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EricCR

Mystery oil leak

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Hi folks,

 

My new-to-me pathy has been trouble free for the past few months but now I noticed a few drops of engine oil on the floor. It's really not a lot and it only leaks when the oil is hot. I got under the car and at first glance it appears the leak is coming from the oil pan gasket. The thing is, I took it to my indie and he says the oil is actually coming from somewhere above the oil pan, and it would require either taking the engine out or the whole transmission to pinpoint the leak (both of course $$$). He's a great indie but he mostly sees my E39 and BMWs in general, so maybe not being familiar with the pathy he's thinking about tackling this the hard way. I'm hoping he's not right, or is he?

 

Here is a pic I took of the oil pan (it's not the greatest photo but I can take more from other angles):

2020-10-01-10-42-06-028.jpg

 

Any common leaky spots up there? How much of a PITA would it be to properly fix the leak?

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Is this an automatic transmission Pathy and I think that's a VQ pan?

If so inspect closely above the oil filter on the side of the engine. There is an adapter plate up there known to leak. It has the oil pressure sensor near, and may be part of an oil cooler. There is a large oring you can replace. Can't remember full details.

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Also common to need to replace the valve cover gaskets and spark plug tubes. If you have the plastic valve covers expect to replace those. All of this can be done without removing the motor, but it's no fun.

I had my mechanic redo the valve covers twice on mine. The 2nd time go the leak from a quart a week disappearing, to about a quart every 2 months.

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You are correct, that's a 2003 VQ with an auto and AWD. Sorry I didn't mention it up there.

 

You mean if I have plastic VCs they could need replacing, so they warp or develop cracks? Or were you referring just to the gaskets?

I'll check the other stuff meanwhile. Thanks.

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The plastic ones have been known to crack, especially during reinstall. Don't remember the cut-in year but it may have been 03.

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Got it, I'll look around that area.

 

Ugh, if it happen to be the VCs then it's the exact same ****** situation I've had with my E39. I've replaced that gasket countless times and after a few months the same leak appears, near the firewall. I'm sure that valve cover (plastic) is cracked or chipped but I'm still in denial.

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The biggest problem with the plastic valve cover is the spark plug seals are not replaceable. 

The common oil leaks on your engine is first the oil cooler O-ring, cheap and easy to replace, and then the valve covers, not so cheap and easy. 

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Had an oil leak when i first got my 98. There was a tip on here about tightening the screw around the VCs. Not cranking on them just a turn or two ( they are plastic).that and Blue Devil oil stop leak every oil change for about a year. Now i get a drop every once in awhile

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I wouldn't put any oil additives in a VQ engine. They are known for too small oil passages that as they age cause start up ticking, as the oil struggles to get to the lifters. We had a 1996 Maxima with this issue, and my 2001 Pathfinder died of lifter death for the same reason. The Pathfinder always got good synthetic for at least the second 130k life I owned it.

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Thanks guys!

 

I do have an update. When I went to pick the car up, we put the car on the lift and my indie showed me the place from where the oil is coming from. Almost exactly above that oily screw (dead center on the pic above) there is a vent or a port and after cleaning everything up and driving it for a bit, that's the only place that leaks a drop or two. The rest of the engine/transmission is completely dry, including the valve covers and the oil cooler area that you guys mentioned.

 

He reiterated that in order to get to the actual leak behind that port/vent thing, he would need to either take the whole motor out or the whole transmission. After what I saw I believe him, unless there is a simpler way we both ignore.

 

Not sure if all that makes sense. I'll get under the car tomorrow to take a better pic. Stupid me didn't do it when the car was on the lift.

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7 hours ago, colinnwn said:

...cause start up ticking, as the oil struggles to get to the lifters...


This worries me. I haven't added any additives (although I admit I did buy a can but still hoping not to use it), but my Pathy rattles for like 1 second (at most) on cold startups and I've been blaming it on a slightly loose timing chain. Both my E39 and a 70's Corolla I own do rattle a bit when cold with no issues whatsoever and I've owned both for 15 and 20 years. Any way of identifying lifters from chain noise?

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Thanks guys!
 
I do have an update. When I went to pick the car up, we put the car on the lift and my indie showed me the place from where the oil is coming from. Almost exactly above that oily screw (dead center on the pic above) there is a vent or a port and after cleaning everything up and driving it for a bit, that's the only place that leaks a drop or two. The rest of the engine/transmission is completely dry, including the valve covers and the oil cooler area that you guys mentioned.
 
He reiterated that in order to get to the actual leak behind that port/vent thing, he would need to either take the whole motor out or the whole transmission. After what I saw I believe him, unless there is a simpler way we both ignore.
 
Not sure if all that makes sense. I'll get under the car tomorrow to take a better pic. Stupid me didn't do it when the car was on the lift.
Isn't that the bell housing, and that vent would be the torque converter case? If so you probably have a rear main seal leak draining through. RMS leaks are common over 150k miles. I had one I ignored.

Does your mechanic have a service manual or subscription service? I was thinking the service manual procedure for either the oil pan gasket or RMS would be to drop the subframe. And yes if RMS you have to drop the transmission. I can't imagine removing the engine. But I never looked close.

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Ok, so the oil looks like it is leaking from the little drain hole between the transmission bell housing and the engine? If so, the most likely source is the upper oil pan lip seal just below the rear main oil seal. The trans doesn't have to come out, but the front axle would in order to reseal. 

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This worries me. I haven't added any additives (although I admit I did buy a can but still hoping not to use it), but my Pathy rattles for like 1 second (at most) on cold startups and I've been blaming it on a slightly loose timing chain. Both my E39 and a 70's Corolla I own do rattle a bit when cold with no issues whatsoever and I've owned both for 15 and 20 years. Any way of identifying lifters from chain noise?
On VQ engines it's lifters. I've never heard of timing chain problems on these. For 1 second don't worry too much. That can stay that way for 100k miles.

To minimize it, I'd suggest using a top quality filter with the best anti drain back valve. No Frams. Some swear by OEM Nissan, but my truck didn't like them. I used either Mobil 1 filter or Purolator Boss. There may be others, but if you aren't paying more than $15 it's probably the wrong filter for a VQ.

Use a decent synthetic and stick to the 5-30 recommendation. Change your oil between 6k and 7.5k miles at least. Of course more frequent is fine. I just think it's a waste with a good synthetic and filter. I used to do 10 K mile oil changes. But as the engine aged and started thinning the oil faster, I didn't reduce the frequency fast enough. I think you've got a lot of life left in it if you do this.

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And to be clear I bought mine at 135k miles and drove it to 265k miles before it got me. Though I would have liked it to live to 300k, I don't feel like I can complain too much.

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Got it. Thanks a lot to all.

I'll confirm the source of the leak with a picture tomorrow with good light, but it does look like it's not something for the amateur DIYer (me). I'm comfortable changing oil, brakes and such, but between the lack of proper tools and time, I leave major repairs to others.

 

As for the rattle, mine is sitting at 130k miles so maybe it will last for a bit. It takes me a very long while to put 100k in any car so I think I should be fine. I use Royal Purple in all my cars and have had good experiences with K&N oil filters.

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I'm actually having this same issue.  I initially thought it was the oil pan and gasket (which are cheap).  I ordered another pan and gasket and replaced everything, but to no avail.  I just bought a diesel F-350 so that has my attention, but I do need to get back to that problem on my Pathfinder.

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