In the midst of restoring a 98 FLHRCI. Been away from EVO's for a while, but regained my senses and got one back. I've read a little about the brown goo that seeps from the cam/bank-angle sensor and this particular bike had that issue with right at 75K on the meter...but was still running fine. I went ahead and replaced the cam pos. sensor with one that had a black "substance" in it.

I kept the gooey one and encapsulated it with epoxy, which I have done on other electronic components. I keep it as a spare, but I have read where some folks seem to think that once the brown goo leaks out....the sensor must be headed south. However.....MOCO wrenches that I've talked to don't think this is necessarliy the case. Maybe that brown goo just would not hold up to the heat generated in the nose cone? I guess my question would be.....has anybody had one of the goo-leaking cam pos. sensors actually fail? I realize electronic components generate heat and I had a sensor fall off a carbureated 97 Ultra once, for no other reason than the adhesive used just melted away, or was poorly attached in the first place.

I'm the kind of guy that packs a spare everything on long trips....especially since this is the HD considered "obsolete" MM EFI system. If somebody can make some comments about this or point me to a thread I'd appreciate it.

 

Several guys have posted over the years that theirs have failed and asked how to fix. Fewer have had the ideas to come back and resort on its repair status.you're one of the few that changed a working part, I think you did the right thing as you never know when that was gonna **** the bed. Better in your driveway than the highway.
Tom

 

In my own opinion , i would not consider the ignition control PCB to be at fault .
If the motor is running as it should i would consider the PCB to be ok and the factory coolant " stuff" to be simply leaking out .
The ign. pcb. does run at high temps. and will effect the factory sealant after many years of operation.
My suggestion is to remove all previous older insulation and replace with newer type.

 

https://www.hdforums.com/forum/evo-c...road-king.html

https://www.hdforums.com/forum/evo-c...ad-king-3.html

Somewhere in the last month or so is an Excellent post by IM. He has a small but good post in top link. Bagger 1997 is super friendly and helpful too. Those are my two go to guys for m&m fuel injection.

If I find the link I'll post it. Bugging me I can't remember where it is.

Tom

 

I was looking for some "proof" that just because the sealant was dripping out, the unit was definately going ****-up.....which I do not believe to be the case. I think it's more of a situation that the wrong sealent was used for the application. Makes one hell-of-a-mess....you bet, but it dosen't necessarily mean it's defective.

I did replace it and even got a spare to pack in the tool box on these longer trips, but that crap had ran out of this bike all over the place and had been doing that for a while. It had 75K on the meter and was still running fine. It gets pretty hot inside that nose cone. I do think that a sealer of some sort needs to be in there to protect the circuit-board and it's components from moisture and I'm sure that's what the intent was, but they just used a filler that could not stand-up to the heat.

I think that unless somebody could prove the melting goo was a positive indication that the unit was going south, all it does is make a mess. However...just for that reason I suppose it should be replaced. The answer I get from a couple of trusted wrenches I know is like..."yeah, I don't know why they put that crap in there" and not a panic notice that it's going to break at any moment. Still....it's better to be safe than sorry and if they had one, the dealer gets close to $200 for it. If you keep an eye out for one, a take-off from a salvaged bike can be had for MUCH less than that and it can be replaced in less than 15-minutes on the side of the road, or handed to the HD tech. at the remote shop 1,000 miles from home that dosen't have one on the shelf.

 

The "goo" is electronic potting compound, it's there to seal and protect components from vibration stresses.

I think the potting material breaks down with age.

When the potting leaks out, the problem is the electronics loose the protection and prone to fail.

Could the potting be replaced?
http://www.epoxies.com/products/pott...FXJp7AodQA0A9g

 

Seeing 'Brown Goo' I wondered briefly if someone had an issue with my name! I am happy to report we have a product over here spelled Gu and pronounced the same way, which is available in dark brown - a thoroughly delicious rich chocolate dessert! Highly recommended......

 

I am an Electronics Engineer by degree and worked in the field for years, but that was a long time ago. IT has outran me now and I'm retired. I use to design and build circuit boards and It is not at all uncommon to find circuit-boards embedded in a protective substance...such as epoxy, or coated with a product to protect it from the elements and I have done that myself on several occasions. The only issue is....does that substance conduct heat good enough to shed it from the circuit you're protecting. I think that's the case with this brown goo. Once it has heated and dripped-out, the components are exposed to the elements, which is the greater danger of failure.

I took the one that had leaked out almost completely dry (still working), cleaned it and filled the cavity with epoxy. I plan to install that one back on the bike and run it locally to give it a good test before I hit the road on a long trip. The only issue I can see is.....will the epoxy transfer the heat generated from the components to prevent self-destruction and that all depends on the heat generated by the electronics. We'll see. We need to remember that the bank-angle sensor is also located in this component and I need to make sure the epoxy has not entered that cavity and locked it up.

I certainly would not hand the stealership $200 for a new one (if they had it), just because the sealer had dripped-out. I would think that an adequate spray-coating like Krylon in that cavity on the circuit-board would protect it.

 

gr.....I would not recommend eating this stuff I'm putting back into mine.

 

Thanks for the recommendation!

Thinking of encapsulated electronics I'm reminded of a solid state aftermarket ignition system I bought many years ago, to replace a points system. The 'module' looked as if had been moulded in a small box made of rough-planed timber, but worked like a charm.