Mrmerlin

I have an 1987 auto and was doing TB,WP,MMs OPG,and all the fluid lines also rebuilt the oil pump with fresh O rings,radial seals.
Anyway I filled the engine with 10W40 Valvoline and started it up ,the oil pressure went to about 3 bar then after it ran for 5 mins went to about 1 1/3 bar.
no oil pressure light,
When the engine is revved to 4k the oil pressure goes up to about 4 but no higher.
I took the oil pump off thinking it may have been installed wrong but it wasnt.
I also removed the pressure relief valves and looked at them they all looked normal and no debris found.
Engine has about 51K miles .
I was considering that possibly the cam journal seals may have fallen out.
the cam cover O rings are leaking that seal the plugs to the tops of the covers where the hoses would connect.
The owner isnt sure about the gauge but seems to think that the gauge was reading low.
I didnt road test the car prior to working on it, (my bad).
Any thoughts??,
Thanks Stan

Dwayne

Was the oil pressure sender removed during your recent work?

Mrmerlin

I removed it after running the car but it wasnt touched prior
I inspected the ends and the wires are connected properly

blown 87

At least one of the plastic plugs has came out of the cam journal would be my guess.

Mrmerlin

any idea how many are reqired to be replaced??
is it 5 or 6?? with the new pins that sit inside each journal

blown 87

I think it is two on one side and one on the other.
They will get deformed and allow a lot of oil past them before they just fall out.

Bill Ball

Greg's idea would affect idle pressure, but it still should be able to peg 5 bar when rev'd, at least cold, right?

No low pressure warning may be a clue that the gauge needle is off, although 1-1/3 bar is not quite low enough to trip the warning. I do know that the sender output in Ohms versus pressure in later cars with dash diagnostics is 184 Ohms at 5 bar. 87 has the same sender but no diagnostics. If you can check the sender resistance with the oil cold and get 184 Ohms, the the gauge is not accurate if it reads lower. The warning sender output and the gauge sender should both read 184 Ohms. 3 bar would be about 100 Ohms. Since senders usually fail binary (work/don't work), don't blame the sender.

Do you hear any cam chain clatter?

blown 87

I do not know if it would peg when cold or not if all three were out.

the sender/gauge could very well have a issues.
The sender for a 87 is different than on a 89 and latter.

Bill Ball

Oh. I thought the senders were the same or should be electrically. I see now they are a different PN 89+. Still, it would be worth checking the resistance. If he sees 184 Ohms, to me, that would implicate the gauge. If he sees 100 Ohms and 3 bar, that would be more worrisome. I think it would be unusual for a sender to just output somewhat low.

Anyway, if all 3 cam plugs were out, I believe the cam chain should rattle like crazy at idle.

To me gauge inaccuracy seems a good possibility (and a happy one)-- or a paper towel left in the oil pan.

borland

Like Bill said, measure the reistance at the sender under differing engine RPMs. Then compare those ohm/Engine RPM readings with your 88' S4. You have no low oil pressure symtoms or warning light to suspect low oil pressure, but if you did, you would want to measure the pressure per the WSM procedure.

ROG100

You need 5 pins

GlenL

You might swap the oil to a thicker rating. If there's an internal leak then it'll show a higher pressure, especially cold.

I'll join the chorus of an electrical problem. Clean a bunch of grounds and see if it improves.

blown 87

I guess with four cams, three would not be enough would they.

I did remember it was a odd number.

Mrmerlin

To add more to this i did remove the left cam cover and the 2 rear plugs look like they are in place, the cam covers are both leaking so I am going to replace the cam cover gaskets.
I didnt hear any cam chain noise thought the heads dont look like they have much oil in them
The only other thing i could think of was that when i was lifting up the oil pan on the jack it was slightly off center and the inner webs hit the pickup but I maneuvered the pan so it then slide on, I dont believe that i was jacking on the oil pickup only slightly did the webs catch.
I didnt touch the oil pickup.
The oil sample that i took looked like it may have some metal in it, this was with the fresh oil and what prompted me to remove the oil pump after doing the timing belt.
The pump was infact installed correctly with the outer ring gear facing the correct way with bevel facing the front of the car and the square edge facing the engine.
Also the flex plate was checked prior to this and there was pressure on the thrust bearing it has .007 thousands clearance this is good (new is .004 in. and max is .016in. )
The car only has 51K miles but all of the fluid hoses were leaking, trans cooler lines and the oil cooler lines so they have been rebuilt with new Aeroqip hose.
The odd thing was when I started the car the pressure only went to about 2.5 to 3 bar at idle, with the engine cold.
Every 928 that i have started has gone to 5 bar when cold so this was the first flag
I ran it for about 10 mins till the fans came on by then the pressure was running at 1 1/3 bar to 1 bar with an idle of about 700RPM. ( no oil pressure light came on)
When i revved the engine to 4 K RPMs the oil pressure would only go to 4 bar no higher so i shut it off.
Is it possible that the pan could have damaged the oil pickup tube?? I was looking for a borescope to look into the oilpan, the oil pickup seems to be a stout item

Mrmerlin

Right now i can take any ohm reading of the gauge as the engine is all apart including the radiator, plus I have to pick up more oil plus the left cam cover is off.
I will try this after i fix the cam covers