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Swapping the electric engine cooling fan of my Volvo 940 for a mechanical one

ChristianFlores

New member
Joined
Mar 14, 2023
The other day my mechanic suggested me that I should swap the electric engine cooling fan of my Volvo 940 for a mechanical one. He argued that mechanical fan clutch is way more reliable than the electric ones, but, at the same time, apparently my 30 year old 940 never had a problem with it's original electric fan. So... What should I do? Is he right about it, or he just want me to waste my money?
 
Sounds like your mechanic prefers working on cars without modern advancements because he doesn't understand them. If it isn't broken, don't fix it.

Not to mention that without a PROPER shroud, the mech fan would be useless. Your car isn't a 1950 chevy that can get away with a basic cooling system. As it is now, you have a nice dual-speed fan designed to cool your engine properly, leave it be.
 
Sounds like your mechanic prefers working on cars without modern advancements because he doesn't understand them. If it isn't broken, don't fix it.

Not to mention that without a PROPER shroud, the mech fan would be useless. Your car isn't a 1950 chevy that can get away with a basic cooling system. As it is now, you have a nice dual-speed fan designed to cool your engine properly, leave it be.
Thanks a lot dude. This is my first used car, so I'm very ignorant in these things. I'm definitely taking your advice.
 
This forum is great for learning about your car. There is a lot of maintenance items that you can handle yourself. Just start by reading about the basics. Start off with small tasks and as you learn you more, you'll be able to handle bigger repairs. This is the best place for a newbie.
 
For what its worth, most of us with older 240's that had mechanical fans steal the E fan off of 7/940's because they work well and are easy to install into our cars. Plus the mechanical fan steals horsepower and makes the engine slower to rev.
 
For what its worth, most of us with older 240's that had mechanical fans steal the E fan off of 7/940's because they work well and are easy to install into our cars. Plus the mechanical fan steals horsepower and makes the engine slower to rev.
Ehhh, I wouldn't say the mech fans steal HP it's probably the opposite. Moving air takes a certain amount of power, e-fans take power as do the mech fan with clutch. The fan clutch is completely disengaged when the rad temps are cool, so the power loss there is minimal. You can stop and hold the fan blades with your hand on a running engine if the fan clutch is in good shape and it's not engaged.
E-fans can move more air (the 9-series fan moves a BUNCH), but they are dealing with (alternator efficiency) X (e-fan efficiency). Where a mech fan is ~100% efficient when it's engaged.

Now if a running e-fan results in more HP than a locked out mech-fan, it's because the mech fan is moving more air and would cycle off sooner vs the e-fan that would be required to run longer to drop the coolant temps. So in an instant the e-fan has the edge, but in a 20min run-time I bet the mech-fan would have the edge.
There's a reason that a lot of longitudinally mounted motors still use mech fans if they have the space.

All this to say, keep the mech fan unless you have a good reason to avoid them (noise).
Keep the e-fan on the 9-series because it's not doing any harm.
 
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The Volvo mechanical fans are definitely a parasitic loss 100% of the time. The advantage to the electric fan is it only comes on when needed. On my 940 here in Oregon, that does not happen very often unless it is a hot day and the AC is on in traffic.
 
The Volvo mechanical fans are definitely a parasitic loss 100% of the time. The advantage to the electric fan is it only comes on when needed. On my 940 here in Oregon, that does not happen very often unless it is a hot day and the AC is on in traffic.
I think the parasitic losses are pretty low on the mech fans. Even with a tropical fan clutch they aren't engaged that often in my experience.
But I agree that when moving the fan isn't doing too much, the cooling systems on these cars are actually pretty decent.
 
This has been hashed and rehashed a bunch. E fans have the advantage. That's why they use them on all new higher efficiency vehicles.


Think of it this way. The E fan will draw XX power out of the system BUT there's a battery in there that spreads that power draw out over a much longer period of time. Therefor the engine only has to "payback" that energy in very small amounts over the course of time.

When the mechanical fan comes on it costs all that power right then and there. And when its off it still costs you some power since it's still spinning.


Running an E fan is worth it to me just for the more responsive throttle. The engine revs up much more readily. It's very noticeable.



I will give you that the mechanical fan moves more air. But the E fan with a very close fitting shroud pulls just as much air through the radiator even if it is ultimately moving less air overall.
 
I was interested to read this discussion, as I have also been considering replacing my 940's e-fan with the earlier old school mechanical one. I don't have any problems with the e-fan, but I actually like the old whirring mechanical fan, especially at start up :D

The only reason I haven't done it, is that the e-fan can be running flat out in a hot summer day traffic jam, whereas a mechanical fan would need me to rev the engine a lot to get similar airflow.
 
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