W123 300D AUX Fan/Viscous Fan

[dennislarock]

Today... the 84 300D has been running HOT ...so, I took the 16" Maradyne Champion low profile aux fan off the '85 TD and stuck it on the 300D, hot wired it and let it run full time. Idling in the sun for 45 min @ 82C coolant 40F AC (constant) at the vents. Ambient 80F.



Yesterday... installed new radiator, water pump, flushed... tested and, finally *removed* the thermostat. But, it still ran hot 85C-90Cish with AC off... 95-100 with AC on and aux (Behr) fan running. Ambient 88F



I'm going to install two (2) electric fans. Please note: I live in New Orleans.



So, if anyone out there has a suggestion on electric fans (make/model/yr) etc. I would greatly appreciate any and all references.


Thanks in advance!


dennis

[Usaguy]

Originally Posted by dennislarock

finally *removed* the thermostat....I'm going to install two (2) electric fans. Please note: I live in New Orleans.

Without thermostat you will run hotter because coolant will circulate back to the block and also through the radiator.

Also you will have a longer warmup time.

Get a BEHR fan clutch, put the thermostat back in and even in hot weather you will not have any problems

[Diseasel300]

Replace the thermostat. With the thermostat deleted you can overheat the engine since the bypass port is not being blocked. This is not a Ford or Chevy.

Running hot can be due to many things, but the stock cooling system should be able to keep up. If you have to have that much airflow, you probably have a clogged condenser coil or a clogged radiator. Replace your fan clutch. The clutched fan should be adequate to cool the engine at all but the most extreme operating conditions. The Auxiliary fan is only there to boost the A/C performance at low speeds and act as an emergency booster when the engine is overheating.

Your ambient temps are not anything unusual and should have the engine running at normal temps if everything is working.

[Usaguy]

Originally Posted by Diseasel300

This is not a Ford or Chevy.

Removing the thermostat is a bad idea on a Ford or a Chevy as well

[Diseasel300]

Originally Posted by christuna

Removing the thermostat is a bad idea on a Ford or a Chevy as well

Removing the thermostat is stupid on any engine. Fix the damn cooling problem.

My point was that on old-school Ford/GM engines, removing the thermostat would allow full coolant flow 100% of the time with the result of the engine running cold. MB doesn't use a once-through setup like that, the thermostat not only opens the radiator inlet, but also closes the recirculating port in the block. No thermostat leaves that recirculating port open all the time allowing full recirculation of hot coolant resulting in a hot-running and potentially overheating engine.

[Usaguy]

Originally Posted by Diseasel300

Removing the thermostat is stupid on any engine. Fix the damn cooling problem.

My point was that on old-school Ford/GM engines, removing the thermostat would allow full coolant flow 100% of the time with the result of the engine running cold. MB doesn't use a once-through setup like that, the thermostat not only opens the radiator inlet, but also closes the recirculating port in the block. No thermostat leaves that recirculating port open all the time allowing full recirculation of hot coolant resulting in a hot-running and potentially overheating engine.

true

[vwnate1]

In the dry Desert, 90* C is considered good .

When you flushed the system, did you use Citric Acid or what ? .

Also did you have the heater on full to ensure proper flushing of every bit of the cooling system .

I've had to drive the car a few hundred miles with the citric acid to flush out all the solder bloom and calcium / lime deposits ~ why it's so important to never use tap water when mixing coolant .

Keep at it, you're prolly close to good, it just takes time .

[dennislarock]

Sorry... I wasn't thorough enough ...I did put the thermostat back in (yes, it is correctly oriented) before I did the Maradyne Aux fan test this morning. My assumption is that my viscous fans just do not cut it anymore (i think I have 5 or 6 of them). A new one is expensive.

Thank You!

dennis

[Usaguy]

Originally Posted by dennislarock

My assumption is that my viscous fans just do not cut it anymore (i think I have 5 or 6 of them). A new one is expensive.

Yes they are a weak point. Most new ones stop working after a while or are bad right out of the box. Been there done that.

The only exception is BEHR. I'm happy with mine.

They are pricey but are worth the expense

[dennislarock]

Damn... some folks are so uptight.

Anyway... I pulled the viscous fan and stuck the Maradyne on the back of the radiator ...and, went for a ride. Ambient 84F. Drove it pretty damn hard, Full AC, pulled over @ red light downtown in the sun and sat for 20 min. Coolant never fluctuated @ 78C, AC never fluctuated 40F @ vents and the Behr aux fan *never* came on.

testing done

Rock on Folks@!@!

dennis

[vwnate1]

So far I've been O.K. with my original fans but I wonder of anyone ever tried a flex fan on one of our cars ? .

I used to install them on American cars & trucks and they were noisier but they worked a treat in in town traffic .