Mystery Oil Leak

[muchtoknow]

My wife has a 2003 QX4 that was leaking around the oil pan. I replaced the gasket there but now another leak has popped up. It is between the oil filter and passenger side front wheel. Any ideas about where this is coming from, so I can avoid simply taking things off to look for it?

[lzrj]

I think I may have the same leak. My 04 only has 60,000 miles and it is leaking in that general area as well. It looks like it is dripping down onto the front axle on passenger side. Have not got under there all the way to try to see where it is coming from.

[Towncivilian]

Is this the part that's leaking?



If so, that's the oil cooler. It's simple to fix - just replace a couple O-rings. Read this thread.

[lzrj]

Ok, I read the thread and I'm a little confused. Is it just the small O ring on the outside that needs to be replaced or does the larger O ring inside the cooler usually leak and need replacing as well. What size or where to order the O rings? I am pretty sure the cooler will be the culprit of the leak.

[fleurys]

It's usually just the big one that leaks. It is inside. you need to order the oring from your nissan dealer. The cooler is not defective...just the oring. They are almost all pinched when you remove them...

[humsafar77]

You might Wand to Check you Steering Box/Rack, You can Check it by checking the Power steering OIl level, if it is decreased

[lzrj]

For anyone who has changed the o rings. Do I need to take to whole oil cooler off to change the o rings or just the outer shell while keeping the main cooler attached. Just trying to find out if I need to order the gasket as well if I have to take the whole cooler off.

[Towncivilian]

You can leave the cooler on the vehicle. The FSM says to drain both oil and coolant, but from what I've read in the thread I linked in my first reply, people usually just work around the cooler lines.

[CanuckQx4]

Ya I did mine during an oil change, but all you need to do is spin the large bolt out of the center of the cooler, leave the lines attached and just turn it so you can quickly clean it and replace the o-ring which is in plain view

DO NOT overtighten the cooler, it is not a "as tight as you can" bolt, I forget the FSM torque spec but its quite low if I remember

[Towncivilian]

See LC-8 for proper torque specs.

[lzrj]

Thanks guys. I will be changing the rings on my next oil change in a few weeks. Looks like I can get both o rings from Courtesy Nissan for around $6 each. Might call the local dealer and see what they charge for them.

[CanuckQx4]

I did not know the bolt had an oring washer aswell, chit

[muchtoknow]

Sorry for making this thread. I should have checked to see the several other threads on the same issue, which is the oil cooler seals. Just as an FYI, it is totally pointless to drain the oil system, as the oil pan is below the cooler. We have a sloped driveway, so the effect may have been more pronounced than on a level surface. There was a small amount of oil trapped in the cooler, but I seriously doubt that draining the pan would have done anything to change that. Also, the coolant lines do not have to be removed, and since they originate from the bottom of the radiator, doing so would seem to create quite an unneeded reason to have to add coolant and also introduce air to the radiator. Although the larger o-ring is the usual cause of leakage, it seems a little silly not to replace both while you have that central bolt out. The small ring in mine was well flattened, having lost its original round cross section shape from being pressed and exposed to oil for 65,000 miles or so, so it seems like it isn't a bad idea to just do it while you are there.

I think the service manual tells the technician to drain the oil so they can charge you for an oil change and detach the coolant lines so they can create a need for a radiator flush or at least new coolant. I probably would have changed the oil if it hadn't been an oil change just a couple of weeks ago that brought the issue to light. I didn't feel like going back in with another full load of synthetic oil. That stuff adds up. I didn't even lose a half quart changing the seals.

Gotta love the wife. 2003 model and only just over 60,000 on the car. Easy fix. Didn't even jack up the car. It is better to loosen the bolt from a rear approach. It is slightly more open that way, and you can pull down hard on the wrench. Reassemably was easiest to accomplish with my fingers until there was at least some torque, so it is good to clean the central bolt well before that. One hand from behind and one from the front allowed it to go pretty fast with three finger on the bolt. The final tighten seemed to go better from the front. There is a line in the way, I think it is a steering fluid line but can't recall exactly. You can push it out of the way pretty easily. This gives plenty of room for getting a wrench in there and pulling down to tighten it up. I guess that is alot of detail for such a simple maintenance issue, but since I created a largely unnecessary thread, I thought I should at least try to get something helpful into it.

Thanks for the replies. Sorry for the dealy in responding. The dealer had the large o-ring but had to order the small one in. Again, it is confusing why you would replace one without the other. I went to Infiniti and both were $22. If you go to Nissan they may be a few bucks less. Another thread said about $15. I couldn't find them at autozone, but I only looked online and didn't bother actually going into the store and asking the part geek. That was the only chain I checked since it is just down the road.

[Towncivilian]

No big deal about creating the new thread. You've contributed a lot of useful info to this subject regarding the replacement of the O-rings. I'm glad you were able to fix the leak easily.

[lzrj]

Anyone know what size the O-rings are? Spoke with Autozone and Oreilly's who told me if I brought them in they should be able to match sizes. But that leads to another problem. How do I take the O-rings off and then be able to drive down there to do that. Hmmm.

[Troll_Star]

I've worked on a lot of Nissan cars (not many SUVs on this side of town AT ALL) from this same era that have this problem. Of about the 9 over the past year with this issue, 6 of them were o-ring problems. Which is a big sigh of relief for both the customer AND myself (after they come in hollering that I'm trying to blow their engine by not tightening down something)

[muchtoknow]

When I looked at the autozone site they had many O-ring sets with a number of O-rings, one of which was supposed to match your needs. My reservation arose because they all seemed to be SAE sizes, no metric. I didn't go that route for that reason although one of them was bound to be approximately the correct size. Again, the geek in the store may be able to find the metric sizes.

[dk203040]

It's usually just the big one that leaks. It is inside. you need to order the oring from your nissan dealer. The cooler is not defective...just the oring. They are almost all pinched when you remove them...

Does the oil cooler itself ever have to be replaced? ...I just finished replacing both O-Rings, and I still see a slow oil leak. Now what??? (2003 QX4).

The fresh oil seems to be on the back, (i.e., toward the rear of the truck), of the part of the oil cooler that has the grooves in it, (the large round copper or brass looking section of the cooler, if I remember right).

Appreciate this forum.

Thanks.

-Dennis

[Towncivilian]

There is a gasket behind the oil cooler bracket - see LC-8 of the FSM. Perhaps that is the source of the leak? Degrease the oil cooler exterior and watch it for leaks, there could be a crack in it.

[dk203040]

Thanks for the quick reply. ...not that. The entire area is clean, and I can see that the area around the engine block is dry.

Does the oil cooler EVER have to be replaced because of oil leaking?

Could I have re-installed the oil cooler wrong? I did tighten the center bolt as tight as possible.

Thanks.

[Towncivilian]

I've never heard of anybody needing to replace the oil cooler and I don't think replacement is mentioned in the FSM. "As tight as possible" isn't ideal - using a torque wrench would have been more accurate and would prevent any possible overtightening. I doubt it's causing your leak, though.

Have you checked for leaks elsewhere, or are you absolutely sure that it's emanating from the oil cooler itself?

[dk203040]

It was unbelievabely tight when I removed the oil cooler bolt.

I'm gonna get under there again tonight or tomorrow.

Don't have a torque wrench, but if I did, I think it might be difficult to use in that tight area.

[Towncivilian]

You're probably right about the clearance. I wouldn't worry about it, really. Like I said, I doubt it's causing any leaks. Thoroughly degrease the engine and underbody to see if the leak might be coming from elsewhere.

[dk203040]

What is the most or a practical way to degrease the lower engine, suspension and frame? ...I will have to do this without lifting or jacking up the truck.

BTW: I got under the QX4 on 2 nights ago and, with paper shop towels, I wiped the area again. ...So far, (2 days now of light driving), and things do look dry for now.

So the oil that showed up after I changed the O-Rings, might had been there from before I did the work. ...Don't know for sure yet. When under the truck with a light it is difficult to tell if I'm looking at fresh oil, or the parts are just shinny from being wiped down.

Thanks again for the input. And I did check one of the hex bolts on the oil cooler bracket, and it was secure.

-Dennis

[zach7685]

What i did was take the car to a do it your self car wash. use their pressure washer and clean it. be careful not to spray directly at connectors for long periods as i got my oil pressure sending unit wet. it dried within minutes. Its a very good way to see if you ever have new leaks.

[dk203040]

What i did was take the car to a do it your self car wash. use their pressure washer and clean it. be careful not to spray directly at connectors for long periods as i got my oil pressure sending unit wet. it dried within minutes. Its a very good way to see if you ever have new leaks.

Perfect. Great idea!

Did you, do you, ...need to use their soap or use some commercial spray-on degreaser?

Or just use the self-car-wash high pressure water hose?

I do think my oil leak was solved with the O-ring replacement that I did several days ago. The photos on these forums were perfect for me to identify the leak solution.

Thanks.