Oil Flow Rocker Arm Shafts

[Dave Faria]

My reason for looking at this is to determine if closing rocker arm end float will increase oil pressure at the tensioner. I've not had the rocker assembly apart and all I know is the main oil flow enters at the top of the intake valve rocker and exits at the bottom of the intaker rocker. It then goes across the bottom bearing and then up the exhaust valve rocker and then exits at the top of the exhaust rocker arm. It then flows back down the chain channel to the oil sump.

 

My Questions:

Does closing rocker arm end clearances increase oil pressure at the tensioner or is oil pressure actually controlled my metering ports in the rocker arm shafts?? Does closing the cleances only decrease the noise by removing play on the shafts???

[Ken H.]

Closing the gap will in theory increase the pressure nominally by reducing losses out the end of the bearing surface, but I suspect it so minimal as to be inconsequential.

[Dave Faria]

That's what I needed to know. It is a fair amount of work for me and I wanted to know if it was worth the effort.

 

Thanks

[Haynes]

Reducing the rocker end float is worth doing next time you're doing the valve clearences. It does make a difference to the noise.

[Dave Faria]

Thanks Haynes. I've got the rocker arms clearances to a max of .003in.. The valve noise is minimal. It is the tensioner side of the right side cam chain at idle that bugs me. It has an intermittent chugging chain sound at idle which compared to other bikes I should not have. I think I can fix the noise by stretching the tensioner spring maybe a 10th of an inch to put more pressure on the chain rail but, the pressure should come from the lube oil hydraulics. I can't find any drawing that shows how oil escapes from a rocker arm after lubrication back into the engine. Thats why I was asking if closing the rocker arm clearance another .001in. would raise the pressure back to the tensioner. Does closing that clearance restrict oil from leaving the tensioner, over head cam, rocker arm lubrication system??? If it does restrict the oil flow it should theoretically, like Ken said, increase pressure at the tensioner but, it is probably minimal. I just need to know if the oil escapes thru a gaping hole at the bottom or actually between the mating surfaces with a clearance of .003in.

 

Thanks Agn

[Kurt Snyder]

I had an issue with the right side tensioner a few years ago. I discovered that the tensioner spring would sometimes collapse when the engine was not running. When this happened the oil pressure would not extend the tensioner. If the tensioner stayed extended when the engine was off there was no problem. I replaced the tensioner but that did not solve the problem. I added a spacer to the end of the tensioner spring for more preload and haven't had a problem since. I found a spacer at the local hardware store with a center hole so the oil flow was not effected.

[Dave Faria]

Thanks Kurt for the response. I just got bk from my local dealership and have a data point. Since the tensioners are hydraulically operated I wanted a oil pressure at idle. I'm sure the pressure will depend on the oil manufacturer's specified viscosity and miles on the oil when tested. The dealer tech. told me around 40psi at the oil pressure switch at idle and running temperature. The BMW shop manual for the 1150 engine says 51psi min.. Before I try a spacer or stretching the tensioner spring I'm going to replace the pressure relief spring. It is specified to open at 80psi. After almost 80k miles I'm hoping it has taken a set and opens at a lower pressure. When cold the oil system, if healthy, will pressurize up to 90psi. So it has been exercised a few times over 80k miles. If a new relief spring does not help/fix the problem then I'll play with the tensioner spring.

[oldyam]

Whilst youre trying the releif valve spring it would do no harm to buy a new tensioner spring ( listed @ $2.13 on OEM ) and try swapping that too.

[Clive Liddell]

Dave,

 

You haven't mentioned it but have you checked that the sound you hear is not possibly the RH throttle body "clack" that many RT's develop.

 

 

[Dave Faria]

Thanks for the responses. I installed a new tensioner spring two days ago. It helped but, not enough. I also checked both throttle bodies by just holding the butter fly so they could not move. The noise didn't stop.

[Ken H.]

Don't just install a new spring, install the new design entire tensioner. It's far better than the orginal design.

[Dave Faria]

ken, I've installed the updated tensioner for the left side. Is there now one for the right also????

[Ken H.]

Same one both sides.

[Dave Faria]

Ken run that by me again. You are saying that the up graded tensioner used on the left side can also be used on the right. I happen to have a extra one and want to be sure.

 

 

[Boffin]

Ken run that by me again. You are saying that the up graded tensioner used on the left side can also be used on the right. I happen to have a extra one and want to be sure.

 

 

Both tensioners are identical, the LH one is mounted on the top of the cylinder and so drains down, The RH one is mounted below the cylinder and so does not.

 

Andy

[Dave Faria]

Ok Boffin. I tried to install the spare left hand tensioner(up graded model) in the right barrel for the right hand tensioner. The left hand tensioner is to big. Do I need another barrel??? I wonder if you have something in England we don't have yet???

[Clive Liddell]

As I understand the original RH tensioner, due to its position, retains the oil and does not need changing??