*FIXED* New electric pusher fan - ktemp now slightly higher

[g300d]

So my electric pusher fan stopped pushing and I got a new fan assembly (Behr) to replace it.

I put the OBC to Ktemp almost everytime I drive, so I'm familiar with the average temp. With the OE fan, it was around 92 deg.

Now with the new fan, I am usually at 96 deg in the same conditions.

Coolant level is fine, nothing else done but the aux fan replacement.

Any ideas why this is?

FIXED!
Summary:
-Aux Fan died
-Aux fan replaced
-Temps on OBC were still slightly higher than when before aux fan died. No other symptoms and AC operating normally.
-Replaced engine fan clutch
-Temps now lower

[upallnight]

Fan is probably not pushing as much air as the original fan.

[g300d]

Could be, it seems the old OE fan (Siemens) was louder at all speeds.

What brand did you get when you replaced yours?

[Jack_James]

Could be casting flaws on the fan as well since it's only a few degrees. Maybe check for burs or casting marks on the new fan, maybe it's not as refined as the old one?

Also the gaps around the fan/shroud play a part in the cooling efficiency of the fan too, make sure it's properly spaced out like the original fan was.

Could also be resistance or voltage drop, not seeing full voltage = not running at full speed?

Those are just the things that come to the top of my head, I couldn't tell you if any of them are the problem, but if it's a quality piece those issues come to mind.

[ants_oz]

Seeing as though the pusher fan only plays a small part in the engine cooling system paradigm, I wouldn't place too much value in the numbers.

You say "about 92" prior to the fan change. So was that 94 or 90? And then there comes the question of "same conditions". How do you know they were "the same". Identical. Perfectly identical.

You're talking about a difference of at most, 4 degrees. That is less than 4% difference in the temps you provided. Are you absolutely confident that there was less than 4% difference in the comparative operating conditions you are quoting for your before and after?

[g300d]

Jack, those are good points, I will compare both for any physical differences. The electrical differences I have no idea how to check.

Ants, most everytime I start the car, I put OBC to Ktemp. When I say most of the time, I mean that I dont remember a time I havent. I constantly monitor Ktemp and battery voltage.

Because of this habit, I have a good idea of what Ktemp is in certain conditions, for my particular vehicle.

Stop and go traffic, uphill driving, and interestingly, part throttle running, shows the highest temps for me. The temps I often see in these conditions are 92 deg, with spikes up to 96 for a bit, then back to 92. Lows to 90, highs to 96, most often at 92.

Though I have not done a strict statistical study of my Ktemps versus time of day, atmospheric conditions, ambient temps, etc., I monitor it often enough and done so for long enough to have established norms for it.

[upallnight]

As long as the AC temp is cold enough, I wouldn't worry too much about the engine temp. The pusher fan is mainly for the AC system whereas the clutch fan is for the cooling system.

[upallnight]

Originally Posted by g300d

Could be, it seems the old OE fan (Siemens) was louder at all speeds.

What brand did you get when you replaced yours?

I also went with a Behr.

[g300d]

Upallnight, thanks for the info!

I think you are right that it is mostly for the AC, and the AC is performing well since the fan change. But it also gets hot enough here that the engine cooling function of the fan is needed, as evidenced that while the fan was broken, coolant temps got up to 100 even with the AC off, as opposed to the usual less than 95 I see running without AC an a working fan. It was driveable though, and I see many members do go without the fan in cooler climes.

Also, I am kind of paranoid with regards to BMW cooling systems, and I noticed a few times that slightly elevated temps were symptoms of a problem...I caught a leaky expansion tank and radiator on separate occasions when I noticed temps slightly elevated. Both times when I replaced the leaking parts, temp went back to usual.

Right now I'm thinking I might have a fan clutch that's not 100%, that's causing the electric fan to work harder. Doing more research on it.

[g300d]

UPDATE:

Driving today, I was seeing coolant temps in the 97-98 range. Definitely higher than I am used to seeing. I decided to replace the fan clutch.

There is a lot of chatter in the BMW forums that Sachs makes a better clutch than Behr, so I got the Sachs.

Opening the box, it is marked as Made in Germany, a good sign I think.



The installed fan clutch could very well be the original one, judging from the markings.



There was oily residue, the clean spot in the middle was made by my finger to confirm it was oil and not plain dust.

Installed the fan along with a new AC belt as the old one had cracks already.