What's the deal w/ my oil pressure? (new guy w/ an '06)

[n8guy]

Hey all, great site rockin' here - reminds me of TwinTurbo.net, of which I was a member back in the day. Some knowledgeable folks, it seems - I look forward to interacting w/ ya'll.

So I just picked up a 2006 Pathfinder SE 4x4 and am a bit confused about the oil pressure gauge. It's odd, to say the least (I can get a picture if you'd like to see it). But my concern is that it seems to indicate that at times, the oil pressure is precariously low, particularly when idle drops down in the sub-1k range. It's doesn't always happen, but it's pretty often. Then I rev it or take off again, and it jumps right back up into acceptable middle-of-the-gauge range. I've checked and there is plenty of newer oil in it.

Thoughts? Oil pressure sensor? Common problem? Haunted oil filter?

Any insight would be great. Thanks again!

[Buzzman]

An oil pressure drop at idle, especially when the engine is warm, is perfectly normal.Every car I've had (that had an oil pressure gauge at least) would show a drop at idle. As soon as I stepped on the gas, it would go back up.Quick story: One vehicle I had showed a major drop in pressure, and it turned out to be a bad pressure sensor. Easy fix at the time.Welcome to NICO by the way.

[Chuck Tribolet]

How low does it go?

I had a bad sender on my '95, but the symptoms were different. It would show15 PSI at ldle, drop to zero from about 1200-2000 RPM, then jump up whereit should be (60ish PSI). There's a special socket you need to pull the sender.

[n8guy]

Thanks for the welcome and the responses!

Here's a picture of it, taken after warmed up, and while running:



And here's a link to a small/short video demonstrating how it drops:

http://galenadrive.com/pathfinder/idle.3g2

[n8guy]

Any thoughts on if this pressure looks too low?

[TJcars2]

Looks way too low. Any lights on? How's your motor sound?

[n8guy]

No lights on (other than the low tire pressure indicator) and the motor sounds what seems to be fine to me. No knocking or anything real obvious.

Assuming it is too low, what could the problem be? It just seems odds that oil pressure is fine at 1500 RPM and then drops that low at idle. Oil pressure sensor going bad or something?

[Pwnin O'Brien]

Your vehicle has an oil pressure indicator lamp which will illuminate if the oil pressure is unusually low. If the lamp is not illuminating, then this oil pressure drop in the low RPM's is normal.

Straight from the 2006 Owners Manual:
Modified by Pwnin O'Brien at 1:25 PM 9/23/2009

[Pwnin O'Brien]

Also from the 2006 Owners Manual:

[Pwnin O'Brien]

Also let me note, when the gauge dial is in the specified "normal" range (in your picture below, it is the area I changed to orange) then everything is within the normal operating specifications. This applies to all Nissan vehicles and all gauges with the "normal" range on the gauge face.



Sorry for the multiple posts, I probably should have consolidated them all down to one post.

[n8guy]

Thanks, man - I appreciate the response.

The "Engine oil pressure warning light" is heartening, especially since the oil pressure gauge is a dummy gauge.

But the semi-conflicting information is still a bit disconcerting. Sure, oil pressure will drop when RPMs do (since the oil pump speed directly correlates to engine speed), but the fact that it looks to be, as you point out, outside of "normal operating specifications" makes me nervous.

I called the local Nissan dealer and they indicated that it's normal, too, and that I'll get a warning light if it becomes a problem. I just can't, for the life of me, understand why, if this is normal, Nissan didn't extend the "normal operating specification" bar down just a little bit further so that my needle would fall nicely within it.

Is there some higher Nissan authority I can contact to get the low-down on this? Like a Nissan engineer or something?

Just to further complicate things, I also found this post, which states:

I just got off the phone with a master tech in virgina and this is what he told me.On two accounts, both on 05 Frontiers, with low oil pressure at ldle when completely warmed up...Root cause was a very small gasket located on the inter timing chain cover that is behind a "L" shaped steel cover on the right hand side.I looked this up and it is a bit hard to see but found it.Down side...No gasket in nissan parts catalog and no service bulletins has been issued.You have to replace the intire cover as a assy.at about $200.00 just for the part.Make sure all the test have been preformed before you have this done.

Bah.

[Pwnin O'Brien]

Understandable. Well the only phone number I could think of contacting (outside of your local Nissan dealer) is the Nissan Consumer Affairs number which is (800) NISSAN-1 (or 800-647-7261). They may be able to help answer a few questions.

[Buzzman]

Is there any way you can compare to another Pathy of the same vintage? Does anyone else you know have one that you can benchmark against?Either that or ask the dealer if they have one that you can see and compare with.If another Pathy has the same reading, then you can probably put this thing to rest.

[n8guy]

Thanks, Pwnin'. I called and they said that it's "normal". I have a reference # now, too, in case something happens (although they refused to send their response to me in writing).

And Buzzman, good idea, although I don't know anyone with a Pathy of the same vintage. I may take it down to the dealership to have them check it out and possibly compare with a similar rig.

I suppose I have enough information to cautiously set this aside for now, ensuring I'm careful to keep an eye out for issues in the future. Thanks for your help, all.

[wizeguy]

Thanks, Pwnin'. I called and they said that it's "normal". I have a reference # now, too, in case something happens (although they refused to send their response to me in writing).

And Buzzman, good idea, although I don't know anyone with a Pathy of the same vintage. I may take it down to the dealership to have them check it out and possibly compare with a similar rig.

I suppose I have enough information to cautiously set this aside for now, ensuring I'm careful to keep an eye out for issues in the future. Thanks for your help, all.

Thats not normal!...Seems very low. I would take it to the dealer and have it put in writing that it's normal...even if you have to pay the inspection fee.Here is a pic of mine with normal operating temp.I might of missed it, but how many miles do you have?

[n8guy]

Yours is also idling a good bit higher than mine. I think, really, that's the overall difference. So if you're parked or stopped at a stop light, and the engine is nice n' warm, is that where your RPMs (and oil pressure) sit?

I'm betting that if I just upped my idle to where you're sitting, that would be the difference.

Thanks for the follow-up - I'll have to take it down to the dealer and see what they think. Although I'm not sure they'll tell me anything different than what they already have.

[Pwnin O'Brien]

Yeah, that idle is high for a warmed up engine. It should idle at 625RPM's.

[wizeguy]

That pic was taken after I cleaned my throttle body and had problems

zer...ht-on

Here is a pic I took tonight...

[Pwnin O'Brien]

That pic was taken after I cleaned my throttle body and had problems

Yeah, I'm an idiot and I completely forgot. Glad to see everything's working again!

[n8guy]

So I took it in this morning and they ran the tests twice (just to be sure I guess?). They claim that the mechanical gauge reads within spec and consistent, even when the gauge drops.

They recommended a new oil pressure sending unit, referring to the gauge reading as being "all over the place". But I'm not sure it's that at all - in fact, it's dead-on reliable (as you can see from the video in this thread). I'm just not sure it's even worth replacing the part.

What do you guys/gals think? What are the chances it's the oil pressure sending unit going bad? Is it worth a replace? If so, where's the best/cheapest place to get the OEM part? $89 didn't seem like a very good part price (from the dealer).

[wizeguy]

The sending unit would be a good start...If it works, it would be the best $89 spent!

So I took it in this morning and they ran the tests twice (just to be sure I guess?). They claim that the mechanical gauge reads within spec and consistent, even when the gauge drops.

They recommended a new oil pressure sending unit, referring to the gauge reading as being "all over the place". But I'm not sure it's that at all - in fact, it's dead-on reliable (as you can see from the video in this thread). I'm just not sure it's even worth replacing the part.

What do you guys/gals think? What are the chances it's the oil pressure sending unit going bad? Is it worth a replace? If so, where's the best/cheapest place to get the OEM part? $89 didn't seem like a very good part price (from the dealer).

[n8guy]

I know this thread is annoyingly long, and for that I apologize. I'll try to make this update as quick as possible.

I took it in and they replaced the oil pressure sender, which didn't fix it (thankfully, I didn't have to pay for it). They also did the 60K mile service, and just to get it to spec, I also had them change the oil (thinking that maybe there was a possibility of something odd happening at the last oil change to cause the issue). They changed it to spec (5W-30 or 10W-30, from what I understand). This is where the fun begins...

The oil pressure immediately REALLY dropped and the low oil pressure light came on (it hadn't prior to this). On the mechanical gauge it read 5 PSI at idle and 20 PSI at 2,000 RPM (spec is 10/40 PSI, respectively). The thought was that someone had covered up the issue by throwing some thick oil in to mask it (quite possibly the people who sold it to me a month ago). Anyway, the dealership mechanics scratched their heads and called the Nissan Tech Line. Here's what they were told:

'A couple times, we've seen the gasket on the rear timing cover come off and cause an issue like this. That could be it.'

So then they want $600 just to diagnose it, an additional $900 to replace the part if indeed the gasket is off, and none of it is guaranteed - if it doesn't fix the problem, sorry bub, you're out $1500, but we'll send you off with a smile.

Anyway, I wasn't sure what to do there, but that didn't sound like a good option, so I had them throw some thick oil back in there (15W-40, I believe), and it was back to the same situation I started with - normal oil pressure until it's warm and drops to about 1K RPM, then drops precipitously.

So I see a few options, and would love ya'lls feedback:

1) try to sell it and get what I can out of it (of course, I'd tell people what was up) 2) have them check the rear timing cover for $600, possibly replace for another $900 3) try to check the rear timing cover myself 4) have another import mechanic (really knowledgeable dude) give diagnostic a whack 5) run it with thicker oil, up the idle to about 1100, and keep watch on it

I'm at a total loss. What do you all think?

[Pwnin O'Brien]

Hmmmmm, that's interesting. Here's a question: If they are going to charge you $600 in labor, which would require actually removing the front and rear timing chain case, then why would they charge you an additional $900 to install some $0.50 gaskets? A lot of Nissan dealers will charge you to diagnose the issue and then subtract the diagnosis fee from the work if you actually get the work done there. I can understand the $600 diagnosis fee, but not the extra $900.

Removing the front and rear timing chain cases is a LOT of labor. It basically requires removal of the entire engine front-end assembly including the entire timing chain assembly. I would only recommend attempting the repair yourself if you have extensive knowledge in engine repair and have all of the necessary tools.

Is the vehicle not covered any longer under the bumper-to-bumper warranty? Is there any sort of warranty remaining on the vehicle?

Here's an idea of what is required in replacing the seals behind the rear timing chain case. Basically every part in the following image needs to be removed in order to get behind the rear timing chain case, you probably need to replace the seals in the image which are between the rear timing chain case and engine. The red arrow is pointing to the rear timing chain case.

[n8guy]

Awesome info, as always, Pwnin. Thank you very much.

If they are going to charge you $600 in labor, which would require actually removing the front and rear timing chain case, then why would they charge you an additional $900 to install some $0.50 gaskets?

I don't know, exactly. I asked the same question and he told me (and verified) that that's what's in the system. My best guess is that they can diagnose the problem by only removing up through the front cover - then they can see if oil is leaking through or the gasket is compromised. I know their plan would then be to replace the entire rear cover, not just the gasket, which was part of the quote, and something like a $250 part. Not sure the details, but that could be some insight.

Is the vehicle not covered any longer under the bumper-to-bumper warranty? Is there any sort of warranty remaining on the vehicle?

To my knowledge, there is no remaining warranty. I would suspect the dealership would have checked that, as well (although I'm not certain). The guy at the dealership did ask me if I had an extended warranty, so perhaps that was after verifying that I didn't have one otherwise.

Here's an idea of what is required in replacing the seals behind the rear timing chain case.

Ok, so that option is out for me. I've done some work, but definitely not something that extensive. So that narrows the options to:

1) try to sell it and get what I can out of it (of course, I'd tell people what was up)2) have them check the rear timing cover for $600, possibly replace for another $9004) have another import mechanic (really knowledgeable dude) give diagnostic a whack5) run it with thicker oil, up the idle to about 1100, and keep watch on it

One down! Thanks again for the incredible information. I'm impressed.

[wizeguy]

Loosen up the oilfilter....drive around the block and burn the motor up....Tow back to dealer and blame them for the loose filter....Dealer buys new motor. I kid!

[n8guy]

Ha. If only I had the balls for that.

So in thinking about it more, here's where I'm at - and let me know if you disagree.

Since upping the viscosity of the oil brings it back to normal oil pressure (at 1100 RPMs or higher), we can (probably) rule out a few things, like:

- bad/dying oil pump - impeded oil pickup tube

In both those cases, thicker oil should worsen the problem, not resolve it. Right?

And since there's not an external oil leak, we can point to it being an internal leak (and this is where my knowledge gets *real* sparse), meaning it's either leaking from the pistol seals and burning off there, or leaking through the rear timing cover into the timing chain area. The reasoning here is that the thicker oil doesn't push past those gaskets as easily, meaning it stays sealed better and PSI gets pushed up.

What other possibilities am I missing? And does it seem almost certainly an internal leak, either at the piston rings or rear timing cover?

[wizeguy]

You might have some worn main and rod bearings and/or crankshaft journals?What type of oil filter are you using?I have a buddy with a 69 Camaro that had a Fram filter and running 0 psi...He thought the motor was junk.... changed the filter and oil pressure was normal again.

[n8guy]

The dealership just changed the filter out for whatever they use as stock, and this issue existed on the previous filter, as well as the current one, so I'm doubting it's that.

I don't even know what a main or rod bearing or crankshaft journal is, so I guess I'll stop trying to diagnose something I have no idea about. Bah.

What do you guys think of me just adjusting the idle up to 1100 RPM, keeping the thick oil in it, crossing my fingers, and driving it? And if that seems reasonable, how do I adjust the idle on this thing? I pulled the plastic cover off the top, but couldn't see any mechanism for adjusting it.

[Pwnin O'Brien]

Unfortunately you can't increase the idle speed, it is electronically controlled by the ECU. Your Pathfinder has throttle-by-wire so there is no mechanical connection.

Here's my suggestion, if you can get the pressure to stay up (using a higher weight oil or something) then you should trade the car in at a non-Nissan dealership. This issue could technically be a number of problems, all of which could be very difficult to diagnose since the leak is internal. Selling the vehicle is generally the last option, but without sinking money into the diagnosis/repair, this is really the only option to prevent more (and probably MUCH larger) issues.

[Big.Phil.XTR]

I had this similar issue. I changed my oil at 120,000 miles and afterwards the oil pressure shot up. I then changed the oil pressure sensor with one I bought online for $15.00. Once the new sensor was in it was reading low after the engine warmed up and would drop even lower at idle. I brought it to a shop to get the oil pressure tested and everything looked great, turns out I bought a faulty oil sensor, so I put another oil sensor that was $75.00 and everything works well now. Oil pump very rarely go out on these vehicles.