Overheating

[sang]

Hi everybody,

My recently purchased 11GS ’95 has an overheating issue. It appears during hot summer days (well, Estonian hot days, i.e. +25-30C) in low speeds. In first case I was in a traffic jam for 30 minutes or less, engine mostly idling and I used 1st and 2nd gears to move. The oil temperature was normal, 5-6 bars all that time. Suddenly the engine stopped. I tried to re-start it and I could do it with a lot of throttle. As soon as revs got lower the engine stalled again. I stopped the bike and let it cool down. After 15 minutes or so it was cold enough to try again. The engine started with no problems and I could get out of the jam with no more problems.

Second time was even stranger. After an hour of riding two up I reached a town. There I rode around like 15 minutes or so in slow speed (20-50 kph). The oil temperature was 5 bars and no problems with the engine until it just stopped. I let it cool down and it started again with no problems.

Later I made a test. After a nice ride I left the engine idling and then raised revs with a choke to 2000 rpm. The engine worked 5 minutes; the oil temperature was 5 bars and then the engine just stopped again.

The bike has done 53K km, it has received good care from previous owners including 50K service. I’ve checked a TPS position and it’s OK, there’s no noise from valves side and no other kind of strange behavior from the bike’s side.

What might be the problem of such kind of overheating? I’ve thought about the thermostat. Or is my oil temperature-measuring device faulty? How can I check it?

I asked these questions from my local BMW workshop but they said this model was too old for them (!?!) and they really didn’t know could they do anything but they were eager to learn. I thought I’d better ask for help from somebody else before I start to pay for these guys’ studies.

Cheers,


Andres

 

[ag1s]

you have to ask BMW if the engine cuts out when too hot. If the answer is yes, then check if Is there any case your temperature sensor does not work and even if the temp bars are five the temp is much higher.

I would start from that.

a.

Hi everybody,

My recently purchased 11GS ’95 has an overheating issue. It appears during hot summer days (well, Estonian hot days, i.e. +25-30C) in low speeds. In first case I was in a traffic jam for 30 minutes or less, engine mostly idling and I used 1st and 2nd gears to move. The oil temperature was normal, 5-6 bars all that time. Suddenly the engine stopped. I tried to re-start it and I could do it with a lot of throttle. As soon as revs got lower the engine stalled again. I stopped the bike and let it cool down. After 15 minutes or so it was cold enough to try again. The engine started with no problems and I could get out of the jam with no more problems.

Second time was even stranger. After an hour of riding two up I reached a town. There I rode around like 15 minutes or so in slow speed (20-50 kph). The oil temperature was 5 bars and no problems with the engine until it just stopped. I let it cool down and it started again with no problems.

Later I made a test. After a nice ride I left the engine idling and then raised revs with a choke to 2000 rpm. The engine worked 5 minutes; the oil temperature was 5 bars and then the engine just stopped again.

The bike has done 53K km, it has received good care from previous owners including 50K service. I’ve checked a TPS position and it’s OK, there’s no noise from valves side and no other kind of strange behavior from the bike’s side.

What might be the problem of such kind of overheating? I’ve thought about the thermostat. Or is my oil temperature-measuring device faulty? How can I check it?

I asked these questions from my local BMW workshop but they said this model was too old for them (!?!) and they really didn’t know could they do anything but they were eager to learn. I thought I’d better ask for help from somebody else before I start to pay for these guys’ studies.

Cheers,


Andres

 

[Taipan]

Sounds like you could be running rich? Has it been dusty there recently? Check the air filter isnt clogged. Worth a look.

 

[cookie]

What might be the problem of such kind of overheating? I’ve thought about the thermostat. Cheers,

Andres

small help, but i don't think the 1100 has a thermostat.

 

[jkersh1]

A couple of thoughts. A bad coil (or whatever the equivalent), plugs, or fuel delivery. Try to narrow down the problem to either fuel or ignition. Next time it happens, verify you have a spark and that the plugs look OK.

As to fuel, I'm not sure what kind of test other than checking for a plugged up vent by opening the cap and listening for a hiss. Disconnect the fuel line and see if the pump is pumping adequately? Haynes manual says the pump output should exceed 1830 cc per minute. Pump for 5 seconds into a graduated container and multiply by 12.

 

[Kenny Rodkiss]

cutting out

Could also be the ignition triggers/sensors which lie under the front black engine cover under the bottom pully that drives your alternator belt.

These sometime give the trouble that you are having in that they break down when they get hot and work again when they cool.

 

[Captain Beaky]

I'm with jkersh1


Probably coils - they are prone to work, and then fail when hot.

Crank sensor too.

But then again, I've had a fuel pump go when warm.
It'd work until the engine got hot, and then die.

Run through the basics.
Fuel & compression & spark.

If the bike runs fine until the cutout, then it's going to be the Fuel or spark. Get it to fail, and check that the Fuel pump runs, and that you can feel the fuel feed pipe stiffen when the pump runs (pump pressure OK).

Smell the exhaust once you have tried to start it (Don't run the starter for too long - no more than 10 secs at a time - they aren't made to run continuously!) If you smell fuel then fuel is getting into the engine.

Then do a spark test - disconnect a pluglead, put a spare plug in and hold it to a grounded bolt on the engine, and crank the bike - spark? Whip the plugs out - whatare they like?

If you have a spark and fuel, possibly check the tappets, but I don't think this'll be the cause if the bike is running well.

When you turn the ignition on, you should hear the fuel pump run for a few secs and stop. If you crank the bike, the fuel pump should run for another few secs. If it doesn't, then the engine management is not seeing the engine turning - crank sensor???

That's all I can think of at the moment. Let us know how you get on...

 

[jkersh1]

In the U.S. BMW Owner's News a couple of months ago, the inestimable Paul Glaves described similar symptoms on his wife’s bike that ultimately was a faulty Hall Effect Sensor, which is what I believe prior post have been referring to when talking about crank sensors, etc. Couldn't, of course, find that issue, but on the IBMWR site the following article -- "Intermittent Engine Cutout Problem Solving" by By Don Eilenberger
Although it is written in reference to K bikes the basic diagnostics are the same. The "question" this article answers is not to be found but not a great mystery.

http://www.ibmwr.org/ktech/intermittent-cutout.shtml

Things I would look at (in IMHO increasing order of probability):

1. Coils - look at them in the dark with the bike idling, just to make sure there isn't a crack in the towers that is causing arc-over. Doubtful due to the 2nd clue, but easy and cheap to do.
2. Ignition wires - worth checking the resistance on them. This would be the first place I'd look if we ONLY had clue #1, but #2 can't be accounted for with this. The wires should be 5k Ohms end to end - +/- 500 ohms (they are typically much closer).
3. Poor seating of the FI computer connector. More than one intermittent K bike problem like this has been fixed by reseating the connector on the FI computer. Easy to do, and no cost at all.
4. Ignition switch or kill switch partial failure. Some people have had problems with deposits on the ignition switch causing intermittent running problems, cleaning it is the cure. This is in the K bike FAQ.
5. Starter deposits - given that the bike probably gets quite a bit of use - there have been instances of intermittent problems caused by carbon deposits in the starter motor (BMW does some odd things with electrical paths - that include the starter when it isn't running . There is a FAQ on the website on removing and cleaning it. Cost is nil, not really hard to get out once you go at it.
6. Hall Effect sensor - this is where I think the problem is. It sounds like the intermittent failure of a Hall-effect sensor. Have seen and heard of this before here on the list (Jeff Dunkle - would you care to chime in??).

The test for this (Jeff's test) is done with a heat gun (or a really good hair-dryer). The hall-effect sensor assembly lives behind the T shaped cover on the right (facing forwards - starboard side of the engine. The cover is easily removed with allen wrenches.

The test - let the engine idle - and direct the heat gun at the Hall-effect sensor. If it cuts out when it gets good and warm - this is a big clue. Then turn the heat gun to just blowing air and cool it, try restarting. If it restarts, this is the 2nd clue. You may want to do this test a number of times to make certain it's the fault.

This - to me - is the most likely cause - given the symptoms you describe. The hesitation at higher RPMS indicates a weak spark to me, caused by a partially failed HES. The complete cutout indicates complete ignition failure - again, pointing (when combined with the hesitation) to the HES.

This - unfortunately is the most expensive thing to fix, so it's worth going through the other ones first in the hopes that it will be a cheap fix.

Your mechanic is correct - intermittents are a bitch to track down since they never exhibit themselves when you're someplace you can really test things.
HTH,
Don Eilenberger, Spring Lk Hts, NJ JMP#1 [email protected]
NJ Shore BMW Riders web page: http://www.njsbmwr.org/

 

[Rugged Path]

Riding this month, it has been in the mid 40's C and typically when riding in the city, my temp gauge always shows one bar less than max. If I hit the red light early, I switch the engine off, just to let it rest.
How does the oil pump work? Is it connected to engine speed or just a constant cycle?

 

[sang]

Fault finding update:

Checked plugs and compression. Plugs are new and looked after a good hot ride in the town OK. Plugs’ color was a light brownish i.e. the fuel-to-air ratio was good or just a little bit lean. Compression was 11.7-11.8 bars in both cylinders, should be also OK.

Thanks jkersh1, now I know what I do during the weekend



The search will continue…


Andres

 

[sang]

2nd fault finding update:

First I tested a heat sensor. It is located at right upper side of the engine in front of the oil tube. I removed the sensor and heated it until the RID showed all the oil temperature bars. Conclusion: it’s all right with sensor and the engine cuts out in moderate working temperatures at low speed.

Then I tested Hall sensors (or crank sensors). I got a lot of help for that from the http://www.ebbo.org/2av54.php. I built a device described there. First test: upper sensor, everything OK. Lower sensor: some kind of trouble. I connected wires like described: black to the terminal 3, red to 4 and white to 2 and nothing happened. I removed the red from the terminal and the LED lighted constantly. I’m really bad in electrics but I understood there’s some kind of problem in lower Hall sensor. Only which kind?

To get to the Hall sensor I had to remove the belt pulley. But how? Is there any special kind of wisdom or can I just put on the gear to avoid the engine to turn? Is there a clock-wise or a contra-clock-wise nut?

Thanks,


Andres

 

[jkersh1]

Checked my Clymers but didn't find anything on that nut. Two thoughts, 1) The nut probably tightens in the direction the crackshaft turns so the rotation tends to keep the bugger on. B) Having a counter threaded nut would result in a lot of stripped threads over the years, so its probably the standard righty tighty, lefty loosey.

Wish I could find my ON issue where this was detailed.

Good luck, keep us updated. You never know when it's your turn.