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Wednesday, October 4, 2023

Doug's Domain

Doug Vetter, ATP/CFI

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Monday, October 23, 2017

Fuel Tank Reinstalled

On Monday I brought the engine, transmission and remaining parts to my technician. By the time I arrived at his bay around 10AM the fuel tank was reinstalled and he was using the clear tubing and other parts I provided to bench bleed the new master cylinder.

After we hoisted the engine, transmission, exhaust, headers, and other parts off the back of the pickup I took a look at the fuel tank work. I couldn't help but ask if he had any trouble with the job. He commented that even after draining the fuel from the tank to reduce its weight, removing and reinstalling the tank required two people, since one person must hold the tank while the other helps to snake the vent lines into (or out of) the body. The job was somewhat easier in my case because I had purchased new vent lines so he was able to simply cut the lines off during the removal process and then install the new lines when it came time to reinstall the tank.

Note, by the way, that while it is possible to save the existing lines if you disconnect them at the evap tank (under the cover in the right rear wheel well) I'd question the sanity of anyone doing that unless (as in my case) the hoses were damn near brand new, since they live in a harsh environment and should be replaced at least once every 15-20 years. Why? Because leaks in this system are an unfortunate reality, and the emissions controls on this car will not let you get away with a leaky system. At the very least you'll have to contend with a CEL. At worst, you'll fail inspection.

If you're planning to pull the tank there are two part numbers you'll need to order in addition to regular fuel hose. First is 16111182814, which is a short blue plastic vent pipe with two rubber hoses (each about 8 inches long) attached with high pressure crimps. The second part is 16111182827, which is actually a group of vent lines that are mostly black plastic but do have a few short (3") rubber hose stubs, also attached via high pressure crimps. The high pressure crimps cannot be removed in the field so if you want to replace the rubber hose segments (and trust me, you do), you have to buy new hoses. Fortunately, at the moment the vent line parts are relatively cheap ($120 for both if I recall correctly). But I'm sure BMW's inventory management software will recognize any increase in demand from all of you reading this article and automatically jack up the price by a factor of 2 or 3. And don't laugh. This is not only possible, but highly likely these days. Thank computers and greedy finance types hell bent on making not just a reasonable profit, but an obscene one.

As I looked more closely at the bulkhead in front of the tank my technician told me that he cleaned up the rust and applied some paint to protect the surface. I'm sure it wasn't VHT (which is gasoline / solvent resistant) but anything is better than raw metal rusting. While the tank was out I saw what I thought was mild corrosion on the brake lines, but my technician said this cleaned up nicely and was painted as well. Had I done this work myself I would have remembered to spray some cosmoline over the newly painted lines to thoroughly insulate them from moisture, much as BMW did on the underside of the vehicle when the car was built, but I neglected to bring it to my technician last week and by the time I remembered it the tank was back in the car. If you're wondering, I am planning to spray cosmoline on the fuel lines and brake lines as they traverse the underside of the vehicle since my cleaning efforts removed what remained of the original stuff. One thing about cosmoline -- it looks very messy when applied and it tends to collect dirt over time, but it really does a good job of preventing corrosion.

Assembly Begins

We then went over the status of the engine and other parts I provided. While pointing at the blue tape I placed on the crank bolt, plainly labeled "needs torque", I reminded him that the crank bolt had yet to be torqued. I also explained that I did not install the A/C compressor bracket because it would have made the engine less stable on the pallet during transport but that I had provided new bolts to replace the corroded originals. I pointed out the Amsoil SAE30 break-in oil I brought for the engine and the Redline D4 ATF that would need to find its way into the transmission. I then mentioned that I had replaced the coolant expansion tank and associated coolant line, as well as flushed the transmission cooler using an approved fluid. Finally, I handed him the freshly painted brake line brackets with brand new grommets and told him they were ready to be installed.

One of the other techs that has been around as long as my tech (and as legend has it, joined my tech in BMW's maintenance orientation classes when the dealership first got the BMW franchise in the late 70s) came over to see what was going on and asked me what I had done to the transmission. I told him a "complete soft-parts overhaul", to which he responded "not to scare you, but we had issues with field overhauls of those units years ago...if not built and adjusted properly they tend to have jarring shifts". Of course, the 4L30E has never provided shifts as elegant and smooth as the ZF in my E46, and the two 4L30E BMW remans I've bought haven't exactly impressed me either, but as long as my rebuild shifts reliably I'll consider myself lucky. "Well", I summarized, "I should know pretty soon whether to praise my transmission shop or condemn it."

Next Up

At this point my technician has all of the parts he'll need to reassemble the vehicle and the process is entirely in his hands. I'm back to business projects this week while I wait for my tech to tell me that he's ready to fire up the engine.