Question about Nissan PU oil pan

I would change the oil.

When my timing chain went on my 90 Hardbody, the oil pressure sending unit had to be changed. After the chain was fixed, the oil light went on again. It takes a while before all the sludge is cleared out of the motor. I think I changed my oil 3 times in 2 weeks just to make sure. My opinion is that it is a dirty sending unit. Change the oil.

: > Sound plausible? Or is there some sort of screen at : > the oil intake tube that would prevent something like this : > from happening? : >

: : There is a screen but when they had the pan off, they cleaned this stuff out : I would hope. Has anyone actually checked the oil pressure with a : mechanical gauge to make sure you do actually have low oil pressure and not : just a bad sending unit? I've never seen a bad oil pump on a nissan : product, although I have seen a few with sludged up engines/pans that would : block the pickup, but your's has just been cleaned out... : -- : : Steve : :

Sure, they changed the rod bearings so I assume they removed the chain guide debris from the oil pan and put fresh oil in wile they were in there.

But I guess it wouldn't hurt to ask them just to be sure.

Thanks for the reply,

I think the oil has already been changed. I did have some thoughts about the sending unit possibly being the culprit. However, it should be said that I've always used synthetic oil the truck, so there probably shouldn't have been any sludge right?

You wouldn't happen to know if the sending unit switch is closed or open when there's oil pressure?

I would think that a good design would err on safety, so if I was designing the sending unit, I'd make it be closed under oil pressure. This way, if there were a wiring fault, the oil indicator light would come on and you'd notice that something is amiss whether there was an oil pressure fault or a wiring fault.

However, this would require some sort of inverting circuit such as a transistor or relay, so for the sake of simplicity, they may have opted for making it open under pressure.

: > hello folks, : > First off, thanks to everyone who so graciously gave : > me advice in a previous thread. : >

: >

: > I got the truck back from the shop again. : > This time they changed out the rod bearings, which they seemed : > to think might have gone bad from water getting into the oil : > when the timing chain *attacked* da motah! : >

: > Right after we picked it up, my wife noticed that the oil : > light was coming on. Sure enough when I looked at it while idling : > the oil light was on. The dip stick reported plenty oil however. : >

: > I called the mechanic and asked him if he thought there could : > be a problem with the oil pump. : >

: > So I asked him what to expect if the the oil pump should happen : > to stop working while driving. He said that motor would probably : > make some kind of rattling sound. So I told my wife that if she : > should see the oil light on and hear a rattling from the engine to : > shut it down as soon as possible. : >

: > Well so far, the oil light hasn't come on again, knock on wood : >

: > But she did report to me that it came on when she was driving : > at a fairly decent clip. She usually favors lower gears and keeps : > the rpms up a bit more than I do when she drives, so it came : > on when the rpm's were probably fairly high and continued to : > stay on even when parked and idling. : >

: > Strangely enough, after I killed the motor and restarted,, : > it never came on again after that for the entire : > 15 mile drive home. : >

: > She asked me what caused that. : > I ventured a theory. : > When the mechanics changed the rod bearings, they said that : > there were plastic remnants from the timing chain guides : > at the bottom of the oil pan. So, my theory was that perhaps : > a piece of plastic got sucked up into the oil pump and : > temporarily blocked oil flow until the oil pump eventually : > chewed it up and spat it out. : >

: > Sound plausible? Or is there some sort of screen at : > the oil intake tube that would prevent something like this : > from happening? : >

: > Thanks : > A very perplexed --Dave-- : >

: >

: >

: >

: :

There is a screen but when they had the pan off, they cleaned this stuff out I would hope. Has anyone actually checked the oil pressure with a mechanical gauge to make sure you do actually have low oil pressure and not just a bad sending unit? I've never seen a bad oil pump on a nissan product, although I have seen a few with sludged up engines/pans that would block the pickup, but your's has just been cleaned out...

The garage replaced my sending unit so I dont know much about it. I dont use synthetic oil either but I would imagine that when it is mixed with antifreeze, something happens to it. Like I said, after the fix, my oil light came on but after a few quick oil changes, it was fine and has been ever since.

Id just replace the oil pressure sending unit and change the oil. likely this will fix your problem.

Does this truck have a sending unit with a "little itty bitty hole" like the unit on my 87 200sx had? Took virtually nothing to plug that up. If so, then seems like everyone's advice about changing the sender should be correct.

Frank

Shawn wrote:

I like Steve T's advice: Has anyone bothered to connect a gauge and check the actual pressure? It's not that big of a task!

A known quantity is better than a guess.

Reading all the traffic on this thread one could suspect the sending unit. But to continue operating the vehicle without knowing is like playing Russian Roulette.

Louis--