X3 N52 Thermostat DIY

This really a fairly simple DIY, the only difficult part is working in tight spaces. This should take 2-3 hours if you take your time. You'll need:

• Either a 3/8" or a 1/4" ratchet
• Ratchet extensions (at least 6")
• A universal joint for the ratchet
• For the hose clamps, I highly recommend an 8mm ratcheting wrench
• (If no ratcheting 8mm wrench, you'll need a small flathead screwdriver)
• Large flathead screwdriver for bleeder screw and radiator drain plug
• A pick with a hook to get the clips off the coolant hoses
• Jacks/jackstands/etc.
• 1 gallon of BMW antifreeze mixed with 1 gallon distilled water
• A 2 gallon or larger bucket to drain the antifreeze in

1. Get your car up on jack stands or ramps
   
2. Make sure the car is cooled down so you aren't draining hot coolant
   
3. Open the hood, and remove the plastic air duct between the intake and the air filter. It just pulls out from either end.
   
4. Get under the car, and remove the splash shield. There's about 10 M8 bolts and two plastic rivets that have to be removed.
   
5. Place your bucket underneath the radiator, on the driver's side. The pink and blue plastic plug is where the coolant will be draining out:
   
   
6. Get a large screwdriver, and unscrew the blue plug all the way out. Coolant will start draining now.
   
7. Up under the hood, unscrew the cap from the coolant expansion tank. Also take your large screwdriver, and unscrew the plastic bleeder screw that is next to the cap you just removed. You don't need to unscrew it all the way, 5 turns or so is fine.
   
8. Once all the fluid has drained, you can screw the blue drain plug back in the radiator. You'll need your bucket to catch the rest of the fluid that will come out when we start disconnecting hoses. If you really want to get all the coolant out so there is less of a mess, you can remove the plug from the engine block and drain the rest of the coolant. I didn't do this.
   
9. Underneath the car on the passenger side, you'll need to get the oil cooler hose out of the way. It just takes one bolt (10mm hex). This is the hose, already pushed out of the way:
   
   
   Now you should be able to see the water pump (barely). It is the black plastic piece behind the sway bar:
   
   
10. Now is a good time to remove the wire that is going to the thermostat. I just inserted a small screwdriver into the clip and just pulled the plug out.
    
11. Now it's time to start disconnecting hoses. There's 4 hoses that connect to the thermostat. 2 have hose clamps, 2 have retaining clips. I found it easiest to get the hose clamps off using the 8mm ratcheting wrench. There wasn't enough room for a regular ratchet, and there wasn't enough room for a screwdriver either. I can't say much for this step besides this is where you'll spend most of the time. Just remember how you got the clamps off, because you've got to put them back on eventually too.
    For the retaining clips, I found the one on the small hose easiest to remove by getting to it from the top of the engine and reaching down with a hook-shaped pick. For the larger one, I got to it from the underside with the same pick.
    The large hose takes some considerable effort to remove from the thermostat. It has a large o-ring inside of it that is gripping on to the thermostat. I don't have much advice besides pull hard. I removed the retaining ring entirely, because I kept accidentally pushing it back on while I was trying to get a good hold on the hose.
    Keep in mind there will be a bit of coolant that will come out of these hoses when they are removed. Keep that bucket and some rags handy, and wear something to keep your eyes coolant-free.
    
12. Once you finally get all hoses removed, you just have to remove the two bolts that mount the thermostat to the water pump. This is where you'll need the 10mm socket, universal joint, and a 6" extension:
    
    
13. You can snake the thermostat out towards the front of the car and then down. Remember how you did it, so that you can get the new one in there.
    
14. I hate to use this line in a DIY, but installation is the reverse of removal. There is literally nothing different. My only tip is to get the large coolant hose back on the thermostat, put a bunch of rags or other padding on the metal cross member, and use that as a fulcrum against your forearm. After I figured this out, this gave me enough leverage to pop the hose back on. Don't put the splash panel back on yet.
    
15. After all hoses are connected, and the wire is clipped back in, and that cooler hose is bolted back to where it should be, now is the time to fill your coolant back up:
    - Make sure that blue radiator plug was put back in
    - Make sure the bleeder screw (next to the fill cap) is still loose
    - Start pouring in coolant. I needed about 1.5 gallons. You should fill until you see coolant coming out of the bleeder screw area. The expansion tank will be almost overflowing when this happens. This is ok.
    - Screw the bleeder screw back in. It's plastic do don't screw it down tight, just snug. When you feel resistance you are done.
    - Put the cap back on the expansion tank.
    - Get in the car and turn the key on (but DON'T START IT).
    - Set the air to the hottest setting (94 maybe?). Put the fan on the lowest setting (but not off)
    - Hold the gas pedal down for about 10 seconds, until you hear the water pump start up.
    - Set a timer for 12 minutes so you know when it is done. Now is a good time to get back under there and inspect for leaks.
    - After the water pump bleeding cycle is done (~12 minutes), open the coolant cap and top it up. If you have to add a lot of coolant, I would recommend re-doing the bleed process. If you only add a little, you're probably ok.
    
16. Put the cap back on the expansion tank, put the plastic duct back on, and put your splash shield back on underneath the car. Remove the jack stands & you're done.
    
17. Clean up & wash your hands so that the smell of coolant doesn't taint your beer.

awesome. I'm doing it. I thought I read elsewhere i=on here that it was a nightmare, but this does not make that seem so.

May I ask what kind of coolant to use? I.E., do us bimmer owners use that 100K crap the American and Japanese cars use?

Awesome write up!

What symptoms lead you to replace the thermostat? It looks like it is right there with the water pump. I have heard changing the pump is a real you know what. How much more effort is required to do that too?

Sonic - it is bmw blue coolant...very very similar to the g85 coolant that Chrysler uses...just with blue instead of orange die. I change mine every 3 years or so, but they claim lifetime...hahaha

I just used the actual BMW coolant, I bought some from Tischer a while back with another order so the shipping was already covered. It's not all that much more than the Prestone at my local auto parts shop. The cheapest OEM thermostat I could find was from RMEuropean and I googled for a 5% off code also.

I changed mine because I was getting a P0597 code occasionally (more often when the outside temp was below ~20deg F). This seems to have fixed it. The engine temp (via the dash gage) didn't seem any different when I was getting the check engine light, but I went ahead and did this anyway.

Yes, the water pump is right next to the thermostat, but I'm not sure how it is attached to the engine, and I don't know how bad the access is to whatever bolts there are. So I can't say if it is easy or not. But the only thing it would save you is draining and refilling the coolant system. Everything else (remove splash shield, remove cooler hose bolt, remove thermostat bolts) literally takes 3 or 4 minutes. I've only got 50k miles, so I'll wait at least another 30k before I tackle that project.

Hey,
excellent post. I also changed the thermostat on my girlfriends 2007 BMW X3 3.0 si due to the SEL returning code P0597. At the time the vehicle had 88,123 miles. I did this back on 11/20/2012. I never posted a DIY because I felt that I didn't get good enough pictures. As you can see its a really tight area to work with.

I'd like to add a bit more information with pictures.

FIG. 1: Beck/Arnley Thermostat | Part #: BEC1430826
Purchased from Auto Parts Warehouse @ $102.23

The two "ribbed" ports (Located at 7 and 9 o'clock) are where the hoses with the hose clamps are connected.

The two other ports (located at 11 and 2 o'clock) are where the hoses with the retaining clips are connected. *** Notice that these two ports have plastic pieces that "jutt" out. So there is only one way these hoses are able to be inserted.***

There are only two bolts mounting the thermostat to the water-pump. Next to the bolts is where the wire connection is located.

FIG. 2: Before removing the thermostat, make sure you see how the original one is connected.
This picture was taken underneath the vehicle, passenger-side.
You'll notice in the picture I removed the two bolts from the old thermostat and placed them on the new one.

FIG. 3: This view is from underneath the passenger-side wheel, looking out towards the front of the car.

FIG. 4: This is a closer view from FIG.3. These are the two hoses with hose clamps.

FIG. 5: Better view of the wire connected to the thermostat and the two bolts mounting it to the thermostat.

FIG. 6: This is what the retaining clips look like.

The Work

There were only a few things I did differently.

1. I disconnected the battery to be on the safe-side.

2. I didn't drain the coolant. Of course I started working on it when the car was cold. Rest assured though that I was drenched in coolant fluid once I started removing the hoses.

3. After removing the oil cooler hose, I unplugged the wire and tucked it in a safe place where it wouldn't get wet. I then I removed the two bolts holding the thermostat to the water-pump. This gave me the freedom to move the thermostat around to gain better access to each one of the hoses. It did require a lot of pulling and tugging to get each hose disconnected, but it is do-able if you're determined!

Don't forget to properly seat and secure each hose. Don't forget to reconnect the retaining clips!
I refilled with coolant, took a few times to get it topped off. Let the car run and checked for leaks, also kept an eye to make sure the car did not overheat.
Last, I went to auto-zone and I cleared the codes.
Its now 2 months later, the SEL has not turned on and the car has not overheated.

Last thing,
the car never overheated to begin with. I never would've known there was an issue with the thermostat unless the car gave out the P0597 code. Anyone can get this done as long as you have the tools to do it.

Hi Cagui1223 & mekaneck!

Thank you for the steps to replace the thermostat. I did mine earlier this week in my 07 X3. I do have one quick question though about the bigger hose coming from the radiator to the thermostat. Once you put the retaining clip back in, should there be in movement in the connection of the hose to the thermostat? I can wiggle mine just a hair. I've only driven about 8 miles since I replaced it and have absolutely no leaks or seepage that I can find dealing with coolant. I might be over concerned though!

Here was my experience of this tasks:

I've always changed my own oil, spark plugs, differential fluids, and transfer case fluids in the X3 so I felt pretty comfortable about taking on this tasks. This was by far the hardest DIY that I've completed. It is fairly straightforward, but those hoses just don't want to come off easily.

I removed the bigger hose with retaining clip first and then the two hoses with the hose clamps next. I was able to get both of the hose clamps off going through the passenger side suspension components. The bigger of these two hoses I was able to use a 6mm socket and extensions to get the hose clamp off. The small of these two hoses I had to use a 6mm wrench.

I saved the last hose with a retaining clip to the end. Once I unbolted the thermostat from the water pump, I was able to get the thermostat out of it location and had enough play in the final hose to move the hose with the thermostat. Once I got the thermostat totally below the vehicle I was able to remove the retaining clip and disconnect the hose. I then reconnected this hose and retaining clip to the new thermostat and fished it back into the recess. I then mounted the thermostat to the water pump.

I was then rather easily able to get the two other back hoses on from the suspension area and clamped down. The final hose was the bigger hose with the retaining clip. It was really tough to get back on. I was finally able to force it back on and the retaining clip fell off. It took about 30 minutes, but I was finally able to get the retaining clip back onto the hose to lock it in place. I did notice just a hair of give when I try to move the hose with the retaining clip in place. It appears to be locked in though.

I then put the new coolant in and bled the system. So far I've driven about 8 miles and do not have any leaks.

Back in November 2012, I had my X3 towed to the dealer due to not starting. It turned out to be a bad fuel pump. The dealer also said that my thermostat was not operating correctly and the DME was not getting a signal from the thermostat. I declined for them to replace the thermostat since they are designed to fail in the open position. However, I did notice through the winter that it would take 25 minutes or so for my heat to really be warm inside the vehicle. After replacing the thermostat, it now takes about two minutes for the vehicle to start blowing hot air with the heat on.

Originally Posted by wil33562

Hi Cagui1223 & mekaneck!

Thank you for the steps to replace the thermostat. I did mine earlier this week in my 07 X3. I do have one quick question though about the bigger hose coming from the radiator to the thermostat. Once you put the retaining clip back in, should there be in movement in the connection of the hose to the thermostat? I can wiggle mine just a hair. I've only driven about 8 miles since I replaced it and have absolutely no leaks or seepage that I can find dealing with coolant. I might be over concerned though!...

I can't recall whether or not those hoses gave way. I just made sure they were in all the way and the retaining clip was properly seated in place. I think as long as you don't have any leaks you should be fine.
Hopefully other members with more experience may best answer this question for you.

This job is a major PITA, especially if you are replacing the water pump too. There is very little access, either from the bottom or the top. I'd hate to just replace the thermostat because to get to the water pump at a later time, you have to first remove the t-stat and then remove the WP. If you have more than 50k and need to replace your t-stat, unless you aren't planning on keeping the car much longer, I'd recommend you do both at the same time. I know the part is expensive (about $350 from BMW dealers on ebay) but the idea of doing this work again later is a non-starter with me.