Hi all,
I'm having ongoing oil pressure issues with a 2h I've just freshened up. I'm running out of ideas with this one and wondering if I'm missing anything obvious.
For context, the engine was pulled and rebuilt to rectify blow by issues(kms unknown, but was running fine). The wiring for the factory oil pressure gauge and low pressure cut off switch had was burnt out, so no real idea of how the pressure was previously. Given the condition of the internals (all looking good apart from rings and bores) i was not on the hunt for any potential oil system issues initially.
I'll run through the last week's events as briefly as possible
Engine pulled, head off. Rods and pistons removed. Crank, cam and timing cover remained in block.
Big end bearings in great condition. Main bearings had moderate wear, but nothing you wouldn't expect from an old engine. Crank journal's std size and in near perfect condition.
New big end and main bearings installed and clearances checked with plastigauge and all sitting in the middle of the acceptable tolerances.
New lifters installed due to cracking on the faces of the old ones
Engine reassembled and fitted back in. I made a new harness back to the harness plug from the oil pressure switches in the hopes it would fix the gauge.
Engine started and run in with 15w40 oil. Everything going well. Did around 200km test drive through the hills to bed in the rings and drove well.
Continued repairing the wiring for the oil pressure switches. Gauge still did not work (ran New wire from the new sender directly to the factory gauge, gauge broken).
Next time I drove it, it started to surge and stall. The pressure switch was triggering the edic to shut down. As this was the first real indication I had of low oil pressure, I installed a mechanical gauge.
Right enough, when the engine was warm the pressure at idle was dropping to near zero.
Started with the basics first. New (upgraded) oil pressure relief valve and spring. Checked the filter Bypass valve. Changed to genuine oil filter. No change to oil pressure.
Changed oil to 20w60 (bit of a patch up fix attempt as the car needs to be back on the road rather quickly) still little to no change
Removed the Sump to ensure I hadn't done anything silly. No evidence of metal/foreign material in the drained oil/Sump/filter. Removed a few mains and big ends to confirm. Confirmed both oil pipes below the Crank were sealed/tight.
Removed timing cover to replace oil pump. Old pump was worn (just out of spec) but nothing catastrophic. Replaced pump and drive gear. The pump housing did have wear in it, but everything measured well within spec with the new pump gears installed.
Confirmed the oil pressure relief valve was fully closed in the housing
Had as much of a visual check of the cam shaft as I could while I have it pulled forward to get the timing cover off, nothing out of the ordinary.
Noticeable improvement with the new pump, when at operating temp at idle it doesn't try to shut down. But the gauge is still only reading about 5psi. For a fresh bottom end with a new pump and running 60 weight oil, I would assume it would be a lot more. While doing 100kmh in 5th, it's sitting just under 30psi.
I'm struggling to think where to go from here... I haven't measured cam journal or lifter bores, but I can't imagine they would be causing that much pressure loss when they look OK.
I've had a close look at the rocker shaft and can't find any fault that would let pressure vent from that feed.
There's no oil in the Coolant, so I can only assume the oil cooler is fine. The oil cooler cover is the only thing i haven't taken off yet. Is there anything behind there that could be causing an issue?
I did find one post online stating there's a 3rd pressure relief valve (not the main one coming out of the pump or the filter Bypass valve). But I can't seem to find anything else about it apart from that post and can't locate it
I notice there's a feed to the alt vac pump and the fuel pump. Have they ever been known to fail in any way, letting oil pressure vent?
Anyway, I'm hoping I've missed something cheap and easy to replace
.
Any thoughts or info would appreciated
Thanks
Andy
I'm having ongoing oil pressure issues with a 2h I've just freshened up. I'm running out of ideas with this one and wondering if I'm missing anything obvious.
For context, the engine was pulled and rebuilt to rectify blow by issues(kms unknown, but was running fine). The wiring for the factory oil pressure gauge and low pressure cut off switch had was burnt out, so no real idea of how the pressure was previously. Given the condition of the internals (all looking good apart from rings and bores) i was not on the hunt for any potential oil system issues initially.
I'll run through the last week's events as briefly as possible
Engine pulled, head off. Rods and pistons removed. Crank, cam and timing cover remained in block.
Big end bearings in great condition. Main bearings had moderate wear, but nothing you wouldn't expect from an old engine. Crank journal's std size and in near perfect condition.
New big end and main bearings installed and clearances checked with plastigauge and all sitting in the middle of the acceptable tolerances.
New lifters installed due to cracking on the faces of the old ones
Engine reassembled and fitted back in. I made a new harness back to the harness plug from the oil pressure switches in the hopes it would fix the gauge.
Engine started and run in with 15w40 oil. Everything going well. Did around 200km test drive through the hills to bed in the rings and drove well.
Continued repairing the wiring for the oil pressure switches. Gauge still did not work (ran New wire from the new sender directly to the factory gauge, gauge broken).
Next time I drove it, it started to surge and stall. The pressure switch was triggering the edic to shut down. As this was the first real indication I had of low oil pressure, I installed a mechanical gauge.
Right enough, when the engine was warm the pressure at idle was dropping to near zero.
Started with the basics first. New (upgraded) oil pressure relief valve and spring. Checked the filter Bypass valve. Changed to genuine oil filter. No change to oil pressure.
Changed oil to 20w60 (bit of a patch up fix attempt as the car needs to be back on the road rather quickly) still little to no change
Removed the Sump to ensure I hadn't done anything silly. No evidence of metal/foreign material in the drained oil/Sump/filter. Removed a few mains and big ends to confirm. Confirmed both oil pipes below the Crank were sealed/tight.
Removed timing cover to replace oil pump. Old pump was worn (just out of spec) but nothing catastrophic. Replaced pump and drive gear. The pump housing did have wear in it, but everything measured well within spec with the new pump gears installed.
Confirmed the oil pressure relief valve was fully closed in the housing
Had as much of a visual check of the cam shaft as I could while I have it pulled forward to get the timing cover off, nothing out of the ordinary.
Noticeable improvement with the new pump, when at operating temp at idle it doesn't try to shut down. But the gauge is still only reading about 5psi. For a fresh bottom end with a new pump and running 60 weight oil, I would assume it would be a lot more. While doing 100kmh in 5th, it's sitting just under 30psi.
I'm struggling to think where to go from here... I haven't measured cam journal or lifter bores, but I can't imagine they would be causing that much pressure loss when they look OK.
I've had a close look at the rocker shaft and can't find any fault that would let pressure vent from that feed.
There's no oil in the Coolant, so I can only assume the oil cooler is fine. The oil cooler cover is the only thing i haven't taken off yet. Is there anything behind there that could be causing an issue?
I did find one post online stating there's a 3rd pressure relief valve (not the main one coming out of the pump or the filter Bypass valve). But I can't seem to find anything else about it apart from that post and can't locate it
I notice there's a feed to the alt vac pump and the fuel pump. Have they ever been known to fail in any way, letting oil pressure vent?
Anyway, I'm hoping I've missed something cheap and easy to replace
. Any thoughts or info would appreciated
Thanks
Andy
