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mschreck
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Bike was in storage for years. Fresh oil, plugs,filter, battery, gas, clean tank and carbs. Great compression. Gauze has never been changed nor cleaned in pickup. I installed filter! Could be 'operator headspace' on filter installation. Do I need to check pressure sending unit also. Appreciate some advice.

Darryl.Richman
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84' R80RT oil pressure lite comes on at idle?

Are you sure it's the oil pressure light (amber) and not the generator light (red)? The generator light should be on at a regular idle and disappear just above that point. The oil light should always be out. It's easy to confuse them.

If it really is the oil light, then you may have gotten the oil filter together wrong. BMW sells one kit, but there are, I believe, three different possible configurations! If you put it together wrong, you'll have low oil pressure and soon ruin your crank. Over on the Airheads list, they call this the $2,000 O-ring.

Also, it's possible to leave the small o-ring inside the filter chamber when you pull the old filter out, and this will also cause problems.

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Darryl.Richman
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84' R80RT oil pressure lite comes on at idle?

(Also, I moved this to the Classic BMWs forum area where more people may see it.)

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schrader7032
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San Antonio, TX
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84' R80RT oil pressure lite comes on at idle?

As mentioned, the oil light should never be on when the engine is running. It's important you figure this out before you do potential damage to the engine.

The issue the $2000 o-ring is getting enough compression on this large o-ring to ensure sealing without cutting it. It all depends on the depth of the filter canister that is inside the engine casting. Normally the depth of the canister is around 3-3.5mm. For this depth, there should be a thin steel shim placed against the sharp edge of the canister followed by the large white o-ring. No paper gasket. If the depth is closer to 4mm, then another shim is needed. If the depth is less than 3mm, then the paper gasket is a good idea.

Having an oil cooler complicates the situation a little. I'm not that familiar with the oil filter cover/thermostat. But it's important to ensure that the white o-ring has a reasonable amount of compression. Too little, and the oil bypasses the filter and goes straight back to the sump with little oil pressure. Too much and the o-ring splits and you revert back to not having any pressure.

What all did you change when you "installed filter"?

Kurt in S.A.

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'78 R100/7 '69 R69S '52 R25/2

mschreck
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R80RT Low Pressure Light

I am going back out to the shop on Wed. morning. Just remember seeing the red light and turning the motor off. Didn't think about the oil filter being installed wrong. Installed it last winter and was more interested in staying warm that paying attention. Especially checking the back of oil filter cylinder to see if there were another rubber gasket stock in there. Thought the problem might have been the gauze element in the pickup strainer in the oil pan. Going to kick the motor over with spark plugs and observe that orange light first. Thanks for all your advice. Quit riding when I returned from Germany in 91'. Now I've got the 'bug' again. No autobahns in TX.

Darryl.Richman
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Re: R80RT Low Pressure Light

"mschreck" wrote:

I am going back out to the shop on Wed. morning. Just remember seeing the red light and turning the motor off.

The RED light? The RED light is the generator. It's the amber light that's the oil pressure light. It's ok if the generator light is on at idle; it just needs to go out above idle.

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mschreck
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Oil Pressure

I changed the filter, cleaned the screen in the oil pan put some air into an oil valley and the light still comes on when the engine becomes warm. Is the next step the oil pressure relief valve?

Darryl.Richman
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84' R80RT oil pressure lite comes on at idle?

So, is it the red light or the amber light that comes on?

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schrader7032
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84' R80RT oil pressure lite comes on at idle?

Is the oil pickup extension inside the oil pan tight? I've heard that if this extension becomes loose, it will start sucking air at one of the joints.

As Darryl said, are you sure you're looking at the oil pressure light??

Kurt in S.A.

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'78 R100/7 '69 R69S '52 R25/2

mschreck
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Spring, TX
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Oil Pressure

Pulled the pan, check the screen, filter, pickup tube, everything that can be checked from the bottom side. Same results. Next stop is the oil pressure relief valve. All day and a sack lunch for this item. Also, my oil light is red not amber.

schrader7032
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84' R80RT oil pressure lite comes on at idle?

I'd replace the pressure sending unit...they're pretty cheap. Then you could rule that out...

Kurt in S.A.

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mschreck
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Spring, TX
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Oil Pressure Sending Unit

Going to check OP sending unit for continuity and/or replace it.

mschreck
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Oil Pressure

At what rpm does the oil pressure light go out on an 84' boxer R80RT?

schrader7032
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San Antonio, TX
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84' R80RT oil pressure lite comes on at idle?

Very low...probably 600-700 RPM. The pressure only has to get to around 5 psi for the light to go out with the stock pressure sender. It doesn't take much RPM for that to happen.

Kurt in S.A.

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mschreck
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Oil Pressure Light

OK, changed the Oil Pressure Light, fired up the engine. OP light came on at idle. Gave it some throttle to 2k light went out and then throttle went to idle llight came on. Guess it's time to move on to the oil pressure relief valve.

schrader7032
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84' R80RT oil pressure lite comes on at idle?

You mentioned on an earlier post that you were going to check the sending unit and/or replace it. How did that work out? I'd want to be sure that was functioning OK before diving into the internals...

Kurt in S.A.

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mschreck
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Spring, TX
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Oil Pressure Switch

I replaced the OP switch. Light still comes on at idle. Run rpm to 2k and light goes off. I will check the oil pressure next. Got to find the correct guage. Don't want to be taking anything apart if I don't have too. Can't remember when I rode the bike in Germany if the light came on at low idle. This happens when you get old.

schrader7032
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84' R80RT oil pressure lite comes on at idle?

The light shouldn't come on at idle, with idle being about 1000 RPM. At least you're building pressure to turn the light off. And since you've replaced the switch and still get the same sequence of lights, I think the pressure test is going to tell you what you already know. Sounds like there might be a restriction in the oil flow or the pump is wearing out.

Kurt in S.A.

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'78 R100/7 '69 R69S '52 R25/2

mschreck
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Spring, TX
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Oil Pressure Light

Problem resolved. Disassembled oil filter housing again. Small 'o' in rear of housing. Replaced filter and correct related items fired it up and no oil light. Thanks to all of you for your advice. I have sure become familiar with the parts of my BMW now. Bike runs fine. Just need to get my carbs syn'd again. Looking forward to another 15 years of riding.

schrader7032
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Re: Oil Pressure Light

"mschreck" wrote:

Problem resolved. Disassembled oil filter housing again. Small 'o' in rear of housing. Replaced filter and correct related items fired it up and no oil light.

Glad you resolved it...

So what exactly was the problem? Missing o-ring? Cut o-ring? Too many o-rings? Is this the square-shaped o-ring that is supposed to be glued to the end of the filter?

Kurt in S.A.

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Kurt in S.A.
'78 R100/7 '69 R69S '52 R25/2

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