Think I should clean the oil pump screen?

[geoffinbc]

Absolutely. Large oil filters off much more flow. Less restriction in the filter means more flow into the engine which is where the oil pressure is read from.

I run a Delco PF2 which as a full 1QT oil filter that belongs on a 460 Ford. I run this filter because I use synthetic oil and have an extended drain interval and leave my filter on for 6000KMS. I am confident I could leave it on much longer but I only pay $4 a pop so it isn't worth not changing it.

My setup uses a Canton Racing remote filter adapter attached to braided stainless lines and a Transdapt filter mount which I took a die grinder to, and smoothed out the passages. After the swap I noticed the pressure fluctuated much less than before. But still the maximum and minimum pressure reading through the RPM range did not vary much.

[85_Olds_Ciera]

Along with the 150,000 miles of wear even though it may have been very little. But all in all 12PSI was good.

Tidbits - After installing the largest Oil filter (AC PF52) possible on OEM adapter, which just clears the cradle....and with new oil pump...it appears to have around full pressure (70 psi ) with cold motor running around 2,000 RPM while driving it. Digital oil pressure gauge ( seen as vertical bars, not numbers) is one bar from maxing out now...which can be done if RPM is raised...new sender.

Even with hot oil, this 150,000 mile motor still runs about 45-50 psi at 2300+ RPM ( 50 mph ).

It seems having that larger oil filter does add a pinch to pressure...when motor is warmed up and running down the roadway...at idle, appears to be the same, some 20 psi now...with new oil pump.

[geoffinbc]

Well take that statement lightly. It said the 3.4L has a forged crank and pistons. All wrong information.

I am not sure what pump is actually in the DOHC motor but a simple P/N cross reference will tell you.

[85_Olds_Ciera]

Engines don't need enormous amounts of pressure. They just need a constant non failing supply of oil.

Tidbit: THE 3.4 DOHC 24 VALVE

The 3.4L DOHC motor was designed....Revamped oiling system with high volume pump. An oil cooler.

[85_Olds_Ciera]

If I remember (havent looked in a while) there is a plug in the block near the filter mount that will serve the same porpose. Check it out it will be easy to spot.

On 1988 2.8 installed in Beretta...now that I think about it....on block side, there is an individual cavity (port) with I think it has a check ball within it...and behind check ball is where Oil Sender is connected on block side.

I had the adapter off...and should have got my glasses...but thats what it looked like...and the adapter had a separate cavity that fed this Oil Sender circuit for oil going to engine (filter's output side).

I guess I will have to put a T line in with sender...what a pill...to do it right and clean gasket off...off comes starter and AC compressor...then you can see it all clearly.

thanks...

[geoffinbc]

Almost all our engines use a port on the oil filter adaptor.


Take a look at these 2 adaptors one is an s-10 and one is a Camaro (black). The pressure is read right as the oil enters the block. This is the ideal location for measuring the pressure. The S-10 adaptor actually has 2 locations. This is left over from when the trucks used to have a seperate guage sender and oil pressure switch which send 12V to the fuel pump. On the newer models the guage and switch were all in one. Your vehicle should use a similar adaptor. If I remember (havent looked in a while) there is a plug in the block near the filter mount that will serve the same porpose. Check it out it will be easy to spot.

[85_Olds_Ciera]

...bubbles in the oil could be seen clearly on the dipstick even when the motor was off.

Unless the parts were examined (oil pump..block), its speculation...Points:

1. Was the Screen placed in correct position? When I put in new pump recently...I made sure it was in same position when I took it out...and spot welded tube to pump after this check.

2. If Screen got plugged, or was not the right screen (too small) could the pump suck air where tube inserts into oil pump?

3. Was the pump's mating surface flat against block...no warpage/etc.

If your engine is tight...there's no need for a High Volume pump...I would agree with you on this point...but with loose clearances, a HV would be OK.

Btw, does the 2.8 engine have a plugged oil port on block/heads that I could get a direct reading?

I have this feeling the OEM digital Oil Sender is not in a choice location...the response lags.

[geoffinbc]

Well the screen causing a failure is a long shot. And the HV pump was observed to be the killer of the 4.3L motor. The bubbles in the oil could be seen clearly on the dipstick even when the motor was off.

[85_Olds_Ciera]

Melling HV pump this may be the case.

2.8 Engine: Melling M-95B: Melling stock replacement oil pump to fit GM cars & trucks, Jeeps and Isuzu's with the Chevy 2.8L(173ci) and 3.1L(189ci) engines in the following applications;

The last piece of advice is NEVER trust the stock gauge.

I'm fully aware....and am aware my bench test of "calibrating" digital dash readout to air pressure applied to Oil Sender Unit is not perfect.

Tonight, I have sent an email to Milling Tech Support....to find out if ByPass Circuit is temperature dependent or not.


From one of your previous posts here:

.
Posted: 11-26-2006, 01:04 PM
.
A member on S-Series used an HV pump on his blown 4.3L build. The engine lasted only a few thousand miles before it ate itself. The problem ended up being the HV pump which was causeing excess airation in the oil.

Do not overlook Oil Screen: here's a tech note from Milling. A bad screen could create the same type of effect...all depending.

Further, screens come in different cross-sectional areas; on the 3.8 motor I put back together, it used a fine mesh screen, whereas this 2.8 uses a coarse screen.

[geoffinbc]

Precisely. And oil is rated just the same The first number you read 0 5 10 or 20 is a crank rating for the oil. Basically at cold temp the higher the number the thicker it is. Your second number is your oil viscosity at 100*C. 10 15 20 30 40 50 and so on, automotive oils rarely go above 70 most oil above 30 are for air cooled or racing engines.

If you are getting a huge oil pressure spike during cold operating temperature then you may be exceeding the pressure relief capacity. It is common practice to increase the relief orifice on pumps that are modified with larger pickups or high volume. If you bought a Melling HV pump this may be the case. It may still be true on a stock pump and a high crank rated oil. Try the 5W you may see a difference.

The last piece of advice is NEVER trust the stock gauge. If you truly want to know your oil pressure you need a mechanical gauge or accurate electric gauge (like an Autometer) with pressure taken on the return side of the oil filter, after oil has passed the filter and is about to enter the main entrance gallery up to the oil passages above the cam.

[85_Olds_Ciera]

Also 5W30 and 10W30 are the exact same Viscosity at 200*F.

Interesting chart here on second page...notice the sentence above the chart:

Figure 2 shows the sensitivity of oil viscosity with changing temperature. The viscosity change as a function of temperature is a huge factor in regulating the
flow with a pressure reactive device.

[85_Olds_Ciera]

The bypass is NOT temp dependent. It is just a spring and piston.

If this is true...then I have no idea what is going on...

[85_Olds_Ciera]

If an engine is requiring large amounts of pressure to stay alive it is like that because it needs that much flow.

How Much Oil Pressure?

Vehicle manufacturers have traditionally recommend a minimum of 10 psi of oil pressure for every 1,000 rpm of engine speed. Using these numbers, most stock engines don't need any more than 50 to 60 psi of oil pressure. With tighter bearing clearances, pressure goes up requiring less flow from the pump and less parasitic horsepower loss to drive the oil pump. In racing applications, the old school of thought was more oil pressure was needed to keep the engine lubed. That's true if bearing clearances are loosened up. But most engine builders today tighten clearances so less oil flow is needed to maintain adequate oil pressure. This approach increases the horsepower output because less power is needed to drive the pump at high rpm.

A stock oil pump is usually more than adequate for most street performance engines, and even many racing engines. NASCAR engines typically get by just fine with no more than 50 psi of oil pressure at 9,000 rpm!
....
...

[85_Olds_Ciera]

The bypass is NOT temp dependent. It is just a spring and piston.

From 2100 RPM onward with motor up to temp....same old reading with this new pump.

Logically, it points to a temp/by-pass relationship...as the temp rises, the by-pass set point lowers.

When springs get hot...their elastic property increases...which decreases set-point.

It has a violet colored spring in this Milling pump...but I could not get any tech info from their site.

This is what I observe....with motor up to temp....no increase in oil pressure past 2100 RPM.

PS: Have they re -engineered these pumps? As I noted, Cumins uses 45 PSI max on N14 motors....I talked to an engineer there...I know this...

[geoffinbc]

The bypass is NOT temp dependent. It is just a spring and piston.

Oil pressure has no correlation with bearing surface. If an engine is requiring large amounts of pressure to stay alive it is like that because it needs that much flow. If you want more flow through the same hole then the pressure increases accordingly.