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E46 M3 (2001-2006) Engine: S54 - Max Hp: 333 hp at 7,900 rpm / 262 lb/ft at 4,900 rpm
Total Produced: 45,000+ - Years Produced: 2001 to 2006.


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Old Sun, Aug-27-2017, 03:57:24 AM   #31
black bnr32
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Default Re: 100 Degree Day - Car overheards 3/4 mark with AC on.

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Originally Posted by malacai17 View Post
FYI, the shop I took my car to just got back to me:

Not enough oil is getting routed to the oil cooler

Smoking gun symptom:
At full operating temperature (ie. driving for 20+ minutes w/ AC on), the engine oil temp is 200F+ (measured via onboard computer), but the oil cooler temp is only ~120F in, out, or at fins (measured via IR thermometer).

His opinion is to replace the oil cooler and engine oil thermostat (and I suspect the lines for all of it too). He says it's all likely gummed up, and since I don't know how long this has been going on as I've only owned it for 3 months, I'm inclined to agree.

I'll report back on this thread after we get everything replaced on whether or not this solves my issue.

Hopefully this points someone else towards finding the root cause for their high coolant temperatures too!

Side question: What is the PN for the engine oil thermostat the mechanic is talking about? I can't find it on realoem.com.
I've always wondered about the oil cooler and thermostat. Please let us know how it goes, thanks.
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Old Sun, Aug-27-2017, 06:37:37 AM   #32
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Default Re: 100 Degree Day - Car overheards 3/4 mark with AC on.

You can probably clean out your oem cooler with gasoline / isopropyl solution then get the BW oil diverter valve and a inline thermostat. That way once up to temp 100% of the oil will pass in the cooler vs 40%ish.

Or if you want a new cooler, I'm using the derale 13x2x6.5 cooler with 10an fittings and braided hose. Works well.

https://www.bimmerforums.com/forum/s...E36-328I/page3
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Old Fri, Sep-01-2017, 02:11:19 AM   #33
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Default Re: 100 Degree Day - Car overheards 3/4 mark with AC on.

It was, according to the car, exactly 100F today at my home after the drive home from work. As a test, I let the car sit idling with the AC on full cold/blast in the driveway for 5 minutes - not a single blink of the temp gauge - just dead straight up like always.

Now - would it act the same at 110F? Not sure, but 100F was no sweat. Keep in mind that the PO had the clutch fan, AUX fan and Tstat replaced about 15k miles ago.

Finally - I've said this before but I think it's one of the underlying factors here - my AUX fan was screaming - so loud that I had to strain to hear the actual engine while standing outside the car, front or back.

Point is this - if you have to ask "how do I know if my AUX fan is working" then I can tel you right now that's it's not and that's at least where you should start.
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Old Fri, Sep-01-2017, 02:43:29 AM   #34
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Default Re: 100 Degree Day - Car overheards 3/4 mark with AC on.

Got the oil cooler replaced today. Done too late in the day for much beyond verifying there's no leaks, will advise after a few drives this weekend.

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Originally Posted by EricSMG View Post
Finally - I've said this before but I think it's one of the underlying factors here - my AUX fan was screaming - so loud that I had to strain to hear the actual engine while standing outside the car, front or back.

Point is this - if you have to ask "how do I know if my AUX fan is working" then I can tel you right now that's it's not and that's at least where you should start.
Indeed you are correct: if your car is overheating when sitting idle and the AUX fan isn't screaming then the AUX fan is a likely culprit.

Unfortunately, mine is the opposite: high coolant temp when moving, and quickly drops back down at low speed/stopped. Thus, my AUX fan doesn't need to go full-tilt at idle.

After asking about the AUX fan, I found this post on trackjunkies very insightful about how the fan operates. Hope others find it useful too!
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Old Fri, Sep-01-2017, 02:57:32 AM   #35
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Default Re: 100 Degree Day - Car overheards 3/4 mark with AC on.

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Got the oil cooler replaced today. Done too late in the day for much beyond verifying there's no leaks, will advise after a few drives this weekend.



Indeed you are correct: if your car is overheating when sitting idle and the AUX fan isn't screaming then the AUX fan is a likely culprit.

Unfortunately, mine is the opposite: high coolant temp when moving, and quickly drops back down at low speed/stopped. Thus, my AUX fan doesn't need to go full-tilt at idle.

After asking about the AUX fan, I found this post on trackjunkies very insightful about how the fan operates. Hope others find it useful too!
Yes, but the AUX fan will always be at or near full tilt, at idle, with AC on if it's hot outside. If it's not very hot, say 85F and you don't have the AC on then yes, the AUX fan will not be anywhere near full tilt but it will still be audible.

But if the AC is on, the AUX fan is highly audible, always, in my experience. The speed of it varies greatly depending on ambient temp even though the engine temp gauge does not ever (in my experience) move.

Looking forward to your oil cooler results. I'm wondering if perhaps some of you have Tstats that won't open all the way, thus partially impeding coolant flow. It is very common for them not to close all the way, resulting in long warm up times and in some cases, on cool days, the temp gauge never even reaching dead center. I suppose the opposite is possible.
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Old Sun, Sep-03-2017, 04:32:32 AM   #36
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Default Re: 100 Degree Day - Car overheards 3/4 mark with AC on.

OK, so I got it out for about an hour and a half today while the temperature reported by the OBC was ~90.

I'm not ready to call it "fixed", but it's noticeably better after replacing the oil cooler.

After ~25 minutes on the highway the oil was finally up to temp (just below 210). Then, at a cruise of 65-80mph in 5th gear (for slightly higher rpms) and the AC cranked down to 59+Auto, I could get the coolant temp to rise up to the 2nd dot when pushing uphill. However, it didn't get above the 2nd dot. Turning the AC down to 70 lowered the coolant temp about halfway between the 12 o'clock and the 2nd dot, where it stayed. The oil temperature crept up to 210 at most, but never went over.

However, heading up a fairly lazy canyon in 3rd gear with the AC set to 70, the coolant temp quickly rose to the red box. Even the oil temp went slightly above 210. @EricSMG: At this point, I pulled over and listened to my AUX fan: yes, it was SCREAMING like a Mac truck.
Both temps shortly dropped back to the middle going back down the canyon.

Went back to highway driving at this point, and still couldn't get the coolant to hit the red box, even back in lower gears and maxed AC. Oil temp stayed below 210 as well.

We'll see how more DDs go this upcoming week, and I've got 2 track days coming up that look to be in the ~90s. It's entirely possible I've fixed one problem, but still have others to be addressed.

Inspection 2 will be due for me in another <1k miles, so I'm starting to make my parts list for that as well.
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Old Sun, Sep-03-2017, 03:41:44 PM   #37
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Default Re: 100 Degree Day - Car overheards 3/4 mark with AC on.

Yeah, you still have an issue for sure. Once thing jumping out at me is that your temp gauge drops significantly below straight up - this indicates a faulty Tstat that won't close all the way (very common as these cars age). It is designed to keep the engine "at" full operating temp and not below. When they don't close, coolant is continuously flowing throwing the radiator and "overcooling" - this is not good for performance, emissions or fuel mileage. I wouldn't call this a major problem but something you should look into.

But, yeah, overheating at 90F? Very, very not normal.

Edit: good to know your AUX fan is healthy! Mack truck is exactly right! Cross that off the list

Edit2: what radiator are you running? Is it aftermarket "OEM"? I've found the aftermarket units to be essentially junk compare to the OE unit, could be a factor here, especially if you've white splatter. You have either a leak and/or a flow problem. And what about your clutch fan?
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Old Mon, Sep-04-2017, 03:52:06 AM   #38
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Default Re: 100 Degree Day - Car overheards 3/4 mark with AC on.

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Originally Posted by EricSMG View Post
Yeah, you still have an issue for sure. Once thing jumping out at me is that your temp gauge drops significantly below straight up - this indicates a faulty Tstat that won't close all the way (very common as these cars age). It is designed to keep the engine "at" full operating temp and not below. When they don't close, coolant is continuously flowing throwing the radiator and "overcooling" - this is not good for performance, emissions or fuel mileage. I wouldn't call this a major problem but something you should look into... And what about your clutch fan?
I wonder if the T-stat could be the issue if it's either stuck open or closed. In regards to a clutched fan issue, I've run my car in 110+ with AC low and no issues and I only run the aux fan. It's only when I bump the AC high in those temps that the needle moves to the third tick, but I've seen that occur on cars that have both working fans.
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Old Tue, Sep-05-2017, 01:48:31 PM   #39
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Default Re: 100 Degree Day - Car overheards 3/4 mark with AC on.

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Originally Posted by EricSMG View Post
Yeah, you still have an issue for sure. Once thing jumping out at me is that your temp gauge drops significantly below straight up - this indicates a faulty Tstat that won't close all the way (very common as these cars age). It is designed to keep the engine "at" full operating temp and not below. When they don't close, coolant is continuously flowing throwing the radiator and "overcooling" - this is not good for performance, emissions or fuel mileage. I wouldn't call this a major problem but something you should look into.
My coolant temp gauge reaches 12 o'clock (between the 1st & 2nd dot) within 2-3 minutes of startup, and stays there except as I mentioned. I do have a brand new Tstat (from FCPEuro) that I plan on swapping when I do Inspection 2's coolant flush anyway, for piece of mind.

Quote:
Originally Posted by EricSMG View Post
Edit2: what radiator are you running? Is it aftermarket "OEM"? I've found the aftermarket units to be essentially junk compare to the OE unit, could be a factor here, especially if you've white splatter. You have either a leak and/or a flow problem. And what about your clutch fan?
I'm not 100% sure the radiator brand, as the PO only provided me this picture of the swap he did:

old_new_radiators.jpg

I'll go through the (few) pages of documentation and receipts that the PO gave me too, to see if there's something in there that indicates the radiator brand. I had the fan clutch replaced within the last month too (BEHR).

Yep, I do have some white splatter marks, but only a few dozen; nothing alarming, but definitely needs to be addressed at some point. Unfortunately the splatters are near the upper radiator hose connection to the radiator (I've already replaced the upper radiator hose), and on the blades of the fan clutch fan which possibly/probably indicates a leak around the water pump. Maybe the water pump wasn't properly torque'd and doesn't actually need to be replaced... we'll see if it continues after I replace the Tstat and re-torque those water pump bolts. <fingers crossed>
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Old Thu, Sep-07-2017, 05:14:30 AM   #40
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Default Re: 100 Degree Day - Car overheards 3/4 mark with AC on.

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I'll go through the (few) pages of documentation and receipts that the PO gave me too, to see if there's something in there that indicates the radiator brand. I had the fan clutch replaced within the last month too (BEHR).
I found a receipt from the PO. The radiator is OEM, purchased from Fields BMW Northfield ~2 years and less than 20k miles ago.
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Discussing 100 Degree Day - Car overheards 3/4 mark with AC on. in the E46 M3 (2001-2006) Forum - Engine: S54 - Max Hp: 333 hp at 7,900 rpm / 262 lb/ft at 4,900 rpm
Total Produced: 45,000+ - Years Produced: 2001 to 2006. at BMW M3 Forum.com (E30 M3 | E36 M3 | E46 M3 | E92 M3 | F80/X)