1999 R1100RT Rain problems.

My 1999 R1100RT died on the side of the highway after a bad rainstorm on the way home from the rally this year. Fortunately my brother was close with his truck to help. Bike would crank fine but not start. Fuel pump was coming on when I turned on the key. After we hauled it from Wisconsin to Massachusetts I borrowed a car. My brother put it in the local shop and when they tried it, it started fine. Now it starts but has a rough idle and a little hesitation. any ideas on where to look? I'm pretty sure it is a wet connector or something like that. Has anyone else had this problem? I have to go get it next weekend and ride to Tennessee.

I saw your post in the other thread. Not totally familiar with the Oilhead, but it might be somewhat similar to the Airhead. One issue on a period of the Airheads was the "crack-o-matic" coil. I think there was a run of dual-tower coil that tended to crack which then allowed water to get inside...not good. That's something that I would look at or consider for your issue.

Associated with the rain, I wonder if you picked up water in your fuel? Understand the heavy rains... A couple weeks earlier, crossing ND, just east of Bismarck, encountered a tremendous storm that took out my speedo and gps on my ‘85 KRS/eml. Not fun traveling without both. Eventually the gps has dried out. Still trying to figure out the gps. Good luck.

grees1 said:

My 1999 R1100RT died on the side of the highway after a bad rainstorm on the way home from the rally this year. Fortunately my brother was close with his truck to help. Bike would crank fine but not start. Fuel pump was coming on when I turned on the key. After we hauled it from Wisconsin to Massachusetts I borrowed a car. My brother put it in the local shop and when they tried it, it started fine. Now it starts but has a rough idle and a little hesitation. any ideas on where to look? I'm pretty sure it is a wet connector or something like that. Has anyone else had this problem? I have to go get it next weekend and ride to Tennessee.

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Sure sounds like the wiring has gone bad on your Hall Effect Sensor (HES) Look up past threads on your symptoms, bet you'll find your answer. Member GSAddict can rewire them for much less than a new one, but if you need one fast, Beemer Boneyard sells new ones. Good Luck!
DP

Yeah, I just replied to that other thread ... water in the fuel is also easily possible, especially if the drain path around the perimeter of the filler cap is clogged downstream.

HES or I'll eat my hat.

BC1100S said:

HES or I'll eat my hat.

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I agree. These are absolutely classic symptoms of failed HES wiring on R1100 bikes.

You should p.m. GSAddict. He rewires them and is known for high quality work.

So isn't the HES buried under some engine cover? Why is it getting wet? Seems like that needs to be cured as well.

20774 said:

So isn't the HES buried under some engine cover? Why is it getting wet? Seems like that needs to be cured as well.

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The HES is located behind the lower belt pulley on the crankshaft, behind the front engine cover. That is not the location where water causes the problem though. The wiring harness from the HES to the Motronic ECU plugs into the bike harness under the fuel tank at a location which can get wet riding in heavy rain.

And, there is a bundle of four wires inside the outer sheath of that harness from the HES to the main harness. And the insulation on those four wires always fails eventually on the R1100 bikes. The location of the crumbled insulation is most typically behind the pulley and front engine cover but inside that outer sheath. If the bundle is undisturbed those naked wires can be side by side and not cause a failure. But the slightest bit of water inside the sheath can cause arcing between the various wires. And the water gets in past the poorly shielded harness connector at the top under the fuel tank.

In one case on Voni's R1100RSL it had squirt and it had spark but at random times. With the key on but engine not turning over I heard a faint buzz. This turned out to be the injectors firing as current arced from one wire to another in the bundle. And the spark plugs were also sparking with the key on but engine stationary.

Once when I washed my Oilhead, perhaps rinsing too vigorously, the four way flasher button, had corroded wiring that the water somehow shorted something that caused a starting issue. Your problem is most likely the HES issue mention above, but I am posting this as another possibility.

Typical Hall sensor insulation failure.
I rewire them for a lifetime fix.
PM me for full details.

20774 said:

So isn't the HES buried under some engine cover?

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The garage isn't open yet so I can't actually go out and check - but are those lines on the side little vents to help cool the HES and the belt...? That would be a direct entry for water.

Have to hear someone weigh in on the openings. On the Airheads, there was a point where there were vent holes on the front engine cover. But the critical element of the points/condenser was further sealed in a cavity at the bottom of the front of the engine. If the HES is that critical to contamination, seems like there should be a secondary barrier.

Pauls1150 said:

The garage isn't open yet so I can't actually go out and check - but are those lines on the side little vents to help cool the HES and the belt...? That would be a direct entry for water.
View attachment 84408

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Yes, that is how the water gets in and turns to sauna steam

20774 said:

Have to hear someone weigh in on the openings. On the Airheads, there was a point where there were vent holes on the front engine cover. But the critical element of the points/condenser was further sealed in a cavity at the bottom of the front of the engine. If the HES is that critical to contamination, seems like there should be a secondary barrier.

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No need for that under normal circmstances - ie: if Bosch had used the correct temperature rated wire in the first place.
The insulation inside the splice turns to dust and when exposed to high humidity will allow for leakage between the 4 conductors.
When the Motronic senses this it shuts down.
Rewiring with the correct temperature rated wire (Aircraft Teflon Shielded) will solve this issue for good.

Insulation breakdown example:

Solution?

The bike is starting now after drying out but according to my brother it has a rough idle and a little hesitation. I am going to try to ride it home
to TN from Mass. Once it is home I will look at the HES and send it for rewire if there is any deterioration.
Thank you all for your help.
Greg

grees1 said:

The bike is starting now after drying out but according to my brother it has a rough idle and a little hesitation. I am going to try to ride it home
to TN from Mass. Once it is home I will look at the HES and send it for rewire if there is any deterioration.
Thank you all for your help.
Greg

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Here’s to a rain free trip.
Let us know how you make out.
OM

grees1 said:

The bike is starting now after drying out but according to my brother it has a rough idle and a little hesitation. I am going to try to ride it home
to TN from Mass. Once it is home I will look at the HES and send it for rewire if there is any deterioration.
Thank you all for your help.
Greg

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I hope you make it home trouble free and without rain. Let us know.

I have said this several times, probably on this site but on others too. EVERY 1100/R/RT/RS/GS left the factory with the same bad wire harness on the HES. Every one of them. The harness has to be replaced or repaired, or you will get stranded eventually. GSAddict is the guy that repairs them beautifully. His repair will last the remaining life of the bike. I think the new replacement units are made with the proper wiring, but can’t be sure of that.

I don’t understand why some folks think that their bike is magically immune to the problem.

The correct insulation type was introduced in mid to late 2002
Some models had it earlier than others.
Easy way to check is below.

Once again Oilhead owners ...

The Oilhead was BMW's first bike following new Euro regulations that auto parts be biodegradable. Your wiring harnesses all over your bike are falling apart at this age ... by design. Suggest you deal with this proactively.