Danny's 92 525it/5

[dannyzabolotny]

Window tint and regular conditioning go a long way towards keeping the seat leather happy. The ones in my car turn 30 years old in November, and are in better shape than most 5-year old cars'. For 12 of those years they had Leatherique every 6 months and 5-15% tint protecting them. I worry about jean studs and pocket knife holsters more than the elements.

This car hasn't seen any love in a pretty long time... 212k miles, salvage title (which is also missing), and hasn't been running until recently for most of a year. I removed a small pile of cigarette butts and air fresheners from the car when I bought it, it was incredibly gross.

[dannyzabolotny]

The other day I decided to tackle fixing the persistent CEL that the car’s been having since I got it running. The code was 1224, so intake temp sensor. I looked at the intake temp sensor plug to make sure that all the wires were there, and then I realized that it only had 1 wire. Justin confirmed that I had the intake temp sensor and oil pressure sensor wires mixed up... d’oh! After switching those around (on a hot engine!) the CEL went off and stayed off, and I swear the car idles better and has a good bit more power now.

My friend Brad also showed me where the cabin air filter was in the E34, so once I replace that I should get much better AC airflow along with less odors. I honestly didn’t know the E34 had a cabin air filter, as there aren’t any under the hood like in my E39.

I love making all sorts of small improvements to the E34, it just gets better and better!

[dannyzabolotny]

With the 525it running properly, I really started to notice the limitations of the tires; they were all low on tread, were from different brands, and were starting to dry rot. Which was great for burnouts and whatnot, but not for safe driving. Lots of vibrations at highway speeds too. I also noticed an intense rubbing when turning the wheel more than a little bit, presumably because the wheels were not originally from an E34 and had the wrong offset.



(Still have to figure out if the 525it still has its factory spec LSD or not... doesn’t look like it)

I remembered that I had some staggered 17” style 32’s laying around from my 2000 540i/6 parts car, so I ordered hub rings from Amazon (to make the 74.1mm E39 wheels work with the E34’s 72.56 hub). Earlier today I mounted them and oh man do they look good.

A few things I noticed while putting the wheels on was how low the brake pads were and how grooved and nasty the rotors were. Those will have to be replaced very soon.



In the back was a 1” spacer along with extended lug bolts. I kept the spacer since it made the rear fitment look way more aggressive.



With the style 32’s mounted, I admired my work (more like, went to the gas station and took pictures while filling up the E34’s freakishly large gas tank).







The style 32’s look awesome, drive way better, stop better, and don’t rub at all. Sounds like a win-win to me!

Now that the tires are not about to explode, I can turn my attention to the other things this car needs mechanically:

- Brake pads & rotors
- Brake fluid flush
- Transmission fluid change
- Oil & oil filter change
- Fuel filter
- Thermostat

Other things I might do soon are the fuel filler door hinge and trunk struts, just because they’ve been bothering me.

[moroza]

Intake air temperature is a critical part of the ECU's calculations. I'm not surprised it runs a lot better with the correct values, rather than those of the oil pressure sensor. "IAT, how many degrees is the air?" "Uhhh...15psi at idle, 45 if you rev it up." "Wilco tango foxtrot, over..."

Or to put it more blandly, I believe the oil pressure sensor is just an open/closed switch, while the IAT is a variable resistor. If it's like the coolant sensor, low resistance is high temperature, and vice-versa. Assuming your oil pressure is good and so is the switch, the engine was running as if the intake temp were extremely high, probably even higher than the actual air in AZ. Did you notice if it ran worse at night?

Your rear exhaust hangers look to be on their last legs, or beyond.

[dannyzabolotny]

Intake air temperature is a critical part of the ECU's calculations. I'm not surprised it runs a lot better with the correct values, rather than those of the oil pressure sensor. "IAT, how many degrees is the air?" "Uhhh...15psi at idle, 45 if you rev it up." "Wilco tango foxtrot, over..."

Or to put it more blandly, I believe the oil pressure sensor is just an open/closed switch, while the IAT is a variable resistor. If it's like the coolant sensor, low resistance is high temperature, and vice-versa. Assuming your oil pressure is good and so is the switch, the engine was running as if the intake temp were extremely high, probably even higher than the actual air in AZ. Did you notice if it ran worse at night?

Your rear exhaust hangers look to be on their last legs, or beyond.

Haha well I forgot all about the IAT, to be honest. My E39 540it doesn't have a separate sensor for IAT, apparently the MAF has that functionality integrated into it (just researched that). So it wasn't on the top of my list when diagnosing the engine running poorly. It ran about the same regardless of day or night. In any case, it's running really well and I now know the importance of having a proper IAT sensor.

Yeah, the exhaust hangers aren't happy, but I'm planning on taking a sawzall to the rear muffler pretty soon anyways. None of my cars have mufflers, and this 525it will be no exception. It'll lose a bit of weight and sound better, so it's pretty much a win-win. And once I get it through emissions I'm basically going to straight pipe it— no cats, no mufflers, just a fat pipe heading all the way back. My 97 M3 doesn't have cats and it's awesome.

[dannyzabolotny]

Earlier today I went and picked up a bunch of maintenance parts at AutohausAZ so I could get caught up on some much-needed maintenance. Oil filter, cabin air filter, thermostat, fuel filter, and more. Any recommendations on oil? I was going to go with Castrol 5W30 synthetic.

After that I stopped by a title agency to get started on obtaining a title for this 525it. Turns out it was salvaged in 2016 (I knew it was a salvage title but didn't know from when) and then abandoned at some point, after which the car's official history more or less ended. Several unofficial owners later and it ended up in my hands. It'll take a few weeks for the process but the title agency is handling all the work so that makes my life a lot easier. In the meantime I got a 90-day registration so I can drive the car around freely.

I've been having a lot of fun with the M50, it's such a simple little engine. Easy to work on, revs happily, and enjoys being beat on. The 525it is hardly fast but it's really fun in its own way because I get to really wring it out for every bit of power, as opposed to always holding back in my 540it.

[dannyzabolotny]

Last night I started doing some maintenance and repair work. The first thing I did was replacing the fuel door hinge. I decided to be cheap and get the Uro part replacement, which worked okay but required a lot of fiddling to install, so maybe next time I'll just get the OE part. Still, the car looks a *lot* better with a fuel door.

Before:



After:



Next up was replacing the cabin air filter, as my E34-owning buddy mentioned it to me the other day. I wasn't even aware that these cars had a cabin air filter, but it turns out they do have one! And it's super buried. I had to remove the glovebox, the floor ducts, and a few other trim pieces to get the filter out. This is definitely one of the more complex cabin air filter replacement jobs I've done.



My efforts were rewarded with this nasty old filter (next to the new filter).



Yes, the old filter was once white (the other side is still white). Looking at it closely, I saw that it was from 2004... so that air filter was 14 years old! No wonder the AC smelled musty and had a hard time pushing out air.

After reassembling everything, I tested the AC and holy cow what a difference! Before replacing the filter I needed to keep the fan speed at 3 to get any amount of airflow, but now it flows well on all settings, with 3 and 4 being an absolute hurricane in comparison.

I love working on super neglected cars like these, because they really reward every bit of maintenance done. I can see and feel the car getting better with every single thing that I do, and that's a pretty rad feeling.

[moroza]

Regarding oil, you may find that crud was keeping some of the seals going, and that synthetic oil removes that crud and results in leaks. But hey, if your RMS starts leaking, it's a great excuse to upgrade to a lightweight flywheel. Unless you have one already?

[atl530i]

Happy to see all of this coming together and always happy to help! I was looking at style 42's (like my last wagon) but may get some 32's for it now. Those look great.

[dannyzabolotny]

Regarding oil, you may find that crud was keeping some of the seals going, and that synthetic oil removes that crud and results in leaks. But hey, if your RMS starts leaking, it's a great excuse to upgrade to a lightweight flywheel. Unless you have one already?

Eh, I'm pretty sure it was synthetic oil in there already. I put Mobil 1 5W30 in there, so I'll keep an eye on things and see if anything leaks. The clutch seems fine so I'll replace it when it needs to be replaced. Not sure about going to a lighter flywheel, I like how smooth and drivable the heavy flywheel is, as well as the lack of chatter/noise with it.

Happy to see all of this coming together and always happy to help! I was looking at style 42's (like my last wagon) but may get some 32's for it now. Those look great.

Thanks again for all your help! Yeah, the style 32's look a lot better than I thought they would, and the car rides absolutely amazing on them. No more shaking or shimmying, just smooth 90+ mph driving.

---------------

So the other day I finished the rounds of maintenance on the 525it. I wanted to address the car running cold on the highway, so I removed the thermostat housing, and what I found was shocking... or rather what I didn't find was shocking.



Looks like there was no thermostat at all! I wonder why somebody would do that? The housing was also covered in nasty old RTV, so I took my time cleaning it and installed the new thermostat in the engine block with the arrow facing up, as per several DIY guides.



Now the engine gets up to temperature pretty quickly and it seems to stay there consistently. With that taken care of, the next step was changing the oil. Nothing to really report there— the old oil looked black and worn out but I didn't see anything scary in it. I got a proper Bosch kit so I replaced the drain plug crush washer and all the o-rings in the oil filter housing. The old oil filter didn't look terrible but it was some cheapo Autozone-grade filter so at least now it's a proper Bosch filter. Then I filled the engine up with 6 quarts of Mobil 1 5W30, and it seems to run much happier. Less ticking in the valvetrain and overall the engine just seems to run smoother now.

The last step was to replace the fuel filter with a new Bosch unit, which was very straightforward and easy to do. No noticeable difference there but now I know the injectors won't get clogged with crud.

With all of the engine fluids taken care of (and power steering fluid topped up with fresh CHF), I could turn my focus towards some cosmetic work. I had my friend Jacob come over with a steam cleaner and some pro-level detailing gear, and together we tackled the absolutely disgusting interior. We got about 40% done today, and it's already a huge difference in some key areas.

The steering wheel is a lot less shiny now and doesn't feel nearly as gross to touch now. We also cleaned all of the contact surfaces like the HVAC, turn signal and wiper stalks, headlight/foglight switches, door handles, sun visor, etc. It really does feel a lot nicer to be in this 525it now, whereas before I was afraid to touch certain parts of it.



The driver's door panel is still falling apart but now it's not disgusting to touch. At some point I'm going to try gluing it up to try and make it a little more presentable.



Check out this before and after of the carpet in the rear... crazy what a difference a bit of steam cleaning can make. Also, the cubbies in the center console are now clean and free of all the nasty sticky goop that was in them before.



The back seat also reacted really well to some cleaning, with the leather softening up considerably. We'll work on it some more soon but I think the back seat is definitely salvageable, which is a relief given that it's touring-specific. We also cleaned the air vents thoroughly and blasted the whole system with steam to try and kill some of the funk that was in the vents. It worked out quite well, and the air coming out of the HVAC no longer smells nasty. Slowly but surely, this 525it is becoming a decent car!

[squirrelhill]

Your touring is really coming along nicely and is it great that you gave her a "new" life.

I imagine that others may chime in, but query whether the 5w30 is heavy enough oil, especially in a warm climate. You may wish to consider a quick interval on the 5w30 and switching to a 15w40 for better protection (and perhaps less lifter noise). FWIW, in the summer, I run Rotella T5 15w40 in my e34 touring (263k miles) and she runs very smoothly.

[e30luv318i]

Wow man ! Great turn around on this car !

[dannyzabolotny]

Your touring is really coming along nicely and is it great that you gave her a "new" life.

I imagine that others may chime in, but query whether the 5w30 is heavy enough oil, especially in a warm climate. You may wish to consider a quick interval on the 5w30 and switching to a 15w40 for better protection (and perhaps less lifter noise). FWIW, in the summer, I run Rotella T5 15w40 in my e34 touring (263k miles) and she runs very smoothly.

Right on, maybe I'll switch to something thicker on my next oil change. I'm not pushing the M50 super hard yet so for now I think the 5W30 will be fine, but once I get more comfortable and start hitting redline more often it's probably a good idea to go to something thicker, especially when it's 110ºF here in the summer. So far it seems happy, 212k miles and running strong!

Wow man ! Great turn around on this car !

Thanks! I saw it as an otherwise nice car that had been through some idiot owners, plus it had a cool interior color and already had a manual swap done, so in my opinion it was worth saving. It was scheduled to be impounded the next day and likely would have ended up in the junkyard, so I'm glad I intervened and brought it back to life. It hadn't run in like a year prior to me buying it, it just kept being passed around from one owner to another.

Last night I went to the local car meetups, where I parked next to two newer (but not necessarily better) BMW tourings. I think my E34 touring still holds up nicely, especially once I do some more cosmetic work.



A lot of people in the local BMW scene recognized the car and were happy to see it back on the road.

[dannyzabolotny]

Today I removed the stock muffler from the 525it. I figured it would make the car sound better and save a little weight, so why not? The exhaust hangers were on their last legs anyways. Removing the muffler was a very straightforward affair, I just had to remove a few 13mm bolts on the clamps and hangers and off it came. This has to be one of the easiest muffler deletes I've done in a while, and it's completely reversible since I didn't have to do any cutting at all.



Now it sounds way better in my opinion, take a listen:



It doesn't drone much on the highway and it's quite civil. Eventually I'll go to an exhaust shop and get proper tips made as opposed to just having the exhaust dump around the axle like it does now.

[dannyzabolotny]

The other day I noticed how rich the 525it was running when I rolled down the window for a moment. I normally drive with the windows up and the AC on all year round so I didn't notice it before. My initial suspicion is that the pink top injectors (21#) are too much for the stock tune, so it's dumping a lot more gas than needed. The stock M50 injectors are 19# green tops, so I got a known good set from a friend today. I'll install those either tonight or tomorrow and see if that fixes the problem. Maybe the O2 sensor needs replacing as well, I'll try that next.

[moroza]

Why is it fitted with non-stock injectors in the first place?

[dannyzabolotny]

Why is it fitted with non-stock injectors in the first place?

Those were the injectors that came with the car, dunno why. I tried sourcing a set of green injectors from a junkyard previously, but they ended up not working very well. So I had the pink top injectors in there for a while since the engine did run with them.

[dannyzabolotny]

The other day I swapped the proper green top injectors in, and now the engine seems to run a lot better. The exhaust doesn’t smell rich anymore, so I’m sure I’ll get much better fuel economy and be able to pass emissions properly.

Now onto the next problem— I think my fuel pump might be on its way out. My friend Brad told me that when he was sitting in the back seat, he could hear the pump quite loudly when under load.

Yesterday I drove it to get lunch and upon getting back into the car it started up and died almost immediately. I tried starting it back up but it just cranked without starting. I left the car in the parking lot and took a cab home, since I wasn’t very far away. Later that night I went to the car with some tools and a spare fuel pump, but I decided to try starting it, and it started right up! I was then able to drive it home without any issues. I’m guessing the fuel pump was overheating or something like that? A similar thing happened with my 750il a while back, where it died but I was able to start it a few hours later.

In any case, the 525it is now safely back at home and will probably stay here until I can definitively fix the problem. Most likely it is the fuel pump, especially since the one in the car is from a junkyard.

[moroza]

That sounds like typical fuel pump failure, but how old is the filter?

[dannyzabolotny]

That sounds like typical fuel pump failure, but how old is the filter?

The fuel filter is brand new, I replaced it in my round of maintenance that I did a few weeks ago. Fresh gas too, and the fuel tank is perfectly clean with no debris. I haven't run the gas tank down to empty either, but I'm guessing the pump is just old— I pulled it out of a junkyard 525i so I have no idea how old it actually is. The fuel pump in the 525it was otherwise original when I had first gotten it, so it's probably not any better (I replaced the fuel pump when I couldn't get the car running initially, turns out it was a different issue).

I guess I'll bite the bullet and spend the $147 on a new Bosch fuel pump at AutohausAZ. I figure that's one of the few things that can truly leave me stranded so it's worth having a brand new one with a warranty. I plan to go on a few adventures in this 525it so the extra bit of reliability will be much appreciated.

[Kingpin025]

Not sure what your plans are with brakes, but you can add 540i/M5 calipers from Rock Auto as a pretty cheap upgrade. You will pay a core charge up front, but I just dropped my 525i calipers in as returns without issue. I just did this exact upgrade on my touring. I would recommend for future wear item replacement consider FCP Euro and their lifetime guarantee on all items they sell. That means if you buy upgraded 540i/M5 rotors and pads from them to go with your new calipers from Rock Auto you'll only have to pay for them once. Here's a link to their policy. https://www.fcpeuro.com/page/lifetime-guarantee

[dannyzabolotny]

Not sure what your plans are with brakes, but you can add 540i/M5 calipers from Rock Auto as a pretty cheap upgrade. You will pay a core charge up front, but I just dropped my 525i calipers in as returns without issue. I just did this exact upgrade on my touring. I would recommend for future wear item replacement consider FCP Euro and their lifetime guarantee on all items they sell. That means if you buy upgraded 540i/M5 rotors and pads from them to go with your new calipers from Rock Auto you'll only have to pay for them once. Here's a link to their policy. https://www.fcpeuro.com/page/lifetime-guarantee

How much were the calipers at Rock Auto? I'm open to doing that since I need to overhaul the brakes either way. I always get brake parts from FCP Euro, their lifetime warranty is rad. The only downside is that it takes forever to ship from there to Phoenix, so for stuff that's needed ASAP I end up buying at AutohausAZ which is local and has stuff available either same day or next day for pickup.

[Kingpin025]

Prices vary depending on which re-manufacturer you select. Less than $100 each, plus core that you get back when you return your takeoffs. Just get on their site and either select 1993 M5 or 1995 540i and see what they have in stock.

[MooseBranch]

Reading through this has been very satisfying lol Nice work on giving it new life

[dannyzabolotny]

Prices vary depending on which re-manufacturer you select. Less than $100 each, plus core that you get back when you return your takeoffs. Just get on their site and either select 1993 M5 or 1995 540i and see what they have in stock.

Awesome! I'll definitely keep that in mind when I get around to ordering brakes. Part of me would still rather go to the junkyard and grab some brakes off a 540i and just rebuild them myself, haha. It can't be that hard and I'd save a few bucks.

Reading through this has been very satisfying lol Nice work on giving it new life

Thanks! It's been nice to bring a car back to life after it was left for dead. A lot of people in the local E34 community thought it would never drive again with how messed up it was, but I proved them all wrong (with some help from bf.c, of course).

The other day I found a 1991 535i in the junkyard that appeared to be in really nice shape— it was a light blue on the outside with a dark blue interior. Very cool, wish I had the money to grab the whole interior, it was in rather nice shape for a junkyard interior. In any case, that car had a fuel pump that looked almost new, so I snagged it for $38 with a warranty. With the new (used) fuel pump installed, the 525it came back to life quite nicely.