very low oil pressure

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very low oil pressure

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very low oil pressure - 6/1/2007 10:06:15 AM

dwn1383

Posts: 1
Joined: 6/1/2007
Status: offline

We just had the 55 pan rebuilt and now have about 10psi showing when it first starts, then when gets to temp, drops down to about 2psi. Tore apart the pump and it looked fine. any suggestions? Thanks.

Post #: 1

RE: very low oil pressure - 6/1/2007 10:47:51 AM

crampfan

Posts: 150
Joined: 5/31/2007
Status: offline

There are a couple of places that you can check, if you are NOT running hyd. lifters in it, you will need to remove the rocker arms and block the oil galley to the push rod ends, as with the stock set up the hyd. lash aduster was in the push rod, and got its oil supply from the rocker arm, with out the hyd. as the cyls. grow it will open up a oil leak at the push rod end. also you can get a little bit more by removing the lifter blocks and plugging the oil feed for the lifter if you are running later lifter blocks. also oil pressure is not that critical on pan heads more flow than anything. hope this help, and good luck.

(in reply to dwn1383)

Post #: 2

RE: very low oil pressure - 6/2/2007 12:41:14 PM

wreck74

Posts: 94
Joined: 1/15/2006
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so, unless your running the in-pushrod type hyd lifter you should block off the oil hole on the end of the rocker arm ? the reason i'm asking is i'm running 1948 lifter blocks with JIMS solid lifters, colony alum. pushrods in a 1959 panhead. the lifter blocks block the oil passages to the blocks so the only oil the lifters get is from the rocker arms. is this good ??

(in reply to crampfan)

Post #: 3

RE: very low oil pressure - 6/2/2007 11:04:30 PM

cck

Posts: 6
Joined: 4/3/2007
Status: offline

Two big mistakes I see on Pan rebuilds relating to oil pressure. Oil pump gaskets, pump to case aftermarket gaskets are 10-12 thou thicker than than stock. May not seem like much, but if your pump gear to crankcase clearance is more than 5 thou, you lose oil pressure. 2 rocker arm clearance, attention needs to be paid to the amount of clearance in the rocker arm shafts. Too much, and your oil runs out in the heads. Not a problem as it ends up in the case and back to the tank, but you will not hold oil pressure. Most of the time it is one or the other that accounts for low oil pressure.

(in reply to wreck74)

Post #: 4

RE: very low oil pressure - 6/3/2007 11:04:34 PM

jmetro

Posts: 243
Joined: 5/29/2007
Status: offline

the pressure relief spring on the pump can be stretched to give you a bit more pressure. if its the cast iron style pump, it is the screw in cap on the right SIDE of the pump.(not the little flathead screw) if its an s&s, its the one with the plunger not the check ball on the top of the pump

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(in reply to cck)

Post #: 5

RE: very low oil pressure - 6/4/2007 8:34:16 AM

crampfan

Posts: 150
Joined: 5/31/2007
Status: offline

I had the rockers pined in mine, that will let a small amount of oil to the top of the pushrod, to see if you are loosing pressure from the rocker to pushrod try warming up the engine and adjusting the valve lash hot, if your oil pressure comes up that is one of your problems, oil pump gaskets are a problem also. Do not stretch the pressure relief spring, that will only raise the pressure when engine is cold, and screw everything up when you get your problem fixed.
Before I found the low pressure problem in my pan, I ran with the oil lamp on for about 50k miles (less than a pound of pressure when hot) just thought I would let you know about that one.

(in reply to jmetro)

Post #: 6

RE: very low oil pressure - 6/22/2007 11:31:54 PM

wreck74

Posts: 94
Joined: 1/15/2006
Status: offline

what do you mean pined ?

(in reply to crampfan)

Post #: 7

RE: very low oil pressure - 6/24/2007 11:59:47 PM

Doc 1

Posts: 1976
Joined: 5/9/2007
From: Florida
Status: offline

quote:

ORIGINAL: crampfan

There are a couple of places that you can check, if you are NOT running hyd. lifters in it, you will need to remove the rocker arms and block the oil galley to the push rod ends, as with the stock set up the hyd. lash aduster was in the push rod, and got its oil supply from the rocker arm, with out the hyd. as the cyls. grow it will open up a oil leak at the push rod end. also you can get a little bit more by removing the lifter blocks and plugging the oil feed for the lifter if you are running later lifter blocks. also oil pressure is not that critical on pan heads more flow than anything. hope this help, and good luck.

This is the biggest problem.....fix what crampfan said and you will be surprised that your oil pressure will stay around 6lbs hot idle.

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(in reply to crampfan)

Post #: 8

RE: very low oil pressure - 6/25/2007 8:24:38 AM

crampfan

Posts: 150
Joined: 5/31/2007
Status: offline

what do you mean pined ?
[/quote]
The machine shop will drill into the oil passage and insert a pin, and weld it back up

(in reply to wreck74)

Post #: 9

RE: very low oil pressure - 6/26/2007 9:16:35 PM

wreck74

Posts: 94
Joined: 1/15/2006
Status: offline

so unless your running the original hyd lifter on top of the pushrod (witch i don't think anybody does) you should have the rocker arms pined. thats good to know, thank you.

(in reply to crampfan)

Post #: 10

RE: very low oil pressure - 7/23/2007 3:00:00 PM

wreck74

Posts: 94
Joined: 1/15/2006
Status: offline

I have a 59 pan with solid lifters and 1948-49 aluminum lifter blocks, (no oil passage in the blocks for the hyd) the rocker arms are in the shop getting pined, .030" oil passage to the top of the pushrod, where will the lifters get their oil ? do i need to drill them or replace them with later model blocks with oil passages ? thanks for any help.

(in reply to wreck74)

Post #: 11

RE: very low oil pressure - 8/27/2007 2:26:21 PM

albionphill

Posts: 7
Joined: 8/27/2007
Status: offline

Hi, i have run my 63 pan with between 5 and 10 psi for the last 15 years with no problems.

The oil pressure did drop from about 15 psi when i changed to solid lifters. I worried about it on and off for years but was told by a mechanic who is into older Harleys that the pressure wasn't as important as oil flow ( pretty obvious i suppose )

I've had the engine apart several times over the years and noticed no wear so asume he was right.

I rebuild refrigeration compressors and many of these run on a very low oil pressure.

Hope this helps ?

Cheers,
Phill

(in reply to wreck74)

Post #: 12

RE: very low oil pressure - 1/17/2008 6:02:34 AM

vpedwards

Posts: 4
Joined: 6/25/2007
Status: offline

What weight oil are you running. A lot of yah-hoo's will tell you that you can run the newer lighter weight oil in the bike...don't.

(in reply to albionphill)

Post #: 13

RE: very low oil pressure - 1/17/2008 6:50:16 AM

sqdealgeorge

Posts: 289
Joined: 12/26/2007
Status: offline

Check the oil pressure gauge put in a new one to see if your pressure comes up ( cold motor) My 1952 pan/shovel has maybe 20 psig cold maybe 3 psig hot been doing this for 22 years. I run a 3 inch piece of clear hose on the oil return line to the oil tank that way I always see the oil coming back pressure gauges will scare ya

(in reply to dwn1383)

Post #: 14

RE: very low oil pressure - 3/24/2008 1:04:00 PM

phdhd

Posts: 9
Joined: 6/17/2007
Status: offline

Assuming you have not mismatched any parts, your gauge is accurate, your gaskets are correct, there isn't any orange silicone sealant in any oil passages and the rebuild was done correctly just pull the cap off the oil tank and make sure you have oil returning to the oil tank. If you do ride it like you stole it. Oh, and take the oil pressure off the engine. It will cause anxiety and worry.

There are 2 restrictions that create oil back pressure in the engine, the pinion shaft bushing and the rocker shaft journals and bearing surfaces. If not for these 2 restrictions there would be little to create a reading on your pressure gauge. Everything else is roller bearings. Roller bearings unlike plain bearings do not provide any restrictions. Remember all fluids follow the path of least resistance. Your oil guage is responding to restrictions in those paths. HD motors do not require much pressure. Volume is more important. Oil scavenging is next in line hence the check for oil return at the tank. Usually the first sign of low pressure is the sound of clacking or tapping from your lifters.

I rode a 1965 pushbutton pan for 15 years. I had the engine rebuilt and it was a faithful and dependable ride. THAT BIKE SOUNDED LIKE THE MOTOR WAS GOING TO GRENADE AT HIGH SPEEDS FOR ALL OF THOSE 15 YEARS. I never had a pressure gauge on it and i did not run clear plastic oil lines. Most of the problems I have seen with oiling systems has been incorrect assembly or mismatched parts. Oil pump failures are rare except when they weren't assembled right to begin with or a lifter roller fails and needle bearings from the roller drops down and jambs the oil pump drive gear and the oil pump drive gear key gets sheared. So short of some systematic disassembly and careful parts inspection for proper tolerances there is not much to do but ride it.

With respect and best wishes,

Regards and good luck.

(in reply to dwn1383)

Post #: 15

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