Priming The Oil Pump

[Bob Grieb]

I am about to start the engine after replacing rings, rod bearings and grinding the valves. The engine has not run in a long time so I am sure I will need to prime the oil pump. I know the location of the priming orface but I am not sure how the operation is accomplished. Do you put a small amount of oil in the orface and try to start the engine. Do you have a reservior ready to put a larger amount of oil into the pump????

I have coated all the bearing surfaces with an assembly lube to avoid friction until the pump kicks in.

Need input on how the priming is accomplished

Thanks

Bob

[Bigdog]

Bob - use a pump oiler and fill the opening. Crank it over with the switch off until it builds pressure. You will also find an opening if you remove the top of the oil filter housing and take out the filter. There is a small hole visible there that can also be used to prime the pump.

[Bob Grieb]

Thanks Bigdog

Do I have to prime at both locations or can I just use the one on left side just in front of the bell housing?

Bob

[Bus Driver]

The bell housing priming is sufficient.

[kinelbor]

You probably all ready have done this, but I would put a few squirts in the cylinders too before starting.

[Bigdog]

Bob - I mentioned the other hole as sometimes that allen head plug gets stubborn and doesn't want to come out. If you have trouble removing it you can use the other location.

[George Willer]

Bob - I mentioned the other hole as sometimes that allen head plug gets stubborn and doesn't want to come out. If you have trouble removing it you can use the other location.

Bob,

The opening inside the oil filter housing is my favored spot because you can tell it's working just as soon as the pump starts turning. It will start spurting. With the more traditional spot, after (if) you get the plug out from behind the hydraulic lines you have that very long wait until the filter housing is filled before you know it's working. That wait can seem like forever!

[Bob Grieb]

Thanks for all the information.

I did lube the cylinder wall with assembly lube as well as oil when I put the engine back together.

I may just use the opening inside the oil filter housing. I like the idea of not having to wait a long time.

Thanks again

Bob

[BigBill]

I'm not too familiar with the cub motors but on the chevy v8's I made a pump turning tool out of an old distributor to prime the engines with the valve covers off till the rocker arms had oil. On the gravely tractors I took a used chevy oil pump and tapped it for pipe fittings so i could attach it to the system and completely prime it with a 1/2" drill motor before putting the fire to the holes. I don't like turning a motor over to prime the pump and system with oil. In the first few minutes to an hour is when the most wear can occur. During assembly I use a moly based lube to prelube all the metal contact areas too. I moly the cylinder walls and bearing journals, cam lobes and cam bearings too besides the lifters.

Once the oil system is externally primed then I will turn over the motor with the spark plugs out and watch the oil pressure gauge to see the pressure comes up on its own. Then its time to fire it up. When i first fire it up the timing is set and the cab is adjusted so it will idle. After it fires up I let a water hose run in the radiator with the pedcock open just a little to take the heat away and just let it idle for a few hours. I have no thermostat in the motor. The water hose runs just fast enough to keep the radiator filled. With no load on the motor to let the bearings see the least load as possible. Once this pre run is done, the oil gets dumped with the filter then with new oil the thermostat goes in, we bring it up to temperature. We readjust the carb and drive it slowly and not putting too much of a load on it.

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

On a cub the oil pump is on the rear end of the camshaft (behind flywheel). . Only way to turn it is to spin the enigne.

[Eugene]

On my rebuild. I primed the pump as indicated in previous posts. I removed the spark plugs and the top of the oil filter. Ignition off. I cranked the engine over with the starter (short bursts) until oil started filling the oil filter housing. Probably took 15 or 20 seconds. Once oil starts filling the oil filter housing, the oil galleries and rod and main journals are full of oil. The oil filter housing is higher in the engine that the oil galleries, rods, mains and cam journals.

Install spark plugs. Start the engine.

[BigBill]

I have seen some oil pumps not pump anything unless there primed with oil or grease before there installed. I always put then in a quart of oil first and spin them by hand if possible or take it apart and fill it with some grease. I have found that some pumps when installed dry won't pump at all.

[George Willer]

I have seen some oil pumps not pump anything unless there primed with oil or grease before there installed. I always put then in a quart of oil first and spin them by hand if possible or take it apart and fill it with some grease. I have found that some pumps when installed dry won't pump at all.

That's why I favor the method that lets you know right away it's working. That's much better than waiting a half minute or so and finding it doesn't pump... as would be the case if there were any air leak at all in the pickup tube.

[BigBill]

A trick with stripped out allen hex screws is to use a punch or a ball pein hammer to move the metal towards the hex opening then you can lineup the hex wrench and bang it in to broach a new hex to remove it. Then you can replace it. All you do is to hit the screw with the punch and hammer straight in to pein the metal back into the hex. I have done this for many years on motorcycles.

I don't like turning over the engine with no oil pressure, i like to pump the system wet first and then check the pump with the gauge.

I prime my oil filters on every oil change were i can too. I just don't like that motor running a few seconds with no oil pressure.

[Bob Grieb]

I completed the priming today and it went well. I removed the plug on the bellhousing and the oil filter. I filled the pump with oil and turned the engine over with the sparkplugs removed. I turned the engine over until the hole inside the oil filter housing started to spurt oil.

I feel more comforatble about starting it now. I still need to get the hood/gas tank on before I start it.

Thanks for all the suggestions/help

Bob