Water in rear end.

**Big John** · 12.06.2011

I bought this truck in Feb. 2011 and immediately before hauling my first load I changed the oil in the engine, trans and both rear ends. I put synthetic in trans and rears and checked them the other day and the front rear was full of water and the rear one was good. The vent caps are okay and clear. Can not find any leaks and no cracks in the housing. I drained it and filled it back up with synthetic. I am going to pull it in the shop tomorrow and check it but was wondering if anyone has seen this before. The front rear was rebuilt about 150,000 miles back by Kenworth.

**Heavyd** · 12.06.2011

The axle housing may have a crack in it at the top of the housing near the spring saddles. This would allow rain water in, but not leak oil out and be easy to miss. I hope I'm wrong though!!!

**bender** · 12.06.2011

When shops do diff repairs they steam clean the axle housing. Water will stay in the axle tubes unless wiped out by hand.

Check closely around spring perches/saddles for signs of movement/cracks for water to enter.

**Wildcat74** · 12.06.2011

Oil floats on water. If the housings were cracked you'd see evidence of oil coming out somewhere due to this. If there are cracks they'll be under/near the spring saddles though as others have mentioned so look closely there, otherwise I wouldn't worry too much about it.

When you say they were full of water, how much water do you actually mean? Enough to turn all the oil in there white?

**alaga** · 01.12.2012

If you have a Mack/Mack rears that design apparently needs to be disassembled to some degree and re-sealed (with silicone sealant) periodically. Mine losing a wheel seal after every rain for a while 'til Mack dlr finally figured out (4 or so repl seals!).