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[tport]

On the way to the Rally of Wales yesterday at 0530 my Omega came to halt at Worcester. The battery light had been on for about 5 minutes before the electrics started to fail (CD player, lights, aircon) and I just managed to get off the M5 before the engine stopped. I tried to restart the engine but of course the engine didn't spin on the ignition.  I got towed back to Nottingham with two very disappointed sons in the back seat!

Using Kevin Wood's excellent 'Battery, Charging and Starting diagnosis' article I found that the voltage across the battery was only 11.3V at fast idle with no load so I suspect the alternator has failed.  I have removed the alternator (120A ref 0 124 515 049) but it looks a little different to the one shown in Marks DTM Calib article 'Repairing the alternator'.  The brushes and voltage regulator are a one piece unit (ref BR14-T3 F 00M 145 257).

What are my options?  I guess I have three:-

- Buy a replacement voltage regulator and hope this is the problem
- Buy a whole unit from a breaker (is a 120A unit common?)
- Get the existing unit refurbished

Can anybody give me an estimate of the cost of these options and advice which they consider the most appropriate?

[TheBoy]

To get you going quickly, contact one of the breakers on this site, then refurb (yourself) the old one

[Big_Roger]

Hi,
As your motor is 3.2 V6 You are correct, it is a different alternator to the 3.0 L versions, which are Bosch PU120
The Vx no you quote is for Bosch XA 120 Alternator and yes it does have a different Regulator assembly BR14-T3-V14.

This the same as what I had. I couldn't find anywhere that stocked the regulator, and Europarts quoted £180 for a Lucas exchange unit but didn't have any stock. Vx could only tell me their replacement unit was price on application.

Wood Auto do make a brand new british built replacement ALT 10360 but didn't have one in stock at the time. at about £100 (non exchange)

You can replace with a Bosch PU 120 which is what I had to do in the end. It is quite common on the 2.5 and 3.0 L engines and the regulator is readily available.

Have you double checked that you don't have a poor connection on the crimped cable connection from alternator to the battery terminal. This is a very common problem.

HTH
Roger

[Brikhead]

...contact one of the breakers on this site...

You can replace with a ... 3.0 L (one)

Bosch 120 A alternator here...
http://www.omegaowners.com/forum/YaBB.pl?num=1289176732
Tenner, collected.

[tport]

Thanks for the sugestion about checking the crimped connection.

I've just gone to check and both connections are covered by heat shrink but appear to be secure.  The 12v lead is quite substantial but the ground cable is very thin however both appear OK.  Is there any easy way to test them?

[Andy H]

Thanks for the sugestion about checking the crimped connection.

I've just gone to check and both connections are covered by heat shrink but appear to be secure.  The 12v lead is quite substantial but the ground cable is very thin however both appear OK.  Is there any easy way to test them?

Quick Way Engine running and headlights, fog lights and rear screen heater on.

If there is a decent current flowing then a poor connection can get very hot (hot enough to burn you or the insulation). If the connection is down to the last few strands then there might not be enough current to get more than warm (but there might be a wiff of gunpowder if you sniff around).

If you are suspicious about a particular joint (and you have a voltmeter) you can pierce the insulation of the cable 3" or 4" from the joint (stick a pin in it) and measure for a voltage difference between the pin and the terminal (with lights on and engine running).  Anything more than 0.1 Volt (100mV) is suspicious.

[tport]

The crimp at the battery end of the cable appears fine and there are no signs of the insulation deteriorating all the way up to where the cable enters the tray at the front of the engine.

Of course I have now disconnected the alternator and can't easily test for an overheating connection.....

[Andy H]

Oops, I should have been paying more attention.

I would check for poor crimps by setting my multimeter to Ohms and attaching the test leads to the ends of each cable in question. Move the cables around (push/pull/twist) and watch for changes in the reading on the meter.

More often than not a dodgy crimp will come off in your hand a moment after you notice the needle flick on the multimeter

[tport]

Check end to end with my pocket multimeter and, despite  wiggling both ends, meter confirmed very low resistance.  My thoughts are now back with the alternator itself

[The Red Baron]

i have a couple of bosch pu120 here in burton if it can help you. 

[tport]

Thanks for all who offered advice, it turned out that the voltage regulator had failed. Fixed this and have now got a healthy 14v at tick-over

[Big_Roger]

Hi,
Glad your'e all fixed up now. I presume it was the BR14-T3-V14 Regulator that you replaced.

Would be interested where you managed to get it from. I couldn't find a stockist.
This is probably what is wrong with my original unit, and I would like to get it servicable again.

Roger

[tport]

No-brand
http://www.woodauto.com/Component.aspx?Ref=VRG46418

Bosch
http://www.woodauto.com/Component.aspx?Ref=VRG46479

In the end I got the regulator replaced by a local outfit who could also test the alternator - worth an extra £5 to ensure I didn't have to take it back off again