I now have a 90 Eclipse (6 bolt) 4G63T (supposedly about 180,000km according
to the donor car odometer) running in my 93 Summit coupe. Oil pressure is
such that the idiot light flickers all the time. The std Eclipse gauge
swings to mid range on
start, then quickly drops to near zero. There's no tappet or big end bearing
and the engine runs smoothly. I'd guess there's about 20 psi. There's
enough pressure getting oil to the turbo, as the supply tube fitting on the
had a wrong size crush washer that spat a lot of oil on first start.
I can feather the gas pedal till the idiot light goes out, then a blip on
the gas turns it on again. The corrrectly tightened alternator belt SEEMS to
squeal (more) occasionally when I depress the clutch. The oil pump is
correctly aligned with the cams.
I've checked the oil pressure relief valve and oil cooller bypass valve:
both look normal.
I know that oil pumps wear out, and worn bearings can cause significant loss
of pressure. Other worn engines I've fixed usually had about 1/2 normal
pressure with worn bearings, and one (a Renault) had an internal pump gasket
failure that leaked pressure back to the sump, thus giving 15-20psi.
Blipping or revving would cause pressure to increase at least a bit.
The 220,000km n/a 4G63 I just took out had decent oil pressure all the time,
despite the thrashing I gave it for the last two years.
I see in my manual that the oil pick up tube has a replacable gasket. It
to be on the pickup, not pressure, side. If this fails or leaks, could this
cause of low oil pressure? It may be causing the pump to suck air (and less
oil) once the engine starts and the level drops down.
Possible thrust bearing wear, though there does not appear to be any
fore-aft crank movement. Crankwalk is not usually a problem in the 6
bolt engine, but could be the problem is evidenced by the alternator
belt squeal. The "blip the gas and idiot light comes on" is a worry. Could
be worn big-end bearing(s).
What I find odd is NO increase in oil pressure on revving the engine. Its
as though the pressure is leaking away somewhere (or not getting generated)
before it gets to the bearings. I'd expect even worn oil pump would allow
increase in pressure. Is this reasonable for the 4G63?
What's the most likley problem here? Oil pump, bearings or both? Or
I'll get the sump off next week and have look at the pick up gasket and
check the mains, thrusts and big ends..