TnFordDad
New Member
Background: I have a 5.4L 3-valve manufactured in 2009, with 195,000 miles. (Probably not relevant, the cam phasers were locked out a few years ago.) My wife was in a wreck (body damage only), so the vehicle sat for a couple of months until insuranced and body shop got it looking good again. Upon picking it up, though, I discovered a new intermittent oil pressure issue. The motor oil level is at 100% capacity. For the last 6 years, at least, the motor has had full synthetic 5W20 oil changes every 3k-5k miles.
Sudden oil pressure changes: Upon starting the motor, it runs just fine (at least while sitting on the level), with the oil pressure guage staying above 50%. I have driven it as far as 5 miles / 10+ minutes, and at speeds up to 45 mph / moderate RPMs, and as long as the road was essentially level or facing downhill, the oil pressure guage stayed a well above the half-way mark (maybe 60-65%). However, fairly soon after starting up notable incline, the oil guage freefalls and bottoms out; the oil light/alarm activates; and I start hearing valve/timing noise. If I stop it at the top of the hill incline, turn everything off, let it sit for a 1 minute, and restart, oil pressure comes right back up to normal. So, it's not a sending unit issue, there really is a drastic loss of pressure, but it will disappear as quickly as it starts. But there is no middle ground of having low pressure--it's either plenty high/good ("on"), or catastrophically low ("off") (yes, I know a crankshaft driven oil pump cannot "turn off," but the difference is so drastic as look like somebody did switch it off or on.)
Motor condition/damage status: I have been careful not to drive it at any high speeds/RPMs, drive it more than 1 minute or so with low pressure, or let it get hot. It's been driven approximately 12-15 miles total since first instance, plus 2 different mechanics idling it to see/hear problem. At this point, the engine sounds great until oil pressure drops and as soon as it returns. So if I need to drop $2k+ on an oil pump / timing component overhaul on a motor with 200k miles, I would rather spend $5k - $8k on a motor replacement. BUT, I am hopeful that the motor will still last a while if there is a cheaper fix for the oil pressure problem.
Questions: 3 shops have advised me to just replace the motor. I have some thoughts about diagnosis and repairs vs. replacement, but I want to see if others can suggest ideas I have not considered.
Sudden oil pressure changes: Upon starting the motor, it runs just fine (at least while sitting on the level), with the oil pressure guage staying above 50%. I have driven it as far as 5 miles / 10+ minutes, and at speeds up to 45 mph / moderate RPMs, and as long as the road was essentially level or facing downhill, the oil pressure guage stayed a well above the half-way mark (maybe 60-65%). However, fairly soon after starting up notable incline, the oil guage freefalls and bottoms out; the oil light/alarm activates; and I start hearing valve/timing noise. If I stop it at the top of the hill incline, turn everything off, let it sit for a 1 minute, and restart, oil pressure comes right back up to normal. So, it's not a sending unit issue, there really is a drastic loss of pressure, but it will disappear as quickly as it starts. But there is no middle ground of having low pressure--it's either plenty high/good ("on"), or catastrophically low ("off") (yes, I know a crankshaft driven oil pump cannot "turn off," but the difference is so drastic as look like somebody did switch it off or on.)
Motor condition/damage status: I have been careful not to drive it at any high speeds/RPMs, drive it more than 1 minute or so with low pressure, or let it get hot. It's been driven approximately 12-15 miles total since first instance, plus 2 different mechanics idling it to see/hear problem. At this point, the engine sounds great until oil pressure drops and as soon as it returns. So if I need to drop $2k+ on an oil pump / timing component overhaul on a motor with 200k miles, I would rather spend $5k - $8k on a motor replacement. BUT, I am hopeful that the motor will still last a while if there is a cheaper fix for the oil pressure problem.
Questions: 3 shops have advised me to just replace the motor. I have some thoughts about diagnosis and repairs vs. replacement, but I want to see if others can suggest ideas I have not considered.
- Ignoring for a moment the incline/uphill variable, what are any/all conditions or malfunctions could cause a sudden, drastic--but not permanent--loss of oil pressure?
- Factoring in that slope/incline seems to have a direct effect on whether oil pressure is "on" or "off," what are your potential diagnoses / possibilities?
- How likely are the bearings, timing components, etc. to have been damaged enough to kill the motor in the near term?
- Any other thoughts, suggestions, or advice?