BMW E61 535xiT Wagon - Turbo Replacement, Cooling and VANOS Repairs

My 5 Series wagon just hit 185,000 km (115,000 miles), and I've had an engine light (low boost error) for the past 4,000 km. A trip to the dealer confirmed that I had a worn waste gate bushing. corroborated by the unmistakable waste gate rattle sound on acceleration. I was returning from a camping trip with the kids and I got on the phone with Turner Motorsports and discussed the turbo replacement options.
N54 Front Turbo Oil Leak
I decided to replace the turbos with new Mitsubishi OEM units - identical to the BMW part but at half the price.I thought about what work I would do while having the front end apart, and I added the following to the work order:

1. Walnut blast the intake valves;
2. Replace the radiator, expansion tank, thermostat and upper / lower coolant hoses (due to the damage to the radiator fins behind the grille and age). I've already replaced the coolant pump about 2 years ago;
3. Replace the VANOS (variable valve timing system) solenoids;
4. Replace all the drive train fluids - engine, transmission, transaxles
5. Ignition - plugs and coils
6. Do a good inspection and replace any leaking drive train seals.

I'll have to keep the car for another 5 years to justify the investment, no worries considering the later 5 series wagons are no longer imported to North America, and the E63 AMG wagon is a bit out of my snack bracket... I figured this project would justify the purchase of some new tools, so number one on the list was a Quickjack car lift system. I went with the BL-5000 EXT - which I measured to fit just long enough to hit the lift points on the 5 series wagon.

Setting up the Quickjack lift took about an hour - you have to add the quick connect fittings to the ends of the the hydraulic hoses and pumps, fill the reservoir with hydraulic fluid or transmission oil, and test the system. Everything went together smoothly, with no leaks from any of the hose connections.

Quickjack BL-5000 EXT unboxed and ready for assembly

Ready for the first lift with the Quickjack
With the lift tested - and with the engine and transmission still warm - I proceeded with a compression test of all cylinders before dropping the engine and transmission oil.

Engine covers, air filter housing and intake duct work removed to access the plugs, coils and throttle valve.
I removed the covers and intake in order to remove the coils and plugs, and access the throttle valve to be able to jam it open with a plastic pry tool. I also removed the fuel pump fuse - #72 on this car, so that I wouldn't be injecting fuel while doing the compression test. Everything went smoothly - starting with removal of the cabin air filter housings, the cowl cover, the engine cover and finally the air filter housing.
Three of the coils had been replaced last year along with a leaking valve cover. I'll be replacing all coils as a set, along with new plugs. 

My 10 year old daughter held my iPhone and took videos of the compression gauge during each test - so that I could see the results after cranking the engine. Results of the compression test are as follows, from cylinder 1 to 6:

170, 170, 165, 175, 170, 175 psi.

All in all - not bad variation - in spec for this vehicle. I wanted to make sure I wasn't wasting my time and money replacing the turbos...

With the compression test done, I drained the engine oil and transmission oil - and sampled both to send out for oil analysis. I'm interested to see the condition of the oil, particularly the lifetime transmission fluid, and to get some indication if there is any abnormal wear.

Oil bottles with samples ready to ship to the lab.
One thing I did find was lots of oil in the main intake pipe at the throttle body. This could be an indication of oil leaking from the bearings in the turbochargers - another indication that the turbos are ready to be replaced.

Lots of motor oil in the intake piping. 
I'll probably be at this project for a week or two - so I'll be doing regular updates as the work progresses.

Sources and Links

I hope you found this post useful. Feel free to ask questions in the comments section below. I answer all questions. If you're interested, you can help support this site by using the following links to in the United States. Turbo parts were supplied by Turner Motorsports. Other parts were supplied by Pelican, BMW Park Avenue in Brossard, and eEuroparts. Oil analysis by Blackstone Labs.



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