Oil all over diff.

[stranger22]

First I would like to say hi, im new to this game but whatever. Just picked up a 98 cummins and I love it. The only thing is that it has oil all over the diff. I can see that it is coming from a tube droping down from the motor, looks like a vent or something anyone know what the hell that is and why it is leaking like that (I guess it could be fuel maybe?) Thanks for your help. Love the site....

 

[argve]

Welcome to the site.

The tube you are seeing is what's called a Road Draft Tube or RDT. What this tube does is it vents the compression blow by gasses to the atmosphere, the gasses will carry with it a vapor of oil so what you are seeing is NORMAL. Don't be alarmed. This is the nature of the beast if you will. On some other brands of diesels they (engine manufacturers) actually run these gasses back through the engine via the intake so that they can be burned but Cummins choose to treat the engine just like what's used on tractors and semi trucks and just vent them below the engine bay.

In a diesel engine compression ratios are much higher than what is found in gasoline powered engines so a diesel will by nature create more blow by past the piston rings so the increased crankcase pressures must be dealt with and as you have found Cummins just vents them.

So again welcome to the site and there is nothing wrong with your truck.

So got pictures of her?

 

[stranger22]

Sweet thanks alot, that makes me feel better. Yeah I'll get some pix of her up here soon !