Hi Guys. Sorry I haven't been on here in a while and making my first post a request for help. Was on here many years ago.
My '05 X3 E83 is overheating and I don't know why. I prefer to not just start tearing it apart.
Was leaking coolant from expansion tank determined using pressure tester. Replaced with new one and system holds pressure. I expect the expansion tank leak started when driver (kid) ran it too hot.
Filled and bleed system using sticky procedure.
Here are the current systems:
30F (0C) degrees outside
Start engine and drive. Temperature reaches straight up on needle and steady. Get on highway and shortly temperature continues to rise till in the red if I let it.
Pull over and check and fan does NOT come on. Red light on dash but it does NOT go into limp mode. Checked engine temp using Carly and it reports similar temperature to the dash.
I put Heater on high cools engine back to temperature needle at 12o'clock (which indicates thermostat may be OK?) Get the car home.
Using ISTA I tested Fan and it ran fine.
Lower radiator temperature sensor measures 3.6 kohm at 61F. Not sure if this is good or not but don't see how this could be problem.
What would you check next?
BTW, I have a mechanical cooling pump.
The only thing I can think is that I have a blocked radiator or maybe partially working pump?
I have exhausted the search and am desperate. Thanks in advance for any help!!!!
I happen to have a fan switch (the lower hose sensor) if front of me. It's right about 60 degrees in the shop right now. It reads 2.3 KOhms.
It seems to me that you have two different issues. Although your fan isn't working correctly, there's another reason that the car's overheating on the highway, where there should be sufficient cool air. (Isn't it way below freezing there anyway?)
I'd advise doing the standard maintenance rebuild of the cooling system, due every 8 or 10 years. At the very least, replace the water pump and thermostat with ones sourced from a BMW specialist supplier, like FCP Euro. While you're doing that, replace the fan switch; it's cheap.
Do you also have an engine driven fan, or just the electric?
Chris Powell
Racer and Instructor since, well. decades, ok?
Master Auto Tech, owner of German Motors of Aberdeen
BMWCCA 274412
German Motors is hiring ! https://www.bimmerforums.com/forum/s...1#post30831471
Thanks for the help!
I have the mechanical belt driven cooling pump. And I agree it's time for overhaul of the cooling system.
I was hoping I could just band-aid the system and sell the car. Its a spare for me as my main transportation is '12 335xi. But can't sell it with it overheating.
In reality I guess regardless of the issue, I am draining the coolant (again) and tearing it all apart.
Temperature sensors are almost always negative coefficient thermistors. Huh? Temperature sensors (thetmistirs) are basically resistors that change resistance as the temperature changes. The resistance of a negative coefficient thermistor decreases as the temperature increases. That 3.6k ohm reading seems high, though it could be correct for that sensor.
I’m betting that the cooling system flow is restricted. Something isn’t allowing enough coolant to circulate when you’re driving at highway speeds. Remember that an engine will generate 4 times the heat when the car’s speed is doubled. It’s basic physics. I’m betting the radiator is partially clogged.
you have a m54 engine just to give you more information, that would to know for further issues
As noted, you're past due for a full cooling system. Worse, the M54 and overheating do not go well together. Even one excursion into the red may have caused damage. Might want to check that you've got good compression and no oil/coolant mixing before you spring for more parts.
Life's tough. It's tougher when you're stupid. -John Wayne
Had a very lovely 100k mile E39 528i today, M54, overheated as recorded by the computer in freeze frame to 280 degrees. After filling system and pressure testing, the car reached 230F ECT around the block, but lower hose sensor said 80F. I've called for thermostat, water pump, and the radiator small hose fitting, which leaks. I have also warned the customer that the rest of the cooling system, AND the engine, are HIGHLY SUSPECT, and the engine may be dead..
As O2 pilot indicated, overheating an M54 is often quite fatal.
Chris Powell
Racer and Instructor since, well. decades, ok?
Master Auto Tech, owner of German Motors of Aberdeen
BMWCCA 274412
German Motors is hiring ! https://www.bimmerforums.com/forum/s...1#post30831471
Yikes, 280 degrees!!
AND, amazingly, the engine has survived intact. Work finished today, ECT is stable at 201-203 F, lower hose varies by load, but between 100 and 150F (it's cold today). It's a beautiful E39, driven very little by the stereotypical little old lady. Car had an oil change in August (by me), got another one today, 600 miles later. Yes, 600. (Hey, I TOLD her she didn't need it, she insisted!)
Chris Powell
Racer and Instructor since, well. decades, ok?
Master Auto Tech, owner of German Motors of Aberdeen
BMWCCA 274412
German Motors is hiring ! https://www.bimmerforums.com/forum/s...1#post30831471
I have been traveling lately for work so the X3 has sat in the driveway.
Finally tore into it today. Removed both the thermostat and pump. The pump impeller looks normal and bearing seem good too.
Hooked up the thermostat to car battery and couldn't get it above 55C measured with laser thermometer. Only gave it 10 minutes so went to the stove and boiled the entire thermostat to 101C and it definitely did NOT open.
A few questions for you experts:
1. Would a stuck shut thermostat give the original symptoms? Overheating on highway, fan doesn't come on, running heater on high brings tempertature down?
2. Should I replace the pump too since I have it removed?
3. Should I replace all the hoses and lower radiator outlet temperature sensor?
Or just replace the thermostat, put it back together, fill and bleed and drive it?
Thanks!
Whet you energized was the heating element that the engine computer (DME) powers to open the thermostat when the engine is relatively cool but the under a high load. Think entering the highway before the engine is fully warmed.
A better test is to put the thermostat in a pot of water and boil it to see the temperature at which it opens. Thermostats are designed to fail in the open position.
You haven’t stated the mileage on the SAV. If it’s over 80k miles it’s time for a cooling system overhaul. That means:
- thermostat (Whaler)
- water pump (Saleri or Graf)
- idler and tensioner pulleys (INA)
- serpentine belt (Conti)
- o-ring for the temperature sensor in the lower hose (FCPEuro sells them; go genuine)
- engine block coolant drain plug crush washer
- coolant (dealer ONLY)
- distilled water
Why have I specified brands? The E46’s Achilles heel is the cooling system. Installing aftermarket cooling system parts is strictly verboten unless you want a very heavy and large paperweight. These engines do not tolerate overheating.
I recommend buying the parts at FCPEuro as its prices are competitive and everything has a lifetime warranty!!!
You noted that the efan didn’t come on. Read this: https://drive.google.com/file/d/1Cac...BTPQDJx6u/view. The sensor in the lower radiator hose may be bad, but it’s a simple thermistor (resistor that changes resistance as its temperature changes). So, I’d read the document and determine if the sensor is bad first.
The place to get part #s: www.realoem.com. Enter the last 7 characters of the car’s vehicle identification number (VIN). Hit enter and bookmark the page.
Go to www.fcpeuro.com for parts.
Thank you very much MarcoZ for your detailed response. I GREATLY appreciate it!
Im shopping now for parts.
Have a great day!
Last question (probably not).....
Thermostat was the problem. System is working again holding solid 97C on the interstate.
After fill/bleed and convinced I have all the air out, I want to adjust coolant down to where the level float is in the middle.
But it doesn't seem to matter how much coolant I pull out of the expansion tank, the float stays at over full. And I pullout out a LOT of coolant, like over 20oz.
Is that normal? I don't even understand this system in that the bleed screw is higher than the proper level? What keeps the coolant in the upper hose from draining down into the expansion tank? It seems like I could pull coolant out of tank all day until there is nothing left in the upper hose? Weird.
Thanks in advance.
Glad you found the problem. It does seem odd that you’re pull that much coolant during the bleeding. I recommend that you bleed it again as you may have an air pocket in the block.
Btw, I bought this from amazon. It screws into the bleeder screw hole. I attached a 1’ long piece of plastic tubing to the other side. This prevents coolant from dribbling all over the place.
Legris 0101 06 60 Brass... https://www.amazon.com/dp/B009PSSQM2...p_mob_ap_share
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