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How did i blow my rear main seal ?


hunter63

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Greetings,

I am a newbie to this site so please bear with me if I am posting in the wrong spot. I filled out my profile sort of but I was not sure where to submit a intro so I left it blank for now.

 

I have a 2004 R1150RT that has a bad oil leak in the R.M.S. area. I have spent many hours trying to make sure that is where my leak is before I tear into it but so far no luck.

 

When I bought the bike it had a blown head gasket. After I changed the gasket I flushed the motor with a mix of diesel and oil.

 

My plan was to fill the crankcase with a diesel and oil mixture and then cold crank the bike......

 

I believe I overfilled the crankcase with my diesel mixture and when I cranked it (run switch off and plugs out) I created a hydraulic action which dislodged the seal. I know it should have expelled the excess fluid through the vent tube that dumps into the air box right? For some reason I believe it did not vent like it was designed . Has anyone ever heard of such a thing happening before ?

 

The bike had no leaks before the repairs to the head were completed. It was never started until after the leak was noticed. The only time the engine was turned over was during the cold crank with the diesel mix in it.

 

After draining the diesel/oil mixture out I changed the filter and added the right amount of oil. I then took the bike around the block once in hope that the leak would go away. It did not.

 

I have checked for a blocked vent line and have also removed the starter and exhaust but everything points to a leaking rear main.

 

I will start my tear down this weekend . I will post my findings.

Thank you

 

 

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Hunter,

 

Looks like a teardown is the only way to definitively diagnose it, as well as repair it if it is the RMS.

 

You might be prepared to replace the clutch disc, plus a few other parts that might/will pop up.

 

There is a Quick Clutchectomy on one of the forums that describes a procedure that removes the rear frame complete, swinging it to the left, frame, wheel, mono shock and swingarm intact. If you don't need to lube driveshaft splines or the paralever pivot bearings, it would be a real time and aggravation saver. Wish I had the link to it to give you, can't find it again.

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Morning hunter63

 

How much did you overfill it?

 

There is a crankcase vent into the air box but it is timed by the crankshaft so only vents for a partial crankshaft revolution.

 

The vent is meant for crankcase air/combustion gas venting not for fluid flow so a gross overfill could allow excess crankcase pressure build up. If grossly overfull of liquid maybe even hydraulic pressure.

 

One of the problems with a boxer engine design is that BOTH pistons move in together & move out together so they change the crankcase internal volume greatly during each revolution.

 

If your crankcase was so overfull as to get into a hydraulic action then you could have easily damages your engine seals.

 

You might try clearing/checking your crankcase venting system-- to do that open the oil filler cap, then make a tube or other sealed extension on the oil filler, then lightly blow into the open oil filler hole while turning the crankshaft slowly. At some rotation of the crankshaft that air blown in should come out in the air box (be sure to drain the air box lower chamber first)-- There is an air box drain valve on L/H lower rear of air box.

 

Also make sure that the crankcase vent hose is not kinked, pinched, or plugged.

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Well that adds a whole new meaning to hydro lock.

 

If there was enough pressure to push the rear main seal I would also be concerned about ever other seal as well.

 

Not sure where you got the idea that filling and flushing an engine with oil and diesel is either necessary or a valid procedure. A recipe for disaster in my books.

 

 

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Greetings,

I am a newbie to this site so please bear with me if I am posting in the wrong spot. I filled out my profile sort of but I was not sure where to submit a intro so I left it blank for now.

 

I have a 2004 R1150RT that has a bad oil leak in the R.M.S. area. I have spent many hours trying to make sure that is where my leak is before I tear into it but so far no luck.

 

When I bought the bike it had a blown head gasket. After I changed the gasket I flushed the motor with a mix of diesel and oil.

 

My plan was to fill the crankcase with a diesel and oil mixture and then cold crank the bike......

 

I believe I overfilled the crankcase with my diesel mixture and when I cranked it (run switch off and plugs out) I created a hydraulic action which dislodged the seal. I know it should have expelled the excess fluid through the vent tube that dumps into the air box right? For some reason I believe it did not vent like it was designed . Has anyone ever heard of such a thing happening before ?

 

The bike had no leaks before the repairs to the head were completed. It was never started until after the leak was noticed. The only time the engine was turned over was during the cold crank with the diesel mix in it.

 

After draining the diesel/oil mixture out I changed the filter and added the right amount of oil. I then took the bike around the block once in hope that the leak would go away. It did not.

 

I have checked for a blocked vent line and have also removed the starter and exhaust but everything points to a leaking rear main.

 

I will start my tear down this weekend . I will post my findings.

Thank you

 

 

Excuse my ignorance, but what is the reasoning behind filling the motor with diesel fuel/oil as a flush, based on a repaired head gasket?

 

RPG

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A penguin walks into a BMW shop...

 

Mechanic says "looks like you blew a seal"...

 

Penguin says, "No its ice cream"

 

I'm sorry for that, but I just couldn't resist. Banned for life?

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Thanks.... That's some great information about how to check the vent tube. I had removed it from the Motor but left it connected to the air box and then checked air flow in both directions and it was clear. I will check it as you suggest though just to make sure.

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I forgot to explain my reason for the flush.

 

I did a really dumb thing when trying to remove the r/h side cam chain sprocket while I was repairing the head gasket. I used my air impact ! At this point I am sure there are a few members that are shaking there heads while saying "you did what ???" Yes. I really stepped in the deep end of the pool when I did that because the force of the air impact broke the end off of my lower cam chain guide rail.

The only thing I can say in my defense is that this was my first head removal on a B.M.W. motor.

Not much of a excuse I guess because I know i should have been more cautious or at least spent more time with my manual since I was unfamiliar with the procedure...

 

It was a clean break of about a inch and a half off the end ( which I recovered ) but I flushed the motor in hope of getting any small pieces that I might have missed.

 

 

 

 

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Thanks for the youtube link Lowndes. When you mentioned a shortcut I was very interested but I did not want to put you through any trouble . I know how exhausting a computer search can be sometimes.

 

I have only briefly viewed it, but from what I saw, it looks like something that I can use.

Thanks again

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Welcome.

Good luck with the rebuild.

Take your time and ask, before doing something.

There are a few folks around who have BTDT.

Best wishes.

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I forgot to explain my reason for the flush.

 

I did a really dumb thing when trying to remove the r/h side cam chain sprocket while I was repairing the head gasket. I used my air impact ! At this point I am sure there are a few members that are shaking there heads while saying "you did what ???" Yes. I really stepped in the deep end of the pool when I did that because the force of the air impact broke the end off of my lower cam chain guide rail.

The only thing I can say in my defense is that this was my first head removal on a B.M.W. motor.

Not much of a excuse I guess because I know i should have been more cautious or at least spent more time with my manual since I was unfamiliar with the procedure...

 

It was a clean break of about a inch and a half off the end ( which I recovered ) but I flushed the motor in hope of getting any small pieces that I might have missed.

 

 

 

OK so going from what you have written you have a broken guide that you haven't replaced because that involves a lot of work that you are also going to have to do to replace the seal.

 

I can't get Johnny Cash singing ... I fell into a burning ring of fire.... out of my head. You may seriously want to check out a complete used engine and just do a swap.

 

Good luck on your adventures in wrenching.

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I did repair the guide. The r/h lower guide rail can be replaced without engine removal.

 

I know I should have removed the engine anyway but the weather was still nice and I was itching to put some miles on a recently purchased bike.

 

Believe me, it will be a long time before I stop kicking my own butt for this mess but a nice ride down a long road would do wonders sooooo I better get to work.

 

Talk soon...

 

 

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I do the diesel flush on my 4x4 on a regular basis. It now has 500,000kms on it . But I don't feel the need on my petrol engines.

I do understand why you did tho .

Just next time make sure to completely drain first, then put in a measured amount.

Good luck with the RMS repairs.

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