My Quirky E34

[ElNormo]

I've got a 1989 535i (E34). About 5 weeks ago, it blew a hose and the engine overheated. The dealer replaced the hose, and said there was no major damage. Since then, I've experienced the following symptoms...

- The OBC occasionally displays "Oil Level Sensor" when starting/killing the engine.

- On some trips, the Check Engine light comes on when I take my foot off the accelerator. Give it a little gas, and the light goes out. Using the stomp method, I get 1233 (Full Throttle Sensor). It will do this for the entirety of a short trip, then on the way home a few minutes later... nothing.

- Occasionally, the headlights will go out. Both of them. Jiggling the switch does not appear to make any difference. After a few seconds, they come back on.

Does any of this make any sense? The car drives great, the body's in like-new condition... But it's got some quirks! Any ideas?

Thanks

Norman

[Robin-535im]

If it were my car, I would consider getting two things: 1) the Bentley manual which will show how to check the sensor operation (you'll need a multi meter too, $12 analog one from radio shack will work fine) and 2) Stabilant 22, which you use on electrical contacts to fix poor-contact-itis, something that can make your car do wierd things.

It may be that water got inside some electrical connectors under the hood, and at a minimum, unplugging and plugging them back in might be enough to scrape off any residue that is causing an intermittant open circuit. You should probably check the sensors to put your mind at ease, but I would think it more likely that the sensors themselves are fine.

HTH

[spddmn713]

It really does sound electrical, I had the same problem with my headlights on mine. It was the LKM (Lamp Control Module). There is a good right up on how to fix the LKM on bmwe34.net. It took me about an hour to fix mine and I had never had a soldering iron in my hand before. I would recommend fixing the solders on the LKM anyway because it seems that everyone has had that problem at some point and it is an easy fix. I have an extra LKM that I have repaired for sale/trade

[ElNormo]

It may be that water got inside some electrical connectors under the hood, and at a minimum, unplugging and plugging them back in might be enough to scrape off any residue that is causing an intermittant open circuit.

Robin,

Thanks for the note. I'm looking into the Bentley manual now. It looks useful, to say the least. In the mean time, do you know some common electrical connectors vulnerable to corrosion? I can start working on some, just don't know where they are...

Thanks

Norman

[ElNormo]

It really does sound electrical, I had the same problem with my headlights on mine. It was the LKM (Lamp Control Module).

Yeah, I was wondering about the LKM myself. I'll pop it out tonight to take a look. Did you just have to resolder the relays on the back?

Thanks for the tip,

Norman

[JonE]

Just do the solder points that look bad (cracked in a circular manner around the solder point). I think the bad ones look a little like a volcano at the top and the good ones just look like a smooth peak at the top. Bruno's site, http://www.bmwe34.net/e34main/maintenance/electrical/LKM.htm has a pretty good write-up on this repair. I think there is another good write-up on-line somewhere else, just can't remember where. Anyone else have it?

[GAGE308]

UGH...well it Definately sounds to be 2 seperate things...The Headlight problem is Most definately is the LKM module...Just Look on this website in Maintenance...Then electrical...then lkm module...Its Just some Bad Soldering joints that forever what reason fail to make contact Then reconnect(in laymens terms)....I fixed Mine...BUT...if you arent careful you can REALLY mess the Entire Printed Circuit board up...Just make sure you are grounded...and dont touch Anything you dont need to...If you arent the electrical soldering type...do a search on ebay for bmw LKM..There is a guy on there who rebuilds them and sells them for $100 But you have to Give him your shitty one after you get it(core charge type deal)...THATS THAT,,,NOW,....with the hose breaking...and that Scary mess...I dont want to Jump to comclusions...BUT...the only Thing I can think of OFFHAND..Is..and i HOPE NOT...BUT...Possibly a headgasket problem...when the car overheated the head MAY have warped and blew the head gasket...Do This: The NEXT time it Runs Shitty...and the check engine light comes on...Pull over if you can...Check to see if there is a lot of Smoke/steam coming out of the exhaust...or even just smell it...If its a REAL SWEET NASTY type of smell....THATS Possibly antifreeze passing.....and thats BAD...also...Look in the Coolant resevoir..."MAKE SURE ITS COOLED DOWN ENOUGH"...and check the antifreeze/coolant...check to see if its REALLY dark...Like it has Oild mxed in it...or you can ...well I CAN feel it and see...also check your oil...you MAY be able to see water in there.....Thats ALL I can think of...HOPEFULLY its Not...and something simple...
Good Luck
Donnie

[GAGE308]

OH....Sorry...I misread it the first time....I thought I had read the engine was ...ro felt like it was Killing...LOL.I cant read fast anymore in my old age.....So ok...It MAY be all elctrical...But ..the LKM Module is just lights only...Id check Those Things anyway..wouldnt hurt...Ive dealt with a FEW different Haedgaskets Dying on me...The KEY is...to Nab it as quickly as possible.. The More an engine is ran with a gasket problem..the possibility of the head itself warping grows....Then it has to be Machined...and all that....FUN FUN FUN...Just Not Fun to Pay for ;-)
Donnie

[ElNormo]

Thats ALL I can think of...HOPEFULLY its Not...and something simple... Good Luck

Sorry to bump this thread. I must have missed your response.

The jerky acceleration was cured when I filled the tank with mid-grade gas (instead of regular). The car's been driving fine since then. Could it have been that the engine simply needed a little more octane? The PO (my dad!) suggested it, and said that he occasionally filled it up with mid-grade.

Norman

[632 Regal]

I believe the car is required to run 89 octane not 87. Could be the fault codes you were getting. The oil sensors occasionally act up as mine did, I took a look at mine and shrugged my shoulders, never did it since. Have you looked at the LKM yet?

[ElNormo]

I believe the car is required to run 89 octane not 87. Could be the fault codes you were getting.

Thanks for the info. I'm going switch between 87 and 89 and see if it's happy that way. That last post about a blown head gasket got me worried, but I think it's really just the octane was out of whack.

Resoldering the LKM, as described on the web, did the trick nicely for the headlight issue. Not too complicated.

Norman

[crashnburn80]

Well I am a newbie here but my 535i blew a coolent hose and the engine overheated about a year and a half ago. I also had the oil level warnings shortly afterward. Turned out my headgasket was leaking. Blowing a coolent hose can be caused by pressure buildup in your coolent system caused by a faulty headgasket. Check your oil for any white residue (caused by coolent in your oil) and check your coolent reservoir for any oil floating on the surface. Hopefully this is not the case.