Water Pump Coolant Sensor leaking
 

Hello all. After replacing my water pump (bearing failed) I started seeing a small leak around the sensor that bolts on to the pump. I reused the same sensor that was there before. I thought I made a mistake not replacing the washer. so I went ahead and bought a new sensor (figured old one is now old) that comes with a washer. Put that on and it's still leaking.. what could it be? I didn't really use a Torque Wrench so I kinda hand torqued it. thanks in advance for any tips.

Picture of the leak.

This is what I would try if I were in your shoes.

Remove the sensor, clean all the staining off the water pump, washer and sensor itself, make sure everything is super dry and then put a light film of silicone sealer on both sides of the washer, let it tac up for a minute or so, not dry but kind of get sticky, and then tap it with your finger on both sides, it will pull the silicone “up” just a little bit and then reinstall and let dry for a dozen or so hours.

You may get some nay sayers who say replace the washer.., but I’m guessing you’ll be fine [emoji106]


2005 X5 4.4i (04/05 build date)
Titanium Silver w/Black Interior

Does it need to be a high temp sealant or any silicon sealant would do?

I usually try to use high temp, red orange or black, as long as it’s sensor safe. Worst case of you have some of the orange laying around, I’ve used that a number of times in the past with good results.


2005 X5 4.4i (04/05 build date)
Titanium Silver w/Black Interior

Apologies, orange is not usually high temp, red and black are [emoji106]. That said I have used orange on everything from the water pump itself to valve cover gaskets and as said, with good luck.

If orange is all you have, I’m sure it will work just as well.


2005 X5 4.4i (04/05 build date)
Titanium Silver w/Black Interior

I have ultra grey.

Love that stuff! You should be good to go with that.


2005 X5 4.4i (04/05 build date)
Titanium Silver w/Black Interior

So i am starting to think the sensor is fine and the very lite coolant residues i see below the sensor is coming from the weep hole? Where is that weep hole exactly? Left side, right side or right on the middle of the water pump?

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Have you or have you had your coolant crossover pipe (runs front to back under intake manifold and valley pan) replaced? The location of the coolant leak from the weep hole sounds like the one the 4.8 leaks from when the crossover pipe rubber ring starts to fail. Had the same on my '08 with 4.8 and just purchased the All German Auto Coolant pipe, installed it and all leaks stopped.

No that pipe was never replaced. I did have the valley pan gasket replaced though like 4 years ago.

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There is a 1/8" or smaller weep hole just above that sensor on the block. If that's leaking at all, your crossover pipe seal is failing. The only resolution is a replacement. If you go OEM then you have to tear down the front end as it is too long to put in with the entire radiator, A/C Condensor, and other various parts in the way. All German Auto's crossover pipe expands to fit the space and is much easier to remove the old and replace with new. I got it done on my X5 between 4 to 5 hours and that included some other work at the same time.

I have done valve cover gasket myself. Would the transfer pipe be easier job? Also i found a less expensive part by URO. Is that good at all?

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Not really easier, but if you are meticulous you should be okay. Intake has to come off and the Eccentric gears on each valve cover do too. Then of course water pump and valley pan. You cut the old pipe in half to be able to pull it out. Clean the areas and install the new. Go to All German Auto's site and take a look around. 11-14-1-439-975 BMW N62 Coolant Pipe | AGA Tools I got the complete kit with valley pan and all the needed gaskets. Worth the extra money to me.

https://www.youtube.com/watch?v=UoCED1jyfL4 quick video on how to do it.

Regarding Uro, I know they're cheaper, but I have never had any luck at all with anything they produce. I do not trust anything from them. Just passing along what I know works and works well. If you do a search for part number from AGA's site you may find it a bit cheaper and it's the same kit. They do have a couple of resellers out there that sell the complete kit for arount $100.00 less. For me it was even more of a savings as I didn't have to pay sales tax or shipping either.

i think I will take it to my local BMW indy shop. 4/5 hours of labor maybe? man this month has been costly $2000 to address oil leaks .. and now this .. what's next? :)

Be careful, some indy's will only want to install the BMW pipe and that is around a $6,000.00 job! Go through the information on the website and video link I provided and make sure you know what you are talking about with them and be able to get them to use the kit too! I know AGA charges around $3,000 for the job with parts included. But I don't know how many hours they list it at!

I have already discussed this with them. They said they have done this repair multiple times with the expanding pipe. They wouldn't give me an estimate though. They want to inspect the vehicle first to get a diagnosis.

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Use an o-ring made of viton or buna-n instead of a sealant. I just did this same sensor.


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A coolant leak from the weep hole wouldn't lead to that sensor.


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yes you are right. is the coolant leak from the weep hole visible without taking parts out of the way? should i be able to see a trace of coolant by simply looking at the front of the engine?

Water Pump Coolant Sensor leaking
 

Yes. Nothing has to be removed to see the weep hole. It is a hole about the size of a pencil. It is on the front of the engine block. It is kind of behind and to the left of the water pump. It does not always look like coolant drops. It can look just wet.


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The traces of coolant definitely start at the bottom of the sensor and run down the water pump .. I will take a close up picture, hopefully I get a better view of the weep hole.

by the way, does coolant need to be drained to remove and re-install the sensor? I did it a couple of times without draining and it was fine, no coolant came out but the last time I did it lots of coolant gushed out and spilled everywhere!!

I used a URO expandable pipe. No issues at all and passed the pressure test. They have great customer service as well. AGA is a different design and is good as well. It is a job to be careful with and follow directions. It's not rocket science.


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Just make sure they do a really good job of getting the front gasket surface clean. It is hard to see and it can have a lot of corrosion, gasket material, etc left over in it that can cause it to fail in the future.

-Rich

For sure. I used a gasket hook tool, wire brush, tooth brush, brake cleaner then distilled water. Hard to get 100%. Mirror is a must for the job.


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Here is a shot of the sensor. I dont see any leaks from around or near the coolant pump!!Attachment 75703

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That leak is from the sensor. With an o-ring instead of sealant it will stop it from leaking very easily. It's a small o-ring. Has to be buna-n or viton for the heat.


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So replace the metal washer with an o ring?

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https://uploads.tapatalk-cdn.com/201...abcec911db.jpg o-ring here



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Thanks for the pic. What size is it? Also, Can i take the sensor out without draining the coolant?

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Water Pump Coolant Sensor leaking
 

Don't know the size. I might be able to check my o-ring kit. Harbor freight sells a viton o-ring kit for $10 that's has a ton of useful sizes. I didn't lose much distilled water when I added the o-ring but I think my coolant system was only 75% full. I would think the angle and height of the sensor would prevent a big loss. It's a quick in and out.


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Any idea what the torque is for the sensor?

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https://www.newtis.info/tisv2/a/en/e...l-unit/5qsI4a9

Should be the same for the 550i as it was for my X5.



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Glad to report that the viton o-ring from the harbor freight kit stopped the leak!! Thank u for recommending that.

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Glad to hear it worked for you as well. :thumbup:

If you can do the valve covers yourself, you can do the transfer pipe as well. You can save a few thousand dollars and learn a whole lot while replacing more parts than the shop would. Maybe its time.

well I am going to wait until I see that weep hole crying :) .. it's pretty dry right now, no sign of leaks whatsoever. also the car may be sold before I get to enjoy replacing the coolant exchange pipe .. still debating whether to keep it or sell it. I have "invested" a lot of money and taken care of pretty much all the known to fail gasksets/seals/orings..etc .. I also revamped the cooling system no too long ago (new water pump, expansion tank, hoses, thermostat..etc). new suspension air bags in the rear.

my x5 looks pretty sharp inside out, the interior is immaculate and has all the features that a 2007 X5 can have.

Having a hard time detaching :) .. too sentimental LOL .. I refuse to sell it for $8400 which is my asking price currently :) .. I feel it's worth a lot lot more :) to me at least ..