I decided to buy a diesel truck and researched "what to buy" on the different diesel forums. After reading them (for about 3 months) I decided on the Cummins. Welllllllll to make a long story short I bought a 1996 3500 4by dually. I was happy (still am...wifes not) with the truck till I got home and noticed a few things. (1) there seems to be a oil leak coming from the front of the motor. (2) the 4by is now a 2by and (3) my ac works great for about 10 minutes then quits till its shut off for about 10 minutes. The oil looks to come from around the front bearing. I think I may have found the problem with the 4by as the vacuum line was melted through. Could the ac problem be with overfill of refrigerant? I just need some reassurance (to pass on to wife that I aint got burnt! Any help appreciated. Thanks...Newbie!http://www.dieselplace.com/forum/smileys/Cry.gif

Do some research here

TDR (http://www.turbodieselregistry.com/)
and here
DTR (http://www.dieseltruckresource.com/dev/index.php?s=)

You got the 4by fixed...

A/C is always repairable. Don't point to Dodge because all brands can have A/C issues. Sounds more like it may just need a recharge.

Oil leak is left. That one you want to study. I don't know how bad it is but it could be as simple as the vent tube dripping. Have you looked close? If it is coming from a rubber hose, that's normal. Also sometimes the injection pump can leak oil. It's oil lubricated. Could be front seal.

A worse scenario would be the dowel pin behind the timing gear cover came out and cracked your cover. It's called the Killer Dowel Pin (KDP). Be careful and rule out the simple stuff first before getting upset.

The KDP thing should be addressed even if that's not the reason. Can you contact a previous owner and ask about it? It involves tearing down the front of the engine and staking the dowel so it can't slide out. Do a search on those forums about KDP. Edited by: hoot

Thanks Hoot, I believe the vacuum lines will be the fix for the 4by and the ac is not a great worry. I cannot say about the dowel pin. Oil leak appears to originate from just above oil pan on front of motor. Oil has blown over the bottom of the motor so its hard to pinpoint. If it is KDP...would there not be a noise or some other symptom present? Right now the oil is my major concern. I cannot see any crack on the front of the motor and the truck runs great. I have noticed that my temp stays down from 120 to 140 is that related?http://www.dieselplace.com/forum/smileys/Disapprove.gif

Clean it up real good with degreaser and careful pressure wash or hose. Then wait and see.

I have seen several KDP's and it is a major oil leak. The main concentration is behind the fan Idler but it will throw it every where it sounds like you need just the front seal. Easy job just remove the belt then the four bolts holding the dampner off and pull the seal and install the new one. Check for vacuum leaks on the hoses on the drivers side of the engine they have been known to rub through. also check the hoses on the passenger side of the front axle sometimes when I put one of those trucks on the lift it will drop the axle enough to pull the vacuum line loose. On the A/C I would get a gauge and check the pressure it could be over full.

your oil leak could be the the blow by vent tube, there is a catch can on the bottom of it and it gets full and overflows, take it off and empty it, or throw it away and extend the hose so the "oil fumes" can just blow under your truck as you drive, i did mine and no more oil drops underneath....possibility

96 trucks do not have the catch can on them they go straight down onto the front axle near the front u-joint

correction noted.