How does harley oil system work

I have a Customer who has a which I told him I thought his motorcycle was sumping and he should take it in as it was under warranty. While I had it on a long straight stretch of roadway at about 60 mph on a test drive, it began to lose power and a loss of acceleration was apparent.

What was happening was the oil was filling the sump and the Lobes of the Crank were being slowed because they were moving through oil — not good. This causes much strain on all parts of the engine.

He did take it in, they did keep it for a couple weeks and found they could not replicate the problem. He picked it up, went on a mile ride and at about miles the Engine gave out for good. While at this time it was way past its warranty date.

He called Harley-Davidson after calling me and they Overnight Shipped a New Engine to the Dealership and he had his motorcycle back in 30 hours. In the meantime, they also provided a lease — all at no charge. Harley-Davidson wants those engines back to study and find out why it happened in hopes of eliminating it in manufacturing.

You either had it occurring or you were waiting for it because so many were experiencing it. About half of my customers have experienced wet sumping on the M8. All experience knocking at start up and some that continue the entire time the Engine was running. Working with several other people we came up with a variety of parts that virtually eliminates sumping and the knocking.

In fact, everyone says their Motorcycles no longer make noise. One Guy brought his back and said there was a Tapping Sound constantly when he was riding. When I test drove it and brought it back, I was surprised to notice what he was hearing me too was the Injectors being pulsed because the Damn thing was so quiet. A few oil lines later, and H-D was in the dry-sump-motorcycle business. An Evo engine being rebuilt on Uncle Loomis' work bench.

These things are tall. Photo by Uncle Loomis. Over the years, other manufacturers turned to oversquare engine designs, particularly in high-performance bikes. The advantage of the oversquare design is that you can have a greater valve area per cylinder and flow more fuel and air, and the shorter stroke allows higher revving.

Both increase power. But Harley has stuck with its undersquare engine design that makes the low-end torque its fans love. What started out as necessity is now tradition. Navigation Menu. Wish List. Please reference our International Shipping Policy for details. International Shipping Policy.

Self-Service Returns. Doesn't fit? Don't love it? Return any unused item within 90 days for a full refund. Start a Return Read our full Return Policy. Lowest Price, Guaranteed. Found it for less? Submit a Price Match. See what our customers are saying about us: Customer Reviews. Zilla Cash Program. ZillaCash Silver. ZillaCash Gold. JavaScript Disabled. Bottom line is that if the vent system is working properly, you shouldn't have excessive pressure build up in the oil tank.

See pics and installation of the plunger and spring for models in the Sportsterpedia. Also Oil Filter Mount Mods for modifications to the pressure regulator system. With the new Evolution engine in , an oil pressure regulator relief valve was implemented to bleed off some of the oil when the pressure thru the filter became to high.

The spring loaded pressure valve was built into the oil filter mounting pad. There is a passage from the filter pad relief valve into the cam gearcase. The discharge from the relief valve drains down into the gearcase.

Then that 'extra' oil and is routed to the crankcase sump through a hole in the case wall and gets pumped back to the tank.

The spring-loaded pressure regulator opens at about 30 psi. However, it is usually only regulating when the engine oil is cold. When the engine is warm, the valve is typically shut, since pressure is usually below 30 psi even at high rpms. In , the entire oil filter mount was incorporated into the right crankcase half. It was mounted into a hole from the gearcase side of the mount. As in the previous implementation, this allowed the relief valve to bypass oil thru the plunger when activated instead of pumping it thru the filter.

The relief pressure was the same, being about 30psi. However, I have only been able to visually verify the existence of these parts on the model engine. Research continuing. Oil Pump Upgrade '' The oil pressure regulating unit was discontinued for 92 and up engines and 91 replacement cases. Excess oil pressure is relieved by a passage drilled in the top of the right case. It is a double duty hole drilled from the center open feed galley down toward 2 cam gear.

This passage is on the oil filter side of both the lifters and the crankpin and relieves high pressure to both. It sprays or possibly drips oil onto 2 cam gear until the pressure gets high in the feed galley. The diaphragm is spring loaded and held against its contact point when the engine is not running or the when the oil pressure is too low while running.

With the switch contacts touching, this closes the circuit to the oil pressure light and causes it to light up with the key on, of course. When the engine is fired up, oil pressure builds in the filter pad, activates the oil light switch and opens the oil pump check valve or check ball respectively allowing oil to enter the engine. Oil pressure is sensed by the oil pressure switch.

By the time the engine reaches over to rpms, the oil pressure is sufficient to move the oil pressure switch diaphragm completely off it's seat. This opens its contact point, breaking the circuit to the oil pressure light and it goes off.

Oil pressure will vary under normal riding conditions. See above for expected oil pressures. However, idle hot oil pressure will vary from PSI on most models. So, at idle, the oil check valve or ball may only be opened just past it's cracking pressure not to it's end of travel. The oil light is important to have since if it is not working, it can be assumed that you have little to none oil flow to the engine.

If the pressure switch doesn't operate the light it should be checked for proper operation or replaced. Don't plug the end till you've primed the pump if applicable. Replace a defective switch as soon as possible. It will either strip the threads in the filter housing or crack the filter housing. Then you have a bench mark 'feel' for how tight to turn the pressure switch with the same type wrench.

This one got tightened too much and cracked the filter housing. Don't over tighten to try and stop a leak. It doesn't take much oomph to seal the pressure switch. Don't use silicone on the threads. Thread tape may break off and enter the filter or the engine. In theory, you should be able to stop a leak from the switch threads without any thread sealer because of the tapered threads.

But thread sealer of some type Loctite, plumbing pipe dope or other is suggested. Keep in mind that any thread dressing applied will pre-load the torque needed. So be sure to back down on final torque when using thread sealants. If you used the proper torque and it still leaks oil, you may need to pull the switch and filter and look for a crack in the housing.

Pull the switch and the filter so you can see both the housing and the hole threads. It only takes a little more than needed to crack the housing. The switch threads are tapered. Turned too far in, the taper widens the hole and expands the aluminum around the hole. The hole is near the end of the filter pad. With little surface area between the hole and the end of the housing, that is the weakest part and where cracks will appear.

If yours has cracked, it'll need to be welded. The crack will only get worse with vibration. The thing about welding is it causes warp-age. Once it's welded, the threads for the switch will probably need to be reconditioned as the hole may warp. If so, you can try and chase the threads with a tap. You may have to go with a threaded bushing bigger threads into the housing with smaller threads on the other end to add the switch back.

Also the main purpose for the filter pad is the machined flat surface for the filter. It will need to be checked for flatness after welding so the filter don't leak.

The no weld version is: 63 Clean the crack thoroughly with brake cleaner or contact cleaner. Screw the pressure switch in to open up the crack and clean it some more. Remove the switch and apply Loctite no substitutes to the pressure switch threads and hole and screw in the pressure switch. After the switch in in place apply Loctite to the crack so it can wick into the crack. Cross your fingers while the Loctite cures. Also check the threads in the hole.

Too much torque will damage aluminum threads pretty fast and to different degrees. Clean the filter mount surface and verify there is no crack and then inspect the threads for the switch. You can run a tap into the threads and try to straighten them if needed. Cracked : This filter housing was cracked due to too much torque being applied while tightening the oil pressure switch.

If the oil pressure light stays on at speeds above idling, always check the oil supply first. Then if the oil supply is normal, look inside the oil tank to determine if oil is returning to the tank from the return hose with the engine running.

If oil is returning to the tank, there is some circulation and the engine may be run a short distance if necessary. If no oil is returning, shut the engine off until the trouble is located and fixed. Conditions causing the oil light to stay on; Low or diluted oil supply, Or a plugged lifter screen under the plug between the tappets, A grounded oil signal switch wire, Faulty oil switch, Faulty or weak oil pump, Clogged feed hose in freezing weather from ice and sludge preventing the circulation of oil.

The Oil Check Valve is located behind the threaded filter adapter in the center of the oil filter mount. The filter adapter I. The check valve operation is dependent on receiving filtered oil through the filter media to lift the check valve cup and allow oil to pass. Therefore, a stopped up oil filter media condition not allowing flow or enough flow may not produce enough oil pressure to open the check valve before the filter bypass opens.

The oil pump check valve plays a role in the operation of the oil pressure switch. The check valve is not a pass through but instead a cartridge type one way check valve operated by a spring loaded cup against a seat pressing at PSI. Oil pressure enters the center of the check valve, lifts the cup against its spring and exits the check valve by pushing around and past the cup and into the engine.

At a point, the cup will float off it's seat up against the spring towards the end of it's travel. According to the FSM, the check valve has two main functions; It prevents gravity oil drainage from the tank to the engine when not in operation. It also acts as a restriction to activate the oil pressure switch. Without the check valve, the pressure would not build up as much in the oil 'pocket' in the filter housing.

It would free flow into the crankcase and disperse. With the check valve installed and the oil having to find it's way around the cup, pressure builds behind it in the pocket. This back pressure builds inside the pump and pushes the pressure switch contacts open, shutting off the oil light. The check valve spring does not control the amount of oil that enters the engine unless it's stuck closed. The flow goes past the check no matter what.

The spring pressure is very light. It regulates creates and manages the oil pressure in the pocket next to the switch before it enters the engine. That pocket is protected for one reason to operate the oil switch, therefore the oil light. If you are not running an oil light, there is no reason to be concerned with the check valve in regards to a running engine. You could remove the light and the check and it would not affect the oil flow thru the engine. The positive displacement oil pump will still deliver oil.

In theory and design, if the pressure in the pocket is low, oil flow would also be low. In practice, there are too many variables on a worn engine,pump, check, switch etc.