2008 BMW 535XI Turbo Coolant Line Leaking

[mxandy32]

Hello, I have managed to trace my coolant leak to the turbocharger closest to the firewall (or rear); as I cannot even see the front turbocharger and where the lines connect to it; I was told the wheel needs removed, along with the front CV shaft to replace the front turbos coolant lines.

Now my question is: What cylinders exhaust ports does this turbo officially get spun by, or what does the coolant return by show which cylinders spool the turbo towards the firewall, or rear; vs the 1st turbo thats closest to the intercooler, or front end)

Rear Turbo OR 2ND Turbo; closest to the firewall, or rear. Cylinders: 1-3, OR 4-6?
(one that coolant line is leaking, but i'd like to replace both of the lines while i'm doing one my as well replace both of them, as far as efficiency)

Just need an answer 1-3, OR, 4-6?

Thanks for your convience!

[pbonsalb]

Cylinder 1 is at the front of the engine so bank 1 is front and bank 2 is the 3 cylinders closest to firewall on bmw inline 6.

Fun job. In 2021, I replaced both turbos and all lines on my E61 535xi as preventative maintenance. These cars need a bunch of it by 10 years of age but if you do it you should have years more of good driving. Big job because no space. I did not explore this option since I was not maintaining piecemeal but you could try removing coolant pump and seeing if you can get in there without pulling the axle.

U shaped oil cooler line off oil filter housing is a common oil leak. Sunroof drains are a common problem for electronics in the spare tire well. Sort it out and have fun. Great cars when sorted. Had ours 10 years and I still maintain it for the friend we gave it to.

[mxandy32]

I just ordered return and feed coolant lines for both turbos, luckily my dads was (recently retired last year) a class A master ford technican, but hes always done side jobs and has worked on all types of cars; in fact at the ford dealership whenever they had a non-ford in the garage from say a trade in thats an import towards a ford car sale, and needs some mechanical work before putting it on the lot for sale it'd have the work done at the ford dealership where was traded in of course; anyways all the other mechanics would always be like here ya go Tony your great with the imports and non-fords and hand it off to him lol. Even though he worked on everything he dosen't luck working on alot of the german imports (Audis & VWs especially). And I do see what he means when he says german engineers do things very different, and not in a way that seems to be ever in the mechanics favor for easy, or, quick (or both) replacements, or any work that ever needs done to them lol. And like he said they don't do it in a way thats bad, bad for the tech doing the said work usually always vs traditional domestic manufacturers like GM & Ford, and even most Japanese imports like Honda & Toyota (always an exception to every rule though).
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Anyways I cannot afford getting a waterpump even remanufactured or i'd be replacing that and thermostat/TS housing, or i'd be replacing that (or more precisely my dad will be, with me watching/assisting).

So my main question is aside from doing both feed and return coolant lines to both the turbos, and i was also def. thinking of doing both the turbos OIL intake and return lines at the same time as well (kind of a common sense replacement if doing both sets of coolant turbo lines), and aside from the waterpump, thermostat and T.S. Housing (I mean I could afford the thermostat and waterpump housing, just not the waterpump itself, the cheapest one ive found was like mid 300s on rockauto.com, checked ebay, amazon, advanced-auto & autozone and all want 450 for waterpump alone, and rockauto wants like $550 for waterpump w/ thermostat and housing included). So would replacing just the thermostat and housing, be efficient, or make sense w.o. waterpump first off?

Secondly while doing both the coolant AND oil feed, and return lines what else is a good, and pretty easy or efficient thing(s) to replace thats not gunna cost $350+ for one part lol?

And third question, ive watched several youtube videos; most of them drop the subframe when doing said job but then i've seen other youtube videos that have said its so insanely difficult to drop the subframe on the 2008 BMW 535XI (the AWD models). So should I drop the subframe at all, and with the XI (OR AWD) is it so much harder to even drop the subframe?

Appreciate any replies, thank you!

[pbonsalb]

At least you will know how to do the work when you have to go back in there again to do more. I understand budgets, but a 15 year old E60 535xi is not a car to maintain on a budget. They are great cars and cheap to buy now, but most need about $3000 worth of parts and a few days of labor. Sort them out and they won't be as likely to be an expensive headache.

If I was trying to be cheap but smart, I would do the coolant lines and the oil feed but not the oil drains except for the gaskets or o-rings. The coolant thermostat seems to go before the pump, but you can also do this work from the front later as a separate job.

I dropped the subframe, but I was replacing the turbos, rod bearings, and oil pan gasket as preventative maintenance. I do not know whether you can get to just the oil and feed lines otherwise. You may be able to find a DIY on that, but make sure it is a 535xi DIY and not a 535i or 335xi or 335i DIY.

[mxandy32]

Well after all this time I've managed to save up for 2 oil turbo supply lines and 2 oil turbo drain lines (1 oil turbo supply and 1turbo oil drain line for each of the twin turbos,all 4 lines brand new), (one turbo coolant supply line and one turbo coolant return line, 2 lines for each of the twin turbos, 3 lines brand new one line rarely used), managed to get a set of both turbos on ebay pulled off a 535xi with 60k miles for $230 incl shipping, zero shaft play no waste gate rattling or premature waste gate wear ( man did I ever hit the jackpot finding these baby's for 200 plus shipping the closest I wzas finding was both turbos pulled off of engined with 130-160k for 300-350 + shipping. I couldn't even find a set of turbos for cores to be completely rebuilt for 200 & shipping, new oe replacement water pump with 2yr warranty , new waterpump thermostat assembly, vr racing fuel pump (most up to date fuel pump made for n54/n55s w 1yr warranty), and today finally got the last few things which were 6 exhaust gaskets (1 per cylinder),2 x turbo to cat gaskets, 2 x cat flange gaskets, 2 waste gate tubing seals, 3 new water pump bolts all I'm waiting for is the thermostat housing to arrive by tomorrow evening and waterpump supposed to arrive latest by Tuesday night, alright got the one motor mount off, the v shaft out, expansion tank, got the exhaust bolts out (needed a torch) tomorrow my dad and I should be able to get the exhaust manifold bolts off and the stock turbos out!

1. Brand new turbo all 4 oil lines
2. Brand new turbo 3 coolant lines, and one used return line
3. Set of both turbos pulled off a 2008 535xi with 60k miles, zero shaft play no waste gate rate or waste gate premature wear.
4. OE Replacement Waterpump w. 2 yr warranty
5. Waterpump thermostat housing
6. Vr Racing High Pressure Fuel Pump (most up to date version of n54/n54 fuel pump made to date) w a 1 yr warranty
7.Set of 6 exhaust/turbo manifold gaskets (one per each of 6 cylinders)
8. 2 x. Turbo to downpipe gaskets
9 2 x Downpipe to cat gaskets
10. 2 x wastegate piping gaskets
11 3 x brand new waterpump bolts
12. 2 x turbo oil return line gaskets

I haven't officially added everything up but I'd say all together spent around around $1250 give or take a few hundred dollars.

The brand new urbo oil and coolant lines were probably around $500-600 alone, then another approx $400 for Hpfp and waterpump and thermostat housing, then $230 for set of turbos shipped, 105 shipped for all the misc. Gaskets n bolts.

[pbonsalb]

Be patient — after all these years those parts are not going to cooperate when you try to remove them.

I know this is a lot of preventative maintenance but you are buying parts as inexpensively as possible. This will set you up well for the next few years. If you want to delay your install, there are replacement WG kits you can buy that are less likely to rattle as they age but you need to be able to weld — since your turbos are off you could take them to someone who welds. You could get 5 years out of these used ones with no rattle or the rattle could start next month. My originals at 150k rattled only during cold start but I had tightened the actuator rods a tiny bit around 90k.

There will still be little things like old vacuum lines and bigger things like transmission service as well as transfer case and diffs fluids and maybe valve cover and oil pan gaskets.

If your pan gasket is leaking, this is the ideal time to do it since you have the subframe down and the passenger side axle out. There is a quick and dirty method you could use later but I have not done it. You cut the gasket on the high side which I think is the driver’s side and then you can put it into place and use some sealant where you cut it. But it’s harder to see how clean your surfaces are and to prevent debris from falling into the pan.