I wanted to add another update to this build thread as the 1er recently passed 140,000 miles and is still going strong, but recently got some time off + some new parts.
I was presented with the opportunity to purchase a E90 335i with a manual transmission that needed a few repairs and the owner wasn’t in a position to invest the money to get it road ready again. I wasn’t able to start the car up to confirm all this, but according to the previous owner the car had a bad water pump and/or thermostat, a leaky valve cover, leaky oil filter housing gaskets, needed tires, as well as a deep cleaning. I was a little hesitant about purchasing a car without hearing and driving it first, but all the maintenance records were included and I felt confident the drivetrain was in good shape. Because of the ailments the car was suffering from, I wasn’t able to drive the car from where it was (about an hour away) to my location, so I had to enlist the help of a flatbed to get it back to my garage before digging in.
Before too long, I had my first E90 up on jack stands, splash shields off, wheels dismounted and started my deep dive to put together a list of parts I’d need to buy,
I headed straight to FCP Euro to utilize their lifetime warranty and made a rather large order for: new thermostat, new water pump, new bolts, two gallons of coolant, a new cylinder head to thermostat hose (these are known to break down by this mileage, new oil cooler and oil filter housing gaskets (including o-rings), new coils, new spark plugs, a new power steering reservoir o-ring, and a few other miscellaneous items. Once those arrived, I was really ready to start the dirty work (literally).
I replaced the water pump on my 135i a little over two years ago back when the car only had 74,000 miles, so now at over 140,000 miles, it was approaching the same amount of miles my first water pump endured before I replaced it as preventive maintenance before it left me stranded. So even though it was still working perfectly, I decided to remove both assemblies from the 335i and the 135i, which takes patience on top of the inevitable coolant bath you’ll be taking. Eventually though, I had all the coolant removed and the water pumps out of both cars. Here’s the new, used, and inoperable water pumps and thermostats laid out prior to re-installation:
I took the new water pump and thermostat from FCP Euro with the lifetime warranty and installed it on my 135i. This would give me a brand new assembly on the 1er, as well as the peace of mind of knowing I had a free replacement waiting if this one ever went bad. The used, but perfectly functioning water pump and thermostat, were installed on the 335i to replace the inoperable parts that were leaking coolant everywhere. At this point I had gotten pretty speedy with the procedure just because I’d done it a couple times.
Once all the water pumps were swapped, it was time to move on to plugs. I wasn’t sure the last time the coils and plugs had been replaced on the 335i, but I knew my 135i was due for NGK spark plugs since I’d been running them for about 15,000 miles, so paying some attention to the ignition system was up next for both cars. The plugs on the 335i weren’t in the best shape, but weren't terrible either.
They were replaced with a brand new set of OEM plugs, and I swapped the lightly used ignition coils from my 135i to the 335i. I then pulled the NGK plugs on the 135i. For 15,000 miles, they looked pristine.
I then used the BMS gap tool to set the .022 I’d been using on the NGK plugs, and installed brand new Bosch coils from FCP Euro on the 135i, which also meant I had a lifetime warranty now on coils for the 1er.
The 335i needed a valve cover gasket next, so I started the teardown for that process. Before long I had the old valve cover off and was ready to inspect for cracks.
Luckily there were no cracks, so I proceeded to fit in the new gasket to the valve cover.
After reassembly and torquing everything back to stock, it was time to replace the oil cooler and filter housing gaskets. Following removal, it was easy to see why there were leaking all down the front of the engine.
Once that was completed, I replaced all the wastegate lines with high temp silicone ones, I drained the original manual transmission fluid and replaced with fresh Redline ATF, I replaced the battery, registered it with MHD, changed the oil and filter, filled up the coolant and followed the electronic bleed procedure. Because the car had been sitting for a while, I made sure to disconnect the injector wires, and prime the system for 10 seconds on 3 different occasions before firing it up and letting everything get up to temperature. To my satisfaction, everything seemed and sounded perfect.
I then spent quite a while refinishing the headlights and giving the exterior paint some attention. Before too long the inside and outside were looking excellent.
After weighing out the affordable tire options for the 19 inch Breyton GTS Race wheels already installed, I decided to go with a set of Achilles Sport 2 245/275 combo tires and glad I did. They filled everything out perfectly and didn’t rub at all on the stock m-sport suspension. Lastly, I added some front splitters and yellow vinyl over the fogs to complete the look I was going for. Here’s a few shots of the car prior to putting it up for sale. At this point, I had considered keeping it, but really have my heart set on a E90 M3 in a year or so.
Not only had I fixed all the problems with the 335i and gotten it running reliably, but I’d also managed to get lifetime warrantied water pump and coils on my current 135i that I’d be keeping long term. Before completely buttoning up the 1er, I had one last new part to put on--a VRSF 335d coolant tank charge pipe that is better fitting for single turbo and inlet cars. Even though I didn’t have the 335d coolant tank, and had just relocated my 135i tank to the driver’s side when I went ST, the ER charge pipe fit had always fit poorly for my setup, so I took the opportunity to swap it out for a better fitting unit that also shows off the Tial blow off valve instead of hiding it out of sight.
The tires on my 135i are reaching the end of their usable lifespan, and I plan on replacing them with the same Achilles Sport 2 tires that I put on the 335i. They’re about half the price of the current Firestone Indy 500 and Hankook V12 Evo2 options I’ve previously had installed on this car and I’ve decided to to try them out. As soon as those are mounted up, I’m determined to carve out some dyno time.