No Oil Pressure on rebuild

I left the plugs out and have spun it a lot with the starter. No oil pressure.. I don't know what to do next.

TW

I do that on every blessed engine I build. Just insures that everything is in it's proper "section" before we "light the fire". :>)

Allan

As to the problem at hand, presumably you filled the oil filter with oil first? Anyway, if you used a good assembly lube on the bearings, cam and other moving parts, you're OK to start the engine, IMHO, and let it idle for 10 seconds or so to get the oil pressure up. At idle, you aren't doing any more damage than spinning it over excessively with the starter. As stated, a pre-luber is the best idea if you can get your hands on one.

Jim

Ya don't "pack it in there" like he said he did.

At room tempreature, that is the same as putting a cork in a bottle. The oil has to get to the pump initially or it will never take "a bite".

Allan

tw

But, at room tempreature and before the engine gets hot enough to melt it, that oil pump with that Vaseline in there is sealing itself off from the rest of the world. They are very good at compressing, but just don't "suck" all that well.

One swallow of oil and it will be just fine.

Hope you get my meaning; I'm just trying to help here. :>)

Allan

It's trying to. The fluid won't compress, therefore the result is pressure/flow.

Allan

Get that crap outta there. :>)

Allan

If no immediate pressure, then I will take appropriate steps.

tw

I have seen this question of no initial oil pressure come up many times. Mostly in relation to Farmall Cubs. The problem is the assembler forgot to reinstall all the oil gallery plugs. The most frequent plug ommitted is the transverse gallery that terminates inside the tappet area at the center of the block. Another unplugged gallery ends behind the camshaft gear.

If you pressurize the block, you will know whether you did a complete plugging job.

But it makes no difference. If you have no oil pressure, you need to find out why. Pressurize the oil system. If two gallons of oil wind up in the crankcase in 15 seconds @ 20 lbs pressure, you have woefully bad bearings or a gallery that is missing its terminal plug. The tractor oil pressure gauage will not lift off zero. The gallery plug will probably be a 1/8" pipe plug.

If you want to pinpoint the source, run the test without the oil pan.

There are three external plugs on a H just above the oil pan on the left side. Anyone of those would be a good place to attach an oil filled pressure line.

I don't know if you have ever heard of pre-lubers. Some trucks and equipment are fitted with these so that the motors never have a dry start. This is the same principle. Do you want a dry start on your newly assembled engine?

What you put in there is a thick grease and undoubtedly the impellers have slung it outward into the pickup tube and elsewhere thus creating a neat little cavity around the impellers and blocking the oil out.

The oil pump is a submersion pump and there is no means of suction to "pull" the oil into the pump. The impellers just get the oil flowing in one direction and force it up the inlet; that's it.

Why did you pack it with petroleum jelly?????

It's VERY common to pack oil pumps with petroleum jelly, or automatic transmission assembly lube, and doing so should be a GOOD thing, certainly NOT causing problems.

Really a thick assembly lube will create a gel like constriction on a paper/fiber media oil filter element and slow oil flow until it dissipates. Packing the pump housing really won't do much anything for this type of submersion pump. If you can get it to flow through the pump it will only accumulate in the filter and create a restriction like above. Oil or a moderate coat of lube is best because after all the pump will be completley immersed.

What other fantasy physics theories you got?

Soundguy

It's a "positive displacement gear pump".

I have packed (with a REASONABLE quantity) of vaseline or auto tranny assembly lube EVERY oil pump for EVERY one of DOZENS of engines I've assembled over the years, with nothing but GOOD luck with the pumps priming quickly. Same thing with automatic tranny pumps.

I have started rebuilt engines even in COOL weather, with NO problems. I don't know where the original poster is, but, surely, the temperature is in the 80 to 90 degree range (or HOTTER) at this time of the year, and the vaseline will be pretty thin at these summer temps, and CERTAINLY not "hurt" anything!

The simple answer is, I have never had an original thought about something that I do not know anything about. I was instructed by the engine man at the machine shop to do that.

tw

As for your pump you might be able to pull one of those oil port plugs under the oil filter pedestal and use an air compressor to blow the grease out of your pump. There is a one way valve in the pump but I doubt it is airtight.

Might try that? If you can unblock the port and get the juices flowing then the engine heat will break down the petroleum jelly.