[cdavi060]

Hey,

I did some searching but didn't find the exact issue on an e90 so wanted to post here. Yesterday I noticed my cars cooling fan was running at full speed on the highway and even in stop and go traffic. Outside temp was 62 degrees. This morning, as soon as the car was started it came on: 52 degrees outside. It cuts on and off with the car it seems. I believe this to be a faulty sensor. Can anyone confirm this is the case and where this sensor is located?

[EndOfAnEra]

Actually it sounds like your water pump is about to fail!

[Delta0311]

Water pump is on its last leg. A failing water pump creates hidden codes.. Have your car scanned.

[cdavi060]

Originally Posted by Delta0311

Water pump is on its last leg. A failing water pump creates hidden codes.. Have your car scanned.

Even with no check engine light? I hate to pay $100 just to tell me the issue.

[Delta0311]

Originally Posted by cdavi060

Even with no check engine light?

Yeah it won't trigger it till it fails, which can leave you stranded on the road some where because you car is overheating. It will trigger hidden codes though.

[EndOfAnEra]

Anyone who ever encounters a continuously running cooling fan should order the water pump/thermostat immediately. That is my plan of attack when my day comes...

[BashShah]

OP, I had the exact same issue as you.
Fan running full speed 99% of the time.
No engine check light, no high temp warning.
But I have Bmw DIS code reader and sure enough 2 codes were stored in memory.
Looked them up and it was water pump.

Changed water pump and tstat and issue resolved.
I did not change any hoses.
Parts cost me $411 and I DIY it. All OEM.

DN

[EndOfAnEra]

Where did you get them for that price? Getbmwparts.com shows them for around 475

[jon_335]

If you decide to DIY, check the plastic flanges on the upper radiator hose and the hose that connects the oil cooler to the thermostat (assuming you have that). Immediately after replacing my wp and t-stat, both of those hoses blew at the flanges … and on separate days.

[cdavi060]

Is the DIY pretty straightforward and about how many hours does it take? It's worth doing vs. paying $400+ labor bill?

[BashShah]

Originally Posted by EndOfAnEra

Where did you get them for that price? Getbmwparts.com shows them for around 475

IMPORT PARTS DEPOT
contact: importpartzone@gmail.com
1-855-822-0479
The above for pump and Tstat.
He will try to give you new bolts, but make sure they are 26mm.
If 32mm, don't buy them.
Our cars need 26mm for the new pump.
And the new bolts are reusable.
Original aluminum ones are not.

I bought the 3 new bolts from eBay for $11.
Search by part number. BMW 11517602123.

DN

[BashShah]

Originally Posted by cdavi060

Is the DIY pretty straightforward and about how many hours does it take? It's worth doing vs. paying $400+ labor bill?

I can't speak for your mechanically inclined aptitude.
But if you can do a OFHG, you should be able to do this, provided you have all the tools.
Eye wear, extremely important.

Look for BAVauto DIY.....I followed that.

DN

[cdavi060]

Originally Posted by DarkNemesis

I can't speak for your mechanically inclined aptitude.
But if you can do a OFHG, you should be able to do this, provided you have all the tools.
Eye wear, extremely important.

Look for BAVauto DIY.....I followed that.

DN

Did the OFHG (oil filter housing gasket) change a few months ago with no issues, so I will give the water pump a try. Purchased one today for $362 which includes the bolts, but they seem to be the 32mm. They are a BMW dealer out of Maryland and double-checked the pump and bolts to my VIN and said all is correct. (http://www.ebay.com/itm/321691156025...%3AMEBIDX%3AIT).

[BashShah]

Originally Posted by cdavi060

Did the OFHG (oil filter housing gasket) change a few months ago with no issues, so I will give the water pump a try. Purchased one today for $362 which includes the bolts, but they seem to be the 32mm. They are a BMW dealer out of Maryland and double-checked the pump and bolts to my VIN and said all is correct. (http://www.ebay.com/itm/321691156025...%3AMEBIDX%3AIT).

I am not sure on the n52 engines.
Hmmmm.

What does the DIY guide say?

Hopefully it mentions it or for a quicker response.
Just start a new topic and ask that question on the forum.

Someone will chime in.

DN

[jon_335]

When I did mine, the night before I did the meat of the work I spent an hour or 2 getting the car up on jack stands, moving all of the crap out of the way and draining the system from the U hose at the WP and t-stat. Probably took me 4-5 hours to finish the job the next day. Just make sure you get those quick release clamps and flanges fully seated or you will dump coolant on your test drive … just like I did. Triple check them.

Agreed that the BavAuto video is extremely helpful.

[BashShah]

Draining from heat exchanger is far cleaner than water pump hose.
You will still get some from the water pump hose but it won't be as messy.

DN

[cdavi060]

Drove the car all week. Fan still runs at full speed but no overheating. Still sure it's the water pump?

[BashShah]

Originally Posted by cdavi060

Drove the car all week. Fan still runs at full speed but no overheating. Still sure it's the water pump?

It is......pull the codes to be sure.

[cdavi060]

Changed the water pump today. Started the car up and 30 seconds later the fan came on full speed. My original question, is there a sensor that I need to change? Clearly it was not the pump...

Unfortunately I don't have the ability to pull the fault codes without paying someone $100

[Efthreeoh]

OP, did you replace the thermostat along with the pump? From the parts prices you quoted it sounds like you didn't. Was the t-stat housing aluminum or brown plastic? Also, if your car has trouble codes and you are replacing the electronic par that is causing the fault code the procedure is to clear the fault code(s) before you make the repair, or at least before you restart the car. I'm not saying this is causing the problem, but the correct procedure is to clear the codes. The Bentley repair manual doesn't specifically state why you clear the codes before the repair, but I suspect it is so to not cause confusion that the code is still present after the repair.

All that said, the coolant temperature probe is in the lower radiator inlet on the radiator where the lower radiator hose connects. It takes about 5 minutes to change out if you plan everything correctly. And you can change it out without draining the coolant. You'll lose a small amount of coolant in the process. Planning everything correctly means you have pliers at the ready, disconnect the connector first, pull the sensor, and have the new sensor in your hand to push back in (and have it oriented correctly).

My advice is if you are going to DIY your car then get a BMW scan tool or at least a code reader of some sort so you can read and clear BMW fault codes. These cars are much easier to diagnose if you have a BMW code reader. If you have a BMW code reader there then is no reason to have an OBD II code reader since OBD II codes are repeated as BMW codes as well.

Good luck with it.

[cdavi060]

Update:

Pressing and moving the wires at the top of the temp sensor in the radiator hose on the passenger side of the car makes the can slow down and even act normally. It seems this whole issue is from a bad connector or faulty sensor.

When moving the wires, a CEL is triggered: P3197 - Radiator temperate gradient too high

[cdavi060]

Solution:

Replaced Coolant Temp. Sensor on side of radiator and fan is working properly.