"In block" oil pressure valve

[Ray Hamilton]

When my machinist tanked my 2.8 block he found an oil pressure valve in the block behind the oil filter plate. He told me I didn't need it as the plate already had one in it, he showed it to me.
When I was installing my engine I noticed that the oil filter had lost all it's oil after priming. It did set for a long time. I turned the oil pump by hand and there was plenty of oil coming out of the oil hole. However on first start up I had alot of lifter noise, everything new, and now in the mornings I still get alot of lifter noise. The oil pressure is 60+ lbs. I wonder if I need to put that valve back in the block. Is the lack of it letting the oil filter bleed out?

[85_Olds_Ciera]

Unless you know why it is there...I would not mess with it.

Also, some oil filters have a check valve in them...and others don't...I bought an oil filter on 82 Century station wagon (six banger I think), and it showed same symptoms you have mentioned when starting up.

[Ray Hamilton]

This filter is a "Bosch". The machinist seemed quite sure it didn't need to be there. I didn't even notice it on disassembly. In the oil filter hole in the block. I still have it, it'll be a bitch to put back in. "K&N" filters state they have a valve to keep the filter from emptying.

[85_Olds_Ciera]

This filter is a "Bosch"..."K&N" filters state they have a valve to keep the filter from emptying.

Like I stated, on that 82 Century station wagon, I put on one filter and you could hear the lifters "firing up" when started...years ago.

You might put on a Fram® Tough Guard® oil filter...like $5.00...which has:

1. Silicon Anti-Drainback Valve

[Ray Hamilton]

What the valve I was talking about is a pressure relif valve and has nothing to do with the lifters as I found out today. The filter is probably the culprit as you say.

[CNCguy]

That is the filter bypass valve and opens to let oil bypass the filter if there is too much restriction in the filter. I guess manufacturers feel that unfiltered oil is better than no oil. It is pretty common to plug a bypass valve and run a gage to monitor the oil pressure. I assume he plugged the hole where the valve came out. You may want to check to be sure. If the hole is unplugged, oil will bypass the filter and the anti drain back valve won't work. If it is plugged, most likely your filter is the issue.

[85_Olds_Ciera]

That is the filter bypass valve and opens to let oil bypass the filter if there is too much restriction in the filter. I guess manufacturers feel that unfiltered oil is better than no oil.

Not true...on that 3.8 motor, the nylon teeth overlay on cam gear could finely shred bits until the oil screen was plugged, then oil pump's bypass would kick in, then oil filter would get plugged, then those fine bits via bypass value would go plug up crank/rod lines...then engine locks up.

[CNCguy]

Not true...on that 3.8 motor, the nylon teeth overlay on cam gear could finely shred bits until the oil screen was plugged, then oil pump's bypass would kick in, then oil filter would get plugged, then those fine bits via bypass value would go plug up crank/rod lines...then engine locks up.

Another know it all bench mechanic. If the pickup screen gets clogged there would be no oil getting to the pump to create pressure. The pumps bypass is to regulate oil pressure not to bypass the pick up screen. The filter bypass is a different animal than the pump bypass and is usually located in the block under the filter or in the filter adapter. I've had a busy day and not in the mood to argue with you. Believe what you want.

[85_Olds_Ciera]

If the pickup screen gets clogged there would be no oil getting to the pump to create pressure.

ON 3.8 motor (1987), not in the pump, but on its screen attachment to pump, there is an orifice there in tube mechanism that attaches to pump.

When screen is filled, it will suck it thru this port, just above the screen...actually, on top side of screen's assembly.

As I recall, five years ago.

[85_Olds_Ciera]

Another know it all bench mechanic.

I'm going to look for that Screen Assembly Thursday...and if found, I will post a photo of it...along with some crow.

The bypass is just above the screen, on the top side, so when screen is plugged, since this bypass is within same cavity as screen, it will suck oil and whatever else is available.

3.8 Motor...have you rebuilt one?

[Ray Hamilton]

This by-pass was in the block, in the hole that goes to the oil filter. The aluminum plate that relocates the oil filter rearward and outward has a by-pass built in. I suppose if you had a vehicle that the filter screws directly on the block this would be necessary.

[85_Olds_Ciera]

This by-pass was in the block, in the hole that goes to the oil filter.

1. I think I have seen oil filters that have a internal bypass...maybe in racing, or in Big Semi Truck motors.

2. I would leave it in there...it makes no sense to remove it...many motors have a by-pass...but unless one has a good reason, I would leave it alone.

I just got a 88 Beretta...and if I can, I will install a larger sized filter for it...once I figure out what oil filters can be used....I have a feeling on this 2.8, I may have to use what is called for, since it is tight there.

[geoffinbc]

This by-pass was in the block, in the hole that goes to the oil filter. The aluminum plate that relocates the oil filter rearward and outward has a by-pass built in. I suppose if you had a vehicle that the filter screws directly on the block this would be necessary.

CNC already answered correctly. This bypass valve must be installed or BLOCKED. It cannot simply be removed or you will never get filtered oil. Even if there is one in the filter mount. Old blocks never has this bypass valve in the block it was always in the filter mount.

[85_Olds_Ciera]

Another know it all bench mechanic. If the pickup screen gets clogged there would be no oil getting to the pump to create pressure....I've had a busy day and not in the mood to argue with you. Believe what you want.

Well now...pic showing top side is enclosed, which represents 87 Olds-Delta 88 3.8L oil pickup...and for ten bucks, I'll send it to you.

The oil screen is on the other side...but notice that hole below the bracket; contains a small chunk of nylon fragment from cam gear in that bypass hole.


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[1988GTU]

1. I think I have seen oil filters that have a internal bypass...maybe in racing, or in Big Semi Truck motors.

2. I would leave it in there...it makes no sense to remove it...many motors have a by-pass...but unless one has a good reason, I would leave it alone.

I just got a 88 Beretta...and if I can, I will install a larger sized filter for it...once I figure out what oil filters can be used....I have a feeling on this 2.8, I may have to use what is called for, since it is tight there.

PF52 is the biggest you can go depending on which adapter then engine contains.