Well as the title states I"m preparing the truck and camper for a 3500 mile trip next month through Zion/Grand Tetons/Yellowstone. Camper is done and resealed, truck got all new fluids and plugs. But I did find a leak that appears to becoming from the rear main seal. Haven't seen anything on driveway so it either just started or is very minimal. What do you guys do in this situation? Change it? Bring some oil just in case? Mechanic wants 900 buck to change it out.Truck is an 04 with 95K miles on it.Thanks

But I did find a leak that appears to becoming from the rear mail seal. Haven't seen anything on driveway so it either just started or is very minimal. What do you guys do in this situationThe situation(as described)is you don't now for sure, so why pay $900.00 to change what you aren't sure of?

I assume you wouldn't get the oil seal changed yet if you weren't going on a big trip? Given you aren't heading for a 3rd world country where finding spares or mechanics might be a problem, I would just take some spare oil with me and keep an eye on it. Worst case you'll have to find a garage on the trip. I guess if you wanted to be more careful you could always source a replacement part so if you need if fixed and find a garage you aren't stuck because they'll have to order one and that will take 3 days, etc. But then I come from owning Land Rovers - they always leak and it has to be a really big puddle of oil on the driveway to bother doing anything about it.

That rear main seal area is a tricky one. Fluids tend to accumulate there as it is a low point and inertia drives leaking fluids to the location. I'd clean it up real well and watch it.

I am in the process of doing the same on my truck, for our trip to Oregon.I wouldn't worry to much, if it is just weeping a little. If you can get a socket wrench up to the pan bolts, check and make sure they are not loose. Don't crank on them though, may cause the seal to split or worse. I always carry extra fluids for the truck, you never know when you need to add some. Good luck and safe travels

The rear main engine seal should not typically be leaking on a 2004 truck with 95K miles on it. As long as there is no oil showing on the driveway, I would not change it out at this point. However, for peace of mind, I would get a rear seal and an oil pan gasket to carry with me so that if I did need to get it done, I would have the parts necessary for any competent mechanic to do the work. You might want to look up what the exact procedure is to change the seal so that you know what parts are required. Some can be changed by dropping the pan, but many others need the transmission removed. Might be additional parts required to complete the entire job.Just as an aside, I had a weep on my transmission output shaft seal and it lasted for 3 years until this spring when it suddenly let go with a vengeance!!

Pre Trip Maintenance | Good Sam Community

15 Replies

wintersun
Explorer II
Jun 09, 2013
Grit dog wrote:
wintersun wrote:
It depends on the vehicle. In some cases the oil from the engine can be forced under pressure into the transmission and damage it. With other vehicles it simply leaks out of the trans housing and causes no damage. I would do more research on worst case scenarios with your particular truck.

I had a Chevy Blazer that blew out the rear seal at 11,000 miles so mileage is no reliable indicator. With the Chevy it went quickly and completely and the SUV was not driveable until the seal was replaced.

What types of vehicles would this be likely to occur in?
This is not the case with any rear conventional engine/trans setup I've ever seen. Only thing connecting the engine to the trans is bolts and any oil leaking out is going to the gound. Curious though.

Not unusual with transfer cases mated to the rear of the engine with a 4WD vehicle.

For any vehicle I would take on a long trip that had a problem I would research it thoroughly before starting down the road. In addition to the lower odds of finding a good garage on the road there is the added expense of hotel lodging and food while the vehicle is being serviced.

My truck's engine light went on before a trip and the code showed a bad NOx sensor. No big deal. Except that it turned out that there were two bundles of wires that were being burned on the EGR valve and rubbing against the AC compressor and they affected many more parts of the emissions control systems. And the NOx sensor had been affecting the DEF consumption of the engine so I was having to stop three times as often at truck stops to get more and that meant changing our route and spending more time on major highways.
mkirsch
Nomad II
Jun 06, 2013
I noticed some small oil spots on the driveway.

Oil change guy told me my rear main seal was leaking. When I got home I crawled underneath and it sure looked like the oil was coming from the filter base area to me.

After that oil change it never leaked again. Either the leak went away by magic, or the previous oil change guy didn't get the filter tight enough.

Just monitor your oil level and if it does get so bad you can't keep oil in it, take it to a nearby shop for repair on your trip.
RockyRoadCamper
Explorer
Jun 06, 2013
Buy the seal you think is leaking, as a spare, just in case.
Grit_dog
Navigator II
May 31, 2013
wintersun wrote:
It depends on the vehicle. In some cases the oil from the engine can be forced under pressure into the transmission and damage it. With other vehicles it simply leaks out of the trans housing and causes no damage. I would do more research on worst case scenarios with your particular truck.

I had a Chevy Blazer that blew out the rear seal at 11,000 miles so mileage is no reliable indicator. With the Chevy it went quickly and completely and the SUV was not driveable until the seal was replaced.

What types of vehicles would this be likely to occur in?
This is not the case with any rear conventional engine/trans setup I've ever seen. Only thing connecting the engine to the trans is bolts and any oil leaking out is going to the gound. Curious though.
wintersun
Explorer II
May 31, 2013
It depends on the vehicle. In some cases the oil from the engine can be forced under pressure into the transmission and damage it. With other vehicles it simply leaks out of the trans housing and causes no damage. I would do more research on worst case scenarios with your particular truck.

I had a Chevy Blazer that blew out the rear seal at 11,000 miles so mileage is no reliable indicator. With the Chevy it went quickly and completely and the SUV was not driveable until the seal was replaced.
CAJW
Explorer
May 31, 2013
BJBear hit the nail on the head. Get a replacement seal and gasket to take along on your trip, a little extra oil, old clothes to crawl under the truck occasionally to check it out and enjoy your trip!
RZAR66
Explorer
May 31, 2013
Check your crankcase breather, PCV valve or whatever your truck has for blockage. When these get blocked or restricted the first things to start leaking are the front and rear crank seals.
Super_Dave
Explorer
May 30, 2013
PS. check your current oil level to verify it wasn't overfilled. Shops do this all the time.
Super_Dave
Explorer
May 30, 2013
Did you recently have an oil change in preparation for the trip? Remove the filter often causes a certain amount of oil spill that shows up as a couple of trips for a day or 2 after an oil change. As stated above, the oil runs down steering arms and motor parts to drip in an entirely differnt place than origin.
Grit_dog
Navigator II
May 30, 2013
Typically main seals don't just blow out right away. The leaking usually gets worse over the course of thousands of miles. Not that it can't happen just not likely.
As mentioned it could be the oil pan gasket too.
Not sure on newer vehicles and where the static oil level is in the pan but an old rule of thumb is if it leaks all the time it's a pan gasket. If it only leaks while running then its a main seal.
Hard to tell which is leaking without pulling the tq conv cover and cleaning it up.