupplies.co.uk/products/ALTERNATOR_REBUILD_PARTS/ALTERNATOR_REPAIR_KITS_AND_COMPONENTS

Location is Walthamstow, E17.

Good luck in getting it sorted.

 

[Robin]

A few years back we had an automotive electrical workshop in Southborne area of Bournemouth rebuild the two alternators we had on our W33 with an OM 636 engine excellent job and very inexpensive, I later had them solder the connection lead needed for a smart regulator on our last UK boat and IIRC they did this plus a full check/overhaul of the alternator for less than 20 quid, job done same day too. Might be worth a day trip if you can find them, maybe someone from Poole or Bournemouth can remind me of the name and contact details, it was in a small workshop behind a private house I think.

 

[david_bagshaw]

we had the same alternator on the OM314 as well. It is a very standard Bosch alternator of the era. The most common fault we had was with the regulator boxes, they can be easily wired out for full out put, to get some emergency charge.

 

[Gwylan]

Google Plymouth, starter and alternator. Will, should come up with an alternator supplier who has given me excellent service a day saved money.
https://www.google.co.uk/url?sa=t&s...IGe1ZezJyTTTPgMrw&sig2=Zylz_QVjW49HvejKPlkBZw

 

[geegrrl]

The Charge Lamp?

What were the symptoms of it failing?

Battery not charging.
Using a voltmeter on the batteries terminals gives;
12.5V with engine off.
12.33V when engine runs
12.38 after 5 minutes of engine running
12.5V again after a few days with the engine off.

Did the light fail to come on or flicker? That is likely to be brushes...

Not sure what light you mean. There is an amber/orange colored light which comes on when the key is turned to the first position (I has assumed it was a glow plug indicator). However now that the alternator has been removed from the engine, this amber/orange colored light no longer comes on.

Attached is the electrics diagram for the OM636. Is this light you're referring to component number 6 - the charge lamp?

 

[lw395]

Battery not charging.
Using a voltmeter on the batteries terminals gives;
12.5V with engine off.
12.33V when engine runs
12.38 after 5 minutes of engine running
12.5V again after a few days with the engine off.



Not sure what light you mean. There is an amber/orange colored light which comes on when the key is turned to the first position (I has assumed it was a glow plug indicator). However now that the alternator has been removed from the engine, this amber/orange colored light no longer comes on.

Attached is the electrics diagram for the OM636. Is this light you're referring to component number 6 - the charge lamp?

Yes, the charge lamp.
If that does not come on, with the alternator in circuit, then check the brushes.

 

[lw395]

Item 4, the regulator is normally built in to modern alternators. Yours may be an electro-magnetic type. Could be worth checking it for burned contacts etc.
You may be able to manually switch it to check the rest of the alternator circuit.
I had something similar on 70s motorbike, I replaced the reg with a solid state one, for about £10 but this was 10 years ago.
A vehicle wiring place should be able to test that for you.
Unfortunately it is hard to diagnose at a distance as some of these things go high to charge, and some go low. There should be current flowing through the DF terminal if the reg is trying to make the alt charge.

Alas I am worse at explaining than fixing!

 

[geegrrl]

Yes, the charge lamp.
If that does not come on, with the alternator in circuit, then check the brushes.

Yes the amber light does come on when the alternator is in circuit. Does that mean the brushes are ok?

 

[geegrrl]

the regulator boxes can be easily wired out for full out put, to get some emergency charge.

Where would I find the regulator on these? And how would I wire them out for full output?

 

[lynall]

A127 has a split mount ie two feet unlike the one yours has.
Forget the output stuff, just find the local electricians and let them look at it.
People have given you good advice.

 

[david_bagshaw]

The regulator is mounted separately from the alternator, follow the wires back. Usually put in a cpbd out of the heat of the engine room either an aliminium box often with yellow tape to keep the lid on, or a squarish block of aluminium and potted electrics with a black plastic front. if the yelow tape type, remove the lid then hold the relay arm in to the contact, ie not the contact welded to the case.that will give full output. (so long as wires windings & diodes are ok)