Low Oil Pressure Cranking 8 sec to light out. Help?

[BillL47]

First post - B8200 3000+ hrs, suddenly noticed the engine (D950) oil pressure light off was delayed when starting. Typically out after the first few revs always before running. It takes 8 seconds. The oil is draining out of the system. In a up-to-temp running condition and after 5 min after shutting down it will again take 8 seconds (Compression released and fuel shut off) to take pressure off the gauge peg. Hot-running - oil pressure at 900 rpm is 25psi, 2000 rpm 45 psi after new oil and filter. Cold (70F) cranking: 25 psi - hot cranking pressure after running: 8psi. Switch grounds at 3 psi as tested.

No metal in filter and no other indication. This happened after sitting in the winter and at spring start up.

OK - that is background - I replaced oil, filter, added pressure gauge for testing and the condition is persistent. Thinking possibles are oil is draining back and just taking time to re prime after shut down. Chain of possible causes 1. pressure relief valve, 2. loose suction bell, 3. Bad oil pump. I dont believe the pump is bad. I am sitting here with a pressure relief valve assembly in hand - about to get dirty and replace it.

Edit: when replacing the filter for the last test, it was nearly empty, so the oil is draining back very quickly.

Any one ever had this specific issue??

 

[GreensvilleJay]

If the oil pressure light switch is made most are, there could be a small hole in the 'rubber diaphragm' in it.
Oil pressure pushes against it, rubber pushes against a disk to connect the switch posts.
Over time and use, the 'rubber' can fail.
the switch should be economical to replace.
In the case of millions of Ford trucks and cars this could lead to a fire and total loss of ride.

 

[TheOldHokie]

First post - B8200 3000+ hrs, suddenly noticed the engine (D950) oil pressure light off was delayed when starting. Typically out after the first few revs always before running. It takes 8 seconds. The oil is draining out of the system. In a up-to-temp running condition and after 5 min after shutting down it will again take 8 seconds (Compression released and fuel shut off) to take pressure off the gauge peg. Hot-running - oil pressure at 900 rpm is 25psi, 2000 rpm 45 psi after new oil and filter. Cold (70F) cranking: 25 psi - hot cranking pressure after running: 8psi. Switch grounds at 3 psi as tested.

No metal in filter and no other indication. This happened after sitting in the winter and at spring start up.

OK - that is background - I replaced oil, filter, added pressure gauge for testing and the condition is persistent. Thinking possibles are oil is draining back and just taking time to re prime after shut down. Chain of possible causes 1. pressure relief valve, 2. loose suction bell, 3. Bad oil pump. I dont believe the pump is bad. I am sitting here with a pressure relief valve assembly in hand - about to get dirty and replace it.

Edit: when replacing the filter for the last test, it was nearly empty, so the oil is draining back very quickly.

Any one ever had this specific issue??

Or just possibly oil clearances have gotten so wide it takes longer to fill the passages....

Most engine oil filters have an anti-drain back valve.

Dan

 

[SDT]

First post - B8200 3000+ hrs, suddenly noticed the engine (D950) oil pressure light off was delayed when starting. Typically out after the first few revs always before running. It takes 8 seconds. The oil is draining out of the system. In a up-to-temp running condition and after 5 min after shutting down it will again take 8 seconds (Compression released and fuel shut off) to take pressure off the gauge peg. Hot-running - oil pressure at 900 rpm is 25psi, 2000 rpm 45 psi after new oil and filter. Cold (70F) cranking: 25 psi - hot cranking pressure after running: 8psi. Switch grounds at 3 psi as tested.

No metal in filter and no other indication. This happened after sitting in the winter and at spring start up.

OK - that is background - I replaced oil, filter, added pressure gauge for testing and the condition is persistent. Thinking possibles are oil is draining back and just taking time to re prime after shut down. Chain of possible causes 1. pressure relief valve, 2. loose suction bell, 3. Bad oil pump. I dont believe the pump is bad. I am sitting here with a pressure relief valve assembly in hand - about to get dirty and replace it.

Edit: when replacing the filter for the last test, it was nearly empty, so the oil is draining back very quickly.

Any one ever had this specific issue??

Are you using the proper Kubota engine oil filter?

What weight engine oil?

 

[BillL47]

Are you using the proper Kubota engine oil filter?

What weight engine oil?

I checked the pressure switch with air pressure and dunked it in water for some time. No leak. Good thought though.

Wide clearances - possible, but it seemed sudden this spring. If it was creeping and getting longer, this would certainly be a cause - I have had this tractor since 1988.

Yes, proper Kubota filter and it did not occur with the last oil change, nor with a new filter and oil last week as it was being diagnosed. I use 15W40 oil and it was my first thought, maybe making oil with fuel dilution, but it is not. It is not making oil and all the tests were repeated before and after a fresh filter and oil change.

All good, valid questions on the diagnostic journey. Thanks - keep them coming.

 

[lmichael]

Either just replace the sensor or put an actual test gauge on to know for sure

 

[BillL47]

Either just replace the sensor or put an actual test gauge on to know for sure

As mentioned in the OP - a mechanical gauge was used to see when it came off the "peg". Note the pressure sender was tested too. It activates around 3 psi and does not leak. I measured with a 30 psi range so it was hard to tell precisely where it activated, but very clear that during 7 sec of cranking there was no movement of the/a pressure gage. 0-100 psi. New.

 

[D2Cat]

Sometimes the plug at the end of the camshaft falls out after many heat/cool cycles. The plug is aluminum and the camshaft is steel. The light comes on at about 7#, so at idle the light is on, faster and it goes out. Plug needs to be back in the camshaft to stop the loss of oil pressure there.

 

[TheOldHokie]

As mentioned in the OP - a mechanical gauge was used to see when it came off the "peg". Note the pressure sender was tested too. It activates around 3 psi and does not leak. I measured with a 30 psi range so it was hard to tell precisely where it activated, but very clear that during 7 sec of cranking there was no movement of the/a pressure gage. 0-100 psi. New.

Based on info provided so far my WAG is oil pump is getting a little worn and struggling to build pressure at startup.

Will it build any pressure at all cranking on the starter?

Dan

 

[BillL47]

Based on info provided so far my WAG is oil pump is getting a little worn and struggling to build pressure at startup.

Will it build any pressure at all cranking on the starter?

Dan

D2CAT - I have read that, but can not verify it is an issue on my D950 engine. It may explain low pressure and certainly a step change in behavior.

Dan, on the starter, compression released, and no fuel - if "cold" at 70F 25psi - run mowing for 30 min at 90F ambient, 5-10 psi - Still enough to knock off the pressure switch. Let it sit for 5 min and took 8 seconds again to move the needle.

If the oil pressure prime lag were increasing slowly year by year the oil pump wear would be a highly suspect, but this step change clouds that confidence. I was wondering about a loosening suction tube or one that is cracked. But -- it seems to pull the oil from the filter. I poke a hole in the top& bottom of the filter to drain it for removal. This time very little oil came out.

On one hand I could just pull the compression release for every cold start and be confident there was pressure, but if the pressure drops while running it would be catastrophic. That is something to be avoided with this "warning" Maybe I'll just buy a new 2650, but really hate to put this on some one else to "discover".

 

[TheOldHokie]

As mentioned in the OP - a mechanical gauge was used to see when it came off the "peg". Note the pressure sender was tested too. It activates around 3 psi and does not leak. I measured with a 30 psi range so it was hard to tell precisely where it activated, but very clear that during 7 sec of cranking there was no movement of the/a pressure gage. 0-100 psi. New.

D2CAT - I have read that, but can not verify it is an issue on my D950 engine. It may explain low pressure and certainly a step change in behavior.

Dan, on the starter, compression released, and no fuel - if "cold" at 70F 25psi - run mowing for 30 min at 90F ambient, 5-10 psi - Still enough to knock off the pressure switch. Let it sit for 5 min and took 8 seconds again to move the needle.

If the oil pressure prime lag were increasing slowly year by year the oil pump wear would be a highly suspect, but this step change clouds that confidence. I was wondering about a loosening suction tube or one that is cracked. But -- it seems to pull the oil from the filter. I poke a hole in the top& bottom of the filter to drain it for removal. This time very little oil came out.

On one hand I could just pull the compression release for every cold start and be confident there was pressure, but if the pressure drops while running it would be catastrophic. That is something to be avoided with this "warning" Maybe I'll just buy a new 2650, but really hate to put this on some one else to "discover".

I have had a lot of experience with this issue on old Fords. Those old Ford pumps dont usually give much warning. One day they are working then the next wont prime on their own.

You are actually getting a pretty clear warning. Personally I would throw an oil pump at it and hope for the best.

Dan

 

[North Idaho Wolfman]

Inspect Ball, seat and spring on pressure relief valve.
Any oil leaks?
You have enough hours to warrant a complete rebuild.

 

[Henro]

Inspect Ball, seat and spring on pressure relief valve.
Any oil leaks?
You have enough hours to warrant a complete rebuild.

Just curious but the OP said the tractor has just over 3000 hours on it. Is that the point where a complete rebuild is needed on a Kubota?

My B2910 has just under 1500 hours after 20 years. Does this mean in another 20 years when I turn 96 I’m going to have to consider a complete rebuild?

 

[BillL47]

I have had a lot of experience with this issue on old Fords. Those old Fordp pumps dont usually give much warning. One day they are working then the next wont prime on their own.

You are actually getting a pretty ckear warning. Persinally I would throw an oil pump at it and hope for the best.

Dan

Thanks for that emphasis, Dan. I hear you now, as I've not had that Ford experience.

 

[TheOldHokie]

Thanks for that emphasis, Dan. I hear you now, as I've not had that Ford experience.

This story is strkingly similar to the ones that come with the Ford pumps I get in the mail - "we thought it might be":

1. Defective pressure relief valve
2. Loose pickup tube
3. Wrong oil viscosity
4. ...

In the end most of them end happily with a rebuilt oil pump. Not always but more often than not. Good luck with whatever it is that's plaguing your Kubbie.

Btw the Ford L-head oil pumps are cast into the front main bearing cap so bolting a new one on require major machine work.

Dan

 

[JerryMT]

First post - B8200 3000+ hrs, suddenly noticed the engine (D950) oil pressure light off was delayed when starting. Typically out after the first few revs always before running. It takes 8 seconds. The oil is draining out of the system. In a up-to-temp running condition and after 5 min after shutting down it will again take 8 seconds (Compression released and fuel shut off) to take pressure off the gauge peg. Hot-running - oil pressure at 900 rpm is 25psi, 2000 rpm 45 psi after new oil and filter. Cold (70F) cranking: 25 psi - hot cranking pressure after running: 8psi. Switch grounds at 3 psi as tested.

No metal in filter and no other indication. This happened after sitting in the winter and at spring start up.

OK - that is background - I replaced oil, filter, added pressure gauge for testing and the condition is persistent. Thinking possibles are oil is draining back and just taking time to re prime after shut down. Chain of possible causes 1. pressure relief valve, 2. loose suction bell, 3. Bad oil pump. I dont believe the pump is bad. I am sitting here with a pressure relief valve assembly in hand - about to get dirty and replace it.

Edit: when replacing the filter for the last test, it was nearly empty, so the oil is draining back very quickly.

Any one ever had this specific issue??

With 3000 hrs on the engine, I'd suspect:

a) stuck open relief valve, and/or
b) loose or cracked oil pump supply tube, and/or
c) worn oil pump, and/or
d) increased bearing clearances.