Diesel in the Crank Case; a journey of failures.

[Feds]

It's been 25 days since my Delica broke down. I put ~500 kms on it this weekend, and I believe I have resolved the problem, so I'll go out on a limb and share my experience here:

August 1, 2014: I am booked for a camping weekend 400 kms from my house. We leave around 8:30 and spend the next 3.5 hours fighting our way through Toronto traffic. As we drive, I notice my oil pressure decreasing, but the van is running fine, so we press on.

At noon we stop for lunch. Oil pressure still low, but seemingly not getting worse. We continue on, clearing Toronto and entering the wide open spaces of the 401 between Oshawa and Kingston. 20 minutes later, I hear what sounds like a runaway: Lots of diesel knock, and a big smoke screen. I take my foot off the gas and confirm: the engine continues to speed up for 20 seconds, then slows down again. I pull over, open the hood, remove the PCV hose, re-start the engine, and see diesel/oil mixture pouring out of the hose. Shut it down, call CAA, arrive home at 7 pm. The van will re-start, but runs rough and is pouring smoke.

My initial thought was that the pump seal I changed a year ago had failed. Order a re-built pump (thanks to Rising Sun for prompt service and shipping), and begin the process of installation. Took me a week as I screwed up the timing marks, but eventually I got it running. It was still farting and fussing, which I chalked up to the timing not being exactly right. However, 50 kms later, my oil pressure is back down to 0 at idle, and no more than 20psi running. Pull the dipstick, confirm: More diesel in the oil.

Now to the injectors: I didn't investigate these first, as I had changed them 4,000 kms ago. Good thing I held on to my originals. As I remove the injectors, I find a ring of carbon around #2. Much cleaning and chipping later, I coax #2 out of the head. I clean everything up, put my original injectors back in all 4 holes and start it up.

Van runs perfectly. No smoke, no knocking, nothing. Over the weekend I do progressively longer test drives and see no change in oil pressure or level.

So, it looks like I had a bad injector. I will get some testing done to determine if the injector failed open, or leaked or what. But for you dear reader, perhaps the lesson you can learn at my expense is to change out the cheap and easy parts first, and to have a little more faith in your fuel pump.

[macro]

Can you explain why a failed injector would cause that?

[Feds]

Not really...

My theory is that the injector was/is stuck open. So for every injection event, too much diesel is getting into the cylinder, starting too soon and ending too late.

This caused rough running/pre-ignition on the front end of the compression stroke, and dumped fuel into the cylinder after combustion. The unburnt fuel would run down the cylinder and get past the rings, filling the crank.