Oil Level Sight Glass replacement?

Any sage advice on replacing the Oil Level Sight Glass on a 1998 R1100RT with 72,000?

My thoughts are to have a spare Oil Level Sight Glass under the seat and replace it when it blows. Looks like a clean the hole, pop it in and add oil procedure.

Should I be replacing the Oil Level Sight Glass before a certain time or mileage?
I was thinking the Oil Level Sight Glass may last 200,000 miles or might fail tomorrow during my commute. I got lucky last year when the Hall Sensor failed close to home.

I keep up with the recommended maintenance schedules and carry a spare alternator belt, headlamp and old clutch cable under the seat now.

Thanks,
Dean Kohlmeyer
Garner, IA

With the age and mileage of your bike, my choice would be to replace it now.

Otherwise (as Sod's Law dictates) you may end up in the middle of the boonies without one and your engine oil spread all over the outside!

I change them periodically - every couple of years or maybe 50K miles or so.

The rubber surround that holds the backing plate (with little holes) and the sight glass lens is just a friction fit in a smooth, machined, hole in the engine case. Irrespective of the fact that the lens discolors with age, the rubber also hardens. Eventually you will be able to detect a slight seepage of oil between the rubber and the engine case.

The sight glass is installed with the metal and the rubber clean and dry. Friction keeps it in place, and while the rubber remains pliable this seems to work fine (usually - more later). But once oil seeps between the hardened rubber and the metal case you have a well lubricated joint. Friction can no longer be relied upon to keep the sight glass in place.

So, at the very first sign of seepage around the sight glass they should be replaced.

Now for that more later - in most engines the sight glass is a tight fit, requiring tapping on an appropriate driver (socket usually) resting only on the rubber ring. On Voni's 1994 R1100RS the recess in the case seems to be ever-so-slightly oversized. On this bike I can press the sight glass into place with only firm thumb pressure.

On this bike I use a substance called Loctite Black Max which is a black rubberized super glue. I put a little on the "back" (inside edge) of the rubber to adhere the sight glass to the case. I don't do it on other bikes where it's not a loose fit because they are too darned hard to remove when necessary.

Paul is the authority on this for sure and he did tell you exactly when to replace the sight glass.

Having said that, I can't help but think you may still be thinking you'll "replace it when it blows".

Don't do that Dean. The crankcase oil could be long gone before you notice and that will wreck the engine.

Happened to this guy.
http://forums.bmwmoa.org/showthread.php?t=25488&referrerid=31621

Your bike is 11 years old - I say replace it now.

Had a friend come over last weekend to replace the sight glass in her R1150R. No signs of seeping or other problems, she just wanted the peace of mind. It took us 2 freakin' hours to get it out! The screw thru the plastic trick didn't work, nor did pushing the screw all the way thru the rear metal piece. Eventually we broke out all the plastic, and I found that the Cycleworks bearing puller tool I had for my airhead fit the glass. THAT got it out, but what a PITA! Keep an eye out for seepage, but otherwise, most of us should just ride!

BTW - Remember Clifford the Big Red Bike, that I rebuilt after the glass blew out during the Cape Fear 1k Mini-Rally last year? Not only did we finish the rally this year, but we won. The comeback is now complete!

MotorradMike said:

Paul is the authority on this for sure and he did tell you exactly when to replace the sight glass.

Having said that, I can't help but think you may still be thinking you'll "replace it when it blows".

Don't do that Dean. The crankcase oil could be long gone before you notice and that will wreck the engine.

Happened to this guy.
http://forums.bmwmoa.org/showthread.php?t=25488&referrerid=31621

Your bike is 11 years old - I say replace it now.

Click to expand...

Note that this link leads to the story of a 1994 R1100RS - built early on in 1993 - similar to Voni's I mentioned above. I'll bet the sight glass isn't as tight a fit as on later motors either.

At some point in the oilhead series wasn't a change made in crankcase venting to reduce pressure on the sight glass. I recall hearing something like that.

MrFrank said:

At some point in the oilhead series wasn't a change made in crankcase venting to reduce pressure on the sight glass. I recall hearing something like that.

Click to expand...

The venting was changed. The version I heard was that it was to reduce the blow off of oil into the air box. Maybe it reduced pressure too. I don't know but had not heard that.

I'm firmly in the "don't change it until it seeps" category. I've put 100K miles (each) on two oilheads with no problems at all. If it starts to seep, I'm gonna change it immediately.

Too darned hard to remove when neccessary...

So, when do you remove the sight glass other than a leak related/ old age reason?Have there been instances of premature failure?First mention I have seen about them.

PGlaves said:

I change them periodically - every couple of years or maybe 50K miles or so.

The rubber surround that holds the backing plate (with little holes) and the sight glass lens is just a friction fit in a smooth, machined, hole in the engine case. Irrespective of the fact that the lens discolors with age, the rubber also hardens. Eventually you will be able to detect a slight seepage of oil between the rubber and the engine case.

The sight glass is installed with the metal and the rubber clean and dry. Friction keeps it in place, and while the rubber remains pliable this seems to work fine (usually - more later). But once oil seeps between the hardened rubber and the metal case you have a well lubricated joint. Friction can no longer be relied upon to keep the sight glass in place.

So, at the very first sign of seepage around the sight glass they should be replaced.

Now for that more later - in most engines the sight glass is a tight fit, requiring tapping on an appropriate driver (socket usually) resting only on the rubber ring. On Voni's 1994 R1100RS the recess in the case seems to be ever-so-slightly oversized. On this bike I can press the sight glass into place with only firm thumb pressure.

On this bike I use a substance called Loctite Black Max which is a black rubberized super glue. I put a little on the "back" (inside edge) of the rubber to adhere the sight glass to the case. I don't do it on other bikes where it's not a loose fit because they are too darned hard to remove when necessary.

Click to expand...

Chaz (guitardad) helped me out... I did the pro-active approach, and posted this story on the bmwbmw board:

About a month ago, I became convinced my site glass was going to blow out of my bike at any time. I am sure it had nothing to do with the impending Cape Fear rally and Chaz's experience last year. (sight glass blew out of the bike 10 miles into rally and drained all the oil, requiring rebuild). I have seen some, perhaps overzealous, recommendations to change the site glass every two years. So since I am at 4 years I thought I should be pro-active and switch it out. This is where Chaz comes in.

Sure, it is a "routine" task, but I wanted oversight just in case. So I headed over to Chaz's last weekend for an oil change and sight glass change. Mind you, there is no sign of seepage...I am just being pro-active. I drained the oil and followed the general process of heating a screw, piercing the plastic, giving a yank, which only cracked the plastic. OK...drilled thru the back of the sight glass metal, gave a yank, and turned the metal backer inside out without budging the sight glass. OK...insert an allen wrench to hook it from behind, give a yank, and nearly lose the allen wrench in the engine. OK...spray some lubricant around the edges of the sight glass and repeat the allen wrench trick...it AIN'T BUDGING!

Chaz pulls out his bag of tricks, and comes up with a tool to pull out bearings. We insert it into the opening, crank it open, and BARELY start moving that &*%$# sight glass. Several more minutes of manipulating finally gets the goddamn thing out. Jeez! So much for routine. Based on my experience, Chaz declined to switch out Pam's, which he had planned that day. So my advice is watch the sight glass, wait for sign of leaking, THEN change it.

It was quite the ordeal. But a happy ending.

guitardad said:

Had a friend come over last weekend to replace the sight glass in her R1150R. No signs of seeping or other problems, she just wanted the peace of mind. It took us 2 freakin' hours to get it out!

Click to expand...

I had the same issue removing the glass on our '04 R1150RT. at 59k mi. it had begun to seep, but surely did not want to come out. An hour of melting, screwing, breaking, poking, prying, cussing, praying, begging and out it came. A little corrosion on the metal mating surface had it glued in tight.

PGlaves said:

Note that this link leads to the story of a 1994 R1100RS - built early on in 1993 - similar to Voni's I mentioned above. I'll bet the sight glass isn't as tight a fit as on later motors either.

Click to expand...

Quite true - definitely not as tight a fit as my friend's R1150R. And here's a great illustration of how these things can get blown out of proportion on the Interwebs......

The linked story is mine. And it's the bike that blew the sight glass during the Cape Fear 1k. And mvscorpio, whose post is just above, is the friend I mentioned in my post. So if you're not paying close attention. several posts (and threads!) about two bikes becomes an epidemic of sight glasses coming out.

I related this topic on the R1150R.org board and a guy there states that he just uses an autobody panel puller. I assume he drilled a small hole, threaded it in , and jerked.

fwiw, I replaced the sight glass on my 96 r1100rs at about 60000 miles when it got so dark yellow I couldn't see the oil level.

I made the hole, then threaded a cork screw into the whole, and hooked the tip of the corkscrew behind the metal back plate, and pulled it out, it wasn't too hard. oiled the new one before installing it.

as I understand it, there's some danger of an old one shattering and dumping all the oil catastrophically, rather than just seeping a little as a warning.

piercej said:

fwiw, I replaced the sight glass on my 96 r1100rs at about 60000 miles when it got so dark yellow I couldn't see the oil level.

I made the hole, then threaded a cork screw into the whole, and hooked the tip of the corkscrew behind the metal back plate, and pulled it out, it wasn't too hard. oiled the new one before installing it.

as I understand it, there's some danger of an old one shattering and dumping all the oil catastrophically, rather than just seeping a little as a warning.

Click to expand...

I've never seen one shatter. But I know of several cases where they blew out - intact - just out.

And then one case where one melted after the bike sat idling for 1/2 hour or so. And then after the sight glass melted the oil ignited - but that was an unusual case.

The danger is crankcase pressure blowing it out.

I also know of one case where a leaking fuel injector added fuel to the cylinder. then crankcase, which fuel ignited on start up and the big-bang blew the sight glass out. Also an oddball case.

PGlaves said:

I change them periodically - every couple of years or maybe 50K miles or so.

The rubber surround that holds the backing plate (with little holes) and the sight glass lens is just a friction fit in a smooth, machined, hole in the engine case. Irrespective of the fact that the lens discolors with age, the rubber also hardens. Eventually you will be able to detect a slight seepage of oil between the rubber and the engine case.

The sight glass is installed with the metal and the rubber clean and dry. Friction keeps it in place, and while the rubber remains pliable this seems to work fine (usually - more later). But once oil seeps between the hardened rubber and the metal case you have a well lubricated joint. Friction can no longer be relied upon to keep the sight glass in place.

So, at the very first sign of seepage around the sight glass they should be replaced.

Now for that more later - in most engines the sight glass is a tight fit, requiring tapping on an appropriate driver (socket usually) resting only on the rubber ring. On Voni's 1994 R1100RS the recess in the case seems to be ever-so-slightly oversized. On this bike I can press the sight glass into place with only firm thumb pressure.

On this bike I use a substance called Loctite Black Max which is a black rubberized super glue. I put a little on the "back" (inside edge) of the rubber to adhere the sight glass to the case. I don't do it on other bikes where it's not a loose fit because they are too darned hard to remove when necessary.

Click to expand...

Wish I had read this before , I would have replaced my sight glass. I had a super nice 400 mile ride yesterday with my 94 R1100RSL running great. This morning I started the bike up to ride to the post office and %#! * the sight glass blew !
It had just started a very, very slight weep. Thanks for this post , I will have a new sight glass ASAP !

patiodadio said:

Wish I had read this before , I would have replaced my sight glass. I had a super nice 400 mile ride yesterday with my 94 R1100RSL running great. This morning I started the bike up to ride to the post office and %#! * the sight glass blew !
It had just started a very, very slight weep. Thanks for this post , I will have a new sight glass ASAP !

Click to expand...

I have advised that every Oilhead rider should remove their oil filler cap and start the engine. Then listen to that odd whoofing sound. If you ever hear it again your sight glass probably just blew out.

PGlaves said:

I have advised that every Oilhead rider should remove their oil filler cap and start the engine. Then listen to that odd whoofing sound. If you ever hear it again your sight glass probably just blew out.

Click to expand...

Sounded a lot like a manifold gasket leak on a car. If I had been ripping down a back road the engine would have been toast ! Glad it happened in the garage ! Ordered a new sight glass from Max BMW today. Thanks for all your helpful post Paul , you are the best

patiodadio said:

If I had been ripping down a back road the engine would have been toast ! Glad it happened in the garage!

Click to expand...

You just used up some luck!
Better help an old lady with her groceries.