Oil pressure gauge, 1988 GT (Page 1/2)
John W. Tilford SEP 29, 11:04 PM
1995 era GM 3.4 pushrod swapped a few years ago.

Oil pressure gauge shows 40 at idle. Maybe I never noticed before, but needle goes up with engine rpm. OK, makes sense. BUT goes down in red warning zone if turn left hard, especially if downhill left tight curve. Sometimes red warning light comes on.

I did not do the swap but assume the oil pan was modified/exchanged.

Oil level is up to full line on dipstick. Oil looks fine, not dark.

Is this normal and I just never noticed because I glance at the instruments when idling at a stop light? Should I be concerned?

------------------
John W. Tilford

theogre SEP 29, 11:34 PM
oil pressure should be very close to constant at all RPM.
Is likely wiring or sender problem often worse if has iffy motor mounts etc.
Or have similar problem w/ stock V6 w/ low pressure and bottom end wear.

Use a mech gauge to check.

------------------
Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)

The Ogre's Fiero Cave

Mike in Sydney SEP 30, 01:39 AM
Sounds like there is a missing baffle or unnotched baffle in the oil pan after the swap.
buddycraigg SEP 30, 07:59 PM
a normal 2.8 does that when the oil level is low.
How did they run the dipstick?
Did they leave it stock?
John W. Tilford SEP 30, 08:10 PM
Buddycraigg, I don't know but suspect the gentleman who did the swap will contact me fairly soon. He monitors Pennock's.
Still, it's odd I had no symptoms for around five years with the same 3.4 and dipstick.

While you're there, would you think the oil pressure sensor would be the same in a 1995-era 3.4 pushrod and a stock 2.8? I was considering just buying a sensor, backing the car up on tire ramps, crawling underneath and changing out the sensor, checking the connection/wires at the same time.

------------------
John W. Tilford

olejoedad OCT 01, 12:02 AM
I replied in your other thread on this topic.
John W. Tilford NOV 04, 07:55 PM
Fixed!

An "oil pressure" search in previous Forum cases found at least two with almost identical symptoms. Both were due to oil pump intake tube dropping into the oil pan. Normal oil level was high enough for oil pump to suck up oil when the engine was level, but not high enough relative to the oil pump when cornering resulted in the oil accumulating on one side and the pump sucking air, so to speak. The two earlier cases shared the diagnostic tip of rubber hammer banging up on the oil pan. Loose intake tube "rattled". One of the previous posters had drained the oil, the other banged and heard a rattle with oil still in the engine.

Kudos to the Meineke mechanics in Ellettsville, Indiana. I called them with the rubber hammer tip, they heard the rattle. One mechanic in particular works on GM short block engines. He tack welded the intake tube in place before replacing the oil pan gasket and oil pan. He tack welds all the intake tubes on his hobby engines.

Many thanks to members of the Forum and to Pennock's for the search function.

------------------
John W. Tilford

[This message has been edited by John W. Tilford (edited 11-05-2021).]

eti engineer NOV 05, 08:15 AM

quote
Originally posted by John W. Tilford:

1995 era GM 3.4 pushrod swapped a few years ago.

Oil pressure gauge shows 40 at idle. Maybe I never noticed before, but needle goes up with engine rpm. OK, makes sense. BUT goes down in red warning zone if turn left hard, especially if downhill left tight curve. Sometimes red warning light comes on.

I did not do the swap but assume the oil pan was modified/exchanged.

Oil level is up to full line on dipstick. Oil looks fine, not dark.

Is this normal and I just never noticed because I glance at the instruments when idling at a stop light? Should I be concerned?



I was going to replace my 2.8 with a 3.4, but decided against it, since the engines look different and part of CA's smog is a visual. If the "FIERO" letters were missing on the intake manifold, they might have failed the car.

In the process of preparing for this, I got a 3.4 oil pan. There are no baffles in the pan. Maybe in later models there were, but not the one that I got. I replaced the old oil pump in the 2.8, and as mentioned in other answers to your thread, the pump and the pickup tube come as two separate pieces which are press-fitted together. It's the same for the 3.4. There are directions as to how the pickup should be installed and the measurement are critical with close tolerances. I was told by others in here that once I got the pickup positioned correctly, that I should tack weld it in a couple of spots to ensure the pickup did not come loose and sit in the bottom of the pan. I did this. So far, so good. My engine has been totally rebuilt so it is like a new engine. Like you, I get 40 psig at idle and around 60 at running speed. If you need an oil pan and a 3.4 pump, I have new ones I will sell cheaply. They are Melling brand components.
Notorio NOV 05, 06:17 PM

quote
Originally posted by eti engineer:

I was going to replace my 2.8 with a 3.4, but decided against it, since the engines look different and part of CA's smog is a visual. If the "FIERO" letters were missing on the intake manifold, they might have failed the car ...



ETI, just for Future Reference, there are several folks on here that have done the 3.4 pushrod swap in California and passed smog without any issues at all. If you look in my old post Ghost Mods you will see who they are.
John W. Tilford NOV 06, 05:05 AM
ETI engineer, my 3.4 has the same (red with 'Fiero" label) intake manifold which formerly graced my original 2.8. The average person looking down on the engine would not suspect the swap.

------------------
John W. Tilford