Oil Pressure Gauge Problems

[SilverOrphin13#]

I have installed a Marshall Oil Gauge and no pressure at idle. I get a few pounds of pressure if I rev engine. I have tried removing the screen and small screw on back of gauge. All resulted in same results. I removed gauge and started engine and oil poured out so I know i am getting oil to the gauge properly. My question is bad gauge, low oil pressure or do I need to adjust pressure on the SS oil pump? Any tips or advice would be gladly appreciated. So update i hooked up directly to pump and same results. I opened the oil tank while running and can see oil circulating. Also filter is full of oil and magnet is clean of particles.

[johnjzjz]

this is a normal thing with a harley oiling system - they relay on flow and you have that and explained how you know its doing just that

evo engines were the first to maintain oil pressure at idle hot - none of the engines before that - if you make it do that - it will ooze oil out if the breather like a total loss machine -and mark its spot at every stop, expect to put a quart of oil in it every time you take it out

[SilverOrphin13#]

Thank you for responding. Frank

[dan r]

Originally Posted by SilverOrphin13#

I have installed a Marshall Oil Gauge and no pressure at idle. I get a few pounds of pressure if I rev engine. I have tried removing the screen and small screw on back of gauge. All resulted in same results. I removed gauge and started engine and oil poured out so I know i am getting oil to the gauge properly. My question is bad gauge, low oil pressure or do I need to adjust pressure on the SS oil pump? Any tips or advice would be gladly appreciated. So update i hooked up directly to pump and same results. I opened the oil tank while running and can see oil circulating. Also filter is full of oil and magnet is clean of particles.

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Tell me more of what parts combination you have.
What weight oil are you running and was the pressure check done with cold or hot oil?
I see a pump from S&S for generator case engines.
Crankcases are Delkron? I believe Delkron generator cases are drilled for the oem 72-80 pump, I could be wrong on yours but the last one I worked on here was.
What brand is that cam cover and is it side or end oiling?
Do you know what the pump drive gear ratio is? 5 to 1 (54-72 gears) or 4 to 1 (73-89 gears)

Normal oil pressure should be anywhere between 12-25 psi when riding at highway speed (2500 to 3000 rpm) It is normal to drop to only a few psi at idle (750 rpm) Low oil pressure is most often caused by miss matched parts or loose fitting clearances in the tappets and rocker arms. I would suspect problems if your engine will not hold 12 psi at speed.

My 63 with a shovel top with the late 4 to 1 ratio pump drive gears, S&S generator engine type pump, oem type tappets and with all bushing loose fit clearances in spec will hold 35 psi running down the road with 20W50 oil when warmed up fully.

[SilverOrphin13#]

All great questions and I bought the bike completed and have no idea about internals. The cases are Delkron and as far as the rest of it I have no idea without breaking into the motor. I do have also have a small leak on front cylinder base gasket, According to flow diagram that is on the return system. I would be safe to say I have oil flow throughout the entire engine. What would you suggest I do? Check the pushrod and rocker arm clearances. I can remove valve cover and check play. Then also check pushrod play. The engine likes to run as it starts 1/2 kicks cold and one kick warmed up. TY Frank

[magnum45pete]

I have heard from a lot of friends......

'DO NOT FIT AN OIL PRESSURE GUAGE, they will fuck ya head up worrying about it, just fit a pressure switch & light, it's all ya need'',

I think there is a lot to be said for that,
I had one on my Shovelhead, taking it off of the rear rocker shaft end cap on the right side of the motor,
I was told IF you fit one, put it on the head, if it's getting oil there, it will be getting oil everywhere is what I was told & did so,
that was untill last week, when for some reason the guage shit it'self of it's filler oil,
some sort of clear mineral oil that dampens the needle movement,
so I removed it & now rely on the light going out,
far less of a worry & not watching it all the time as I was before,

[dan r]

Originally Posted by SilverOrphin13#

All great questions and I bought the bike completed and have no idea about internals. The cases are Delkron and as far as the rest of it I have no idea without breaking into the motor. I do have also have a small leak on front cylinder base gasket, According to flow diagram that is on the return system. I would be safe to say I have oil flow throughout the entire engine. What would you suggest I do? Check the pushrod and rocker arm clearances. I can remove valve cover and check play. Then also check pushrod play. The engine likes to run as it starts 1/2 kicks cold and one kick warmed up. TY Frank

First, why did you put a gauge on it? Was it for looks or did it make you suspect low pressure because of strange un explained noises? Knowing how some gauges are, it's pretty hard to find one that can measure pressure accurately at that low pressure. Do you have another gauge for testing? The true place for the most accurate location for pressure tests is on the rear of the pump cover where the oem sending unit is normally installed. Any test further from the pump will show a lower pressure than at the pump. Just like voltage and long wires, same as lower air pressure from a long hose, lower water pressure from a long pipe. You will see pressure drops when checking further down the line.

Second, don't just blindly start taking things apart. Further inspection and tests can and should be done. It's easy to pop a push rod clip, slide a tube up and figure out if it has hydraulic or solid tappets. If hydraulic, do they clatter when hot and at idle or high speed? With hydraulic tappets, if there is no or very little tappet and rocker arm clatter that changes to much worse when hot, then you might think about breaking out the tools. Properly adjusted solid tappets will make a slight ticking noise when cold and get a bit louder when hot, that's normal. Proper solid tappet adjustment is a slight drag when twisting the push rods but no slack when cold. Gear whine and generator engines is somewhat normal, straight cut gears make noise and isn't a problem unless extreme.

If it's running normal without excessive noise in the tappets and rockers, it has enough pressure and maybe an inaccurate gauge is the problem.

Most often gauges are installed for looks and then they strike fear in you when there is no problem.

[SilverOrphin13#]

I tried the gauge at oil pump cover and also at the screen port. The pump revealed more pressure(1-3#). The noise(normal noise) is constant from start to warm up. I also have a gauge that reads 1-100# of pressure. I am going to inspect pushrods for play just to satisfy my paranoia about them and order a gauge that displays 1-18# pounds of pressure. Thank you for response.

[SilverOrphin13#]

I did a pushrod test and all were finger tight and felt good. These are the tappets and maybe someone can help me identify them? TY Prior

[johnjzjz]

you could have evo lifters or the china replacements for stock hydraulic lifters

cant tell from the picture but you dont have oem shovel or pan lifters

[bigfoot]

I have been riding my old 58 Pan for 45+ years, rebuilt it a few times over the years, and it has always had zero showing on the gauge at an idle when its hot. When I first start it and it's cold, it will show 35 lbs. A roller bearing engine does not build much pressure. Unlike an automobile engine with babbitt bearing inserts. If you look in the old Harley owners manual, they call the oil light an "oil circulation Light", not an oil "pressure" light. As long as it is circulating, you are fine.

[rhysmort]

Anything pre 1955 shouldn't really have pressure, like BF states above, rollers need flow not pressure. Don't confuse these for car engines!

If you have good return to the oil bag, forget about it. I'd even suggest removing it. I've never had one on any of my old harleys and they've all taken me plenty of miles without issue.

[SilverOrphin13#]

Thank you guys for all the help and information. Frank