Thursday, April 30, 2009

Weekend Project: BMW Double VANOS rebuild

Double-wha? Simply put, VANOS (Variable Nockenwellen Steuerung) is BMW's name for their fancy oil-driven system for variable valve timing in their 6-cylinder engines. Oil is pumped into pistons which move the camshafts fore and aft to hit slightly different cam profiles, thus increasing engine performance and fuel economy. The problem? Due to a failure of materials design, basically every VANOS engine from 1992 to 2006 will eventually develop leaks that prevent the pistons from functioning correctly. If you're under warranty or willing to spend the money, they will happily fit a rebuilt VANOS assembly with the same design flaw and the same failure mode. A full explanation can be found at Beisan Systems, written by the clever bloke who figured out the problem and the solution for his own car, only to be told by BMW that "no further development" would be done on the design.

Luca, one of the members of the local San Diego BMW Z Car Club (SDBMWZCC) had done the research into this problem for his own stable of BMWs. Luca is an awesome shadetree mechanic, and I've never seen him do something half-assed, so if he was going to fix his wife's Z4, it was going to be done right, which meant fitting the upgraded O-rings and Teflon seals from Beisan Systems into the VANOS pistons. And in a display of car-club-generosity unmatched in many months, he also organized a group purchase to bring the price down the price of the parts, then hosted a clinic at his condo where several other Z-owners could turn their own wrenches under his guidance!

With a Sunday appointment, I readied my tools and headed off to the clinic. None of this work is terribly difficult, but quite a few parts have to be stripped back from the head in order to get the VANOS assembly off, including the valve cover, spark coils and harness, and fan. Since the cars are low, this isn't exactly easy, but this process is really good for getting familiar with the more intimate parts of the engine, and I got my first really good look at how the VANOS system interacts with the cam shafts.

Once removed, we drained the VANOS (onto a diaper for easy cleanup, seen here), disassembled and cleaned it, then reassembled it. The actual upgrade takes only a few minutes, its just too bad that you have to spend several hours pulling things off the engine to get to it. After the new seals were fitted to the pistons, everything gets reassembled and refitted, re-torqued, and replaced.

Sadly, getting this intimate with the Z did reveal some of her other flaws, namely some crusty guff near the thermostat housing that indicates a coolant leak. I'll be dealing with that next, but I'll be passing that one off to a professional because I lack the tools and patience to deal with draining, refilling and correctly purging the cooling system on a BMW.

And finally, after a test drive, I can report that yes, the fix was worth the effort and makes a noticeable difference. There is a noticeable increase in "urgency" from the engine, especially at the lower revs. The transition into VANOS can be felt but is subtle, but overall everything feels more powerful now. Most importantly, I know I won't have to look forward to doing this again in 20k or 30k miles as I would with the OEM seals.


Sunday, April 12, 2009

Guest Room Remodel - Budget Murphy bed with Ikea Pax cabinet frames

Over the last couple of weeks, I've undertaken a complete re-do of our guest room.

One of our key goals was to keep the room multi-functional, so we really wanted a Murphy Bed (folding wall bed) to make room when the bed wasn't needed. Unfortunately, even the cheapest Murphy systems we could find were well out of our price range. With a Queen bed, side cabinets and a rudimentary headboard, delivery, and installation, we were looking at nearly $5000, and that's just for a thin white-melamine cabinet with vinyl-foil doors.

I knew I could do better (price-wise) if I did something myself, but I don't have the equipment or time to make full cabinets or raised-panel doors. Wanting an alternate solution I did a lot of searching and scheming and eventually hit upon the idea of using Ikea Pax wardrobe cabinetry (somewhat modified).

This was a long-ish project, so I won't go through every step here. You can see the evolution of the project along with descriptions of many steps here on the Web Album.

Since the main reason for undertaking this myself rather than just purchasing a basic melamine Murphy Bed was cost ($5000 or so, as of November 2008), let me break down the main expenditures: Queen-size Murphy Mechanism + Foundation .... $390
Floor saver (attaches frame to wall instead of floor)............$80

2 x Pax Cabinet Frames, 20x23x93.................................$180
1 x Pax Cabinet Frame, 39x23x9...................................$100
4 x Pax Birkeland Doors, 19 5/8 x 90 1/8.........................$480
2 x Pax Birkeland Glass Doors, 19 5/8 x 90 1/8...................$240
3 x Gravyr Handles 2-pack........................................$24

Melamine Sheets (Home Depot).....................................$60
2 x Piano Hinges, 72" (ACE Hardware).............................$30

Dimmable Halogen Lights, door-switch, wiring, etc................$40

Assorted Hardware, Hole covers, magnetic catches, etc............$10

"Wrought" Iron Headboard from our old bed........................$0

......................................... Rough Total ..........$1634

Even accounting for a few tools that I had to buy (<$50) and a big pile of Komplement accessories and sales tax, you can see that I came out way ahead.

So, what did it take to pull all this off? Surprisingly little.

As far as tools, I needed a Circular saw, a Table saw (borrowed from a friend), Cordless Drill, various drill bits including 15mm and 35mm forstner bits (the tools I bought), hammer, screwdriver, and various measuring tools, squares, and a few clamps.

This whole build was based on using standard Ikea Pax wardrobe frames. This meant I could fit stock Birkeland doors, which in my mind was the biggest hurdle to overcome. The only real trick to this is that the Pax frames only come in two widths: 19 5/8" (1-door wide) and 39 1/4" (2-doors wide), whereas a Queen bed and frame needs roughly 65" clearance. The solution was to "extend" a wide cabinet to a "double-wide" cabinet and make the doors bifold (4-doors wide).

To do this, I made new top and toe-kick panels in the adjusted width. Using the original top as a guide, I machined my new top to have the same pockets for the Ikea cam-lock hardware so that everything would assemble the same way as the original cabinet frame. I then added a horizontal stringer bolted to the wall to keep the top piece from bowing under its own weight. The toe-kick was similar, except that instead of a full bottom to the cabinet, my toe-kick is only topped by a strip that fills the gap to the Murphy base frame (the center cabinet is "bottomless" and the Murphy Bed frame sits directly on the floor, bolted to the wall.)

Attaching the doors is nearly identical to the Ikea method, except that given the added weight of a second door panel, I felt compelled to add three additional hinges on each side. These were mounted just like the regular hinges into additional recesses I drilled into the doors.

The lighting is actually not Ikea, because I came across some Dimmable Halogens for a great price at my local Dixieline. Rather than just put in the lights and a dimmer, I also built a switched outlet into the cabinet frame. A momentary switch is mounted such that power to the lights is only "On" when the cabinet doors are open, since I didn't want the hot halogen lights left on by accident when the bed was folded up into the cabinet.

The other big improvement in this implementation vs. the cheap commercial Murphy Beds was the headboard. Since the Pax wardrobe cabinets are deeper than I need (even accounting for a pillowtop mattress), there is room between the wall and upright bed frame to accommodate our spare "wrought" iron headboard. When the bed is lowered, the headboard can be slid forward and bolted to the bed frame with two wingnuts. This provides a REAL headboard for our guests to lean against for reading, etc., something that was not provided by the cheap commercial beds we looked at.

Final results? We're very pleased.

The actual Murphy mechanism from went together very easily and is well built, and their "Floorsaver" is a unique offering, as far as I can tell. Being able to bolt exclusively to the wall studs instead of into the subfloor made things much easier on me. My only knock is against their "foundation", which is really nothing more than a pine wood frame, some corrugated cardboard, and a quilted covering stapled on. For the $110 difference, I would just order the mechanism without the foundation and just make one from plywood, were I to do this again.

The Ikea cabinetry isn't as nice as real hardwood, but it actually feels less cheap and more sturdy than the thinner particleboard/melamine on offering from commercial Murphy Bed sellers. For our room, we actually wanted the white cabinets, but we could have also selected one of the other Pax finishes. NOTE: If using a cabinet finish other than white melamine, you'll probably want to buy one additional Pax cabinet frame. Use the side pieces from this extra cabinet as the raw lumber for the new top and toe kick panels. It will be slightly more expensive that buying melamine in sheets, but it gives you the option of "other-than-white", another difference versus the commercial Murphy Bed makers.