Oil pressure

[Normanott]

This cub has been sitting for 15 1 years, I primed oil pump at filter housing and can get oil to come out of bleeder hole but it's not building oil pressure, and not filling filter housing, Will filter housing stay full or does it bleed b back into pan when not running. When I remove gauge no oil will come out of bleeder hole when cranking. Any ideas.

[John *.?-!.* cub owner]

It will drain down a little. How long did you wait for oil pressure, it normally takes a cub that is a little worn as much as 30 seconds to build oil pressure. A recently rebuilt one may do it as quick as 15 seconds, but they are rare. Do not overlook the possibility of a bad gauge.

[Normanott]

Gauge ok, no sign of oil at gauge hole, what keeps oil from draining from filter housing? I made an adapter from a pop bottle and Filler cap. I took out the plug on top of filter housing put the bottle in, when I crank it pushes oil up into bottle some air at first but lots of oil. I think the oil is returning to pan too fast not allowing housing to fill, housing must be full to show pressure?

[Glen]

Hi,
Yes, the oil pump has to fill and pressurize the oil filter chamber and all the passages in the engine, before there is oil pressure shown on the oil gauge.

Below is a page from the late 1955 Cub owner's manual showing the parts that are in the oil filter housing. The long bolt has a small hole in the bottom that the filtered oil goes through to return to the oil pan. Be sure the hole is open, like it says on the page.
The oil in the oil filter housing takes some time to drain back to the pan when you shut off the engine.

http://farmallcub.com/rudi_cub/www.clea ... e%2022.jpg

If you have the right long bolt, an oil filter in the chamber, and the pump is pumping, after priming the pump, the system should pressurize soon. Like John said, it can take up to 30 seconds.

[Crimson Tim]

Gauge ok, no sign of oil at gauge hole, what keeps oil from draining from filter housing? I made an adapter from a pop bottle and Filler cap. I took out the plug on top of filter housing put the bottle in, when I crank it pushes oil up into bottle some air at first but lots of oil. I think the oil is returning to pan too fast not allowing housing to fill, housing must be full to show pressure?

A couple thoughts that may or may not be appropriate depending on clarification:
Oil gauge should show pressure when the engine is running. (After 15-30 seconds, as mentioned). Higher speed = higher pressure.
I do not think it will show pressure when cranking with the starter, no matter how long you crank.
I do not think it will show pressure when hand cranking, no matter how long you crank.
According to what Glen said, it won’t show pressure until the entire system, including the filter housing, can pressurize. Therefore, your idea with the pop bottle in place of the housing cap (sorry, “soda” bottle. I live in the south now), is a great one for seeing whether oil is moving but probably doesn’t seal well enough to let pressure build up.
Even if it does seal well enough, I think the bolt that holds the filter housing cap on closes a big hole that returns oil to the engine, so unless you put the bolt back, you are right, the oil is just rushing back to the engine with much less resistance than normal circumstances.

Somebody please correct me if I am off base with anything here.

[Normanott]

I put plugs back in hooked up my boat tank, started it up, oil pressure came up after about 30 seconds. Thanks for help. I just thought I had a problem, it takes a while for filter to fill, once full oil pressure showers on gauge.

[John *.?-!.* cub owner]

I couldn't find them when I looked just now, but in the Blue Ribbon Service manuals there is one showing the engine lubrication system. The pump has to fill not only the oil filter housing, but all the oil galleries around the lifters and cam. They all drain out while setting.

The bolt that holds the cover over the oil filter controls the oil flow. It id hollow and has a small hole in the side near the top, and I believe the hole in the bottom end of the bolt is also small these are to control the flow. When you take the bolt out that holds the cover and filter in place, all the oil drains out before you have a chance to see how much is in the housing.

[Normanott]

I found a diagram of oil system also, I'm use to seeing pressure a little sooner in other motors I've worked on. Lots of good info here. Thanks again.

[Glen]

Hi,
John, I don't hardly ever disagree with you, but look at the link in my post above, the pic from the Cub owner's manual shows the oil holes only at the bottom area of the bolt, so the oil that has gone through the filter can run back to the oil pan.
One hole goes up from the bottom of the bolt, and the other in from the side, and they join.

Maybe you meant the top hole is the inlet in the block, to the chamber, not sure.

[John *.?-!.* cub owner]

Glen, I would have to pull one of mine out to see, but I was thinking the side hole was further up, but my memory is not very good, so you are probably right.

I think one of the reasons for it being slower to build oil pressure is the location of the oil pump, which is toward the left upper side of the rear of the engine block behind the flywheel. It has to suck the oil up out of the oil pan, and I think the oil may drain out of the pump, especially if it is worn or sets for a long time. On most engines the oil pump is located in the oil pan and is submerged in the oil so that is not a problem.