You guys have been a wealth of info with my T's, but now I need some advice on a -------------------'97 Nissan pathfinder. The nissanforums are terrible.
It sat for about 6 months (nose slightly up). now when i drive it it will run fine until it warms up, and then the oil pressure light goes on and the valves will tap(I shut it down right away and towed it home) If i start it now it is ok until it gets warm, then the light goes on. let it cool and we do it all over again. I spoke to a couple of mechanics at nissan, and they think it is a clogged oil pump screen. Between them they have only replaced one oil pump in a combined 20 yrs. this car has always run on synthetic oil, and seems clean. we put in engine flush, and ran it until the light came on ( about 8 minutes) then changed the oil and filter. There was no change.
The mechanics suggested dropping the pan and cleaning the screen. This is a major job!! droping the front diff., hoisting the engine, dis mantling the front end of the engine. Not something I prefer to do.
I thought that i could back wash the screen through the oil filter with a cleaning solution, maybe Kerosine ? I am not sure which way the oil flows to the filter. does it come up from the pump thru the center hole or the holes surrounding the center? I thought i could rig up a fitting to replace the filter, and run the solution with a pump into the filter holes thru the oil pump and screen, and let it drain into a bucket where it would be pulled up and filtered and run thru again. then i would put the drain plug back in and let the solution sit for a while and then drain, and try it with new oil and filter. What do you guys think? any chance it might work?
thanks
john

I know you said its making noise but is that just because its hot or is it the problem. I would change the oil sensor and go from there. Is it a V6 transverse mounted engine?

I don't think Nissan would recommend kerosine. There might be perishable fittings or parts that would not react well to it. Find out what the Japanese dealers use for back flush solution if you go that route.

Sorry not to be of more help. Maybe others will chime in!

I bought a new GMC 350 V8 window van in 1968 and put Mobil 1 in right away. Then it was advertised to go 25,000 miles without a change. My tappets started rattling with about 30,000 miles on the engine and 1 oil change, after Mobil 1 was added.

I got a new valve cover gasket and removed the rocker box cover. The rear rockers were badly worn and out of adjustment. A routine adjustment of all the rockers cured my problem. I never had to mess with the other side.

More interesting though was the fact that the rocker box cover was completely filled with a blackish-brown substance with the consistancy of old jello.

Mobil 1 was never used again in any of my vehicles. Now it is advertised for 15,000 miles between changes.

I don't recall if Nissan uses an oil filter bypass or a filter housing bypass. Since you changed the filter and it's still occurring, it sounds like you have serious pressure loss. Possibly, the pressure stays above the switch limit because the oil is cold/thick.

Pull the oil pressure switch and install a gauge. Start the engine and check the "real" pressure. At idle, you should have around 30-40psi when the engine is cool and up around 60psi when cold. As the engine warms, the pressure will drop to no less than 10-15psi at idle and 30-40psi fast. If you don't get these readings, no amount of flushing will help--The pump is bad.

When the engine is warm and the pressure has dropped (engine running), pull the dip stick/wipe/reinsert and see if there's any oil showing. If not, your oil isn't draining back into the pan from the topside fast enough. This could be clogged return holes in the head. (#3 below and the most likely.)

There could be a number of causes:
1. Bad pump.
2. Bad relief valve
3. Clogged return ports
4. Pickup tube loose
5. Pickup screen clogged
6. Main and/or cam bearings worn
7. Clogged oil galley
8. Cracked block

Hope this helps a little.

I agree, it sounds like a plugged screen. There is a process now that flushes the crankcase of the engine. See if you can find a shop that does this. It is similar to the transmission flushing that they do now. After that change the oil and use 1 quart of Transmission fluid for one of the quarts of oil. Good Luck.

Ken's list is very good advice. Yhe pickup usually has an O ring in the suction side. It may have dried out.

As a lark, park the car so the oil pump and pickup are on the low side. This may cover up a bad O ring and it may suck ok. This is how I solved a problem I had once.

The fact it was ok when it was parked eliminates a lot of hardware problems.

I had a Nissan back when they were almost still Datsun. They stalled me off with stories until it came out of warranty and then they bit me hard. I had a starter problem and they replaced several starters but it was actually the ring gear on the flex plate but they didn't want to replace the ring gear until it went out of warranty so that I would have to pay for it. They were actually just putting on new "Bendix" gears on the starter to carry it along and not replacing starters.

I will never ever go there again. They were not kind in my opinion rated on those actions. just ask me and I will tell you all about it. Many thousands of dollars of bad will. 1986 MAXIMA top of the line with all of the electronic gizmos . . . . $1600 for a gas gage hooked to a computerized trip system on a digital dashboard ? . . . . and that is just the tip of the iceberg.


Donate it and get a real vehicle. Been there . . done that. Had a 240Z before that and it was the same thing. Do it to me once .. . shame on you. Do it to me twice, shame on me.


This is my opinion and not a Model T Club opinion, but spent the money and so it is real.

In my honest opinion . . . The way dealers fix things today is to keep replacing things until it works. If they replace 15 things and it does not work and then they fix it at number 16. You pay for all 16 and that is the name of that tune . . . . .

Cut you losses. there is a reason things are as they are. Sorry to be so cross, but even though it was almost 20 years ago, it still hurts.

I contacted the local Ford dealer the other day to work on my daughter's Taurus. I did not have time but wanted the oil pressure switch replaced. They said the labor would be $45 plus parts. So, I went to make the appointment and the girl lets me know that there will also be a $90 diagnosis fee. There was no diagnosis, I asked to have the switch changed, she said that there would still be a diagnosis fee. So they lost that deal. I am still fuming about the terribly fouled up recall repair they did recently for the second time that needs to go back again.

How many miles? What weight oil are you using? How frequently has the oil been changed? Did you "flush" the engine when you started running it again after storage?

If it's a clogged oil screen then I'd expect problems all the time, not just when the engine is warm.

You might try running a thicker oil but that would be a temporary fix at best.

The car wasn't used for about 6 months. I put it bak on the road and used it ocasionally for about a month when the problem stared, Up until than it was good. just before the light came on it seemed a bit sluggish, could have been my imagination. now it will idle for about 8 minutes and the light comes on , or drive 1 1/2 miles. the oil was changed riht before the car sat. It hah the Valvoline synthetic 10-40 installed w/ new filter. when i chnged it last week, i tried a regular 10-40, with no change. I am going to hook up a preasure guage this afternoon and will keep you posted. thanks for all the great advice
john

John, It could very well be your pick up screen is pluged. We run into that quite often at the shop. Bad news is i have never seen the problem go away by flushing! If you do manage to back flush the picup tube you will never get all the gunk out of the pan. Another problem is that the pump is a gear pump, so I don't see how you'd back flush any way. Be on the safe side, drop the pan even if it means pulling the engine you maybe surprized by what you find. First though, do what Ken says and get a real pressure reading. Keith barrier

Doug, a new car dealership is a license to steal! My neighbor went into the Honda dealership and wanted a new gas cap, as the Check Engine Light was on. He knew the most common reason for that was a poor gas cap seal from working in his dad's gas station, part time, a few years back (dad is dead and the station is gone now). They said they would have to do a quick test to ensure that was the problem, because of environmental concerns. He said go ahead, not knowing there was a fee for that quick test. Yup, he was right, he needed a new gas cap. The total cost for labor was $72 for the test plus the $36 for the repair. Then this was several years ago. Prices have gone up. Ford and GMC wonder why they are in trouble!

My theory has always been that LEMONS are made at the dealership and not at the factory. I have never taken a new car back to the dealer, except for a recall notice. Last time, they messed that up too.