I had something unusual happen with the last oil change on my 97 Nissan PU (2.4l 4 cyl, 188k miles). The engine runs normally, no unusual noises, smooth as ever, no oil consumption, no oil light, but the oil light does come on with the engine not running, i.e. just before starting the engine. Wednesday, I am doing an oil change and all is normal until I remove the oil filter.
This filter is a real bear to remove, it can only be done with a cap wrench, two separate extensions (6" and 3", in that order) and ratchet. Normally, it is very tight, but this time, it wasn’t even finger tight, it just started spinning off. I had been running the engine so it was warm as I always do for an oil change. The second unusual thing was that usually there is a lot of oil spilling out of it as I remove it, this time nothing. When I got it off, it was bone dry. It had oil in it at one time but it looked like it hadn’t had any in awhile. The drain back seal was dry like it hadn’t seen oil in months and the oil filter gasket was dry as well.
I finished the oil change, I’ve driven the truck for two days now and it still runs fine. Go figure. BTW, the oil stays pretty clean in this engine. It just gets a medium brown, never black. That is true of all of my vehicles though.
Strange. “Not even finger tight.” Sounds like oil should have been blowing right past the gasket onto the road. How much oil came out of the pan when you drained it?
Clearly the engine never lost oil pressure, so I’m betting that Rod is correct… but I’m not sure the bypass valve isn’t in the usual place, in the filter assembly, and not in the engine. Filters typically include a bypass valve to prevent loss of pressure if the filter gets plugged. Yours may have been malfunctioning. The good news is that no damage has been done.
I have problems linking, but look up “engine oil filter diagram” on your internet and you’ll see cutaway drawings of various filters showing the bypass valves.
That is quite odd. At least we do know that unfiltered oil isn’t sure engine death - at least over the short term. I guess you’ll find out if you have an problem in the block or if it was just a bypass problem on that last filter the next time you change the oil. Out of curiosity, what brand was the dry oil filter?
The truck never lost or used any oil, I got 4 quarts out which is the capacity. The filter is a Purolator classic. Despite how loose the filter was, the gasket was dry.
On many designs, only a fraction of the oil goes through the filter once the bypass pressure is exceeded.
I would pull the new one off almost immediately to verify it’s operating normally. Drain the oil into a clean container and just pour it back in when done. All you lose is time and you gain comfort in knowing…
This is odd.
If it were me, I’d pull the new replacement filter off to see if it’s filled with oil. If it is, then the blockage was in the old filter. If it isn’t, you’ve confirmed the blockage is upstream of the filter.
Stoveguy has a good idea.
Not to be redundant, but the bypass valve is in the filter assembly. If it was malfunctioning, as would be my guess, it got tossed with the old filter.
I don’t want to be redundant either, but the filter was reported to be loose and dry with a dry gasket. That means the oil was never getting there, so whatever bypass it has doesn’t seem in the picture… On that, of course, we just have to go on keith’s report. He didn’t start this thread on April 1 did he?
I believe that the engine has a filter bypass. And I believe that the bypass valve’s default position is to bypass the filter. But I am basing that on working on Z24 engines several years ago.
Touching the filter wont prove anything because the lower radiator hose runs right up the side of it. It gets hot regardless. The filter is located in a logical spot as far as the engine is concerned, it should be real easy to get at, but the Nissan engineers ran the radiator hose up one side, a large wire bundle wraps around the other side and the power steering hard line run over the top.
I figure they must have hired a difficulty enhancement engineer from GM for this engine. Don’t even ask me about the PCV valve, I haven’t even found it yet. As far as I can figure from the drawings in the factory service manual, you have to remove the starter to get at it.
I looked in the FSM (factory service manual). The oil filter sits on a bracket just above the oil pump, the bypass valve and oil pressure sending units are in/attached to this bracket as well. If the engine is out of the truck, it would be easy to check the valve, just remove the filter and look, but in the truck, it is pretty well hidden.
I’m going to be tied up for the next couple of weeks so it will be later before I can do anything. I am not worried about the filter being bypassed, I am convinced they don’t do much anymore now that the engines are sealed up pretty tight and I am using synthetic oil. This last oil change had about 7000 miles on the oil and had been in the truck for 14 months and it came out pretty clean.
The truck is not driven on short trips, every time it is started, it runs for at least 20 miles and more often 50 to 100 miles, it just isn’t driven very often, once or twice a week.