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      09-01-2016, 01:21 PM   #16
chadillac2000's Avatar

Drives: ST N54 135i
Join Date: Nov 2008
Location: NC

iTrader: (7)

I had many learning experiences on my 535i over the years of ownership. One of which was a DIY intake valve cleaning using the soak and scrub method. Back when I did this prior, I was also forced to replaced the oil filter housing gasket, oil cooler gasket, and oil cooler o-rings because they were leaking. Seeing as how I had just turned 60,000 miles on this 135i, had collected all the necessary parts to externalize the PCV system and add in catch cans for the high and low sides, it seemed appropriate to set aside a full day to do this tedious task once more. Here are all my supplies laid out:
  • Brakleen
  • Gun cleaning kit with brass brushes
  • OEM oil filter housing gasket
  • OEM oil cooler gasket
  • OEM oil cooler o-rings
  • OEM thermostat to cylinder head hose

Since the intake manifold obviously has to be removed in order to clean the intake valves, and the gaskets surrounding the oil filter housing and cooler are prone to failure, replacing them seemed like the right thing to do in order to avoid removing all these parts again in the near future to access the gaskets. My 535i developed an aggressive oil leak because of the failure of one of these gaskets and made a mess everywhere; something I was definitely trying to dodge this time around. The first task at hand was starting to rip out the parts in the way of myself and those valves. Im getting pretty speedy and installing and removing all the N54 cold side parts at this point. A tip for anyone doing this: to remove the black box under the intake manifold simply grab each side of the box and pull upwards with some force. The tabs will bend and the box will slide off.

I purchased the thermostat to cylinder head hose to avoid being stuck with a car that wouldn't hold coolant. When I did this same job on the 535i, I removed the top of this hose connection so I could access one of the oil filter housing bolts, but when I went to put it back, the decomposing internals wouldn't allow a proper seal. This left me without wheels for a few days until the part came in. Fortunately this time I used an 8mm wrench on the oil filter housing bolt and was able to avoid removing the thermostat to cylinder head hose at all.

It wasn't long before I got my first glimpse at my valves that have been accumulating carbon buildup since 2008.

Cylinders 1-6 were all in need of a thorough bath. Lucky for me, as the car sat, 3 of the cylinders were fully closed. Here was my method for getting the job done and one that worked very well with minimal effort.
  • Place plenty of towels under the cylinder head ports to avoid making a big mess.
  • Fill the closed cylinder completely full with Brakleen.
  • Allow to soak for at least 30 minutes.
  • Using a syringe or turkey baster, remove some of the liquid so it doesn't spill out when scrubbing with a power drill.
  • Take the brass brush attachments and insert in a power drill.
  • Work every nook and cranny of the valves to agitate and remove any of the stubborn carbon not willing to let go.
  • Suck out as much of the leftover liquid as possible with your syringe/baster.
  • Using a shop vac with some 6mm vacuum hose duct taped on as an attachment, completely suck out the contaminated Brakleen (very little remaining so I wasn't worried about combustion in the shop vac).
  • Spray in a little more fresh Brakleen, and hit it with the brass brush one more time.
  • Vacuum out excess
  • Used a compressed air attachment to dry and blow out the completed and clean intake valve. 1 hour from start to finish on the first 3 valves.
  • Put the car in 6th gear, and roll the car frontwards or backwards to close the other valves. I was able to get 2 of the remaining 3 closed on the 2nd try, so I went ahead and filled those two.
  • Repeat all steps until the valves are clean.

Filling up an intake port to the brim with Brakleen is always nerve-racking the first few times:

In between scrubbing and waiting for the Brakleen to soak and penetrate the carbon buildup, I took the time to remove the difficult to navigate bolts holding on the oil filter housing and oil cooler attachments. I had to use a few different tools to access some of the hard to reach bolts on the bottom side. Pictures of this process were scarce at this point as I opted not to drain the oil and coolant beforehand, so keeping things clean was a struggle. New oil cooler gasket in:

The RB External PCV system includes some high quality parts. Here's a shot of the throttle body attachment that seated with a nice, satisfying click into place.

Much better.

I had originally intended to make a custom bracket that attached to the driver's side strut bar, but because of limited space due to the AC lines and cone intakes, I ordered another BMS OCC bracket to mount the Mishimoto. Now both cans are mounted in convenient areas, firmly attached to the strut bar, allow the attached hoses to sit in a relaxed position, and should be easy to empty. Pretty happy with the results.

6 hours of my time and $100 in supplies (not counting the RB External PCV, BMS OCC, and Mishimoto OCC of course) was all it took to have my valves looking fresh and brand new gaskets that should help stay in front of any future oil leaks from the usual fail points. On top of the peace of mind of knowing valves are clean and gaskets are replaced, the new catch can system should keep it that way for a while now. I will report back with my findings in the near future.
Visit Chadillac2000's 2008 135i Road Warrior Daily Driver Single Turbo Build Thread HERE

ACF PTE 6062 BB Top Mount ST Kit, Fuel-It! Stage 3 LPFP, Phoenix Racing Port Injection Manifold + RACE FMIC, JB4 + BMS ST E85 PI BEF

Last edited by chadillac2000; 10-08-2016 at 10:30 PM..
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