Overheated Bad!

[txfoster]

My son started the bike in the garage and forgot to turn it of. Some time later it shut of by its self. Yes it cooked the tupperware like a microwave. My chrome headers are now blue all the way to the cat. Checked compression and its 125psi per cylinder. No spark (checked HES it is still good) and fuel pump primes. Any thoughts before I pass out because of visit to BMW!!!!!!

[redryder]

Sorry to hear of your bad luck...your's is a lot like mine. Haven't had this problem (yet), but could it possible that you've overheated and fried your coils? Also, I don't know if the Germans used real wire or silicon wires for the spark plugs. If they used silicon, could be that its overheated and broken down to where the spark won't get through.

[txfoster]

BTW I measured my coil and its Primary is 1.5 Ohms

and my secondary is 6.5k ohms

Plug wires say on lead 1K but 1 of them is 3.2k and the other is 4.1k.

[SWB]

BTW I measured my coil and its Primary is 1.5 Ohms

and my secondary is 6.5k ohms

Plug wires say on lead 1K but 1 of them is 3.2k and the other is 4.1k.

 

My BMW RT manual indicates resistance should be primary 0.5 (K Ohms I think) between terminals 15 and 1, and secondary 13 (or 1.3??) between 4a and 4b.

 

I did this test a few months ago, and figured out what they meant between "primary" and "secondary", but memory fails now. But 1.5K on the primary sounds too high.

 

I agree: replace both coil and plug wires. You can probably get both used from bmwboneyard.com, or a good deal from Chicago BMW.

 

Regrets.

[KDeline]

I guess I never heard of overheated good........

[txfoster]

The thing that makes me the most upset is the $3k 2 tone paint job on the tuperware....

[BobFV1]

Tex -

 

Thanks for posting this, and I'm so sorry this happenned to you! Around BMW's, every several months to a year I see or hear a story like this on a forum, in a magazina, or at a gathering and each time I think "boy - that could so easily be me", and it focuses me on taking extra care to avoid this unfortunate situation.

 

Sorry I can't help you with your mechanical issue, but I just wanted to say thanks for posting and sorry about your bad luck. Hopefully, this will put you at the head of the line to win the lottery or something!

[bmwmick]

The primary should measure 0.5 Ohms and the secondary should be 7.5 K-Ohms The manual still indicates 13 K-Ohms but the later coils I've seen all measure 7.5 K-Ohms.

Did you zero the meter leads before looking at the primary? Even the meter leads can add 0.2 Ohms to the reading if you didn't zero them out.

How did you test the HES? That is the most likely failure point with that much heat. Also check the oil temp sensor.

Pull an injector and watch for a squirt while cranking. The 180 degree Hall sensor provides the timing for the injectors and the TDC Hall sensor provides the coil signal. Put a volt meter on one of the coil primary wires while cranking. You should see a dip towards ground while cranking. If that's missing, you'll never see a spark. The Hall sensor signal gets shaped by the Motronic unit to provide that ground to the coils.

You could also just wire up 12 Volts to the coil primary with a plug in the end of the secondary wire grounded to the engine and then momentary touch the other primary terminal to ground.

(Do this with the coil DISCONNECTED from the Motronics). If you see a spark, the coils are good.

The secondary wires are probably OK, they measure about 1 K-Ohm per foot.

 

Mick

[Reddog99]

One common result of this type of overheating is that the crankcase gets hot enough to melt the insulation of wires touching it. This means the hall-effect wires become grounded to the case. I've seen it happen...

 

Pat

[Joe Frickin' Friday]

One common result of this type of overheating is that the crankcase gets hot enough to melt the insulation of wires touching it. This means the hall-effect wires become grounded to the case. I've seen it happen...

 

Indeed, but txfoster sez the HES checks out fine.

 

txfoster, you have no spark. Do you have fuel injection? You said the fuel pump primes at key-turn; however, that behavior is independent of HES functionality. Suggest you pull a fuel injector out of the throttle body (don't flex the hard fuel line too far) and see if it actually squirts fuel when you crank the engine. If yes, then your HES is doing its job. If no, then your HES or your Motronic has a problem.

 

Can you describe the results of your HES diagnosis (voltages, behavior as you rotate the crank)?

 

IIRC, people have reported that the Motronic will refuse to run the engine if it doesn't see a signal from the oil temperature sensor - and that that sensor (or its wiring) has been known to fry when the engine overheats in these unattended warm-up situations. Can anyone confirm? Might be worth checking that. Anyone have data on what the OTS resistance is supposed to be at room temperature (or where it is on the block)?

[bmwmick]

Suggest you pull a fuel injector out of the throttle body (don't flex the hard fuel line too far) and see if it actually squirts fuel when you crank the engine. If yes, then your HES is doing its job.

 

Mitch,

Not quite the whole truth, go up and read my previous post.

The TDC Hall sensor provides spark timing and the lower sensor provides fuel 'squirt' timing.

Smiller had the very same problem here:

http://bmwsporttouring.com/ubbthreads/sh...true#Post537702

He had fuel but no spark.

 

The oil temp switch is at the top rear of the engine on my '96. 3 K-Ohms at 72 degrees

Mick

[Clive Liddell]

Mick,

You wrote:

"The TDC Hall sensor provides spark timing and the lower sensor provides fuel 'squirt' timing. ..."

 

But my understanding is that the TDC sensor (or both?) cause the fuel pump to start momentarily?

[Joe Frickin' Friday]

Mick,

You wrote:

"The TDC Hall sensor provides spark timing and the lower sensor provides fuel 'squirt' timing. ..."

 

But my understanding is that the TDC sensor (or both?) cause the fuel pump to start momentarily?

 

My experience has been that both sensors will trigger the fuel pump to spin for about 1 second; when the engine is actually running, it's far less than 1 second from trigger to trigger, so the fuel pump runs continuously.

[No_Twilight]

My experience when my HES died is that I had spark AND fuel. The broad discussion of HES failures hadn't taken place yet so it took me almost a week of working on the bike every day to finally decide it was the HES. Based on my experience I'd say that they both do fuel and both do spark so when one dies you get a half dose of each. I could get my bike to idle very very roughly, appartently on one cylinder.

 

So bottom line: neither one is a good test for confirming HES function in my opinion. You might check spark in both cylinders and find you have spark to only one. That is a guess though and there are other things that could cause spark to only one cylinder. Also, IIRC, this might not even work because I think I remember that both HES units spark both cylinders so they will still be both showing spark but one will only be getting it only on the exhaust stroke and no spark on the compression stroke.

 

--Jerry

[big-t]

people have reported that the Motronic will refuse to run the engine if it doesn't see a signal from the oil temperature sensor - and that that sensor (or its wiring) has been known to fry when the engine overheats in these unattended warm-up situations. Can anyone confirm?

 

 

 

Fact...Unplug the oil temp sensor and it will not run

 

Same as for most FI vehicles/coolant temp sensor.

[bmwmick]

Mick,

You wrote:

"The TDC Hall sensor provides spark timing and the lower sensor provides fuel 'squirt' timing. ..."

 

But my understanding is that the TDC sensor (or both?) cause the fuel pump to start momentarily?

 

Clive,

I agree and I think that EITHER TDC or 180 will signal the fuel pump to RUN but the 180 sensor signals the injectors (BOTH) to squirt.

TDC should cause BOTH plugs to spark too. This is just a simple wasted spark system.

 

Mick

[txfoster]

Thaks for all your input, it was the HES. Put a new one in and she fired up. The only thing that is strange is she rattles more at start up and every once in a while it rattles going down the road. Doesn't sound very good.

[Eckhard Grohe]

Rattle=Cam chain tensioner???

[smiller]

Or rattle = pinging? Perhaps you advanced the ignition timing when you installed the HES.

[bigboy]

check the butterflies in the throttle bodies these sometimes rattle.

[RFW]

Also, I don't know if the Germans used real wire or silicon wires for the spark plugs. If they used silicon, could be that its overheated and broken down to where the spark won't get through.

Real wire?? Silicon Wire??

 

First, the "silicon" you refer to is "Silicone", and it is the insulation only, not the conductor. If he is LUCKY, the spark plug wires ARE silicone insulated, since silicone is EXTREMELY temperature resistant (it is ordinary silicone RTV sealant that glues the tiles on the space shuttle, for example).

 

It is most likely, however, that the spark plug wires are just standard Hypalon insulated, since that is normally what BMW and everyone else uses.

 

As for the "wire" you refer to, they use standard resistance wire to reduce radio interferance. This is not particularly relevant, however, since the first thing to go would be the insulation, not the conductor inside.

 

Bob.

[No_Twilight]

Rattle=Cam chain tensioner???

 

That would be my guess. Supposedly they all do that but it should stop after oil pressure comes up.

[Softtail]

Did you really get pissed and want to kill him? I would have freaked big time, and then killed him. How do you forget to turn a bike off? No one touches either of my bikes, ever!! I would have been so pissed, I don't think I would ever get over it!! <<<<<Softtail>>>>>>

[txfoster]

Not the intake system. To describe the sound its like when you first start your car in the morning and it starves for oil for 10 seconds same sound!

Oh yea it sounds like it comes from the left side.

 

Its not doing it while in motion just start up my mistake.

[No_Twilight]

Glad it's not doing it in motion. I'd say you've given a pretty good description of the chain tensioner noise. Rumor on the street is that they all do it but I haven't listened to them all. Mine does it. I didn't notice it at first but now it is easy to hear--I wonder if your ears just have to get tuned in to that noise. My guess is you listened harder after the event.

 

Enjoy your ride,

Jerry

[Odiedog]

Sorry to get into this late. If you search the archives you'll see my similar tale last year. My Hall sensor checked ok too. I couldn't find anything else wrong so I bought a new HES from Chicago BMW (great service) and it started right up. They can check out ok using the LED method and still not work. I felt your pain about a year ago!