Oil pressure idiot-light

[crazydrummerdude]

So, I had an unscheduled top-end rebuild on my R75 this winter, and apart from 2 of the aftermarket push-rod tube seals splitting, I've been pretty satisfied with the result.

The bike runs fine, strong, and just feels really even (whatever that means).

A month ago, on a trip back home from my shop (10 mile ride), as I got off the highway, my oil pressure light came on for maybe two seconds.

Two days ago, I was riding to my friends house, and it came on again. I immediately let off, and pulled over, but by the time I got to the shoulder, it was off, so I kept going.

(As a side-question, the bike now seems to leak oil onto the frame on the left side, under the cylinder. The cylinder isn't leaking and/or dripping onto it, and I can't find a traceable route for oil to get onto the frame, other than the oil pressure switch wires (but I doubt "that much" (not that much) oil could take a ride down a wire and get onto the frame). I'll get a picture posted pretty soon.)

What's the deal?

[widebmw]

Spray some powder foot spray around the area of the leak.
The oil will leave a track back to the Source.

[Boxerkuh]

I would suggest that you clean the area really good with some brake cleaner. It will remove all the oil and evaporate dry. Then you can use talc powder or baby powder and liberatly put is all over the area. The oil may reappear and show were it starts. Remember that one drop of oil at speed will look like you lost a quart of oil. Any oil residue on you left lower pant leg? You can also try to tighten the plug one time, but this will only be a temporary fix. I have replaced a few of them over time... if you don't want to replace it, during the next oil change you can take the plug out and clean the area up and put a little bit of Yamabond 5 under it. The plug is pretty cheap (about $15) and easy to access, so it may not be worth all the hassle of trying to do a temporary fix...

[James.A]

Nathan, we always start with the cheapest, easiest fixes first. With the motor running, doink the wires from the sending unit. See what happens. It is low on the block behind the left cylinder if I remember correctly. Next, try changing the sending unit with one known to be good, better, different. You have a spare parts bike, don't you? Your bike is relatively low mileage, and shouldn't have an oil pressure problem. The next step would be to pull the oil filter and look inside the cavity for a dis-lodged spring or ball from an internal check valve. Our early airheads have a cap and bolt to secure the cap on the filter chamber. It is bullet-proof unless the cap comes loose. Don't be afraid to call for guidance. 309 251 0877.

[skiteach]

Very good chance it's the Oil Pressure switch. Those Bosch sending units are prone to failing that way. Aftermarket senders seem to be worse. It's located by left jug and would leak onto the frame. If you pull the wire off the terminal, you'll most likely see oil there. Clean with carb cleaner or similar cleaner. Reattach wire, run for a bit and recheck for oil.

[sumran]

My sending unit went leaky. I was amazed at how much oil was coming out of it, event though it was not broken.

[zoridog]

I just replaced my oil pressure switch last night. Cost was $17. Took out the old and put in the new ... about 2 minutes. It took longer to find the wrench. Difficulty is on a par with changing a sparkplug.

[kbasa]

My sending unit went leaky. I was amazed at how much oil was coming out of it, event though it was not broken.

+1. When the switch failed on my K75, oil was coming out of the end of the sender, right where the wire connects.

You should take the old sender out and find your local NAPA. They have a cross reference and will sell you a Bosch 2002 unit, if memory serves. And it's like $6.

Hey, did you ever figure out what was up with your charging system? Did you get a battery for it and fix the ground wire? Did that clear it up?

[crazydrummerdude]

+1. When the switch failed on my K75, oil was coming out of the end of the sender, right where the wire connects.

You should take the old sender out and find your local NAPA. They have a cross reference and will sell you a Bosch 2002 unit, if memory serves. And it's like $6.

Hey, did you ever figure out what was up with your charging system? Did you get a battery for it and fix the ground wire? Did that clear it up?

Ah, excellent. Any ideas/vaules for a torque on the unit?

(That reminds me, I should update some of those threads on advrider.. I've just been pretty busy with school.)

With a lot of cleaning/re-newing connections, switching things out, and changing out my old (heavier-than-I-remembered-weight) oil, and a Saturday with James Strickland (woodnsteel), I got my bike back together and running fine (as mentioned, the only initial issues were the 2 split seals). There are still 2 main issues that I don't understand as to why my charging system acted the way it did, and I've asked around, and still am not satisfied with the explanations I've received.

James made the 3+ hour drive in his car with a box full of parts, and got to my shop at something like 8:45am, and worked with me until almost 4pm. He donated his grease for a spline-lube, and anti-seize for the exhaust nuts.. and offered a bunch of knowledge. He did all of this free-of-charge. :buds

Like I said in my cheesy article in January's ON.. of the few BMW-lovin' good friends I do have, it makes me excited for all those to come.

[535is]

Ah, excellent. Any ideas/values for a torque on the unit?
It isn't stressed. Just has to be tight enough not to leak or fall out.

FWIW, BMW was apparently unable to source a decent oil pressure switch from anyone back in Airhead days, because this is also the most common oil system failure on their cars of the time. Since a majority of them seems to fail anyway, I do not hesitate to replace them with 'questionable' ones from NAPA/AutoZone/Advance Auto/wherever. It isn't much of a risk since it this is always the first place I look for a leak or for an aberrant blinking light. In fact, at $6-$7, I usually carry a spare. :thumb

[sumran]

+1 on the light torque. It is a large nut and the way it made it can be easily damaged from excess torque. Just enough to get a seal with the soft copper crush washer.

[crazydrummerdude]

Can this be done without draining the oil?

(Yeah, I know, I could probably just look in my manual..)

[kbasa]

Like I said in my cheesy article in January's ON.. of the few BMW-lovin' good friends I do have, it makes me excited for all those to come.

:nod

Totally with you.

And I think the sender only gets something like 7ft. lbs. It's pretty small.

[20774]

Can this be done without draining the oil?

Yes...just lean it over on the right side...maybe rest the jug on a milk carton or stiff pail.

[Bill Burke]

Nathan-
Use a 24 mm deep socket. And use the copper crush ring that comes with it. Snug is fine. If it leaks, tighten it a little more. Use of an open end for this job risks cracking the plastic switch sealant, resulting in leaky new switch. This job can be done on the center stand, engine off. Won't lose more than a few drops.

[James.A]

Ah, excellent. Any ideas/vaules for a torque on the unit?


With a lot of cleaning/re-newing connections, switching things out, and changing out my old (heavier-than-I-remembered-weight) oil, and a Saturday with James Strickland (woodnsteel), I got my bike back together and running fine (as mentioned, the only initial issues were the 2 split seals). There are still 2 main issues that I don't understand as to why my charging system acted the way it did, and I've asked around, and still am not satisfied with the explanations I've received.

James made the 3+ hour drive in his car with a box full of parts, and got to my shop at something like 8:45am, and worked with me until almost 4pm. He donated his grease for a spline-lube, and anti-seize for the exhaust nuts.. and offered a bunch of knowledge. He did all of this free-of-charge. :buds

Like I said in my cheesy article in January's ON.. of the few BMW-lovin' good friends I do have, it makes me excited for all those to come.

Nathan, you could well be the airhead guru going forward. Look man, I'm 48 and you are under 30. How else are we to make our beloved airheads the last gasoline powered internal combustion relics on the road unless we share our knowledge and expertise?
This is a heady and serious obligation that I have saddled you with. I would have done the shop day with anyone who might have asked for help, but you are the one who asked for help. I'm no Oak, or Matt Parkhouse, or Paul Glaves, but we are obligated to our fellow owners just the same. Sharing that which we know.
When I am dead and gone, you will be the person who carries forward the knowledge and ethic that we all love and value.

As an aside, There is a man named John Cashman who makes a living travelling around the country in a motorhome fixing vintage Ford and Lincoln convertibles. I'm tellin ya, Nathan, when I'm 70 and you are 50 we could do this.

Thanks for the props, what is mine is yours for the taking.

[kbasa]

woodnsteel knows what's up.

pass it along, just pass it along.

[James.A]

woodnsteel knows what's up.

pass it along, just pass it along.

Thanks man, you don't need me. But if you did, I'd let you buy me a train ticket.

[zoridog]

Nathan-
Use a 24 mm deep socket. And use the copper crush ring that comes with it. Snug is fine. If it leaks, tighten it a little more. Use of an open end for this job risks cracking the plastic switch sealant, resulting in leaky new switch. This job can be done on the center stand, engine off. Won't lose more than a few drops.
+1

[kbasa]

Thanks man, you don't need me. But if you did, I'd let you buy me a train ticket.

I've been in Nathan's spot and now I'm closer to yours courtesy of folks like you.

[crazydrummerdude]

Here is the picture I promised. You can clearly see where the oil begins to accumulate on the frame.

You may also notice a split push-rod tube seal.. but that's not the point.

[James.A]

Note how the frame gets shiny right where the wire from the sending unit meets the frame tube. I would venture a guess that oil is oozing from the sending unit and migrating down the wire.

[crazydrummerdude]

Note how the frame gets shiny right where the wire from the sending unit meets the frame tube. I would venture a guess that oil is oozing from the sending unit and migrating down the wire.

Yep.

More than a week since I changed the unit (and the pushrod tube seal).. and virtually no oil drips at all on the parking lot(s)/driveway(s)/left shoe.

:drink