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legionnaire1857 09-23-2012 03:36 PM

Engine hangs at high rpm
Hey guys, I have had a problem with my E28 for a while now. It's a 1987 535is. I have replaced the distributor cap and rotor, the spark plugs, the air filter, fuel filter and a few other things. The problem I'm having is terrible gas mileage and not as much power as my engine should be making. If I rev the engine slowly all the way to redline, the engine hangs up at about 5000 RPM and starts making a tapping or snapping sound, I can't tell. It either sounds like an electric arc, or some kind of tapping. It is RPM related, so it's really fast. I adjusted the valves about 2k miles ago and got no difference. Disconnected the O2 sensor, no difference. Fuel injector cleaner, no difference.

The coolant temp sensor tested okay. I have also adjusted the wiper track on the air flow meter. None of this has helped my high rpm hang up.

I also did not buy new wires when i changed out the rotor and dist cap, so spark is not completely eliminated yet. $110 for those things! One last thing... I don't know if it's supposed to do this, or maybe it's just a characteristic of this car. When I'm driving, and I push the clutch in, the RPM's drop very quickly. I have to change the gears lightning quick to get a smooth shift. The car idles fine, and the RPM's drop fast but never go lower than idle and it never stalls. Maybe it's just me, maybe it's a related problem with what's wrong with my car. Feels like I've got a 2 ounce flywheel! Thanks for reading, any help would be great

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legionnaire1857 09-23-2012 04:28 PM

I don't think it is a stopped up cat, the exhaust pipe is blowing like a mofo at idle. It's getting dark here, and I just revved the engine like crazy to see if I could get an arc out of the wires and got nothing.

I also forgot to mention that this happens while under load and just sitting in neutral. It's like somebody shut off the gas at 5000 rpms under wide open throttle in first and second gear.

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south26 09-23-2012 07:02 PM

Have you checked your fuel pressure? It could that your main fuel pump is starting to go. Or your injectors are getting tired.


BMWFatherFigure 09-24-2012 07:31 AM

Fuel pressure check and injector clean. Remove injectors and have them cleaned and flow checked on a bench..

legionnaire1857 09-24-2012 04:05 PM


legionnaire1857 09-24-2012 04:15 PM

Everyone is telling me to check the fuel pressure, but I won't have access to a fuel pressure gauge until this weekend when I can borrow one. I'm trying to go as cheap as possible, and buying a fuel pressure gauge to use one time isn't very economical...especially if it's not the problem.

south26 09-25-2012 03:47 PM

OK, not sure what you want us to do about that. You asked for help advice was given.


legionnaire1857 09-25-2012 04:30 PM

Not asking you to do anything, the above comment was simply a statement saying why I haven't checked the fuel pressure yet. I think you read into it wrong.

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south26 09-26-2012 01:40 PM

OK, that makes sense, sorry.


legionnaire1857 09-29-2012 09:31 PM

Copied from

Well, I drove the car to a friend's house today to get that fuel pressure test done. He has been a technician at the BMW stealership for about 30 years now, so he has worked on most BMWs from the 1980s on up.

I showed him what it was doing, the 5k RPM rattle or stutter or whatever it was. Turns out it was a rattle. He revved it up to 5k and heard the noise, then took it to the rev limiter just to see if it would go...nothing I haven't personally done before. After he did that, it started running REALLY sh*tty. He said, "Man, this thing's got a miss. It might have jumped time, we need to get the valve cover off and check it out."

Took the valve cover off and lo, a rocker arm had completely broken in half. What luck, this was my only transportation for the time being. The cam lobe for that particular valve was very worn, with a nasty ridge on either side of the lobe. All the other lobes were fine. Now, I understand that this could have been causing a rattle at about 5k RPM. I find it a little harder to believe that it would cause a sudden and major disruption in power under WOT. I find it really hard to believe that a rocker arm can just snap like a twig for no apparent reason, but it did. I would certainly like to know why, though.

The car had not jumped time as we thought...but the timing chain was really loose. It was just a matter of time before something happened anyway. Does ANYONE have any idea what might have caused a rocker arm to just break like that? It sounds like it was on it's way out anyway and the high revs were just the straw that broke the camel's back. Any suggestions or advice would be appreciated!

south26 09-30-2012 06:08 AM

Not sure, but I would put another head on it. I happen to have one if you are interested.


86528EJJT 10-01-2012 06:41 PM

I installed a new Mass Air flow sensor. Now my 528E screams up to red line and above till rev limiter kicks in. PS Advance Auto has rebuilt ones at a great price and gets it next day.


BMWFatherFigure 10-07-2012 06:41 PM

Sounds like your current cam is RS (Australian for broken). Source a replacement or send it for a rebuild (personally I'd go for the wrecker option). Replace rocker(s) - poss wrecker again. Check compression and oil feed. I guess lack of oil started the rot. Once the cam was under oiled the rocker and cam lobe wore each other out and finally snapped the rocker.

If compression good and oil feed checks out OK replace the 't' chain, cam and rocker. Back on the road!

85hypershark 10-26-2012 09:20 PM

Common problem when pushing these engines. The have an oil starvation problem in the cam area.There are is a remedy by a guru somewhere on this site. I have broken a few rocker arms too. Just par for the course when running these cars hard and the miles you can get out of them. Nothing last forever, luckily you didn't bend a valve or punch a hole in piston...

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