Wednesday, August 16, 2017
Items Sent to Powdercoating
I discovered a local powdercoating shop called Coast2Coast Powdercoating last year during my rear brake overhaul. The owner, Chris, handled that transaction very fairly and the caliper brackets still look like new, so after surveying several items that I wanted to have refinished I couldn't help but bring them to Chris and ask what he could do for me. There's something to be learned here so I'll itemize:
These units are made from cast aluminum. While the powdercoat on the mounts themselves held up reasonably well, the finish on the small metal heat shield that attaches to the right side mount failed due to heat damage. I asked Chris if he had any high temp powders and he said no, mostly because they don't really work any better than standard powders in his opinion. At most, standard powdercoats are good to 300F while the high temp powders are good to around 400F. But the difference isn't enough to justify the higher cost and shipping hassles of high temp powders (they are sensitive to temperature in storage, which makes shipping them during the summer problematic).
When I asked him for alternatives he offered to ceramic coat the mounts but admitted the cost would likely be unreasonable for something like this; rather than ~$30-40, he would have to charge $100. Out of curiosity I asked why and he told me that a single quart of the ceramic paint is $280 plus shipping. Observing that the powdercoat on the mounts themselves had survived, likely due to the heat-sinking properties of the aluminum, he recommended a recoat with standard powder and then suggested that he media blast / prep the metal heat shield so I could paint it with VHT (500F rattle can paint), so I decided to take that approach.
Motor Mount Heat Shield
This is a small hemispherical metal cover that attaches to the right side engine mount to protect it from the radiant heat generated by the exhaust. This part was quite rusty on the underside. Chris looked at the part for an instant and declared that the finish again failed due to heat, so he recommended the VHT approach for this part as well. As it turns out this stupid little part is now $35 (my cost) from BMW, but it will only cost a few bucks to prep and paint. I don't know what BMW is smoking these days, but it must be pretty good stuff, because that's a crazy price for something so simple to manufacture.
This brace spent a good part of the last five years bathed in oil courtesy of my leaking engine so most of the finish is in excellent shape. However, I found a bunch of rust expanding out from the mounting holes that are used to secure it to the subframe. Last I checked X-braces are no longer available from BMW so I decided to re-coat this unit. Chris examined the part and suggested the failure probably occurred as a result of tightening the bolts. The powder was crushed and rotated under the bolt, which allowed moisture ingress and hence rust. He recommended we recoat with standard powder and then take the extra step of applying a light coat of oil to the face of the mount so that bolt heads glide over the finish rather than destroy it. I'm not sure it will make any difference but I'll let my tech know to do that since he'll be tackling that part of the installation.
This is another cast aluminum part. With twenty years of grease, dirt, corrosion and dried cosmoline this really looked like shit to be honest, so I had no idea whether it would clean up. I was fully prepared to buy a new part for around $40 and have Chris finish that but he offered to take the part back to his blasting cabinet to attempt to clean up a small section. When he returned a couple minutes later he said he thought it looked pretty good and I agreed. He conceded, however, that he didn't really spend the proper time with it and suggested that the properly prepped part would very likely look a lot better. As the base metal appeared to be in reasonably good shape he thought it would finish nicely. As a result I asked him to prep and powdercoat the part.
Cylinder Head Coolant Flange
This is a small 90 degree coolant pipe flange that attaches to the rear of the head. This cast aluminum part looked pretty crusty and while I had no plans to powdercoat it I asked Chris if he could clean it up with some glass beads. When he returned a couple minutes later the part looked better than new. As a result of this experience I may bring him some other aluminum parts from the front of the engine (like the hydraulic belt tensioner support) just to make them look pretty. I will, of course, need to clean them to the best of my ability first (likely using mineral spirits) to avoid contaminating his blast media.
Total price for all of this work? $80. That's less than the cost of a single engine support. Money well spent I think.
Before I left I also spoke to Chris about blasting the rust off the front support so I can bring that to a local body shop for finishing. He said he could handle that with his larger blasting cabinets so provided the rust damage isn't too severe I should be able to save the original front support and avoid a $200+ charge for a new part. The body shop will have to use paint codes for this so it won't match the body color perfectly but frankly it doesn't have to, as the part is out of sight under the hood.
Assembly Parts Order Arrived
Today I visited the dealer to pick up a bulk of the parts I ordered.
The only parts that were deemed unavailable, at least for now, were the cruise control actuator mounting flange and the guide tube for the oil dipstick. When my parts rep queried BMW on availability BMW Classic responded and suggested that the parts would be available sometime around the start of 2018 -- unfortunately a bit too late for my project. As a result I'm planning to have the cruise control flange restored and zinc plated. Why can't I just sand and paint the flange, you ask? The flange is zinc plated from the factory and common spray paint, which has an alkyd base, will not adhere to it. If you're curious about this use your favorite search engine to look up "saponification". The guide tube rust is minimal, so I plan to take that to Chris and have him blast the small area of consequence, and then I'll touch it up with some VHT satin black.
I am particularly happy that the coolant distribution tube, which mounts to the intake side of the block, was delivered. The original had rust in all the wrong places, including the T-joint from which I could envision coolant beginning to seep and then eventually gush, all mostly hidden from view under the intake manifold. The new part looks as nice as one would expect and should look great installed on the newly refinished engine.
My starter's part number had ended, but in this case it meant that the original factory new Bosch starter has been replaced with a Bosch reman. The starter motor on the unit I received is a bit smaller than the original, particularly in depth. It's probably a bit lighter as a result too, but I didn't weigh it prior to returning the original for $85 in core credit. For what it's worth, the starter on my 98 model year vehicle is the one with the threaded mounting holes.
Thankfully I received the "covering plate", which is that oddly shaped piece of thin metal that goes between the engine and transmission, as the original really looked like shit. The downside is the new part isn't plated, which means it will likely rust almost immediately, so I'm planning to send that out along with the flywheel to be plated via an electroless nickel (EN) process. Although it's more expensive, nickel has far superior corrosion resistance than zinc for a given thickness, and generally doesn't fail as quickly under equivalent environmental conditions. The other perk of EN plating is that the process deposits the plating metals evenly across the entire surface, which is essential for a balanced part like the flywheel. Why am I bothering to plate the flywheel rather than replace it? It's about $450 -- my cost -- and despite the money I'm throwing at this project I have to "pull the ripcord" at some point, as skydivers say.
I'm still waiting on two items from this order: the "guide plate" that mounts to the back of the cylinder head to securely route the O2 sensor wires around the back of the engine, and the tunnel heat shield. In the meantime I am also planning to add a few more items to the order, including a new refrigerant hose that connects the compressor to the condenser, as mine is looking quite crusty, as well as a couple o-rings for the coolant distribution pipe since I discovered today the pipe doesn't come with them.
The new cylinder head should be arriving tomorrow. I've heard a lot about this head and can't wait to see if it meets with my high expectations. And yea, one of these days I'll actually get back to the hood release work. I'm simply dragging my heels since I now know I'll need to dismantle the entire front end to remove the front support. I'm really not looking forward to aligning those f*cking headlights again.