Got Oil... won't prime.

[KarlVP]

On the rebuild of FiFo's AMC 401.

It has oil in the bitch, but it won't prime the oil pump. Wasted an entire drill battery spinning and spinning, nothing.

What gives?

 

[Not Jobless]

Are you spinning it the right direction?

Bad pump?

Plugged pick-up?

 

[KarlVP]

Are you spinning it the right direction?

Bad pump?

Plugged pick-up?

Yes

Brand new pump

Brand new pick up.

We're gonna try packing it with vasoline and see if we can get some suction.

 

[Robinhood]

The vaseline trick has worked for me on AMC motors before they can be a real bear

 

[Bunk1]

Thats a jeep thing, right?

 

[Binder]

We're gonna try packing it with vasoline and see if we can get some suction.

:awesomework:

Is a 401 a internal or external oil pump?

 

[KarlVP]

:awesomework:

Is a 401 a internal or external oil pump?

External.

 

[TreeClimber]

AMC oil pumps are integral with the aluminum timing cover and are externally accessable. Try the vasoline trick. If that doesn't work, just start the damn engine. On my AMC 401, I primed and primed and primed and nothing. Never could build pressure (don't know why), but we got frustrated and fired it off anyway and I had pressure within seconds. I knew that the cam was really well lubed, and I'd also made sure to oil everything during assembly, so I was a little worried, but not paranoid. Anyhow, it fired right away, and I watched the guage real close while Tom adjusted timing and fuel.

No problems on mine, years later

Edit, why are you priming it / why the new pump? Is it a new engine or are you just trying for more oil pressure?

 

[Binder]

Definately pack it.

 

[KarlVP]

Edit, why are you priming it / why the new pump? Is it a new engine or are you just trying for more oil pressure?

Total (poor mans) rebuild. New RV camshaft. New accessories (oil pump, timing gears and chain, new lifters, new water pump, etc). It's for a J-20 FiFo is going to use as his tow rig.

Oil pressure was at ZERO when we picked the truck up from the previous owner. We drove it over the pass and it lost 2 quarts in the process.

Rebuilt motor, hoping to use the rig to tow fifo's XJ to Elbe this weekend.

 

[TreeClimber]

Be careful. The oil pump housing is part of the timing cover, and as such could be the problem. NOT the gearset, but rather the housing itself.

Also, how did you determine ZERO oil pressure? By listening to the valves clatter? Or by a guage? I'd be careful before I trusted a 20 year old guage. Also, be aware that old AMC's tend to burn number 8 exhaust valves (and number 1s too). And finally, just as a reminder, 401s are externally ballanced, whereas 304s and 360s are internal. That means the harmonic ballancer (which is shot on your motor) and flexplate/flywheel are carefully ballanced in lieu of the crank.

 

[Totalled]

Hmmm.. gear style.. yeah, they push oil better than they suck it out of the pan.. pack it up.

 

[KarlVP]

Be careful. The oil pump housing is part of the timing cover, and as such could be the problem. NOT the gearset, but rather the housing itself.

Also, how did you determine ZERO oil pressure? By listening to the valves clatter? Or by a guage? I'd be careful before I trusted a 20 year old guage. Also, be aware that old AMC's tend to burn number 8 exhaust valves (and number 1s too). And finally, just as a reminder, 401s are externally ballanced, whereas 304s and 360s are internal. That means the harmonic ballancer (which is shot on your motor) and flexplate/flywheel are carefully ballanced in lieu of the crank.

We got the newfangled nickel plated one. The aluminum housings tend to expand and lose pressure over time.

I wouldn't say we had ZERO pressure, but having no lobe on the old camshaft (#8 cyl) and a pretty well concave lifter was a damn good indication that the motor wasn't getting enough oil.

Aside from that, this isn't an issue of trying to repair an oil pressure problem, it's an issue of trying to prime an oil pump after a rebuild. The vaseline thing will come into play tomorrow. After that, I'll post an update.

 

[FiFo]

Well, I packed it full of vasaline, an still can't get it to prime. Only thing I can think of is to get a more powerful drill.

and like Karl said, the timeing chain cover, oil pump gears, oil filter adapter, oil filter, and pick-up tube are all new.

 

[pokey]

just make sure your spinning it the right way I know fords and chevys spin backwards:eeek:

 

[darius]

I've put together a few AMC motor's back when i worked at olympic, i alway's just used regular bearing grease to pack the oil pump full. Also I never tore into a single AMC motor that didn't have the lifter's going flat.(if the were dished on the bottom, they arent supposed to look like that)

 

[KarlVP]

Still no priming or oil pressure. Packed full of vaseline and tried. Nothing.

We assembled everything and fired the motor. Still no oil pressure. Filled the filter and put that on. Still no oil pressure. Got a mechanical gauge and hooked that up. Fired the motor. Still no oil pressure. (Only tried running it for about 30 seconds each time)

So we dissassembled everthing and checked the oil passages in the block they are good. Tried priming it by putting a tube on the oil filter screw neck and letting gravity feed it straight to the pump. Nothing.

We are at a loss. Anyone have any ideas how to pressurize the pick up tube so we can force oil into the pump from there?

 

[PUO-BANNED]

Vaseline isn't thick enough, try wheel bearing grease.

we have a air powered lube setup at the shop and have used it a few times in buick V6s' to get them to prime. we assmbled the cover and oil pump then pump grease directly into the oil filter screw neck. works every time.

Otherwise you may have forgot something.

 

[TreeClimber]

Hope this helps, as I typed it.

1979 Factory Jeep Service Manual

Oil Pump

The positive-displacement gear type oil pump is driven by the distributory shaft, which is driven by a gear on the camshaft. Crankcase oil is drawn into the pump by an inlet tube and screen assembly which is pressed into the pump body (figure 1b-30). The pump incorporates a non-adjustable pressure relief valve to regulate maximum pressure. A setting of 75 pounds maximum pressure is built into the tension of the spring. In the relief position, the valve permits oil to bypass through a passage in the pump body to the inlet side of the pump.

Removal

Note: Oil pump removal or replacement will not affect distributor timing as the distributor drive gear remains in mesh with the camshaft gear.

1. Drain engine oil
2. Remove oil pan.
3. Remove oil pump retaining screws, oil pump and gaskets

Caution: Do NOT disturb position of the oil inlet tube and screen assembly in the pump body. If tube is moved within pump body, a replacement tube and screen assembly must be installed to assure an airtight seal.

Assembly and Installation

1. Install oil pressure relief valve, spring, retainer and cotter pin.
2. If position of inlet tube in pump body has been disturbed, install replacement tube and screen assembly. Apply light film of Permatex No 2, or equivalent around end of tube. Use tool J-21882 to drive tube into body, making sure support bracket is properly aligned (fig 1B-34)
3. Install idler shaft, idler gear, and drive gear assembly.

Note: To ensure self-priming of the oil pump, fill pump with petroleum jelly before installing the oil pump cover. Do not use grease.

4. Install pump cover and replacement gasket. Tighten cover screws to 70 inch pounds torque.

 

[TreeClimber]

I'd repack that pump, and pack it real good and full, but use Vasoline.
I'd make damn sure that the pickup tube is sealed into the pump body so that it's not sucking air down there, but sucking oil instead.
And if I KNOW that I did a really really good job of lubin' up the camshaft, then I wouldn't be afraid of running the engine for a few minutes. Taking of course into consideration that a oil change MUST occur as soon as the break in run of the motor occurs.