Post Offroad Trip: Leaking Gear Oil + Front End Whine. Help?

[nobb]

Hi guys,

I went on a moderate off roading run this weekend. Nothing really intense...there were a few scrapes on the underside but it seemed like the stock skid plate would have protected against these. I did not notice any visible underbody damage after the run.

However, that being said, upon further inspection today it seems I have a gear oil leak somewhere. I havent pulled the skid plate yet, will do that tomorrow. However, the leak is all over the power steering rack and on the rear of the skid plate. The gear oil could only come from the front differential or my manual transmission.

It is most likely from the transmission, since I see most of the gear oil in between where the engine and the transmission mate. I am 90% certain there was no leak before. My rear main seal should have been good this whole time. Is it possible my offroading trip damaged the rear main seal? Or are there other considerations on where the damage/leak is for tomorrow when I drop the skid plate?

One other thing to note is that I notice a small whine that seems to follow the engine speed (not wheel speed). So this might indicate some sort of rear main or transmission seal problem?

If you guys have any thoughts that would be great!

 

[Dous]

You are 100% positive it is gear oil?

 

[nobb]

Yup. Not motor oil, and not power steering (ATF).

 

[Dous]

You seem pretty confident it wasn't leaking before the off roading
I have seen the 7.5" housing crack, doesn't happen all that often, but that is about the only way to have a sudden leak, either that or blowing a CV axle seal.

If it was the rear main that went it was going to go anyway; it incurs no additional stress off road, besides the possibility of some extra heat.

 

[nobb]

I am pretty sure it wasn't leaking before. I noticed a small whine right after my offroad trip, which was definitely not there before. Would low gear oil cause the gears to whine? As mentioned previously, the whine is proportional to engine speed and NOT wheel speed. This would indicate to me a problem with the transmission (which is mated to the engine) and not the differential.

I sure hope it isn't a housing crack, but it would be strange that my seals would blow all of a sudden during offroading. But then again, I did do some minor mud crossings which ended up caking my engine in mud. I will check my front diff breather tomorrow.

If the rear main blows, wouldnt that cause an engine oil leak instead? Is there a seal on the transmission input shaft that could blow?

 

[curtperry]

You are right. If it varies with RPM and not road speed then it's not the diff. So either the sound and the oil leak are unrelated, or it's not gear oil.

The front diff can leak from the breather and get on the rack - mine does because I overfilled it. It causes no ill effect except slightly lower oil level in the diff and an ugly mess.