Oil Pressure Question ... is my engine dead?

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Hi,

The oil warning (pressure warning) light flickered when coming to a stop and with engine idling after a period of highway driving. Oil was only 5k km old and is the correct spec fully synthetic (5w-30 and matching all the manufacturers requirements) etc. Level is OK.

So checked the pressures using a plug-in gauge:
cold
@idle 1.75 bar = 25 psi
@2000 3.25 bar = 47 psi

hot
@idle 0.25 bar = 4 psi
@2000 1.5 bar = 22 psi

Replaced oil and filters and re-measured, so cold is while the engine is still warm but with fresh oil in

warm
@idle 1 bar = 15 psi
@2000 2.2 bar = 32 psi

hot
@idle 0.5 bar = 7 psi
@2000 0.75 bar = 25 psi

Tested the next day, so engine really cold again
cold
@idle 1.75 bar = 25 psi
@2000 4 bar = 58 psi

So, need some advice now on interpreting these numbers. When cold the figures are all within engine specifications. Hot, they are too low.

There is no undue noise from the engine, except for the top-end tappets when idling, which I would expect with such low pressures, so I am hopeful that it is not bottom-end problems.

The oil pickup was replaced ~40k kms before and I assume that because the pressure is OK when cold then this is not causing the problem.

Does this imply that the engine is dead (main bearings worn) or that perhaps the oil pump is worn, or better still there is just a sticking pressure relief valve somewhere?

Any advice what to check / do next? Oil pump is a pig to get at behind cambelt etc, so not a quick job to pull off and check.

Many thanks
 
Sounds like one of the two things you mentioned or more than likely a combination. What engine and mileage? Perhaps go to a 40wt oil and see if you get adequate pressure until you have another problem that leads you to removing things that will make it easier to take a look.
 
Back in the Bad old Days a situation like this would just mean I would start using progressively heavier oil.

I remember on one car, a Sunbeam Stilleto, I was running 20w-50 AND STP oil treatment.
I put several thousand miles on that car before it went to the wreckers yard.
 
The turbine engineer in me says to check the instrumentation first...i.e. pressure sender.

If you have both a switch AND a pressure sender, then you probably have a genuine pressure problem. If the switch is computed off the sender, I'd swap senders just to check.
 
The definitive test is using a mechanical oil pressure guage and then move forward.
 
Originally Posted By: rjundi
The definitive test is using a mechanical oil pressure guage and then move forward.


Originally Posted By: rc84

So checked the pressures using a plug-in gauge:
 
I had a voltmeter in my Bobcat that would never show more than 12V with engine running. I brought the alternator to a rebuild shop and they said it was fine. I could not test it with a DVM as the Bobcat would "creep" down the drive if I was not in the cab. Finally got a chance to test it with DVM with someone else in the cab. It was fine.

There was buildup of sawdust in all gauges and the voltmeter could not go past 12V.
 
cold oil pressure means nothing so stop posting that info. 4 psi is a little low assuming its idling at around 700 rpm. id bump it up to thicker oil and drive it till it dies.
 
If the 4 psi is correct( like Shannow suggested, a real gauge, not a reading of the current sender.) then the main bearings may be worn. A thicker oil is what i would do. The old rule is 10 psi per thousand rpm. I don't think that works for newer variable displacement oil pumps. Perhaps a 0w 40 would do better.
 
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I had a mk1 Focus estate tddi with the old 1.8 turbo lump

The oil pump was so worn the oil light would come on at tickover when hot, as soon as you raised the revs it went off.

I did 10k miles like this, with the precaution of keeping the revs above tickover when stationary.

Sold the car with mega miles on it via eBay, advised the new buyer about the oil pressure issue, he changed the pump and it was fine from then on.

It is possible to use a thicker oil I suspect.

Though from my research the 1.6d is specced for 5w30 in all makes it is fitted to.

I would be looking at getting the sump off and making sure the pickup is clear and changing the oil pump regardless of how hard it is to do.

Why was the pickup changed?

Was it blocked?

If it blocked once it could block again.
 
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I would do anything. Thicker oil may give you a higher idle pressure and turn the light but that doesn't mean you get more flow.

Decades ago I drove an old Skoda with a completely worn bottom end around for months with no measurable hot oil pressure and it didn't stop running. Only the annoying vibration made me fix it.
 
I once encountered an engine that triggered the low oil pressure light without having bearing clearance problems. The customer had a turbocharged Chrysler PT Cruiser, and overheated the engine. By the time the owner stopped at our repair shop, the oil light was on, even there was no bearing noise or lash adjuster tick. Once we repaired the cooling system, the light never came back on.

Do you know exactly what your engine coolant temperature is? Coolant temp sensors often fail without causing an error code. That is because they can fail by displaying a normal engine temperature, instead of having too little or too much resistance to clearly cause an error code.

Since there is usually one temperature sensor, there may be parts of the engine that heat up differently. This often happens when a plastic water pump impeller cracks, or if air bubbles are trapped in the cooling system.
 
Assuming your "plug in gauge" noted in the OP is in fact a reliable mechanical oil pressure gauge and not an electric gauge of some sort that leverages the factory sending unit I would indeed agree that you have a worn bottom-end, likely rod bearings, which tend to wear-out before the mains do in most engines that I have experience with.

If this is the case you can't really do anything about it without a tear-down or at least a partial tear-down. You could roll-in new main and rod bearings assuming the journals are OK, but of course that requires inspection, which will of course require a partial tear-down.
 
Hi,

Many thanks for all the replies.

Yes by 'plug-in' guage I meant a mechanical pressure guage. I do not know how accurate it is but it is new and a reputable brand, so maybe a bit off but not too much.

I will replace the coolant / thermostat / sensor, check & clean the EGR values and check & clean the oil cooler etc. in case this brings down the temperature. But tending to agree with everyone that it sounds like main bearings .. gulp.

If anything positive will post back.

Thanks
Russell
 
According to my data system on that engine you should have between 2.3 - 3.7 bar @ 2000 rpm (hot) so you obviously have a pressure issue, something in the oil circuit is definitely worn.

If there are no noises coming from the engine then I'd be looking towards the oil pump.
 
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