oil migration question
Thread Starter
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Road Master
Joined: Mar 2006
Posts: 775
Likes: 2
From: OC California
oil migration question
Okay, here goes. 74' XLH. I have been working on this sucker for quite some time putting it back to road worthy condition. Lots of new parts and machine work involved. So I get everything lined out. Starts first crank (electric) but misses midrange. I fix the Super-B problem and am ready for the street. I get a couple miles from home and the oil pressure light goes on. So I get on back home and check the oil. It shows below the fill line. Gee, I thought I filled it. Oh well, put in another quart and hit the road again. I went a couple more miles and returned home to check chit out. Oil is now below fill line, WTF, no leaks. You people familiar with 74's know where I am going now. Only place for that oil to be, in the primary. Pulled the primary level plug from the cover and low an behold out comes about 2 quarts of fresh 60. I can not find anything in either one of my manuals about the "pressure relief valve" thats sits between the crankcase and primary. In the old days some people used to seal that bad boy off. It seems like the logical culprit. Myquestion is what good is that sucker and is it safe to plug it off? This is assuming it is the relief valve and not a serious problem like a crack in the case.I am going to pull the primary cover and check it out this weekend.
Stellar HDF Member
Joined: Feb 2006
Posts: 3,035
Likes: 17
From: Houston Texas
RE: oil migration question
Cal.....
A couple of questions here:
With your rework of the engine, did you remove the oil pump or any of the gearing connected to drive the pump?
If so, did you properly retime the rotary breather valve?
It sounds to me like this may be the problem.
The rotary breather valve is the round turret at the top of the oil pump with the spiral gear that is driven by the oil pump drive spiral gear, located behind the pinion gear on the crankshaft.
The rotary breather valve needs to be timed to open as the pistons come down. This allows the scavenge oil to be moved from the crankcase breather oil trap into the timing cover. The oil is then scattered around throughout the timing cover lubricating the generator drive, the gears, etc.
The air pressure that was created from the pistons coming down is expelled through the tube located below the generator. Only air comes out because an oil slinger on the generator end separates the oil which keeps it inside the timing cover.
When the pistons go up, the breather valve closes and this creates a vacumn inside the crankcase. The oil in the timing cover falls to the bottom brass screen and flows into the bottom of the oil pump where it is pumped back to the tank.
That is how the system works.
What makes me suspect that your breather valve timing is not correct is the excess oil being pumped into the primary area. If the breather valve is not timed correctly, then the pressure from the pistons coming down acts as a huge pump and the oil has to go somewhere. The breather valve is closed (due to improper timing) so the oil cannot be transferred to the timing cover. So, the oil gets pumped through the breather screen on the primary side, where it just sits and accumulates inside the primary. And, oil does not get returned to the oil tank properly.
This is the only thing I can think of that could cause your primary to load up with engine oil. I would not run the bike until you get this sorted out.
If you need any direction with timing the breather just let me know.........pg
[IMG]local://upfiles/8331/ED94BDC50C6846FF972DB334D27BADD6.jpg[/IMG]
A couple of questions here:
With your rework of the engine, did you remove the oil pump or any of the gearing connected to drive the pump?
If so, did you properly retime the rotary breather valve?
It sounds to me like this may be the problem.
The rotary breather valve is the round turret at the top of the oil pump with the spiral gear that is driven by the oil pump drive spiral gear, located behind the pinion gear on the crankshaft.
The rotary breather valve needs to be timed to open as the pistons come down. This allows the scavenge oil to be moved from the crankcase breather oil trap into the timing cover. The oil is then scattered around throughout the timing cover lubricating the generator drive, the gears, etc.
The air pressure that was created from the pistons coming down is expelled through the tube located below the generator. Only air comes out because an oil slinger on the generator end separates the oil which keeps it inside the timing cover.
When the pistons go up, the breather valve closes and this creates a vacumn inside the crankcase. The oil in the timing cover falls to the bottom brass screen and flows into the bottom of the oil pump where it is pumped back to the tank.
That is how the system works.
What makes me suspect that your breather valve timing is not correct is the excess oil being pumped into the primary area. If the breather valve is not timed correctly, then the pressure from the pistons coming down acts as a huge pump and the oil has to go somewhere. The breather valve is closed (due to improper timing) so the oil cannot be transferred to the timing cover. So, the oil gets pumped through the breather screen on the primary side, where it just sits and accumulates inside the primary. And, oil does not get returned to the oil tank properly.
This is the only thing I can think of that could cause your primary to load up with engine oil. I would not run the bike until you get this sorted out.
If you need any direction with timing the breather just let me know.........pg
[IMG]local://upfiles/8331/ED94BDC50C6846FF972DB334D27BADD6.jpg[/IMG]
Thread Starter
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Road Master
Joined: Mar 2006
Posts: 775
Likes: 2
From: OC California
RE: oil migration question
Pinion, I knew you would reply and I knew you would ask this. Yes the oil pump was rebuilt and yes it was timed with the pinion gear (pun intended?). I have good exhaust coming from the breather tube. If the breather were out of time would I still be getting this? It does appear the oil is migrating with the engine off as well. That would tend to eliminate the beather timing question. I would like to eliminate any and all other possibilities before pulling thegearcase coverjust to find out the breather is timed correctly. I really don't want to pull the engine to retime it either. Bike is electric start. Do you see any harm in pulling the primary cover and turning it over to see where the oil is coming from?
Novice
Joined: Oct 2007
Posts: 23
Likes: 0
RE: oil migration question
hi i would still check to make sure to see if oil is coming from the return line by pulling the plugs and turning it over, then as you say the beather is timed correctly i would make sure that the primary fill plug vent is not pluged or if you replaced it with a non vented type,this being pluged could cause a vacuum on the primary side and suck the oil over
Stellar HDF Member
Joined: Feb 2006
Posts: 3,035
Likes: 17
From: Houston Texas
RE: oil migration question
Cal...
'I have good exhaust coming from the breather tube. If the breather were out of time would I still be getting this?'
If the breather was out of time you would still be getting a strong flow of air out of the tube because the pistons coming down make this pressure flow out of the open tube, regardless of where the breather is positioned. In otherwords, the breather still is rotating and letting air escape through the open tube.
The timing of the breather is important because it must open when the pistons come down and close when the piston go back up. This is what moves the oil from the breather trap into the timing cover. If this is out of time, then the oil does not move out.
Did you do the timing yourself on the breather?
Or did someone else do it? If that is the case, how much do you trust the person who did it?
To check the timing it means that you must loosen up the pushrods, remove the timing cover and remove the pinion gear. If you have done this yourself before, then you know that a special remover/installer tool is required and that the thread in the end of the crankshaft is 5/16-24 (fine) and is a left hand thread. (I made my own back when I rebuilt my engine and have attached a photo below for others who may need to make one.)
After the pinion is removed, there is a spiral gear behind it that is a slide fit on the shaft. There should be a mark on one side of the gear. That side faces out toward the pinion gear.
This spiral gear (as well as the pinion gear) can only be installed in one position due to the single large spline on the crank.
Push the spiral gear onto the shaft, engaging the breather sleeve gear to where the hole in the breather valve will be centered in the slot on the breather sleeve bushing. Then reinstall the cams.
I am sure you know all of this, so forgive me for the repeat of the procedure. I am just trying to explain it in a way others who do not know how this is done will be able to follow this thread.
If your timing is indeed correct, then I am stumped. If you did the timing and trust yourself, then that is good. If someone else did the work, I would go in there and make certain it was done. A pain in the butt I know, but I can think of nothing else that would cause the problem you are having. Keep us posted.....pg
[IMG]local://upfiles/8331/8549E78D23F947BEA215385E74F92683.jpg[/IMG]
'I have good exhaust coming from the breather tube. If the breather were out of time would I still be getting this?'
If the breather was out of time you would still be getting a strong flow of air out of the tube because the pistons coming down make this pressure flow out of the open tube, regardless of where the breather is positioned. In otherwords, the breather still is rotating and letting air escape through the open tube.
The timing of the breather is important because it must open when the pistons come down and close when the piston go back up. This is what moves the oil from the breather trap into the timing cover. If this is out of time, then the oil does not move out.
Did you do the timing yourself on the breather?
Or did someone else do it? If that is the case, how much do you trust the person who did it?
To check the timing it means that you must loosen up the pushrods, remove the timing cover and remove the pinion gear. If you have done this yourself before, then you know that a special remover/installer tool is required and that the thread in the end of the crankshaft is 5/16-24 (fine) and is a left hand thread. (I made my own back when I rebuilt my engine and have attached a photo below for others who may need to make one.)
After the pinion is removed, there is a spiral gear behind it that is a slide fit on the shaft. There should be a mark on one side of the gear. That side faces out toward the pinion gear.
This spiral gear (as well as the pinion gear) can only be installed in one position due to the single large spline on the crank.
Push the spiral gear onto the shaft, engaging the breather sleeve gear to where the hole in the breather valve will be centered in the slot on the breather sleeve bushing. Then reinstall the cams.
I am sure you know all of this, so forgive me for the repeat of the procedure. I am just trying to explain it in a way others who do not know how this is done will be able to follow this thread.
If your timing is indeed correct, then I am stumped. If you did the timing and trust yourself, then that is good. If someone else did the work, I would go in there and make certain it was done. A pain in the butt I know, but I can think of nothing else that would cause the problem you are having. Keep us posted.....pg
[IMG]local://upfiles/8331/8549E78D23F947BEA215385E74F92683.jpg[/IMG]
Thread Starter
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Road Master
Joined: Mar 2006
Posts: 775
Likes: 2
From: OC California
RE: oil migration question
Pinion, you know I always ask these questions when I am hoping for a miracle answer. You always kill me with common sense and logic. 
I was afraid of the breather tube answer. I did put the breather in myself. [:@]Ichecked the cam lobes replaced a washer or two and checked the end tolerances. They were good and cams in time. Engine was on the bench with primary parts off, trans out and top end off.So I remember the oil pump has to go in with the cam cover off. I Left everything in place, ran the crank around to the advance mark and slipped the breather in so the timing dot was facing out and finished off theoil pump installation.Do I trust myself? Hell no. I willbite the bullet andthe cam cover comes off this weekend.Thanks.
I was afraid of the breather tube answer. I did put the breather in myself. [:@]Ichecked the cam lobes replaced a washer or two and checked the end tolerances. They were good and cams in time. Engine was on the bench with primary parts off, trans out and top end off.So I remember the oil pump has to go in with the cam cover off. I Left everything in place, ran the crank around to the advance mark and slipped the breather in so the timing dot was facing out and finished off theoil pump installation.Do I trust myself? Hell no. I willbite the bullet andthe cam cover comes off this weekend.Thanks.
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Stellar HDF Member
Joined: Feb 2006
Posts: 3,035
Likes: 17
From: Houston Texas
RE: oil migration question
Cal....
Good that you do not trust yourself. I do not trust myself either.
When you install the spiral gear onto the shaft and engage it with the breather gear, it is similar to installing a distrubutor in a car engine. You have to 'over compensate a bit' to get the hole in the breather to register in the middle of the slot in the bushing when the gear is sitting home against the crank face. That is because of the spiral movement.
Before you take anything apart:
Put the timing mark dead center in the timing hole before you remove the gears to see if the hole and slot are mis-aligned on the breather. If you find them to not be lining up correctly it is going to make you feel a lot better re-doing all of that timing business. Let me know how it goes......pg
Good that you do not trust yourself. I do not trust myself either.
When you install the spiral gear onto the shaft and engage it with the breather gear, it is similar to installing a distrubutor in a car engine. You have to 'over compensate a bit' to get the hole in the breather to register in the middle of the slot in the bushing when the gear is sitting home against the crank face. That is because of the spiral movement.
Before you take anything apart:
Put the timing mark dead center in the timing hole before you remove the gears to see if the hole and slot are mis-aligned on the breather. If you find them to not be lining up correctly it is going to make you feel a lot better re-doing all of that timing business. Let me know how it goes......pg
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Joined: Nov 2007
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RE: oil migration question
Ben in that spot before got things out of time did it ony once learned my lesson big time. I would like to ask you one thing , Is your transfer valve in the primary case working ok? I had one go bad and it sucked the oil out of the oil bag into the primary
Stellar HDF Member
Joined: Feb 2006
Posts: 3,035
Likes: 17
From: Houston Texas
RE: oil migration question
Cal....
I have been thinking about your last post and I have a question regarding this:
'So I remember the oil pump has to go in with the cam cover off. I Left everything in place, ran the crank around to the advance mark and slipped the breather in so the timing dot was facing out and finished off theoil pump installation.'
Do I understand you to say that you have not removed the pinion gear and drive gear for the breather gear before? Instead you rotated the engine timing mark to line up in the timing hole center, and then inserted your oil pump into place? The breather tube would have to have rotated, leaving the small hole in the breather facing outward. This small hole should be centered in the notch of the bushing, rather than be just facing outward.
If that is the case, things may be a little different with the engine installed in the frame. In the frame you cannot drop the oil pump out the bottom. To re-time the breather you will need to remove the pinion gear and the spiral gear behind that. The pic of the tool needed to take the pinion off is shown below. The lip edge on the half round catches the backside of the pinion teeth and pulls the gear off the shaft. As I said, I have made a puller at home in the shop.
If you need any help on getting the pinion off just let me know..........pg
[IMG]local://upfiles/8331/55497A32C6C8469F9FCB885356C7ECFC.jpg[/IMG]
I have been thinking about your last post and I have a question regarding this:
'So I remember the oil pump has to go in with the cam cover off. I Left everything in place, ran the crank around to the advance mark and slipped the breather in so the timing dot was facing out and finished off theoil pump installation.'
Do I understand you to say that you have not removed the pinion gear and drive gear for the breather gear before? Instead you rotated the engine timing mark to line up in the timing hole center, and then inserted your oil pump into place? The breather tube would have to have rotated, leaving the small hole in the breather facing outward. This small hole should be centered in the notch of the bushing, rather than be just facing outward.
If that is the case, things may be a little different with the engine installed in the frame. In the frame you cannot drop the oil pump out the bottom. To re-time the breather you will need to remove the pinion gear and the spiral gear behind that. The pic of the tool needed to take the pinion off is shown below. The lip edge on the half round catches the backside of the pinion teeth and pulls the gear off the shaft. As I said, I have made a puller at home in the shop.
If you need any help on getting the pinion off just let me know..........pg
[IMG]local://upfiles/8331/55497A32C6C8469F9FCB885356C7ECFC.jpg[/IMG]