Questions come up about oil pressure on the twin cam motors from time to time. Your oil pressure, according to factory Harley Davidson specs is as follows: With a warm engine, oil pressure at cruising speed of 55 m.p.h. and up should be 30 - 36 p.s.i. At idle, at least 10 p.s.i. With initial start-up being around 44 p.s.i.with the colder oil temps.
Twin Cam Oil Pressure
- Thread starter glider.
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So how can you tell if the pump is going bad, pressure guage is off, or if the springs are weak? My pressure runs around 26PSI (indicated) when cruising in the summer. I added a HD oil cooler yesterday and the indicated pressure dropped a bit more to 20 or so. I verified proper installation by removing, inspecting, and re-installing. All checks came out OK per the installation instructions. I would prefer not to trash an engine.
BUBBIE
Well-Known Member
IF you could set an air compressor at 25 lbs and play with the FORCE that that gives ,,,,,, You would get a better understanding of just how much pressure and volume oil move at that pressure...
I can't see a problem with a motor with 20 or more lbs of pressure IF it is constant at highway speeds...
I am NOT saying that pressure is good but just stating so you and others think just how much 25 lbs is.....
A LOT
You didn't put enough information here for me to give an answer..::: what year is bike? how many miles on it? what oil and filter do you use? has the pressure always been at what you see? when and How did it change if not always this pressure? Has it been recently been taken apart?
need that to give an opinion..
signed....BUBBIE
Hoople
Account Removed
True story from 35 years ago.
Close friend of mine owned an un-hacked 1966 396/325 Chevelle. I was away out of town for 3 months and had not seen him. While I was away he had installed a set of mechanical gauges (oil, water temp & charging volts) under the dash near the console. The oil pressure gauge was mechanical with no electrical sending unit.
When I came back in town I went for a ride in his car and told him the new gauges looked nice. I could not help but notice the oil gauge pointer would sit on ZERO while we were just riding down the street. So I said to him " What's with your oil pressure, it's on zero" He said it has been that way since he installed the gauges a couple of months back and he believed it was just a bad gauge.
But the whole time I could not help but notice the lifter noise that was coming out of the engine along with the fact that when you accelerated quickly or went around a long sweeping curve the oil pressure would suddenly pop up to 50 PSI for a few seconds.
I told him, I thought the oil pickup had come out of the oil pump. He was not a mechanically inclined guy so he did not understand what I was talking about, but he trusted me and had the oil pan removed by a mechanic. Sure enough the pick up tube and screen had fallen out of the oil pump and were laying in the bottom of the pan.
They re-installed it and tack brazed it in place. All was well after that. Never a bit of trouble from the engine.
Now this was a water cooled engine so it's not the same but my point of the story is you have to be impressed that the engine actually withstood this for several months without spinning a bearing or doing any damage to the valve train.. The only time the cam bearings and rockers got any oil was during take off or a long sweeping turn and that was only for a few seconds..
It does make you wonder.
Close friend of mine owned an un-hacked 1966 396/325 Chevelle. I was away out of town for 3 months and had not seen him. While I was away he had installed a set of mechanical gauges (oil, water temp & charging volts) under the dash near the console. The oil pressure gauge was mechanical with no electrical sending unit.
When I came back in town I went for a ride in his car and told him the new gauges looked nice. I could not help but notice the oil gauge pointer would sit on ZERO while we were just riding down the street. So I said to him " What's with your oil pressure, it's on zero" He said it has been that way since he installed the gauges a couple of months back and he believed it was just a bad gauge.
But the whole time I could not help but notice the lifter noise that was coming out of the engine along with the fact that when you accelerated quickly or went around a long sweeping curve the oil pressure would suddenly pop up to 50 PSI for a few seconds.
I told him, I thought the oil pickup had come out of the oil pump. He was not a mechanically inclined guy so he did not understand what I was talking about, but he trusted me and had the oil pan removed by a mechanic. Sure enough the pick up tube and screen had fallen out of the oil pump and were laying in the bottom of the pan.
They re-installed it and tack brazed it in place. All was well after that. Never a bit of trouble from the engine.
Now this was a water cooled engine so it's not the same but my point of the story is you have to be impressed that the engine actually withstood this for several months without spinning a bearing or doing any damage to the valve train.. The only time the cam bearings and rockers got any oil was during take off or a long sweeping turn and that was only for a few seconds..
It does make you wonder.
I have an '07 Ultra Classic with a little over 49 K miles on it I,m using 20w/50 hog oil at crusing speeds the oil pressure is at about 32 psi but idling at at stop ligh it's close to zero although it dosen't sound like there is no issues ( no knocking or anything like that) is this an oil pump going bad or a weak main bearing. I just had it in the shop for it's 50 K mile service and they said everything checked out ok.Just like a second opinion. Thanks
R_W_B
Senior Member
Well two things, first off I remember (when it was brand new) that 1966, 396ci/325 hp Chevelle. That was some car. They (Chevy) also had a solid lifter model that was 375 hp, and that thing was downright mean.
But I watched a YouTube video once about 6 months ago, of a guy that had an old junk car and he actually drained all the oil out of it and drove it down the road (during the video) to see just how long it would run. The thing ran for quite a while. I mean like a good 5 mins before any noticable symptoms started showing. And it ran a good 5 mins more after that before it finally siezed up. There is a film of oil that hangs on the parts enough to go further than one would imagine.
If you have any doubt at all, buy a mechanical screw in gauge. Comes with a rubber hose, I bought mine at Harbor Freight for $12 on sale yrs ago. You remove the oil light sending unit and screw in the gauge (sometimes might need a plumbing pipe adapter for size).
Use teflon paste on your sending unit when you replace it. Tighten snug but don't over tighten, it's pipe threads, they compress the further in they go.
I had a permanately mounted mechanical oil pressure gauge on my previous harley and when it first cranked it jumped to 45 psi even on an idle. After warm up it ran at 45 psi but would drop to 20 psi at idle.
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