Oil pressure loss with bolt up crank??

Fast Eddie · Jan 6, 2014

Gents,

whilst stripping and cleaning my crank, I looked at the joining faces. Whilst they are well machined, they don't look like they're designed to seal.

I dawned on me that with hot oil, under pressure from the pump, and under greater pressure from centrifugal force, oil could escape from the joining faces.

So, does it? And if it does, what effect is there on oil pressure?

comnoz · Jan 6, 2014

Of course if it leaks it will reduce oil pressure. I always use a light smear of 515 sealant inside the bolt circle. Jim

Fast Eddie · Jan 6, 2014

comnoz said:
Of course if it leaks it will reduce oil pressure. I always use a light smear of 515 sealant inside the bolt circle. Jim

Thanks Jim. Is that 515 a Loctite product?

I'm using JS / Carrillo rods, which I believe do not have the oil jet holes in them. Do you have any idea how much this would improve oil pressure by?

Al-otment · Jan 6, 2014

Fast Eddie said:
Gents,

whilst stripping and cleaning my crank, I looked at the joining faces. Whilst they are well machined, they don't look like they're designed to seal.

I dawned on me that with hot oil, under pressure from the pump, and under greater pressure from centrifugal force, oil could escape from the joining faces.

So, does it? And if it does, what effect is there on oil pressure?

Never heard of this area creating a problem. As you say the surface finish is probably adequate to provide a seal. Fit an oil pressure gauge to check max. and min. pressure. Regarding the effect on oil pressure if there's a leak on the system, have a guess - it's either going to go up, down or stay the same. Tell me, how big is the demand for satnav's on short circuit race bikes

.

comnoz · Jan 6, 2014

Fast Eddie said:
comnoz said:

Of course if it leaks it will reduce oil pressure. I always use a light smear of 515 sealant inside the bolt circle. Jim

Click to expand...

Thanks Jim. Is that 515 a Loctite product?

I'm using JS / Carrillo rods, which I believe do not have the oil jet holes in them. Do you have any idea how much this would improve oil pressure by?

Yes, Locktie 515 anaerobic sealant.

I have not done a back to back test for oil pressure after plugging the oil holes. I have always used a bit of JB weld to plug the holes on stock rods also. Jim

Fast Eddie · Jan 6, 2014

Al-otment said:
Fast Eddie said:

Gents,

whilst stripping and cleaning my crank, I looked at the joining faces. Whilst they are well machined, they don't look like they're designed to seal.

I dawned on me that with hot oil, under pressure from the pump, and under greater pressure from centrifugal force, oil could escape from the joining faces.

So, does it? And if it does, what effect is there on oil pressure?

Click to expand...

Never heard of this area creating a problem. As you say the surface finish is probably adequate to provide a seal. Fit an oil pressure gauge to check max. and min. pressure. Regarding the effect on oil pressure if there's a leak on the system, have a guess - it's either going to go up, down or stay the same. Tell me, how big is the demand for satnav's on short circuit race bikes .

I get the dig, but...

A sensibly ridden bike, operating well within its design envelope, can easily do very high mileages without failure. And, they will probably eventually suffer from gradual wear, as apposed to catastrophic failure.
A bike where the performance envelope is being used / pushed / challenged is going to find the weak link in that design envelope pretty quickly.
I'm unlikely to break any high mileage records. Work / family / life prevent me doing a 'Ted Simon' these days. But I do like to use the performance on offer, and have broken plenty of rods, cranks, cases, etc!
I've learnt it is time and money well spent in trying to stack the odds in my favour against such catastrophic failures!
I'm actually thinking of opening a museum of motorcycle shrapnel one day...

Fast Eddie · Jan 6, 2014

comnoz said:
Fast Eddie said:

comnoz said:

Of course if it leaks it will reduce oil pressure. I always use a light smear of 515 sealant inside the bolt circle. Jim

Click to expand...

Thanks Jim. Is that 515 a Loctite product?

I'm using JS / Carrillo rods, which I believe do not have the oil jet holes in them. Do you have any idea how much this would improve oil pressure by?

Click to expand...

Yes, Locktie 515 anaerobic sealant.

I have not done a back to back test for oil pressure after plugging the oil holes. I have always used a bit of JB weld to plug the holes on stock rods also. Jim

Thanks Jim. Again!

kommando · Jan 6, 2014

I refitted an original sludge trap plug to a B44 crank after cleaning the trap, then applied pressure, first air bubbles appeared followed by oil, so out it came and refitted with loctite 515. No leaks.

gripper · Jan 6, 2014

Damn, never thought of that when I rebuilt my crank. I don't think I'll loose any sleep over it though. Kommando, how much pressure did you apply before you got oil coming out?

kommando · Jan 6, 2014

Used an oil can, cold 20/50W loaded onto end of crank. I needed to check as I have removed the pressure release valve and diverted some of the oil to the rockerbox, the pressure release route to the bottom end was blocked, as a roller bearing big end does not need or create back pressure it provides cooler oil to the top end at the expense of flow to the big end. So as the big end provides not much back pressure that leak was not at a high pressure.

Al-otment · Jan 6, 2014

Fast Eddie said:
I get the dig, but...

A sensibly ridden bike, operating well within its design envelope, can easily do very high mileages without failure. And, they will probably eventually suffer from gradual wear, as apposed to catastrophic failure.
A bike where the performance envelope is being used / pushed / challenged is going to find the weak link in that design envelope pretty quickly.
I'm unlikely to break any high mileage records. Work / family / life prevent me doing a 'Ted Simon' these days. But I do like to use the performance on offer, and have broken plenty of rods, cranks, cases, etc!
I've learnt it is time and money well spent in trying to stack the odds in my favour against such catastrophic failures!
I'm actually thinking of opening a museum of motorcycle shrapnel one day...

I'm all for meticulous preparation, so your question was valid. I've never had any reason to suspect a pressure loss from this area. Applying sealant should ensure everything is ok but it's not going to stop the crank from breaking. Vital to check there is a 0.090" rad. where the big end journal meets the crank cheeks and that, with the big ends in the 12 o'clock position, the studs at 11, 1 and 6 o'clock are a interference fit into the flywheel. Also essential to check min. and max. oil pressure on start up. Max. pressure is controlled by the PRV and is shimmed to achieve 44-55lb/sq.in, engine and oil hot, when revved. Apologies if you knew this already.

Fast Eddie · Jan 7, 2014

Al-otment said:
Fast Eddie said:

I get the dig, but...

A sensibly ridden bike, operating well within its design envelope, can easily do very high mileages without failure. And, they will probably eventually suffer from gradual wear, as apposed to catastrophic failure.
A bike where the performance envelope is being used / pushed / challenged is going to find the weak link in that design envelope pretty quickly.
I'm unlikely to break any high mileage records. Work / family / life prevent me doing a 'Ted Simon' these days. But I do like to use the performance on offer, and have broken plenty of rods, cranks, cases, etc!
I've learnt it is time and money well spent in trying to stack the odds in my favour against such catastrophic failures!
I'm actually thinking of opening a museum of motorcycle shrapnel one day...

Click to expand...

I'm all for meticulous preparation, so your question was valid. I've never had any reason to suspect a pressure loss from this area. Applying sealant should ensure everything is ok but it's not going to stop the crank from breaking. Vital to check there is a 0.090" rad. where the big end journal meets the crank cheeks and that, with the big ends in the 12 o'clock position, the studs at 11, 1 and 6 o'clock are a interference fit into the flywheel. Also essential to check min. and max. oil pressure on start up. Max. pressure is controlled by the PRV and is shimmed to achieve 44-55lb/sq.in, engine and oil hot, when revved. Apologies if you knew this already.

Please don't appologise to me, I'm new to Nortons, so happy to soak up any good info!
I realise this won't stop my crank breaking, just thinking about oil pressure.
RGM do a PRV set to 60lb, is this a good idea?
I don't want an OPG on the bike permanently, but I will be fitting one as a temp measure when its rebuilt to get the baseline info as you describe.
Putting a radius around PTO shaft is already on the cards.
I wasn't aware about the studs you mention needing to be an interference fit. I don't think mine are. I guess the only way to address this would be to go to MK111 3/8 studs?

Al-otment · Jan 7, 2014

Fast Eddie said:
Please don't appologise to me, I'm new to Nortons, so happy to soak up any good info!
I realise this won't stop my crank breaking, just thinking about oil pressure.
RGM do a PRV set to 60lb, is this a good idea?
I don't want an OPG on the bike permanently, but I will be fitting one as a temp measure when its rebuilt to get the baseline info as you describe.
Putting a radius around PTO shaft is already on the cards.
I wasn't aware about the studs you mention needing to be an interference fit. I don't think mine are. I guess the only way to address this would be to go to MK111 3/8 studs?

Figures I gave (should have been 45 - 55lb/sqin) are out of the Mk3 manual. I'd ran around for years with out ever checking the PRV, when I did get around to it I was surprised at the low pressure, something like 30lb/sqin. A couple of shims brought it up to approx. 50lb/sqin.
Radii are good practice in general where shafts stick out as on the PTO shaft, but it's the big-end journal's (as well as the mains) that need to be checked for the 0.090" radius specifically.
The three studs give positive location, I don't know if it's only the Mk3's that had this but I think it's a good mod for any crank.

Hobot · Jan 7, 2014

I'd ran around for years with out ever checking the PRV, when I did get around to it I was surprised at the low pressure, something like 30lb/sqin.

Oh my Gosh, you mean you ran years of extra wear and tear w/o sufficient oil pressure - sure a good thing you caught it in nick of time : )

Next time in might put valve grind compound on the faces and rub em around till the polished faces are hard to part from the Vanderwall electronic bonding closeness. The forces that act on crank flywheel tend to tip its fasces apart from cheeks stretching bolts more than shearing across them.

Al-otment · Jan 7, 2014

hobot said:
I'd ran around for years with out ever checking the PRV, when I did get around to it I was surprised at the low pressure, something like 30lb/sqin.

Click to expand...

Oh my Gosh, you mean you ran years of extra wear and tear w/o sufficient oil pressure - sure a good thing you caught it in nick of time : )

Next time in might put valve grind compound on the faces and rub em around till the polished faces are hard to part from the Vanderwall electronic bonding closeness. The forces that act on crank flywheel tend to tip its fasces apart from cheeks stretching bolts more than shearing across them.

There was no problems I was aware of, big-ends required first regrind at 100,000 miles. Modern oils obviously help to reduce wear - if you've got the measuring tools you may as well use them. Point is if you don't check you don't know. Don't know why you'd want to run oil pressure outside of factory spec.

toppy · Jan 7, 2014

you do no need to put jb weld or simlier in the rod holes according to Mick Hemming an old cure for engine that were over oiling their crank cases was to simply fit the shell with the oil hole in the cap not the rod and the plane shell in the rod so blocking the oil feed hole. Simple effective and not worry of bits of jb weld coming out an flying around inside the engine.

Hobot · Jan 7, 2014

1+ on just flip the shells. Oil jets were a Norton bad piston batch mistaken useless solution to siezures. Not enough oil squirts to cool any and plenty lube on wrist pins w/o them so that much more oil for crank load surfing.
I pumped hole to see prefect soild stream hits mid line of pin but strikes near the inside seam.

Oil pressure loss with bolt up crank??

Similar threads