So I'm doing some R&R on the old girl and it looks like I have a cracked injector cup.

I was only planning on doing the injector o-rings and glow plugs, but when I pulled the #5 injector I noticed the end of the injector looked to have a little surface rust on it. I dismissed it at first, but after reinstalling the injectors with GPs out I rolled the engine over by hand and heard a good amount of fluid get purged from the passenger side. That seemed odd because I used a vacuum extractor to suck the fuel/oil out after pulling the injectors.

Well, when I lifted the pass side valve cover off I saw coolant all over...worst being all over the #5 injector solenoid, same one that showed a bit of rust. I looked in the degas bottle and it was really low, and looked to have some crud at the fluid level line.

Am I correct that the only way coolant is getting there is a cracked injector cup?

 

When an injector cup goes usually the fuel ends up in the coolant not the other way around usually you make coolant not get low. Sounds more like your oil cooler is shot or just the O rings.

 

Stick your finger in the Degas bottle and see if the crud smells like diesel... Did you start her up and run it for any time?

 

Check out the left hand most injector. See the rust at the bottom. That is #8. It only had 152,000 miles on it. The cup in #8 had a tiny crack. There was no fuel in the degas bottle. So, if your injector had rust in the same area as this one, it very well could have a cracked cup and you caught it in the early stages.

We tested the cup with about 12 PSI of pressure and it produced a leak.

 

I haven't started it since tear down, but I did smell the degas bottle and it just smelled like coolant. Would oil cooler cause coolant in just one cylinder?

 

Thats exactly what the #5 injector looked like.

 

This is the accompanying cup, obviously post removal. You can see the crack on the side of the cup near the bottom 1/3. The other spiral scratches are from the Riffraff removal tool that should be available to rent. The crack is located where there is "only" coolant exposed to the outside of the cup thus the bottom o-ring on the injector was able to confine the coolant to the lower portion of the injector once the coolant penetrated. Had the crack spread upwards about another 1/4 to 1/2 inch, there would have been fuel in the degas bottle because it would have created a path, the crack specifically, that defeated the o-ring. Eventually, it would have spread.

 

Well, at least it is not #7.....

Wish there was better news.

 

No, it should not. It should affect them all equally.

 

Thats what I figured was going on...How do you rent the RiffRaff tool?

 

Should I just replace #5? I figured it was one of those things you just do all 8 if you have to do it at all...

 

Call Clay in the morning. He'll have it to you Tuesday morning if you are in a hurry. He'll send the tool, eight cups, and the sealant.
Do all eight. Your truck will be down the same amount of time regardless. You should let the sealant cure for no less than 12 hrs.

 

thats what I figured. Not a huge deal since I have it torn down already anyway. Thanks for the reassurance I diagnosed it right!

I need to drain the coolant from the block to do this, right? If not I'd rather take it to the dealer for a full flush after it's fixed.

 

Yes, drain the coolant. Also, drain the oil and fuel rail if you can, if not, no worries, it just makes clean up a bit easier.

Purchase several round brushes to fit whatever tool that you have that will fit in the rearmost holes, 7 & 8, if it fits back there it will work for the rest, to clean out the old retaining compound from the heads in all of them. Make sure that the bristles are not too course or stiff. Get yourself a small mirror.

Test the install of the new cups before putting the injectors back in the holes with about 10 psi.

When you reassemble, hand turn the engine very slowly for a few complete revolutions with the glow plugs out and then with the starter regardless of whether you mighty-vac the cylinders or not. Then install the GP's. Consider replacing them as well if they are the originals.

I would do my own flush and you'll want to do an oil change relatively soon after the reassembly as well.

 

Before I'd pull a cup I'd pressure check the coolant system. If it holds, the cups are good.
This could also be just left over coolant that went in the cylinder. If not well then pull the cup.