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BMW 3-Series (E90 E92) Forum > E90 / E92 / E93 3-series Technical Forums > DIY Guides > DIY: E90 / E91 Xdrive water pump replacement



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      06-22-2018, 12:11 AM   #1
bryanjb
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DIY: E90 / E91 Xdrive water pump replacement

Just finished the water pump replacement job on my 2011 E91 sport package Xdrive (wagons rule!) using a new OEM P**rb**g pump and t-stat. Car has 95K and the pump still worked, but I’m under the car replacing transmission fluid / gasket / filter, and these thing are known to fail without warning, so…

I’m in the northeast, but my car is from Texas and has never seen winter or salt – most everything came out clean and easy. Lucky, I know – but these cars are shielded well, so unless there is *really* substantial corrosion, most everything should come out ok using standard rusty car voodoo. Total job duration for an arthritic amateur hack like me was 6 hours.

I've looked at a handful of 2wd pump replacement procedure videos and write-ups, and found them useful for general orientation and project scope. There is lots of good information out there, so I won’t repeat the redundant stuff here. Bavauto has a very good 2 part video on YouTube.

It has been mentioned that the water pump / t-stat replacement for Xdrive cars is quite difficult, as they have significantly less space to get around. This is generally true, but the job is absolutely doable. Some essential tools are a good light - I have a gooseneck Dewalt LED - and a magnet wand or something of the sort. Lots of rags and eye protection, obviously. I also found I needed some tacky goop to hold the Etorx bolts to my Ujoint + extensions while reinstalling the 3 pump mounting bolts. Other than that, nothing needed beyond average toolbox items. Plan on plenty of getting up and laying down, but mostly just relax and take it slow. I found it handy to have a chunk of something to rest my head on while pushing and pulling parts while lying under the beast – saved straining and stress while looking into tight corners. Besides possibly frozen bolts, there are really no showstoppers or surprises – just some tight clearances and a need to keep bolts under control while accommodating moderately limited access. Small hands will be an advantage – but no luck there for me.

The key difference for this pump / t-stat replacement procedure with our Xdrive cars is to first remove the electric radiator fan. The pump and t-stat will be maneuvered and replaced using forward clearance. I also took out the air box, as it is easy and gives lots more room to work. My wagon has the AT, so the transmission cooling block has to be detached from the rad cooling fan. It is held on with one small screw that can be seen on the bottom of the block from under the car (after shields are off), attaching the AT cooling block to the rad fan. The coolant expansion tank also comes out for access to all the hoses below.

I used my quickjack lift (about 2.5 ft clearance net), but there is no reason that 4 stable and secure axle stands would be any less good. Nothing in this job seems to need heavy force. All the basic prep is the same as the 2wd platform. Get the car up, remove the bottom shields, (Xdrive has an additional stiffener plate under the engine, held with 5 mongo bolts), drain coolant thoroughly.

Another useful nugget is to know the tough spots - there are obviously a couple, and this is where things differ from the 2wd procedure. The major problem spots are the bolts that mount the pump to the N52 block (Etorx) and those that attach the t-stat to the pump (10mm hex). The 10mm t-stat mounting bolts are steel (important for later - can use a magnet to help install) with no access for a socket drive. I found a 10mm open end wrench did fine breaking the 2 hex bolts loose, and my right hand (palm-up-from-the-front) fit in ok for spinning them out. The Etorx bolts on the pump needed extensions and a U-drive. I have a couple of Ujoints, and the stiffer one helped keep the whole assembly from flopping around while getting to the Etorx bolts.

Getting the short (pump outlet) rubber side hose off and back on is also a bit fussy. Gently prying clamped hoses off with a large screwdriver and using clean coolant as lube for re-assembly is workable.

Minor tough spots are the electrical connectors for the t-stat and pump power. The electrical connector locks need small screwdrivers and patience to keep from breaking the keeper clips. Both the t-stat and the pump power electrical connectors have seals, and so require a bit of smooth force and patience to get off – juggling and prying with a couple of screwdrivers worked for me. Additionally, the pump power harness has a brown ground wire held on to the engine block with another Etorx - I found it far easier to just remove that and free the ground wire, allowing the connectors / harness to be pushed way out of the way.

I really hate working with coolant (or anything) dripping on me, so I did most of the drainage work from above, after starting with the radiator drain plug, and detaching hoses by pulling locking clips or unscrewing clamps as needed. The longer hoses can be gently pushed out of the way as needed.

The t-stat needs to come out separately, with all hoses detached. No way will the pump / t-stat come out as an assembly. BMW was kinder with the hose clamps (compared to what I’ve seen in 2wd procedures) with my AWD wagon, as I was able to get every one off, either from above or below. The LED light comes in handy here, as the 8mm hex hose clamps are mostly buried, but (hopefully always) oriented correctly for access to loosen and tighten. Access to screw clamps from below for example can be between the subframe (which mounts the steering rack), and the front axle. Hose clamp access is really is self-evident once you look from under the car. Some coolant will still dump, but no more than a couple of cups at this stage. I had the pan handy, and just kept clear while the last of it drained. Once the 2 steel 10mm hex bolts holding the t-stat to the pump are out, the t-stat comes out easily toward the front.

The pump at this point has the curved hose and the side hose still attached. The 3 Etorx bolts require a 6” extension + Ujoint + Etorx socket – all three come out easily enough – just keep the Etorx socket secure on the bolt heads – the angles taken up by the Ujoint are pretty steep. Use lots of light, watch and control carefully. Free the pump outlet (side hose) clamp, again accessible from below with extensions, an 8mm socket, and a good light. The curved hose on the pump inlet (center) stays with the pump as it comes out. Make sure and release the electrical cable from the clip at the bottom of the pump. The pump comes out toward the front of the car, which again is easy with the radiator fan out of the way. Be careful not to damage the frail radiator fins.

On the workbench with the pump, swap the curved hose onto the replacement pump, carefully noting orientation. Tighten the hose clamp fully (last chance). Swap the electrical cable clip onto the new pump, being careful not to obstruct the lower Etorx mounting hole.

Time to put it back together? Generally, every time a hose has to go back on a neck, make sure to pre-arrange the clamp, observing where it fits and clocks, making sure to keep it accessible to maneuver once the hose is back on the neck. Also be careful to not drop bolts, as they may fall into a very inaccessible place in the subframe / steering rack area.

The pump will go back in from the front with a little finesse. Once it is in place and close to final location, make sure to put the pump / t-stat wire harness back in the clip on the pump – this is the last time it will be accessible. Also check orientation of the t-stat electrical cable – it needs to T off toward the passenger side. Plug in the pump power connector loosely. Test fit the pump by aligning the bolt holes. The pump outlet side hose (short rubber to solid aluminum tube mounted in turn to the exhaust side of the engine block) will need to be pushed around until it drops over the side outlet on the pump. The toughest Etorx bolt is the bottom one toward the rear of the car. It helps to put the *top* Etorx bolt in first – loosely – to hold everything near where it belongs. The two bottom Etorx bolts are both tough because the subframe only allows a bit of clearance, but it is just enough to clear the Etorx socket, Ujoint and extensions (I used a 3/8” drive X 6” here).

This is where the sticky goop is necessary. I put a chunk of sticky into the Etorx socket to keep the bolt from falling out, and maneuvered the Etorx bolts, Ujoint and extension (rearward one first) into location. I found it helpful to have a screwdriver in my other hand to help steer the Etorx bolts into their holes – especially the rear lower one. The aluminum bolts have a no-thread lead in, which is very helpful while trying to start them. Put all 3 Etorx bolts in loose, pushing the pump around as needed to start them threading. For torque, 10Nm +90 degrees is spec’d, I got them contact tight and then added a little less than 90 degrees – seemed tight enough to me. Once the pump is mounted tight, push the pump power connector home until the keeper clicks. I had to pull the pump out a little way two or three times to get everything where it belonged – the pump power connector and cable was somewhat restrictive – a good reason to leave it loose-ish until last. Put the pump power ground back on the block with its Etorx bolt - prior to reinstalling the radiator fan preferably.

T-stat in next – everything just needs to fit back where it was. Tricky part is getting the 10mm steel hex bolts back in place – use a magnet wand to get them started without risk of dropping them. Screw them in by hand, then 10mm open end wrench them tight. Get all the hoses back in place, look closely to be sure *every* hose clamp is tight, and every quick connect is socketed correctly, with its locking clip pushed home. There are 4 or 5 quick connects getting cycled for this procedure, and every one will go on all the way to a visible hard stop – very easy to tell its loose if there is any room to push them on further. T-stat electrical connector can be put on and locked now.

The fill and bleed procedure is easy to find and effective – had to fill in 3 or 4 stages as it bled the air out.

Let me know if there are any questions. Doesn’t look like I’ll get any pix up for this, but hopefully I can clean up the verbiage if needed.

Last edited by bryanjb; 06-22-2018 at 07:22 PM.
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awd, e90, e91, replacement, thermostat, water pump, x-drive, xdrive

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