Combines low oil pressure on 1660 w Navistar engine after oil filter change

I doubt that the filters would make a difference. Are you using the same weight oil. If not mistaken the Navistar engine uses a single viscosity oil such as 30. Try a test guage and get an actually reading

I am using same oil (brand and viscosity) as before oil change 15W40 multigrade oil (change every 100 hrs). Could it be pressure regulating valve or by-pass valve beside filters going badIJ But then what is probability that one of the valves (or something else) vent bad exactly the same time when oil and filters were changed. Could be probably bad batch of oil filters. I will try tomorrow with different brand.

Check the filter, some of the fleetguard filters have a bypass valve in them so when the filter gets restricted the oil will bypass. This should not cause psi to read though. You say you left to drain for a day or two, would someone have started the engine to move unit and not realized the oil was drained and not said anythingIJ If it was run for say 30 second with no oil pressure it may have spun a brg.

I know this sounds silly but once we had to change our sender, hell of a coincidence though!

Combine was in the shed, shed was locked. I am the only one to operate the machine, and it was in the same position for these two days (you cannot move the combine inside the shed without opening doors). Theoreticly, someone could ignite the engine without oil in it, but that is very inprobable. Today I am gonna change oil filters (other brand) if I can buy them and try again. I also suspect pressure regulating valve is stucking, also will try to connect oil pressure gauge (mechanical type) to see 'real' oil pressure. Only thing I would ask you guys is to tell me what is correct pressure on this type of engine (DT 466 case ih 1660 combine) when cold or hot oil.

I will try sender also, but gauge in cab is showing low, and low oil pressure light is on, so it would be both of them. I will try to connect mechanical gauge see my previous message.

Sounds like the oil pump drained completely and then "dried" out. When this happens you loose the oil film on the gears that form the seal and then the pump is basically not able to create a low pressure area for air pressure to push the engine oil into the pump. Memory is failing me this morning on the 400 series engine, but I don't remember any way to "prime" the oil pump from the outside. Might check around with a repair shop and see if they have a prime pump or pressurized oil tank you could install in an oil galley plug and then pump or force oil into the engine and get some oil into the pump to create the seal. Could also try some SAE 10 oil in the engine as a lighter vis oil might get into the pump easier. Just some thoughts this morning.

I had a similar problem with a Cummins Big Cam. We took out the pressure regulator plunger and spring, cleaned them up, put it back together and it works fine. I think that the oil pump is behind the front pulley on the crankshaft. Not too hard to replace or get to. Do you have low pressure or zero pressureIJ That should tell if your pump is doing anything.

Problem solved... probably. When we took old oil filters out, and mechanic who worked with me did prime some oil in filter base (so this could be the way to prime oil pump from outside) we also try to run starter without oil filters for a moment to see is oil pump supplying oil at all. Oil pump was supplying oil normaly to the filter base. Changed oil filters to other brand, run the engine, and nothing happend (or same thing happed - oil pressure raised normally up for some 20-30 seconds and then it started to drop down). Then we decide to take out oil pressure regulating and by-pass valves. Both of them seemd to us fine, normaly operating without any stucking at all, but still we did put apart oil pressure regulating valve and put one additional shim in it (maybe spring became 'week'). We have tried to measure opening force for regulating valve and now it is set to approx. 3 kg_cm square (45 psi). Put back everything back together, and same thing happens. Turned engine off, ignited it again after some 20 seconds and everything worked normally. I did try it again several times and it did work fine, only oil pressure on oil gauge in cab seems to me little bit higher than before (but I did not try it with hot engine, tomorrow I will try it in field). My explanation is that probably some cavitation occured (cold thick oilIJ) around by pass valve. Also I am interested what will happen tomorrow morning when I start the engine... Anyway thanks for trying to help me. Edo