Jan ’23: I’ve been looking for one of these cars for a while. At this time, these cars are the final iteration of the naturally aspirated inline-6 with a manual gearbox and hydraulic steering. So I went looking for a 128i coupe with a manual gearbox. They’re not as common as I had hoped, but one eventually popped up locally on FB Marketplace. Relatively high mileage (170K), engine problems, dead battery. Nothing much out of the ordinary, eh?
This particular one is a pretty early production base model coupe, known internally as the E82 chassis. Mine is Karmesin (crimson red) over an Anthrazit (black) interior. The upholstery is BMW’s vinyl leatherette, known as ‘Sensatec’. I’m pretty impressed with the durability and the feel, it does seem like a decent material. The only installed option is the cold-weather pack, with heated seats and headlight sprayers. Oddly, the build sheet reports that it’s a hot weather version.
I’ve been trying to figure out the rough running problem; this car is equipped with the N52, a 3.0 liter inline 6 that BMW installed in virtually everything. The single-stage intake manifold results in about 200hp. These engines are pretty durable in general but they do have their issues. This one has no problem starting, but it runs incredibly rough. No power, low idle, stalls in short order. The PO claimed it had zero compression in a cylinder. Sounds about right.
I’ve replaced the battery. The car woke up from a long nap in relatively good shape. No major problems, my scanner reported cyl 1-6 misfires, multiple cylinder misfires, and a MAF out of range error. My primary suspicion is a massive vacuum leak, but these motors do have occasional problems with dropped valvetronic springs, cam timing phase errors, and can also have broken bolts in the VANOS drive gears in later versions.
My first repair was the PCV system in the rear of the engine; these kits are available on Amazon for about $20. It’s not really easy to take this apart, but I found that a good sharp 1/2″ wood chisel became my tool of choice. Although the internal diaphragm was indeed split, there was no change. The motor is still barely running.
Feb. 23: I pulled the VANOS check solenoids next. They were in decent shape, I tested them with 12VDC. They seemed to work well. I cleaned them & swapped them around. No change, the motor is still barely running.
March ’23: Until the weather clears up, I’ll take my time on maintenance and build up my tool kit instead. I’ve invested in a BMW timing kit, replacement parts (jack pads), tooling for the BMW N52 (long T50 & T60), and a new jump pack. This car blew out my old one; it was admittedly several years old. I guess it was time?
May ’23: I’d bought a cheap borescope to see what the pistons looked like. Every damn one of them had marks from the exhaust valves. Time to do a little exploratory surgery…I’ll pull the cylinder head to see what’s broken.
June ’23: I’m not going to suggest pulling the head in the car. I chose to do it that way, and it’s not really the easy way, unless you have a really substantial toolbox. While it might seem more convenient, and can be done, I honestly think it’d be easier to remove the whole engine. The engine bay is tight on the E82, everything is really hard to get at. The exhaust manifold is especially hard to get at. The wheel wells are deep, the cowling is tight, and the engine sits well back into the engine bay. The cylinder head is actually too far under the cowl to pull it vertically. In the pursuit of chassis balance & handling, BMW sacrificed a good bit of serviceability. I’m particularly annoyed about the wiring harnesses. They can’t be disconnected from the chassis in any routine fashion, and they’re routed directly over the middle of the engine. They’re about as perfectly in the way as it’s possible to be, seemingly no matter what you’re doing. That’s why used BMWs with mechanical problems are cheap. I know this is only a 128i, but it’s a manual, in decent overall shape, and even the right color combo for me. I’ve invested less than $4K all-in. That includes the car, sales fees, taxes, transport costs, parts, tools, even taking my long-suffering wife out to a nice dinner. That’s the theme of this blog, isn’t it? Fast ‘n frugal machinery.
July ’23: So now that I’ve finally gotten the head off the car, I can confirm that the cam timing was messed up. The big question is…why? One way is caused by serpentine belt ingestion. This can happen due to a drive belt getting ingested through the main front crank seal. I suppose it’s time to drop the oil pan next, just to verify that there aren’t any ribbons of serpentine left in there. I didn’t see any bits of chopped up belt in the top of the motor but it’s best to cover all the bases where BMW is concerned.
Well, I have some updates. Not really good ones. As noted above, the exhaust cam timing was quite a bit retarded. I pulled the cam, and found this:
As you can see, the exhaust cam is pretty well spent, and both cam bearing shells are severely damaged. I also noted that the locating lugs on the bottom shell were all cracked off. It’s apparently pretty easy to install the cam bearing shells incorrectly. When the bearing shells aren’t precisely installed, the steel cam rapidly wears out the aluminum bearing saddles, opening up the cam tolerances. Oil pressure drops, and then the oil-driven VVT can’t properly vary the exhaust camshaft timing. I’m surprised it ran at all!
Aug. 23: So I took a day off and went to my friendly local PnP. Grabbed a few parts to repair my poor broken BMW.
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- Here’s the new cam, moderate wear in the sealing rings
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- Not perfect, by any means, but far better than the old one.
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- There is minor bearing wear. It’ll do for now.
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- Here’s the old cam, ready for the scrap heap.
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- Closeup of the cam problem. That got hot!
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- Three stages are better than one.
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- Old & new intake manifolds
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- Head to head comparison.
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- The old one stage intake.
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- Back of the three stage manifold.
So you can see the old cam in these pictures, along with closeups of the replacement cam. I found a broken E60 530i in the PnP. As a bonus, it came with a three-stage manifold too. Essentially, I’ll end up with a 130i once we’re done with the installation & flash.
I also took a look at the valves and gave them a quick sealing test. First, I screwed the spark plugs back into the head. Then I flipped it upside down, carefully leveled the head with some scrap wood blocks, then filled each of the combustion chambers with isopropyl.
No significant leaks! There was the tiniest bit of weeping from the single open intake valve, but surprisingly little even overnight. The intake valves were closed tightly enough that I could verify the exhaust valves were good in that cylinder. I believe it’s the #3 chamber in the above pictures.