Alternator melting question

[DanR]

I've noticed black stuff over the air conditioner below the alternator. I remember years ago hearing this was something to watch out for but forget the details.

Any advice or experience as to what's melting in the alternator and how soon this should be fixed.

Thanks

[CarBuff]

The "Black Goo" is a sign that your alternator's Voltage Regulator is melting.

 

The VR can be replaced easily enough (it's a Valeo alternator if you want to shop around locally). But many owners have simply purchased Bosch AL49X alternators which provide more amps at lower RPMs. The Bosch requires a longer carriage bolt on the lower mounting bracket (80mm long). Some have felt the need to "clock" the Bosch also, change the orientation of the wiring connections, by loosening the three long screws that hold the front and back on so that the wiring terminals are in a different spot.

[DanR]

Thanks for that.

[Qavion]

It will look something like this inside...

Danny, new regulators are relatively easy to find. I was in a hurry and paid a premium for mine (courier delivery from Brisbane) @ A$175. Unfortunately, you'll need to take your inlet manifold cover off to get to the two screws and the spade connectors. Whilst you're there, check your brushes for wear. The new regulator may be much fatter than the old one, but there is a cutout in the inlet manifold cover which gives a little clearance.

Cheers

Ian.

[DanR]

That looks ewwww....

Would there be any value in making some flying leads and mounting it away from the alternator in a cooler spot?

[CarBuff]

No. It's the current that passes through the regulator that heats up the potting compound and causes it to drip.

 

[DanR]

Could metal or so be added to the regulator body to act as a heat sink? My car's only done 60 klms. So seems premature for this to happen.

[CarBuff]

The issue is that the Valeo alternator does not put out much amperage at typical idle speeds (esp. with A/C or lights on). So, the car 'runs off the battery' more than a typical car, and when normal RPMs resume, the alternator is in more of a CHARGE mode than a MAINTAIN mode.

 

That's why the Bosch is a favorite alternate. It will maintain 13V right down to 900 RPM where the Valeo needs 1100+ RPM to keep the amperage up.

 

++++++++++++

 

My Valeo worked fine for 76K miles. But it had a drop of Black Goo underneath when I refreshed my engine, so it was replaced.

 

 

[Qavion]

My car's only done 60 klms. So seems premature for this to happen.

I got about 13 years out of my first regulator replacement (15,000km), so perhaps it's based on time as well as mileage. The newer regulator I fitted a few months ago is larger than the old, but I don't recall if it has bigger fins. Who knows, maybe potting compound technology has improved over the years?

I'm wondering if the regulator's proximity to the temperature of the plenum will influence its longevity (my chargecooler pump was forever breaking down before I switched to electric), so at least there is plenty of cool air now in the plenum, at least during normal driving. My new regulator now sits about 2mm away.

Perhaps you could ask Steve about it at Lotus Marques?

http://lotusmarques.com/info/technical/30-lotus-esprit/760-lotus-esprit-turbo-alternator-problems

 

Cheers

Ian.

 

P.S. Are regulator components actually attached to the case, or do they float in the potting compound (using that as a conductor of heat)?

 

[DanR]

Thanks Atwell and Ian. Great info. Car's now 20 years old so I suppose that's ok for a maintenance issue.

I'll check out the bosch alternative which I think is common on bm's.

[DanR]

I've ordered another regulator from Steve at Lotus Marques.

I think there's a major problem with poor or no cooling air flowing forward through the alternator. It needs a shroud for the rear of the alternator. If air could be picked up from the deck and directed via a hose to that shroud then it would have to run cooler.

90 amps can generate a lot of heat. Any shroud would have to squeeze into the tight gap between the plenum and alternator too.

Wonder if anybody has done one already and if so how.

[Qavion]

I've ordered another regulator from Steve at Lotus Marques.

Danny, did you order a gasket for the plenum, too? (or is yours not sealed?)

I'm curious to know how much you paid for the regulator (Knowing Steve, probably half of what I paid elsewhere)

I can't recall if the alternator is completely sealed. Would directing unfiltered air in that direction cause worse problems?

[DanR]

No Gasket. I've made them in the past so no biggie. You're right about Steve's price. That included post from Melb to Syd.

Contrary to what seems to be the case, alternators "suck" their cooling air from the rear and exhaust it out the front. The fans are a centrifugal design to enable this. Our engine bays get extremely hot and probably more so than most cars.

I've driven with wool strands taped on the vents and rear deck, and even at 100kph they are limp with virtually no air flow moving them. So if there was a shroud and duct to a cooler air source there'd have to be a benefit.

 

[benjamincalleja]

On 25 November 2015 at 11:16:29 AM, DanR said:

Thanks Atwell and Ian. Great info. Car's now 20 years old so I suppose that's ok for a maintenance issue.

I'll check out the bosch alternative which I think is common on bm's.

Hey Dan ask Steve from lotus marques he does up a real beauty custom for the esprit, more charging power but less load (more efficient) and better sized than the Bosch. 

[DanR]

Thanks Ben. I fixed it today with a regulator I bought from Lotus Marques. So all good now for another 20 years and 60 thousand klms, hey?

I decided leave it as standard and not to spend too much energy doing something different. I don't do a lot of k's in it, only a few thousand a year.

Cheers.

[benjamincalleja]

sweet good to hear!  i just changed my interior lamp as a side note, was always unhappy with its light output but didn't realise the PO put in a 3W glove when the manual states 10W!  now much much better and so easy to change...