1998 6.5 T/D Bought for parts

[Aftermath]

So I just bought a complete drop in already removed from the truck and the owner installed a 454. I think it's a 504 block. The crazy thing is that this truck has 17k on the clock. So I only paid $150 for the complete engine, worth that in parts for sure.

So here's the story I got: it started smoking white smoke and skipping all of a sudden. There's fuel in the oil. He thought it was Injectors, replaced a few injectors and no change. Without further investigating, and literally immediately he pulled it out and installed the 454 and sold it to me.

So I've had lots of these engines, mostly ended up cracked heads and blocks when I buy them for the parts. Before I strip this one down, I wanted to get some feedback. Does this sound like it could be a bad pump, or most likely cracked heads?

Thanks in advance

[More Power]

It's somewhat rare, but I have heard of a few instances where a bad seal in the fuel injection pump caused diesel fuel to leak into the crankcase. The injection pump housing is under constant pressure, so a seal leak could cause a lot (depending on the size of the leak) of fuel to leak past and into the oil.

A stuck injector usually causes other problems... like a dead miss, white smoke, a hard combustion knock.

These fuel injection pumps are the "fixed displacement" types, meaning the fuel injection pump and its pumping plungers determine the volume of fuel delivered to the injector. At light pedal, only a little fuel is delivered to the injectors - not enough to cause a diesel fuel in oil problem... unless there's a dead cylinder (lack of compression - bad piston/rings). In that situation, the fuel won't combust, allowing some of it to move past the piston and into the crankcase. Jim

[DmaxMaverick]

The injection pump is double-sealed (double-double, actually), with a weep hole between the seals. Each seal is a double-lip type, one at the pump end of the input shaft, and one at the flange (cam gear) end, with a trust shim at each end. The weep hole is at 6 O'clock on the input shaft housing. In order for the IP to allow fuel to get into the crankcase, it would have to leak past the pump-end seal, pass a weep hole (it would have to be plugged, or flow so high, to maintain some pressure), then leak past the oil seal at the flange-end. Add to that, housing pressure of the pump is limited to the "return line" pressure, which would mean that is plugged, too. A leaking weep hole will leak fuel into the engine valley, and drain down the back. Difficult as it may seem, it's happened a couple times in my recollection, but only on DB-2 pumps. DS-4 pumps are basically the same at that end so it could happen just as often, but I haven't seen/heard of one. I suspect that is due to the DB-2 having HPCA, which increases the case pressure (to advance timing) during cold starts.

There is a slight possibility for fuel to leak into the crankcase from a mechanical lift pump, but it has triple redundancies, too. It's happened. Not an issue if your engine doesn't have one.

All that said, white smoke and missing with fuel in the crankcase screams broken piston. It should also have very high blow-by.

[Aftermath]

So I lierally just picked this engine up and was able to talk to the company "mechanic". Sure enough 17k Miles on the odometer. This guy is as country as cornbread and admittingly knows nothing about diesel engines. So here's the real story; after sitting for "some time" they went to crank it up and noticed there was a mis, and white smoke coming out of the tail pipe. He removed the injector lines one by one and the only non-working hole was coming from #6. All other cylinders were working. He replaced #6 injector with no change. They immediately pulled the engine and installed a 454 crate motor. No excess fuel in the crankcase. I asked about codes and they couldn't remember although this all happened within the past month.

The owner of the company just told me that between 95-98 they had (8) 6.5's in their fleet, and they had problems with all 8 and he wasnt going to spend another dime on this last 6.5 truck. Had I been there a month ago, I could have bought this truck complete $1500. HD too....dang it!

[DmaxMaverick]

You may get away lucky then. Maybe only a head gasket or something simple.

[Aftermath]

I know, too bad I didnt get the entire truck, man that thing is super clean 17k miles though.

So pull the valve cover, all looks okay, pull the head?