So, I have one of these alternators in hand and the motor needs to be put back together. We also have a new front main harness from Greg that will 100% be part of the refresh.

I have two questions:

1.) 928s leak a lot of oil around the area of the alternator. However, this alternator does not have shielding like the stock alternator. It is true that the stock alternator will probably ingest quite a bit of oil despite the shielding that the fresh air hose is hooked up to. My car shouldn't leak any oil once re-assembled. BUT, is this a potential problem, if the motor is not completely sealed compared to the stock alternator?

2.) Getting back to heat, is there not some way to hook up the fresh air hose? I understand that the newer 911s supposedly have a hotter engine compartments. But, it also seems not correct to just leave it hanging there.

I am just trying to put all these observations into perspective. Can anyone comment?

This alt was originally from a newer 911 and those run much hotter than most 928s ever will so a cool air supply is not necessary in our application.

I also wouldn't worry about oil getting ingested. The shielding behind the alt is only there to direct the cool air supply from the back to the front of the alt and give optimal cooling to the diodes.

I'd fix the oil leaks regardless. No alternator does well when sprayed with oil. Even the stock unit is sort of open in front around the pulley and fan. the new one from Greg has an axial outflow fan in the middle, so will be drawing in air from the front and rear. If there's oil loose in that area, it will get in and coat the windings.

In my limited experience, oil on the alternator comes from leaking cam cover gaskets, sometimes camshaft seals, but most often from power steering hose leaks at least on cars I've had my fingers in. Be sure to replace any tired PS and maybe the oil cooler hoses on your car.

Most cars have open-frame alternators. Somehow they survive. I know from personal experience that they don't do well with engine cleaning chems, so better to keep it clean than to let it get oily and try to wash it.

My bad. I meant to write "911s supposedly have hotter engine compartments." I edited above. I still wonder what one can do with the fresh air hose.

Bob, I am not the kind of guy to leave things leaking in an engine compartment. (Not that you could know that.) I will have ALL new hoses on this car including a complete set of Greg's fuel lines.

Nonetheless, given the oily messes I see in engine bays, we have to stay the stock 928 alternator does an excellent (or at least way above average?) job dealing with massive oil slicks...

The restriction on cleaning with cleaning chems might be a good thought with this alternator given the open design. In Northern EU countries, it is standard procedure to wash down engine compartments prior to inspections. I am going to talk to some people about how this handled with 928s.

I've had no reports of any issues from oil, on cars equipped with my alternator. Perhaps everyone who is installing one of these has engines that don't leak, but I'm seriously doubting this is the case. Certainly, the voltage regulator is encapsulated and doesn't care about oil. The "windings" are wire covered with that clear, super tough, winding insulation. I guess if there was a "flood" of oil that got to the alternator, the brushes could get oil between them and the armature....but I'd think centrifugal force would make pretty quick work of any oil there.

I've got to think that alternators are designed with a certain "tolerance" of oil, since they live in an engine compartment.

As far as the cooling duct is concerned, I simply leave it close to the front of the alternator, if it is in good condition. I've also thrown a couple of them away, if they are badly damaged. From my testing, I've found that this newer designed alternator (with the windings exposed and fans on both ends) do not suffer from the same heat soaking that the original alternators did. The cooling duct is essentially a "vermiform appendix" when using my alternator (as far as I'm concerned) and I place it near the front of the alternator simply to pull air through the hose for better function of the temperature sender for the HVAC system.

:corn:

My negative experience with cleaning alternators is rooted in using solvent-based chems and then water to clean them on the car. the bearings are good but still manage to suck that stuff in and start the failure routine. No doubt it's easy to clean an oil-fouled alternator. I've done it often enough. I've learned by experience not to try to do it on the car. Learn from my experience. It's cheaper and easier than learning stuff like this on your own.

Are these still available…..

Yes.

We try to keep a couple units assembled and ready to ship, a the old pricing.

Bosch has been increasing their prices on....well, everything.
Including the alternator that we build our "928 version" out of.
Mary has been able to "hold the line" on our price, for now (by reducing our margin.)
However, she told me, after the ones we have are gone, the price will have to increase.

I've been considering one of yours Greg to solve my non-charging while idling issue on my TwinScrew 86.5 928, with all three Fans (after market - two pull and one push) running.
This is especially bad in stop and go traffic on a hot day when the pusher fan is needed and or AC on, as the engine will start to miss as the voltage drops to 11.5 :(

I recently had two Stock Alternators rebuilt and they tested at 140 amp output at speed, unfortunately I didn't get the idle amp output, I see yours is at 80 amps, correct?
Do you know what the stock Alt puts out at Idle please?

Thank you,

Dave K

Sorry, but I do not.
And you are 100% correct. The ignition system and injection system on these cars is very "power dependent" and requires more than 11.5 volts to be happy.

All I knew was that the stock alternator, even freshly rebuilt from Bosch, was barely adequate for a stock S4/GTS with the A/C running, the stock fans running, the stereo on, and the headlights on.
And people with big output stereo equipment were in trouble.

When I added on my upgraded A/C system, which had an additional fan and a higher amperage main interior fan, the stock alternator could not keep up, at idle.

Put one of Greg's alternators on mine (which replaced a one year-old rebuilt stock alternator) and it made a big difference, especially in the Florida heat. IMO, it's one of the best things you can do for a 928.

I'm so glad I bought one back when they first went on sale. My current alternator seems to be losing the juice when it gets warm. Can't wait to get Greg's unit installed.

I can tell you when I put Greg's alternator on the battery got much needed relief and starting the car from cold the starter spins significantly faster. Un-rebuilt windows run up and down better. Stupid voltmeter will sometimes read below 12 V but thats because it needs a pod refresh. I did the Bosch rebuilt alternator thing with extra windings but same thing for me, it doesn't charge at idle so you really aren't any better there.

Put Greg's alternator on; its a great piece of kit for our cars...looks cool too! Also, get the supplementary wire; it goes from the other alternator terminal to the starter...nice little boost and easy to thread through things...I just followed the original wire pathway and zip tied it to the orig wire to hold it in place.

I'm certainly not trying to "pimp" these alternators...my stuff sells quite nicely, all by itself.

But I just wanted to mention:
I've had a fairly big run on these units, in the last couple of weeks....and I went back and counted how many actual billet housings I have left to actually build this fantastic product.

I have the capability to build 6 more of these alternators, currently.
And since my CNC machinist did not "survive" Covid, I will be forced to have another machinist program and machine my housings and then make another "run" of these.
That's a major re-investment and will only occur after I have enough "back orders" to rationalize having that many $$$$ invested.

That could take a few years....
Long story short, if you've been on the fence on ordering one of these, you might want to hop off the fence and get it done.