617A electric fan - your setup - Page 5 - PeachParts Mercedes-Benz Forum

Mxfrank · #61 01-28-2015, 11:23 PM

Quote:

Originally Posted by The Gears

I found that anything less than 100c on and 95c off had the fan running almost all the time. A normal temp and thermostat full open is 90c. Al least on a 126 and I believe on a 300 as well. Same engine.

What do you care if the fan runs all the time? The idea is to keep the engine cool, not spare the fan. The design point of a cooling system is the temperature at which the thermostat starts to open...not the point at which it reaches max travel. For most Mercedes of this vintage that's going to be either 80 or 85. If your gauge regularly reads much more than that, you're doing something wrong.

tjts1 · #62 01-28-2015, 11:49 PM

Running the fan continuously will shorten its life dramatically as well as the alternator bearings. You really don't want an additional 30a permanent load. On my om603 the electric fans triggered by an 82c switch and are running maybe 5% of the time. The rest of the time its really not necessary. The temp gauge is nailed at 80c. Both the 71c thermostat and 82c temp switch are BMW PNs and both also fit the om617.

Mxfrank · #63 01-29-2015, 01:17 AM

Quote:

Originally Posted by tjts1

Running the fan continuously will shorten its life dramatically as well as the alternator bearings. You really don't want an additional 30a permanent load. On my om603 the electric fans triggered by an 82c switch and are running maybe 5% of the time. The rest of the time its really not necessary. The temp gauge is nailed at 80c. Both the 71c thermostat and 82c temp switch are BMW PNs and both also fit the om617.

Of course the fan doesn't run all the time. My point is that whether the fan runs 0%, 5% or 50% is less important than whether the engine is properly cooled. Last I checked, fans were cheaper than engines.

tjts1 · #64 01-29-2015, 01:30 AM

Quote:

Originally Posted by Mxfrank

Of course the fan doesn't run all the time. My point is that whether the fan runs 0%, 5% or 50% is less important than whether the engine is properly cooled. Last I checked, fans were cheaper than engines.

Last I checked, when your only source of cold air dies, your engine isnt far behind. Running the electric fan anywhere near 50% of the time is asking for a dead electric fan and an overheated engine.

ah-kay · #65 01-29-2015, 03:03 AM

If the engine cooling depends on an electric fan then I would not run it at more than 50% duty cycle. This is common sense whether the fan is cheaper than engine or not.

This is my set up on most of my cars to compliment the clutch fan. I glued, I do mean glue, a thermoswitch onto the thermostat housing and zip tied it just for good measure. This is a normally open ( NO ) thermoswitch you can get for $0.50 or less from eBay and with a lot of temperature selection. I pick 90F. One end of it is grounded to chassis and the other end is wired in parallel to the three prong switch ( pick the connector which triggers the aux fan ) on top of the thermostat housing. Basically you use the switch to trigger the aux fan at a temperature you selected. All is done for less then $1. You can remove the clutch fan if desired but I do not.

Is it necessary? I do not think so but it is a back up if the clutch fan failed. Is it useful? I think so. Is it easy to install? Yes. Is it cheap? Very.

Mxfrank · #66 01-29-2015, 10:25 AM

Open the hood on a random modern car, and you will find the sole fan is an electric. It won't be strapped to the core, it's shroud mounted to shape the flow across the entire core. On many cars, the electric fan runs 100% of the time, driven by a proportional controller. The construction of these fans is exactly the same as the aux fans in your 617 or 60x equipped cars. Rigging your fan to an 85C or 90c switch will make it come on only portion of the time, but when it comes on it's needed.

Again, gluing toaster parts to your car shouldn't merit a comment. As with the 60X motors, 617's have spare ports in the water jacket that can take standard 22mm switches...available in any single setting you prefer from 75C to 140C. If you're going to do something, at least take a few minutes to do it right.

ah-kay · #67 01-29-2015, 10:42 AM

Your comment has no merit anyway. Why bother?

tjts1 · #68 01-29-2015, 02:02 PM

Quote:

On many cars, the electric fan runs 100% of the time, driven by a proportional controller.

No, there are not modern car where the electric fan runs 100% of the time. That simply doesn't exist. Most modern cars use a PWM controller which can vary the speed of the fan as needed as opposed to my simple ON/OFF setup. PWM control offers a lot of advantages when you're trying to minimize the electrical load and keep the engine within a very narrow temperature range for emissions reasons. Again, very good setup but beyond the scope of this discussion.

Since several people PMed me for the BMW part numbers I mentioned earlier here it is.

82c temperature switch: 61311364274
This has a 14mm x 1.5mm pitch thread, identical to what MB uses on the OM603 and likely OM617

71c thermostat: 11531713040
I think the one I have a Behr brand.

funola · #69 01-29-2015, 02:14 PM

Quote:

Originally Posted by tjts1

............ PWM control offers a lot of advantages when you're trying to minimize the electrical load and keep the engine within a very narrow temperature range for emissions reasons. Again, very good setup but beyond the scope of this discussion.

...................

Why is PWM control beyond the scope of this discussion? Kestreltom built one and I am thinking of building one myself.

funola · #70 01-29-2015, 02:16 PM

Quote:

Originally Posted by Mxfrank

What do you care if the fan runs all the time? ...............

I'd be concerned about over cooling, inefficiency, shortening the life of the fan and alternator, lower mpg etc etc.

ah-kay · #71 01-29-2015, 04:47 PM

Quote:

Originally Posted by funola

Why is PWM control beyond the scope of this discussion? Kestreltom built one and I am thinking of building one myself.

It is because no one understands what is pulse width modulation. And it is expensive. Is my $1 solution worthy of consideration

?

dieselbenz1 · #72 01-30-2015, 11:05 PM

Quote:

Originally Posted by ah-kay

It is because no one understands what is pulse width modulation. And it is expensive. Is my $1 solution worthy of consideration

?

I like your 1$ solution but the black tie wraps are rated for -40 degres and with the ss tang would never break. I also tend to agree with you for an everyday driver PWM maybe over the top with the added components that would be needed to be installed. Moving air with fans is non linear so 2 stage fan would be adequate which is not difficult