My 128i 5-Part DIY - ATF, OFHG, EAC, WP & Tstat, VC gasket & plugs

[MarinerZ4C]

This 2008 128i convertible (E88) was new to me in March, with under 67K miles.

It’s a remarkably clean and rust-free car – fair-weather driving and low miles. The PO drove it Summers-only for the past 4.5 years. He had replaced struts and shocks recently, plus one BIG item: He had a BMW specialist shop replace the oil pan gasket ($$). I drove the car sparingly until I was able to schedule my time to do what I consider some serious deferred maintenance. Here’s my list, and some Tips / LINKS to posts I used to help me along.

ATF drain-fill (4X) to ensure the GM-France transmission lives a long life. I followed this post. The car was up on jack stands, and I used nearly 16 quarts Delvac1 ATF (synthetic, meets Allison specs, sourced from Summit Racing). It’s time intensive to get transmission to spec temp before each drain and for final fill – use hand-held IR thermometer to measure, and watch out for hot exhaust! Use ¾ inch PVC threaded 'stand pipe' to remove old filter seal. I used a CRP filter, BMW plugs, and a BMW pan bolt set (pre-treated w thread locker).

OFHG, Oil Filter, and Oil – There were the very early signs of seepage wicking up the OFH casting. I used a Viton® Oil Filter Housing Gasket (made in Spain) bought from ECS Tuning. Maybe other vendors have switched to Viton® as well, but I can’t confirm. I used a MANN filter and BMW oil pressure switch. Bolts are steel and can be reused.

TIP: My car has the N51 SULEV with a semi-rigid fuel line making access to the Torx® bolt under the intake even harder than FCP Euro video – BUT if you have a ratcheting E10 box wrench, this bolt can be reached from the front, sideways, and you’ll be fine. It’s easier if the oil pressure switch is removed first (and I changed it out anyway).

EAC Sensor – I had an intermittent code for the EAC sensor glued into N51 radiators. This sensor is just a thermistor or thermocouple buried in plastic to measure temperature. This requires radiator removal. BMW only sells complete radiator with sensor ($$$), so I followed MINIz Guy’s post and ordered a Mercedes sensor. Remove the pins, replace them into the BMW connector, and it fits. The recommended Loctite 4204 adhesive (branded for Mercedes) only comes in a tube that could do 100 of these, and it costs between $16 and $25 from FCP Euro, ECS, or RM European.

Water Pump & Tstat – I don’t usually fix things that aren’t broken yet, but a thirteen-year-old water pump with electronics didn’t inspire my confidence at 67K miles. I bought a water pump (Pierburg, OE), a Tstat (Borg Warner/Wahler), BMW coolant, a Tstat-to-Pump hose (Rein), and a Tstat-to-Oil Filter Housing hose (Rein – w Aluminum “Mickey Mouse” flange). The pump comes with the necessary 3 Aluminum E10 bolts. I mostly followed a couple of YouTube videos [ 1, 2 ] – but one thing I did differently that might help someone else, was that I removed the Tstat with both clamp-on hoses attached to it. Keep in mind, I had the radiator out to replace the EAC sensor, so I had more room, and clocking the hoses on the Tstat was easy with old and new parts side-by side on my garage floor. With more room the “hard” WP bolt was far easier too.

Spark Plugs, VC Gasket, Valvetronic seal, ESS seal, ES Sensor – My VC gasket and ESS seal were beginning to leak, so I decided not to wait until it all got really bad. I followed this YouTube along with a blog from FCP Euro. I replaced the spark plugs as well – using NGK Iridium plugs. I used Elring VC gasket, Valvetronic motor seal, and Eccentric Shaft Sensor (ESS) seal. Because I didn’t know what shape the ESS would be in before I started, I ordered a VDO sensor from RockAuto (least expensive) to have on hand, and I installed it to avoid going back in later. I found a video on how to remove and reuse the spark plug tubes, so I offset some of the extra cost for an ESS that might not have needed to be replaced.

Comment: The N51 motors have Supplemental Air Injection (SAI) on cold start, and the SAI valve makes this job more challenging. I suspect BMW might have planned for this job to be done leaving the pump in place on the cylinder head, because the two E10 valve cover bolts on either side of the valve are not captive the way all the other 17 VC bolts are. At first I wondered if someone had been in before me and messed with them, but the holes for those two bolts are smaller ID and have standoffs to prevent over-compressing the gasket. This design lets you take the bolts out of the VC for removal and installation, and those bolts are easily replaced because they are on the accessible side of the VC. But I had already removed the SAI valve.

For added room in getting the VC off and on again, but not removing wipers, see this E90 post by Asetoy2nr.

Hope this helps someone reduce the time to look up procedures or speeds the process for them on one of these five DIY tasks. Now I'm ready to drive !

[JustCallMeJo]

Originally Posted by MarinerZ4C

TIP: My car has the N51 SULEV with a semi-rigid fuel line making access to the Torx® bolt under the intake even harder than FCP Euro video – BUT if you have a ratcheting E10 box wrench, this bolt can be reached from the front, sideways, and you’ll be fine. It’s easier if the oil pressure switch is removed first (and I changed it out anyway).

I just finished doing this and I kept wondering how the FCP Euro guy was getting to that torx bolt... it was super frustrating. I was finally able to get it worked, but not a great time. I'll check out the box wrench next time.

I was searching FCP Euro and wondering if maybe a tool like this would be useful in etorx... https://www.fcpeuro.com/products/1-2...gearwrench-104

I'm gonna bookmark this page now...