Cool harness and new 150A alternator

[550Maranello]

Chaps,

I installed JimF cool harness alongside a 150A alternator which was an easy fit, no re-clocking needed. The used ML430 alternator was $148 from Potomac Pat and a new VR - just to be safe - from Rusty was $28.

The engine's temp has not passed the 90 degree mark - it is around 87? - with the AC on. I am very satisfied with this mod.

I also replaced the windshield washer pump - it was toast - and the three grommets under both pumps and the fluid reservoir. The price of the pump was $193.80 [$228 retail] from MB.

We are taking the 500E to Newtown, CT, for a week vacation.

Thanks much to Dave, Gerry and others for the great advise and suggestions concerning both projects.



Kind regards,

Orazio

 

[remotemark]

Orazio -

What was the part number of the alternator you used?

Mark

 

[550Maranello]

Hi Mark,

Bosch 0 123 520 012.

Kind regards,

Orazio

 

[remotemark]

Orazio -

Have you noticed any difference in the car's performance since you made the switch? No loss of power, I hope? I just wondered if there is a significant difference in the amount of force required to spin the bigger alternator.

Mark

 

[szvook]

I had a 150A alternator for almost one year and did not feel any power loss at all. I now have a 160A alternator for the past month and again no power loss as well.

 

[spleuba]

Reviving an old thread. Just a couple of easy questions: (1) What is a Cool Harness? and (2) When installing the 150A alternator, do you need to change out any cables?

Thanks very much.

 

[emerydc8]

I can help you with the Cool Harness. It's just a resistor that plugs in between the coolant temperature sensor on the top front of the engine and the sensor harness. It causes the high speed cooling fans to come on at a lower temperature. I think the factory has them set to come on at 105 degrees. The Cool Harness that I had caused the fans to come on at 92 degrees.

I ran into a problem here in Tucson because it gets so hot in the summer that the underhood temperatures, as measured by the new (tricked) data come out of the sensor, exceeded the maximum temperature for the air conditioning compressor to operate, so the compressor wouldn't engage after the car was driven and then parked in 115 degree weather. Some guys save the money for the harness and solder the resistors directly across the sensor. I'm sure you can find out which resistors to use if you search some of the Mercedes forums.

There is also a way to trick the viscous fan into engaging at a lower RPM by drilling a hole and inserting a small bolt into one end of the bi-metal piece that pushes the pin to activate the fan clutch. That seemed to help quite a bit in the hot temperatures.

Can't help you on the alternator.

 

[gerryvz]

Scroll down toward the bottom of the page and you'll see information on the Cool Harness.

http://www.k6jrf.com/MB_S500.html

It shouldn't be necessary if your cooling system is in good order....

Cheers,
Gerry

 

[spleuba]

Thanks very much. Very helpful.

 

[samiam44]

You'd only feel an alternator difference @ full load (<110Amps). The physical size of the 143 is the same. It looks every similar, perhaps just bigger winding, better diode heatsink etc. to get the extra amperage.


Michael

 

[Jelmer]

I ran with the CH92 for quite a while, worked OK'ish, but if your visco is dead, the radiator is too old, or something else is wrong, the aux fans won't be enough to keep the car cool.

Also, I found that with my electrical fans *and* the aux fans (via A/C at high power) the normal alternator is still able to provide enough power at idle ...

 

[gsxr]

I ran with the CH92 for quite a while, worked OK'ish, but if your visco is dead, the radiator is too old, or something else is wrong, the aux fans won't be enough to keep the car cool.

Exactly correct, particularly in hot climates, although nobody wants to believe this.

Also, I found that with my electrical fans *and* the aux fans (via A/C at high power) the normal alternator is still able to provide enough power at idle ...

Have you measured the voltage at the battery with all four electric fans on max speed? Then turn on the headlights, HVAC fan, seat heaters, rear defog, etc etc and measure again?

 

[gerryvz]

Have you measured the voltage at the battery with all four electric fans on max speed? Then turn on the headlights, HVAC fan, seat heaters, rear defog, etc etc and measure again?

I know that there's global warming, and also that y'all have some funky sorts of weather & climate stuff goin' on up there in Idaho, but I have to say I'm REALLY having a hard time thinking of a scenario as to when the rear window defroster/defogger and seat heaters would be required to be running at the same time as the A/C....

Cheers,
Gerry

 

[gsxr]

HVAC = HEATING, ventilating, air conditioning. The main power consumer is the blower motor. Cold day = heater on high, bun warmers on, possibly rear defog (although the latter doesn't pull much current). Make it a cold night and you get headlights/foglights on as well.

:fish:

 

[J-Sauce]

Don't forget the subs banging away in the trunk.

 

[gerryvz]

Cold day

Huh? What's that?

 

[gsxr]

Huh? What's that?

damn Texans. They put on jackets any time it dips below 80°F... pffft....

 

[Jelmer]

Strangely though, I don't have the AC running often when it's cold. Somehow, the fans and aux fans have much less work to do And in the heat, one doesn't use use the heated seats etc. But, you're right that it would probably be too much for the poor alternator to handle. For the occasional "dual fan" situation, I don't worry so much.

 

[gsxr]

The primary consumers are the stock twin fans (~25A), the Flex-A-Lites (25A?), HVAC blower (25A), and headlights (10-20A depending on low/high beam and bulb wattage). Plus the power consumed by the engine management system (approx 10-20A, IIRC). You could easily need 75-100A at idle on a warm summer evening. The stock alternator can't supply that much and the voltage will dip below 13v. Not a big deal, but with the 150A upgrade being easy & cheap, it's a no-brainer IMO.

 

[gerryvz]

any time it dips below 80°F...

Well, it did get down into the mid-60s last night. Daytime temps this week are forecast ~90F, so fall is definitely here. Convertible season is just around the corner....

 

[supernova]

I turned on my heater on the way to work. Co-worker told me he turned the his heater and seat heater on. If it ain't 90+ it seems cold

 

[gerryvz]

I turned on my heater on the way to work. Co-worker told me he turned the his heater and seat heater on. If it ain't 90+ it seems cold

Took my E500 into work today ... no heat/AC on the way into work -- just the sunroof open. Way home, definitely A/C all the way.

It's cool out now...as of this week I can start working in the garage at night again. 8:15 PM and it's down to 80F outside. BRRR !!