928nut

Anybody running alternator(s) without the cooling cover at the back ?

I "upgraded" mine to a 120A Bosch unit purchased from Eagle Autoelectric. I noticed the clocking of the terminals was a bit different from the stock unit and the cover also looked a bit different. Needless to say, the cover does not fit, as I feared. Otherwise the alternator was a direct bolt-on fit and is working as I hoped. No more radio cutouts due to excessive voltage fluctuations.

Just wondering how critical the cooling cover is to the longevity of the alternator ? (or any other issues it could bring about)

Mark Anderson

up graded ? What does Eagle have to say? Porsche went out of their way to,supply the alternator with cool air. I’m sure others found a better and cheaper path

Speedtoys

It's critical to power output, and health.

The VR adjust down as it heats up by design...and too much heat kills alternators.

Best solution, Greg Browns alternator which is a front-to-rear airflow alternator design, that entirely removes the need for cool air being ducted from behind.

928nut

Time will tell if it was an upgrade or down-grade. Eagle didn't have much to say - "sorry, we didn't know the cover wouldn't fit".

Dealing with them was a pain. The hombre I was dealing with didn't like many questions, didn't speak good English and eventually told me to take it or leave. Ironically, the workmanship of this "re-manufactured" unit is excellent.

I hope the fact I live and drive in northern climate will help offset the lack of fresh air intake. I'll find out soon, new driving season isn't far away.

Speedtoys

Why would you not get a stock unit?

Air temp isnt the issue...the exhaust manifold is.

928nut

Because I didn't believe the stock unit produced sufficient output. Records show, this car always had an issue with low or marginal output, even before I bought it, and I was determined to put in a higher output alternator. This unit seemed to fit the bill.

I knew Carl had a monster alternator with exact fit and function of the stock unit but the price tag seemed too high for me. Didn't know Greg had a "solution" available as well.

Again, we'll see how it will turn out. I'm sure I've seen posts from other members who installed this unit, hope to hear from them, see what's been their experience.

dr bob

Generally, the rear can be re-clocked to get the terminals (and cover...) to fit if the case size is actually the same. If it's a drop in Bosch, there's a pretty good chance that the cover can be used.

Remove the voltage regulator and the brushes/holder from the rear of the case. A couple screws... Then remove four through-bolts and the nuts, and you'll want to use the old longer original bolts here on reassembly so they reach through the mounting face on the case. Rotate the case to the clocking you desire. Four long through-bolts. Reinstall the regulator and brushes, being careful to get the brushes in correctly. IIRC you can use an unfolded paper clip for this. Then the two regulator screws, the cover gasket, the wiring gets connected with the rubber grommet for the case, then the case, the four nuts to hold it, up into place and the mounting bolts and adjuster. Belt. Tension the belt correctly per the WSM.

Speedtoys

This is one of those areas where "belief" and "facts" become intermingled.

The OE unit has been fine for people since 1977.

Most (to a massive extent) threads that say "Its low" is via the view of a 25-40yr old pod gauge where every one of 8-14 wire connection points is old, corroded, and add cumulative resistance to the path to the needle...so it is "low".

Or an alternator full of oil and crud, with a worn/weak VR...

jpitman2

Acid test required. Get a DVM and see if the pod gauge constantly reads the same difference from your meter. If the difference fluctuates, its useless. Get a USB adapter for the cigar lighter socket that displays volts as well , calibrate that against a meter, they are not very accurate, but error should be less than 0.4V. Then drive around and watch what the voltage reads once everything is thoroughly hot. I bet it sags more than a little. My alternator died after ~20mins driving, but was fine before that - heat, old age.

https://www.jaycar.com.au/dual-usb-4...splay/p/MP3692
jp 83 Euro S AT 57k

The Forgotten On

Greg's alt is nearly $1k but really worth it. The alt it's based off of comes out of a modern 911 so the 928 engine bay is paradise in comparison.

I have one on my S4 and it works perfectly.

But for future reference the rear of the alts on a 928 are specific to allow the shroud to be attached to it. Most rebuilt ones from Bosch don't have the studs to mount the shroud.

Speedtoys

That circuit is no better than the pod one, if left in the same state of inattention.

V2Rocket

according to the parts interchange the 928 alternator is the same as the later 944 alternator.
in the 944 side we have found that the 90s-2000s Nissan Quest/Mercury Villager minivans have a near-bolt-on alternator at about 125-130 amps stock that is widely available at most parts stores (since it was a Ford product). just need to grind some meat off the lugs to fit the alt bracket.

they have internal fans and lots of vent holes and are physically smaller/lighter than the 944/928 alt and survive happily without the cooling shroud even next to a million-degree turbocharger in the 951.

FWIW.

vanster

Bite the big one and buy a Greg Brown alternator. This way you can run H'4's and AC at the same time and not worry about it. Also it maybe that last alternator you will ever buy

928nut

Good to know, thanks for the info. If my current experiment bombs out, the alternator gets fried, I may try this option.

928nut

Thanks for the tip, dr. bob. I may take another look at it but I am afraid, it will not work. This is not a 928 alternator, the cover is different, doesn't have the recess to clear the oil pressure sender body and the air intake tube is .400" smaller dia. Not sure what car it is from, maybe a 944, Eagle will not say. Nevertheless, I may try to come up with some mods to make it fit.