No oil pressure during rebuild test; please help.

[thomasjpierce21]

I have a 1989 Donzi Regazza with a 4.3 and am in the process of a rebuild. All new bearings, etc with all clearances meeting spec. When I tested the oil pressure with the orginal distributor staft and a dummy shaft with the same diameter I cant get the pressure to build. I have tested the block with air and it build pressure so I know there is nothing wrong there. The oil pump is pumping the oil just fine its just not not building enough to send it through the lifter valleys and up through the push rods into the heads. Any reason why this could be happening? I've done every test I can think of this is quickly becoming one of the biggest mysteries I have encountered.

Your help is greatly appreciated!

Capt. Tom

 

[Fishermark]

Re: No oil pressure during rebuild test; please help.

When I tested the oil pressure with the orginal distributor staft and a dummy shaft with the same diameter I cant get the pressure to build.

I don't know what you mean by that exactly... but simply turning the oil pump with a shaft of the same diameter isn't going to work. It needs to cover the oil galleries. Like this:

If that's what you are describing... then I'm not sure what to suggest next. How are you turning the tool? You need to get a good 1/2" drill and turn the tool till pressure builds up.

 

[mkast]

Re: No oil pressure during rebuild test; please help.

Not being present at the test, I'd ask, "What direction is the shaft turning?"

 

[Don S]

Re: No oil pressure during rebuild test; please help.

If you have the proper tool for the oil pump, after you have oil pressure, turn the engine over with the starter while the drill turns the oil pump. They will oil then.

 

[a70eliminator]

Re: No oil pressure during rebuild test; please help.

If you didn't prime the oil pump spin it till your blue in the face, then pull off the oil filter and prime the pump.

 

[Don S]

Re: No oil pressure during rebuild test; please help.

If you didn't prime the oil pump spin it till your blue in the face, then pull off the oil filter and prime the pump.

Why remove the oil filter, the pump will fill the filter, the filter is right after the pump for getting oil then the oil passages.

 

[a70eliminator]

Re: No oil pressure during rebuild test; please help.

What I'm saying is (now this on my ford's) the oil pump requires priming before it is bolted to the block, you pour oil into the neck while turning before bolting it to the block, I had a dry one on my last build and rather than pull the pan and remove the pump, I just pulled the oil filter off and with a funnel and hose back filled the pump, it then took right off.

 

[Bt Doctur]

Re: No oil pressure during rebuild test; please help.

In most cases a brand new ,dry oil pump body will not pull oil from the pan.They need manual priming before it`s installed on the block to wet it up a bit. You must use a full distributer body minus the cam gear,(grind or machine the teeth off) and a good 1/2 inch drill to spin it. The dist housing is what directs the oil flow to the lifter galleries and up to the rocker arms.
just using a rod to turn the pump won`t work.

 

[thomasjpierce21]

Re: No oil pressure during rebuild test; please help.

Thanks for all the feedback guys. I figured out that the mock distributor shaft that I had wasn't properly covering the hole above and below to create pressure. It was only covering the hole at the top and allowing the oil to fall back into the crankcase rather than travel across the lifter valleys.

Just one of those Chevoret things that you have to find out by working on them.

Thanks again.