Important! Oil pump specs... I think we have a WINNER!

[Kid_Again]

If you'll remember my last post in the original thread, you'll see that VNV thought that there was something wrong with the bypass plate.

So, see the attached picture. He was absolutely correct, the engine rebuilder plugged my bypass . So, if I understand the workings correctly, when the oil filter canister reaches a critical pressure value, the bypass kicks in, bypassing the oil filter and forcing oil directly into the engine. IF all that's true, there is now no pressure drop at the oil filter which would account for the high pressure seen in the galleys. I KNEW that I should have ordered a new one from LICS. OK, ONE more order and I should be in good shape.

God, he will be insufferable now .

 

[Viet Nam Vett]

If you'll remember my last post in the original thread, you'll see that VNV thought that there was something wrong with the bypass plate.

So, see the attached picture. He was absolutely correct, the engine rebuilder plugged my bypass . So, if I understand the workings correctly, when the oil filter canister reaches a critical pressure value, the bypass kicks in, bypassing the oil filter and forcing oil directly into the engine. IF all that's true, there is now no pressure drop at the oil filter which would account for the high pressure seen in the galleys. I KNEW that I should have ordered a new one from LICS. OK, ONE more order and I should be in good shape.

God, he will be insufferable now .

God, he will be insufferable now

No I won't.. I'm just glad you found out where the High Pressure problem is. Now will wait and hear from the experts... ;help

 

[JohnZ]

See the photo below of the bypass system; under normal conditions, the oil enters from the pump on the right to the outer portion of the filter, goes through the filter media, and exits through the center of the filter to the main oil gallery.

If the filter media becomes plugged (or nearly plugged, causing a large pressure drop across the filter), the bypass valve (fiber disc and spring) on the left opens, allowing the oil entering from the pump to go directly through the valve to the oil gallery, bypassing the filter media partially or entirely. This protects the engine in the event of filter restriction or blockage.

When the bypass valve is plugged, all is fine as long as the filter is functioning, and 100% of the oil is filtered, as all the oil is forced to go through the filter; however, if the filter becomes restricted or plugged, oil flow to the main gallery becomes restricted or blocked entirely, resulting in loss of oil pressure. Plugging the bypass is NOT a great idea for a street engine. Many race engine builders plug the bypass, as filters are changed regularly, their thinking being that a plugged bypass ensures 100% filtration (but there's no backup if the filter develops restriction or plugs up).

I don't think fixing the bypass valve will have any effect on your oil pressure; oil pressure is a function of the relief spring in the pump and bearing clearances. A functional bypass valve ensures constant oil flow regardless of the condition of the filter; oil flow with a plugged bypass valve depends on the condition of the filter, which is a constant restriction.

 

[Kid_Again]

I now need to REJECT my reality and substitute yours.

Perhaps I should become a member of www.wehavenoideaaboutcorvettes.com in order to continue to live in a fantasy land.

As always, thanks, John.

Plan B

 

[Viet Nam Vett]

I now need to REJECT my reality and substitute yours.

Perhaps I should become a member of www.wehavenoideaaboutcorvettes.com in order to continue to live in a fantasy land.

As always, thanks, John.

Plan B

Plan B...?????.... It took me 10 seconds to figure out why that link you posted above didn't work. ...Gheeeeeeeeeeeez..!!


Now WTF is plan B:confused

 

[Kid_Again]

Plan B? I'm thinking a new short block because it's the only thing that I didn't swap out. Everything else is new.

 

[Kid_Again]

OK, I'm back to basics. Tearing apart everything from the oil pickup to the valve covers looking for a problem. As of now, all the oil passages that I can access are perfectly clean and clear.

Here's an interesting link that adds nothing fundamentally new to what has been posted here but does explain the difference between high pressure pumps and high volume pumps and why you don't "need" more than 50 psi for the street:

Oil Pumps for Street Stock - Tech Articles - Stock Car Racing Magazine

As a post script, I've taken apart the current oil pump and am in the process of blueprinting it to the level possible. I've flattened every surface to remove machining marks (I know that there's a spec for the gap between the bottom of the gears and the base plate and will find that from a previous post before I re-assemble). I mic'd the gears/shafts and everything is reasonably straight and consistent.

I then went to pull the bypass spring and follower and to my surprise, the follower was tough to push out of the bore. It figures. After forcing it out, the follower did not show any scratch marks but it wasn't consistently shiny. After putting the follower on a mandrel on the lathe and surface finishing with steel wool, the follower measures a fairly consistent .439 in diameter which is the same as the follower from another stock oil pump that I just happen to have apart (at one point, I had three separate pumps apart, side by side).

I then clamped the base that contained the spring/follower into the lathe and ran some loose steel wool on a split mandrel up and down the bore a few times. I know, real machinists just cringed. Not a lot came out but it's all shiney down the length of the bore that I can see.

The follower now runs smoothly down the bore. Yup, I may have opened up the space a bit more than a pro would be happy with but I'm thinking of the tolerances that went into building the pump anyway and I'm comfortable that I didn't do anything stupid.

I've checked everything else that I can and I don't take a chance with Bubba fixes like plugging the bypass. New bypass plate arrived today.

So, I follow the good advice. People like JohnZ say if it's oil pressure, that's determined by the oil pump so go back and look at that again:bash. People like VNV say go back to basics :bash.

So far so good. I should have the car ready to fire up by Monday at the latest after I go over everything, including Hib's advice on the oi leak at the intake manifold/block area. And now, Tom Bryant's advice on where to measure the oil pressure at the front of th engine.

And besdies, I just advertised for a 383 short block on the CAC if anything else goes wrong!

I can't beleive that all this problem may have come from a malfunctioning oil pump.

Only me