2004 Dodge 3500 4x4 5.9 6CYL cummins Diesel
Drove 4 min to store and on the way back no heat.
Got home,looked at the coolant it was low but had oil when I put my finger in,then looked and seen the coolant reservoir was overflowed with nice thick black diesel oil.
Never overheated then or ever in it's lifetime. No coolant in the oil,just oil replaced coolant.no smoking,clean exhaust,No coolant smell and runs great still,no oil into the exhaust,just the coolant reservoir and some in rad????
Was thinking blown head gasket,but might be the oil cooler????
Anybody seen this issue before. Any way I can tell if there is a breach in the oil cooler first????

 

Is there an oil cooler on the truck? (oil/water cooler....) Oil pressure is significantly higher than cooling system pressure....

 

Ya it's got an oil cooler on the passenger side of the truck. I'm gonna drain the rad and coolant reservoir then pull the oil cooler today and pressure test it to see if there is a breach,I'm thinking at this point,at the amount of thick black diesel oil that overflowed my coolant reservoir that it's the oil cooler breached,but needs to be checked before I go do a head gasket for nothing,if the oil cooler isn't breached,then it's the head gasket. Seems there isn't any other reason for my condition.

 

I don't think there is any pressurized oil passing thru the head gasket. Highly likely is the cooler, or a gasket in it. Oil is under MUCH higher pressure than the cooling system..... How is your oil level?

 

Ya I'm thinking it is the cooler. I'm just at the cover on it now,had to stop for lunch,lots of things have to get removed to gain axes to the cooler plate. The rad hoses are just puking out thick black diesel oil,the coolant reservoir is full it,thick nasty black engine oil,all the lines are full,the heater core is probably full of the oil also.Drained the rad and took a bucket full of oil.

Anyone have a good way of cleaning out the cooling system,hoses,rad,reservoir,heater core ect. I don't know how bad it will be to run the stuff through if I have to put in a new cooler,which is highly probable,but will know tonight when I get the cooler plate out and pressure test it.

 

Load it up with water, take it to a shop that has a GOOD flush machine, let 'em know what happened, and have them flush the system and refill.

 

THe o ringd I n your oil cooler gave out. Oil psi is higher than the psi In your coolant system. Had the same exact problem,you must have a heavy foot like me 🙂. Other then the head gasket it's the only other cross connection that can make that possible. Engine oil is routed across a manifold that has coolant being pumped thru it from the water pump. Can say with 99% if the engine didn't get hot and there's no water in the oil,it's definitely the oil cooler,which is way better than it being a head gasket.

 

Got the oil cooler pressure tested and shop said it failed in 3 places.
I'm up in Canada trying to source out a new oil cooler but the parts stores can't find any suppliers,
so that leaves me ordering online. I have a 3rd gen 5.9L cummins and need to know if the oil cooler
is the same match on all gens for the 5.9L cummins or if I have to only buy the 3rd gen.Does it matter,
they are the same block or is there a difference in the mounting,bolt holes,gaskets,alignment ect on the blocks?

 

Looks like 03 to 07 are all the same.

 

At this point I ordered a new oil cooler and new gaskets,had them sent,got them installed. The old oil cooler failed pressure test in three places. I have been flushing the cooling system,fill drain a few times,then fill with water and dishwasher detergent,I have done that 4 or five times. When I run it I keep getting thick tar like oil rising to the rad cap. I can't tell if it's fresh oil still entering the coolant or the oil that flooded the system. The coolant reservoir was overflowed with thick tar oil,so I know the rad fins and heater core would have been full. I don't notice the dip stick getting lower and no water is entering the oil. I'm hoping there isn't a breach in the new oil cooler or gaskets. Anyone had to flush out thick tar oil from theirs before and does it keep coming till it's flushed 100 times lol?????