[cbrider73]

I have been driving BMWs since 2000 (1998 E39 528i). The plastics under the hood has sucked on all of them. Turns out the B58 is no different with regards to the cooling system. I have been 100% DIY my whole driving career and decided to do a minor "refresh" after I started losing coolant and my splash shield was soaked. 80,000 mile 2-owner car very well maintained. If you are a "while you are in there" type person, then stay tuned. I went a little wild...

Turned out after I pulled the manifold that my only significant leak was the turbo coolant pump hose that goes from the little electric pump to the OFH - it was leaking from the o-ring at the OFH connection. I COULD have just replaced that hose and moved on, but no. I had already ordered the following before even tearing into anything:

-Aluminum OFH (oem gaskets, etc...)
-Aluminum water neck
-Heat management module (HMM)
-Water pump
-That main upper rad hose

Well, after taking off the manifold and seeing the mess of hoses (and connectors that were tuning brown...not a good sign) I decided I didn't want to go back under there for a while. Order #2 for parts:

-Turbo coolant pump
-Turbo coolant feed line that wraps behind the head
-Both heater hoses
-HMM to water neck hose
-Expansion tank to head hose
-Expansion tank to HMM hose
-Hose from turbo to OFH
-Quality complete cooling system o-ring kit for an E90 because I could tell a lot of the fittings were the same size. Replaced every o-ring in any hose that I did not replace. Dude on eBay sells the packages. Hit him up. It's good to have some around...

So while waiting on that order I decided to walnut blast the intakes "while I was in there". That harbor freight setup with the fine crushed walnut shell (don't buy the course - too big and clogs everything) was around $150 including the port adapter I got off eBay. I think the setup and learning curve took longer than actually blasting the valves. Worth the effort, but took a good part of a Saturday to get it done.

Sooooooo, got everything buttoned up, bled the intercooler system all good. Went to do the engine coolant bleed and was getting a HMM valve stuck open code through ISTA. Turned out I got a bad HMM (URO part). Heavily bummed to have to pull the intake back off and all the other stuff. So heavily bummed I spent the big money on the BMW part for $500. My original HMM was fine. It made some squeaky sounds when the car woke up, so I replaced it - twice. Good times.

So, I got everything buttoned back up again and the car runs great now and I have some peace of mind. Some notes and suggestions are below.

-Water neck was grody looking for 80K miles, but still structurally sound. Same with the gasket, still pliable. Replace this anyway.
-OFH didn't look bad at all. Gaskets still squishy and no weird stuff. Probably could have gone past 100K miles with it
-Original water pump was fine. Probably would have waited, but I am sick.
-HMM was working fine, but was getting squeaky when waking the car up. That is the servo motor sound you hear. Bothersome at least.
-Total cost of all parts including the walnut blast stuff was probably around $1,500. - A lot of the hoses were BMW because I couldn't find cheaper alternatives.
-Get some extra o-rings for when you drain the coolant systems. Old hoses WILL leak soon if you don't at least pop in some new o-rings. All the intercooler hoses looked fine. Just replaced o-rings on the hoses I disconnected.
-The wire covers for the circuits that run parallel under the head were falling apart they were so heat damaged. I recovered them all and ran them through some 1.5" velcro heat protective covering, I recommend at least recovering them to prevent bare wires in the future. See picture.
-No crank no start on first try with lots of codes. I had an ECU connector not fully seated. These like to be fully seated manually, THEN raise up the locking lever. Don't use the locking lever to pull the connector into the socket!
-The intake valves were not N54 bad, but bad enough that I did not want them to go another 80K miles. See pictures.
-Don't wig out on the ECU connectors. I verified that they only fit into their sockets 1 way. The plug shapes keep from plugging in wrong. Take pics/vid first.
-Obligatory "unplug your battery"
-Prime your oil system before starting! I used ISTA - took about 5 cranks to build pressure, so I did 7.

As others have said, it's not a hard job, but it is very involved. I can see it overwhelming inexperienced DIYers. It was one of the more rewarding jobs I have done because I feel like it truly is better than it left the factory. Well, a bunch less plastic now, anyway. The B58 is still my favorite BMW power plant that I have owned to date. I have owned M52, N52, N54, N55 and have a good frame of reference. That rod-bending torque gets me every time.

[dradernh]

Originally Posted by cbrider73

The B58 is still my favorite BMW power plant that I have owned to date. I have owned M52, N52, N54, N55 and have a good frame of reference. That rod-bending torque gets me every time.

As a non-DIYer who nevertheless participated in the full rebuild of two engines - one I owned and one in high school auto shop class - yours is an impressive post.

Before the B58, my favorite engines in cars I owned were the M88/3 in an M635CSi (in this country in 1985, an incredible revelation for a daily-driver level street car costing "only" $43,500); the other being the S50B32 with a full list of pro-level race upgrades in a race car.

I consider the B58 to be the perfect street/track engine, with its torque always leading the way.

[cbrider73]

Originally Posted by dradernh

As a non-DIYer who nevertheless participated in the full rebuild of two engines - one I owned and one in high school auto shop class - yours is an impressive post.

Before the B58, my favorite engines in cars I owned were the M88/3 in an M635CSi (in this country in 1985, an incredible revelation for a daily-driver level street car costing "only" $43,500); the other being the S50B32 with a full list of pro-level race upgrades in a race car.

I consider the B58 to be the perfect street/track engine, with its torque always leading the way.

M88 and S50 are some cool engines, especially the S50! As we say, you aren't buying a car when you buy a BMW. You are buying the powertrain. I am a big straight-6 fan and BMW was the only one holding on for several years. Now Mazda and Dodge have some. I won't get one, but glad they are going back to a 6. I am getting an itch for an M57 or M58 turbo diesel car....I got problems.

[who is this noob]

cbrider73,

Great post. I’ll remember to inspect those wires when I do this service.

The B58 mid-range is great but sometimes when pushing hard I yearn for less at the bottom and more at the top. Maybe there’s a tuning app that would allow me to switch maps on the fly. “Soft torque” engine calibration would be fun in these instances.

[cbrider73]

Originally Posted by who is this noob

cbrider73,

Great post. I’ll remember to inspect those wires when I do this service.

The B58 mid-range is great but sometimes when pushing hard I yearn for less at the bottom and more at the top. Maybe there’s a tuning app that would allow me to switch maps on the fly. “Soft torque” engine calibration would be fun in these instances.

I know what you mean. I daily an N52 car with the 3-stage intake and tune, so it should be making around 260 HP and 230 ft/lbs of torque. It likes to be revved out and doesn't make much power unless you do. It's more fun in to drive if you are just wanting to beat on a car. It feels like a dog after driving the 240 around...

A good tune can definitely help the B58 up top, but it will always be a torque motor based on the long stroke and twin scroll turbo. Get a big turbo upgrade and that moves the power band to the right quite a bit.

[Dantesboyz]

Im mid a very similar project
Replacing all three pumps, OFH and flange.
Also doing a CSF heat exchanger, on xdrive so I had to use the relocation bracket for the transmission cooler.

I did have to trim the plastic shroud by the cooler lines for the modification but looks like its gonna fit nice.
Ill work on it more this week, but let me know if anyone has questions.