The Nissan Path

I have owned my Pathfinder since 2003 - bought it new. It has almost 230,000 miles on it and has performed well so far. In May of 2010, I paid a guy to change the rear main seal, as the local Nissan dealer's service department told me such was the cause of an oil leak at the time. It now has an oil leak again, and the same service department said the rear main seal is leaking again. They will not work on it because they say they cannot guarantee the work. They say the reason they can't is that a spring in the rear main seal will push through the seal and into a groove in the crankshaft, which they believe is likely there, ruining the seal and causing another leak fairly soon. They say the only thing to do in such a case is replace the engine, which costs $5000-6000.

I'm just looking for advice, as I think it ridiculous to replace an engine for a groove in the crankshaft. Thank you to anyone with some reasonable advice.

It's impossible to say if the seal wore a groove in the crank or not without removing the trans/flywheel/rear main seal to view the crank. There is another possibility: it's not the rear main seal but the rear lip seal of the oil pan.

Thank you. Which one is most likely? And will it take much for me to check it myself? Just so you know my experience level, I've done a lot of car work, just none in the past 10 years. Once, I rebuilt a Dodge van motor.

Unfortunately, it's not always the easiest thing to figure out because you can't see the area that's leaking with removing the trans. Biggest difference between the two leaks is that a rear main seal will leak anytime the engine is running, whereas a real lip seal on an oil pan will usually only leak while driving, when the oil in the pan will push towards the back off the pan while the vehicle is driving. If you have the time to let the car sit overnight, let it set so any residual oil in the bellhouse will leak out. Put a clean piece of cardboard under the vehicle and start the engine and let it idle. If there is a significant rear main seal leak, you should start seeing oil dripping onto the cardboard. If you don't, it could be the oil pan.

That information sounds great. I will try it within the next few weeks, as I am pretty busy now. I'll post then to tell you the result. Thanks again.

I tried what you said this morning, letting the engine idle for 10 minutes after letting it sit overnight. There were two drops of oil on the cardboard and a drop forming on the transmission bell housing (about two mm away from the engine) afterwards. Incidentally, I don't know if it has an oil pan rear lip seal. The oil pan is really shallow and its interface with the engine is in a horizontal plane.

Anyway, I guess the rear main seal is leaking. Perhaps there is no groove in the crankshaft. In such a case, do you think it reasonable to change the rear main seal myself? Also, if there is a groove in the crankshaft, could I just change it out instead of get a new engine? I saw that crankshaft assemblies sell for about $820 at the Nissan USA eStore. Again, I appreciate the advice.

I dont think the crank is grooved. That normally happens when there is dirt that act as an abrasive. The crank is hardened and yes the front seal gets dirt in there and groves the crank. There is a repair sleeve for the front. But not the rear.

My guess is either it was a poor job done last time or the main bearings are worn.

Sorry I haven't replied for a while. Thank you for the information. I've tried the earlier advice and it seems to be the rear main seal. I let it idle with cardboard underneath it, and two drops came down in 10 minutes. I've driven it quite a bit since then, and the oil level is staying fairly steady, as far as I can tell. I check it weekly.

I hope the crankshaft does not have a groove in it. If it starts leaking worse, I will either take it to a mechanic or do it myself. I have seen before that there are instructions on how to change the rear main seal on the internet. I'm sure I can do it if I have the time. Once again, appreciate the advice.

I've found that shops tend to go to the 'change the engine out' option fairly quickly these days. Problem for them is once you start disassembling the engine, you can get into it for a really high amount of hours very quickly. At $100-150/hr labor, it doesn't take long to justify just changing the engine out with an exchange engine from a reliable source. Would probably reduce comebacks, and if they buy the replacement from the right supplier, it would probably come with some warranty that would limit their liability if things don't go as planned.

Now, if you can find an independant shop, or reliable backyard mechanic that charges $50-60/hr or less, the logic changes, as you are into it for less labor which rules out justifying a rebuilt or exchange engine.

t

Thanks for the comments, Terry. I think I have pretty much settled on waiting and watching, then changing the rear main seal myself if/when the need arises. All the info given helped me understand the problem better. I'm going to sign off on the thread now. Thanks to all again.