Remote Mounted Voltage Regulator -

[JK McDonald]

Has anyone tried using one of the remote voltage regulators on their 928 ? The idea is to remove the V/R out from under the radiated heat of the engine and exhaust manifold for a more consistent and stable alternator charging voltage under load.

The voltage at the jump post and at the battery tends to fall off gradually on my 84 in the summer heat. After a cold start-up the alternator voltage is 13 - 14 volts but tends to gradually fall off at idle to about +12 volts with the A/C, blower, stereo and lights (if needed) are turned on. I haven't had any starting problems and normally just rev my RPM up a notch while at a red light - but the performance reviews of several of the remote mounted V/R products sound good. I think something could be modified using a few separately available parts just to test the theory if a specific part can't be found. Here is one site as a general overview.....

Volvo Adjustable Voltage Regulators

I've cleaned and checked all the usual suspects (14 pin connector, grounds, battery and jumper post connections, etc) I've also pulled and tested my alternator stator windings, diodes, potential internal electrical leaks and external wiring and found no problems. So I'm initially rocking between a remote V/R and installing a slightly smaller drive pulley. If that doesn't fly well enough I'll bite the bullet and install a larger capacity 120 amp alternator. The most sacreligious one I've read about that fits at a reasonable price is from a 1988 Camero. The only potential issue with this option is that the cooling ducting will no longer fit - so I may be back to the original heat issue ?

On going V/R tests are now in the works -

Michael

[Danglerb]

When I bought my Mustang new in 1991 part of the "hot rod" mods was to install underdrive pulleys, which made the voltage dip at idle with AC etc on. Fortunately I was never stuck sitting at an idle for several hours so my battery provided the needed current without issue, unless a battery was already on its last legs. A decade or so later I put in a newer higher output factory alt from a newer model year, and the dip at idle when hot didn't go entirely away, but all the "problems" did.

Short answer, I don't think there is a "problem" with the factory setup, but the appearance of a problem can be largely removed with a newer model alt provided the cooling is addressed.

[JK McDonald]

After contacting a couple of sites that sell a remote mounted voltage regulator for many European alternators, for some reason there seems to be nothing currently available for the Paris Rhone design. Something to do with the slip rings (size, spacing, set-up ?) which seems strange to me. My current regulator has Paris Rhone on it's housing so this may actually be the problem. Has anyone seen a heat related life expectancy on the V/R used in the 928 ?

I plan to order a new German built Huco V/R plus come up with some kind of insulated heat shield to try and fend off some of the exhaust manifold temps a bit. I'll also make sure the cooling ducting from the left fender is still in good shape.

If the Huco V/R doesn't properly hold the hot idle charging voltage under load I'm bumping on up to somewhere around a 120 - 140 amp high capacity upgrade. Here is one setup that looks promising - are there any other preferences ?

140amp CS144 Alternator Swap - 1983 928S - Rennlist Discussion Forums

Thanks Michael

[Arizona_928]

I installed one in a 951. It's kinda cool to have. I liked it. But really no practical gains or improvements that I saw. Was fun to brag to other turbo guys about having it. Ha ha


That second link is pretty cool. Running a serpentine belt is going to be tricky. Not that hard though. Might look into a ls1 alternator bracket and truck alternator. You can get those gm alternator connectors at rock auto.

[JK McDonald]

Well - finally got back to my alternator temperature project. Even though my battery and alternator are relatively new, as the outside summer temps climb - at idle with the A/C, blower, lights on, my alternator voltage (at the battery terminals) drops to about +12.5 volts. As mentioned previously I've statically tested the internal components of the alternator plus the alternator and battery have passed a load test. Even though the voltage regulator brushes seemed ok I installed a new Huco Regulator assembly which did improve the alternator output at idle to about +13 volts. At highway speeds everything has always been fine.

After reading several discussions about heat related alternator performance issues I wondered how much the radiated heat from the exhaust manifold may be part of the apparent long term thermal deterioration. I came up with a proto-type heat shield that seems to work really well and although I initially fabricated it in two pieces, in retrospect I think it could have been made as one part. First a couple of cardboard patterns were fit in place then I sandwiched a layer of 1/4" fiberglass insulation between two thin sheets of aluminum siding and did some fine tuning. The edges were all crimped over just a touch while trying to leave an air pocket within the interior of the panels for a little better (less heat transfer) insulation.


The squared off notch in the upper left corner is cut out for the power steering pump bracket and the uneven lip along the top fits into several block recesses below the exhaust manifold. The slightly bowed top far right side fits snugly between the left motor mount and it's factory heat shield. There is a step running vertically down the middle that follows along the back side contour of the alternator housing.


Once the heat shield is in position - it is held between the left motor mount & it's heat shield, pushed slightly behind the power steering bracket upper edge and (at the bottom) - a zip tie goes around the plastic cooling air inlet. Under the zip tie is a short section of foam pipe insulation inserted between the new heat shield and the circular air duct inlet to provide a stand-off air spacer.




During an ops check - by touch I found that the heat radiated from the exhaust manifold down to the alternator metal housing is significantly less. The warm alternator idle voltage with the A/C, blower and lights on is now +13.4 volts. I'm planning on a high temp "smoke test" through New Mexico - Colorado to begin next week and should know something more definite on my return.

Drive Careful, Michael

[AirtekHVAC]

That's really cool. No pun intended....

[harborman]

The plastic cable tie might not take the heat.

[JK McDonald]

Hey Harborman - You are probably right about the longevity of the plastic zip tie. I'll find some of those thin metal zip ties used in high temp applications.

I took Miss Purdy out in the heat just before noon for about a 100 mile shake out road test. On my return I checked the idle voltage at the jumper post and battery with a typical electrical load (A/C, Med Blower, lights) and still read a steady +13.4 volts. Yeah - Huco 14 Volt V/R. Even the dash volt meter is reading 13 volts. I had already taken the Pod apart to clean all the instrument edge connectors - but as well documented we know that the dash volt meter is only for a very general wild a$$ guess of the alternator status.

I checked the heat shield for any sign of movement and it was still secure. I had tried to be careful when forming and positioning the heat shield to keep an air gap on both sides to limit (as much as possible) any transfer of heat from physical contact. The alternator housing was pretty warm to the touch (probably heat transfer from it's mounting hardware) but not any where as hot as it was before the heat shield installation.

My real alternator output improvement may well be primarily from the new Huco V/R but - perhaps the installation of the heat shield will extend the life of my electrical system and make it a little more reliable in the Texas summer heat.

I've been a little paranoid of alternator issues ever since several years ago when during our initial cross country trip in Miss Purdy my wife had looked over to ask "why was that meter jumping around like that for" ? This was just before the alternator failed out on interstate well west of Amarillo. AAA saved the day but now any gauge or warning light flicker has my wife's grip on her cell phone tighten a notch.

Michael

[JK McDonald]

My home made "Possum Trot" alternator heat shield plus new Huco VR worked flawlessly and made it back from Colorado without a hic-up. The low gas prices has every motor home and over sized 5th wheel ever sold out on the roads. Most of the multi-lane highways weren't too congested but when these lumbering beasts strayed off interstate they would gradually congregate into long slow moving packs because they couldn't get out of each others way. The speed limits through the mountain passes for cars and pickups are definitely only a suggestion and on many stretches were obviously considered the minimum speed for the locals. One fire engine red RX8 rotary engine Mazda that blew past everyone and quickly disappeared had to be pushing 100 mph.

My only complaint was that the Colorado Highway Department must have saved their money allocated for guard rails on the Million Dollar Highway to Ouray to spend on medical mari-jane inspectors. As I'm sure the native Coloradans already know - going over one of those steep cliff drop off's would definitely ruin your day.

Man what a beautiful place to live. The rocky mountain lows were in the 40's at night with the day time highs in the 80's - Miss Purdy is now back in Texas simmering on "London Broil".

Drive Careful - Michael