BMW E28 Fuse Box

This article discusses the fuse box for the E28.

A client with a 1998 BMW E28 M5 contacted me, looking for a fuse box. His car`s fuse box had melted in one or more areas, and he figured it’d be prudent to replace it.

I was sure that I didn’t have a unit in stock specific to the M5, so my tech looked into this in more detail. The best available information she found showed that the part number is 6113 1369596 and that all E28 variants use this same part number.

Interestingly enough, the 1981-1982 BMW E23 7-series also uses this same part number — but only those model years.

Allegedly, the accessory fan and A/C fuses are the ones that have problems with melting, and a box with no melting is rare.


BMW E28 and E34 5-Series M20 Engine Drive Belt Preventative Maintenance Interval

This article discusses the ideal interval between drive belt replacements for the E28 and E34 with the M20 engine. I’m focused here on the belt that drives the alternator and water pump, not the timing belt. We might as well include the belts for the air conditioning compressor and power steering pump, respectively.

Obviously, it’s a good idea to replace the drive belts regularly. As to what “regularly” means: when I started to write this article, I didn’t know a good answer to that question. I still don’t, though I read someone official-sounding suggesting that a good interval is anywhere from 40K to 70K. That seems reasonable to me. BMW probably has an official number too, but that no doubt is highly conservative, and it also presumes original BMW equipment, which most people probably don’t use on a 30-year old car.

I’ve had a drive belt fail on my 1987 BMW, and it was disconcerting to see the alternator warning light come on and then to see the temperature gauge slowly climbing while my conscience was whispering: “you DO know this engine has an aluminum head, and you know what happens to these when they overheat, yes?”

This sort situation is best avoided. I replace the timing belt on my M20-engined cars every 60K miles. Replacing the drive belts then too . . . that’s my new, improved plan.


Looking at Actual Parts, Carefully

I recall my surprise at analyzing some 3-series E30 glove boxes, and discovering that the glove boxes for cars with the later-than-Motronic-1.0 computer had a shallow notch at the inner front corner, so that the thicker fuel injection cable (three rows of pins vs. the earlier two) doesn’t chafe. It’s a very logical engineering change, and not surprising. The glove box with the notch even has a different part number.

What made this surprising is that the official BMW parts list mentions only one variation. So, by analyzing the parts, physically, carefully, in person, I found out more than if I’d just read about things online.

For a while, I tried to figure out what made some cars have the earlier-style glove box vs. not. The change seemed to center around 1987 but I couldn’t put my finger on it until I realized that cars with the older version of Motronic computer had the older version of glove box, and 1987 was the year when things changed a lot as such — but the 1987 325i cars had the newer-version computer whereas the 1987 eta-engined cars still had the older-version computer.

imag4894This experience really inspired me to go look in person at what’s actually going on. It reminds me of when I worked at an automobile assembly plant (not for BMWs, sadly). The production control folks had recently managed a change by which cars of a particular model would be fitted with chrome tips on their exhausts. The parts were ordered, brought to the production line, and the assembly instructions were changed to tell workers to put the chrome tips on. But, at the end of it all, my job included being the reality-check person, to go see if in fact all of this planning had actually resulted in chromed-tip exhausts on cars exiting the assembly line. For me, there’s nothing as solid and reassuring as seeing something first-hand.

So, today’s project involved Mass Air Flow Meters on the M30 engine. I own a 1980 BMW 633 CSi, a 1992 BMW 735i, and several models in between, including a 1984 BMW 633 CSi and a 1984 BMW 733i. My tech and I inspected the mass air flow meters on all of these cars, and checked the part numbers. Of course, it’s possible that some of these parts were not originally on the car, but I’ve personally driven each of these cars so I know that the part at least works on that car.

Although the 1992 car has a pretty plastic cover on top of the mass air flow meter, when the cover is removed, the part is the same as on all the other models we analyzed. And so, now we have a good handle on mass air flow meters for the M30 engine.

There are still a million things we DON’T know for certain, but it’s nice to have a fairly good handle on at least this tiny part of the puzzle.

That’s the sort of confidence and certainty that we enjoy.

I want Empathy when I Buy Parts, Dammit

The local BMW dealer parts counter guy seems to be a nice man, but … sad. I can guess why. Day after day, he deals with the following two sorts of dialog, many times a day:

“Hey, I’m looking for an alternator for a 1987 BMW 535i.”
“What’s the VIN?”
“I don’t know. I don’t have it with me. I’m at work. The car’s at home.”
“I need the VIN to look up the parts.”
“Well, I don’t have it.”
… and it doesn’t get better after that.

Assuming the person does have the VIN, the next conversation goes something like this:

“How much for the alternator?”
“Say, what?”
“For the alternator?!”
“Wow! The entire car cost me maybe $2K and that had a working alternator. That’s crazy.”
… and it doesn’t get better after that.

Aftermarket prices are often better, and sometimes not by much. Sometimes, when I heard the price, I thought “Forget that,” or some less-polite variant.

Seems to me that whoever comes up with these prices has no idea of the basic viability of someone who’s not made of money, trying to keep their E28 or E34 going. There seems to be a basic disconnect when the parts prices are so high that a customer reacts with incredulity. Basically, the vendor and the customer don’t relate to each other. They’re are not on the same page. There’s no empathy.

* * *

BMW parts prices can suck, but there’s a parallel to that: software.

How often have you used software that sucks, because regardless of how technically cool it might be, it sucks for you because it doesn’t work for you? Whoever made it didn’t empathize. As to whatever your situation was, they didn’t “get it.”

There is a better way. In the software industry, it’s called “Eat your own dog food.” Wikipedia defines it as: Eating your own dog food, also called dogfooding, is a slang term used to reference a scenario in which a company (usually, a computer software company) uses its own product to demonstrate the quality and capabilities of the product.”

It’s a great idea.

That might be the best reason to buy your used parts from my little company. What’s in it for you? You’re understood. That’s it. We also drive old 5-series cars and we’re trying to keep them going, with a tight budget. We empathize.

For a while, I’ve driven a 1987 535i whose rear window was a plastic sheet. And, I survived. I didn’t have a used rear window, and I didn’t have money for the “new parts” solution.

My little used parts business is not the world’s smartest when it comes to E28 or E34 cars. We haven’t been in business the longest. We don’t have massive depths of technical insight. We don’t have a huge inventory. We often mis-estimate the time it’ll take to get a part into inventory.

But, dammit, we relate. We have our own little sad fleet of several floundering old 5-series cars, and we struggle to keep them going on a tight budget that includes wondering how we’re gonna pay the rent this month. We get personally stranded when a main fuel pump dies, and we have to walk home and figure out what’s wrong, how to remove the bad part without causing a fire, and how to replace it without paying three figures.

This struggle makes us relate to customers who struggle, just like us.

We need to buy food, pay the rent and somehow keep viable, as transportation, an almost-30-year old car that most people have given up on, long ago.

We tenaciously refuse to let these cars die. We make plans, we find money, and we pull through — so that we can keep driving these magnificent pieces of engineering, even if the dash lights don’t work and the heater fan is broken. At some point the way we’d turn on the lights on one of the company E28 cars was to hot-wire the parking lights’ wiring to the low-beam circuit. But, dammit, we kept it going until we could figure out a better way. We’re still in the game. We’re fighting and if driving the car one more day is victory, then we’re winning.

If you like that mindset, buy your stuff from because you’re dealing with someone who “gets” you.

Windshield Removal on an E28 BMW 528e

Whenever I try to remove a windshield intact from a donor car, I work on the assumption that I can salvage the windshield or the rubber, but not both. Someone more skilled than I am can, no doubt, do better.

The first step is to inspect the windshield on the donor car well. Wash it well, and then sit inside the donor car and look at an external light source through the windshield from various angles. Even if the windshield lack major rock chip damage, it might still be in poor condition due to many minor problems that cumulatively make for a big problem. If you decide to proceed:

Close the hood and lift the wipers.

Using a flat-bladed screwdriver, take about twice as much time as you think is reasonable, and gently pry loose the amazingly fragile chrome-plated L-shaped trim pieces at the lower corners.

Use the same time management principle, remove the long chrome strip at the lower end of the windshield rubber. It is very easy to damage this part in the process.

The remaining structural element involves a plastic strip that makes the top and sides of the windshield rubber more rigid. Pull that out gently, keeping in mind that it might well be brittle.

The remainder of the work involves using a sharp knife to cut away the portion of the windshield rubber that prevents the windshield from being removed towards the front of the car. Cutting rubber is fairly tricky, and it’s easy to make the knife slip and get cut.

Make sure you remove all of the rubber that keeps the window in. Missing even a tiny section will create uneven pressure that can cause the windshield to crack when you remove it.

Before you remove the windshield, plan and prepare where you’re going to put it down. For me, it seemed less tricky to put it down with the center of the windshield facing downwards.

Drive Shaft Removal on a BMW 528 E28 with Automatic Transmission

My 1986 E28 528e is in exceptionally good condition but right before I bought it, it was parked for a many years. I have learned that this sort of thing causes a few typical points of failure. That includes the universal joints in the drive shaft. I had something similar happen on my 1973 Volvo 145, that I parked for several years — a not-so-smart thing to do.

The symptom on the BMW manifested itself with a pretty severe seat-of-the-pants (as opposed to front-end) shimmy at low speeds. My local drive shaft fix-it place diagnosed the problem as the front universal joint being a) completely frozen up and b) non-serviceable. Were the latter not the case, a $15 part would solve the problem, such as was the situation for my Volvo 145.

The last time I heard that the drive shaft on my car was non-serviceable was some years ago, on my 1987 E30 BMW 325. The part cost me $500. So, now that I’m cheerfully in the used-parts business, I could solve the problem myself, this time.

The donor car for my 1986 528e was a 1984 automatic 528e. I haven’t as yet measured and analyzed precisely how the drive shafts differ between stick shift and automatic 528e cars but I’ve been told they are different so I made sure the donor car also has an automatic transmission.

Before removing the drive shaft, it’s a good idea to get the rear of the car up on jack stands. Chock the front wheels because the rear wheels will have to move freely.

Get underneath the car and find the 17mm nuts at either end of the drive shaft, and douse them with penetrating oil such as WD-40 or PB Blaster. That way, the chemicals have time to do their work while you focus on the exhaust, heat shield and center support.

Removing the drive shaft requires first removing the exhaust since that’s pretty much directly below the drive shaft.

Next, there is a large heat shield whose six nuts are best removed with a 10mm socket and a short extension. Some large washers prevent the nuts from pulling through the heat shield, and once you have removed the washers, the heat shield should be ready to fall on your head, which shouldn’t hurt too much since it’s fairly light.

With the heat shield removed, the center support becomes visible. Its two nuts are best loosened with a 13mm socket and a short extension. The ideal approach is where you loosen the nuts to where you can remove them by hand, but leave them in position … for now. That way, the drive shaft doesn’t sag in the middle.

Recruit an assistant (preferably one with pretty shoes, feet, ankles and calves since you’ll be underneath the car and that’s probably all you’ll be able to see). I recommend as a supplier of assistant footwear — if you’re going to be working on your car, you might as well enjoy it. Ask her to put the transmission into “park.”

Loosen one nut using a high-quality 17mm ring wrench, ideally a ratcheting one such as those that are part of the Sears Craftsman range. You definitely don’t want to strip this nut. Remove the nut.

Ask your assistant to put the transmission into “neutral.” Manually rotate the drive shaft ninety degrees and then ask her to put the transmission into “park.” Remove the next 17mm nut.

Repeat this process for the remaining two nuts, and then repeat the process for the four 17mm nuts at the front of the drive shaft. You might find the transmission-related parts to be in the way. My donor car had already been stripped in that respect, so that wasn’t a problem for me.

Thank your assistant, and compliment her pretty feet and calves. Ponder the irony that if you’d complimented her shoes, she would probably have liked the compliment more yet. Gently dismiss her.

Next, put something soft (not your assistant) under the drive shaft in case it falls to the ground, which will be the case if things go according to plan. Remove the 13mm center support nuts so that the drive shaft sags. Gently pry at the front yoke with a large flat-tip screwdriver until it separates from the transmission. Try to avoid having it fall on you as it comes down.

Do the same for the rear yoke, and pull the drive shaft forward and out, so that it too falls down, again ideally not on you.

You’ll notice that the drive shaft is large but relatively light, and that in the center, the front and back halves are connected via splines. I’ve been told that it’s a good idea to mark where and how the two pieces fit together, as to their relative positions. Better yet to not even separate the two pieces.

Re-installation consists of taking the part to your local drive line shop and paying them to re-install the part, which might include seeing if it’s in balance and doing something about it, if it’s not.

Transmission: ZF 4 HP-22 Automatic Transmission

For its time this transmission was very advanced. It was a four-speed automatic transmission in an era when this was highly unusual.

It also has a lock-up torque converter. This feature means that, at 60 mph or so, the automatic transmission starts to behave like a stick-shift transmission. This helps power and fuel economy, both.

This transmission is light yet very strong.

It is also very durable. It has a long life-time especially when serviced fairly regularly. Fortunately, it has several design features that make it easy to service.

BMW didn’t make this transmission; it was made by arguably the world’s leading manufacturer of automatic transmissions, a German company named ZF. This transmission was used in the flagship models of elite automakers such as Alfa Romeo, BMW, Jaguar, Land Rover, Maserati, Peugeot and Volvo.

This variant of the transmission contains no electronics and so it is extra simple to work on and trouble-shoot.

Engine: M20


Inspired by the classic BMW M30 six-cylinder engine, this is the “baby six” with a more modern design.

Small, light, durable and almost indestructible as long as it’s not allowed to overheat and as long as the timing belt is changed regularly.