I believe I may have two issues going on here. I created a video showing a few snap shots of what I believe is oil in the degasser bottle as well as what happens during start-up after the trucks sits for a few days.


As mentioned in the video text, the GPs and UVCH were all replaced back in May. At that time, I also checked all the torque values for the rocker arms and injector hold down bolts. I also verified continuity of the new UVCH and inspected the 42 pin harness. Based on my research I think I may have cracked an injector cup or maybe exasperated an existing crack which is now causing the increased smoke and rough idle on start-up. The GP replacement job stemmed from smoke during cold starts only, but now the truck is smoking anytime I let it sit.

Along with the engine work, I also did a complete coolant flush where I replaced the T-stat, degasser bottle, and radiator coolant hoses. The system was flushed with distilled water and filled with Rotellas ELC per Gooch's list/procedure. The previous coolant was contaminated with an oily substance, but I don't remember it being this bad.



I don't know if these two issues could be related or completely independent. I have seen a few post that mention oil in the coolant can indicate damaged or improperly installed injector cups. I am trying to determine what diagnosing I can do before start unbolting or blindly part swapping.

A few things I am considering.

1. Is there a way to diagnose a bad injector cup?
2. If it's an injector cup failure, would this be a good time to upgrade injectors?
3. Should I bother performing a buzz test? Idk if I'm able to hear a misfire. People talk like it's obvious, but idk if I've ever heard it before or could diagnose it.
4. Could this be an oil cooler failing?
5. How do I diagnose an oil cooler leak?
6. If I need to reseal Oil Cooler, should I go ahead and replace it? (OEM cooler with >250k miles)
7. Is there an upgrade or better OEM repair for a leaking cooler?

I am continuing to do research on this topic and questions, but I am pretty limited on computer time (1hr/day at best). I hate asking questions that already have answers, but I can't seem to find them or make the time to find them. I'm hoping you guys can help steer me in the right direction and get my truck back on the road.

Thanks!!

 

1. Yes there are 2 ways I'm aware of. One is to pressure test the cooling system, the other is to use a combustion leak kit. I believe Harbor Freight has kits with the necessary hardware to do either test.

2. If your planning to replace them soon anyway, then yes you'll have the injectors out already so it does make sense.

3. No, won't tell you if a cup is cracked only if the solenoid fires and how well.

4. Yes.

5. Not 100% sure, but I would guess that pressurizing the coolant system while the engine is off would allow to hear a leak.

6. Not necessarily if it's good I don't see the point. Rubber o rings fail period. It's not a if or can thing, it's a when thing. All rubber deteriorates and breaks down, some just take longer than others.

7. Nope OEM is as good as it gets.

 

Also big thanks for your video documentation and full description! Almost like we are there. Really appreciate that!

Plenty of solid advice from udsuth above.

I'll just add my guess is the oil cooler O rings are failed. That explains the oil in coolant in the degas bottle. Not so much the cold start smoke. But R&R on the oil cooler is straightforward. OEM O rings only. The tubed intercooler inside rarely fails but inspect it closely.

I'd rebuild that first and see what problems continue.

Btw what oil are you running?

 

Subscribing. The only thing that I can add to this discussion is my experience with coolant reservoirs and the plastic that manufacturers use to make them. The deterioration of the plastic on your coolant reservoir is consistant with what I have seen over the years as a VW/Audi repairman. Retired now, but I had to deal with that same type of failure across the board and none of the vehicles that I serviced had oil in the coolant.
My own truck, a 1999.5 F-550 7.3 got the same treatment that you did with new Motorcraft reservoir and hoses everywhere. Motorcraft reservoir failed at the seam, spraying brand new coolant all over the passenger battery. Returned the leaking one to the local dealer where I bought it and got a replacement. Took a 1,600 mile trip and when I arrived, same failure. Bought an aftermarket replacement reservoir and that one didn't leak. Fast forward a year later and the aftermarket one still didn't leak, but looked exactly like your's does, minus the oil in the coolant.

 

I just watched the video for the first time and am a little curious. Set the playback speed to 0.5 and start listening from about 0.34 mark and tell me if y'all hear what I think I hear. It happens quick so might take a few times.

 

I think I hear it too.

Can we get a video of the engine cranking with the 42 pin disconnected?

 

What I hear is cold idle loping and/or misfire of cold cylinders. All the glow plugs good?

 

Generally oil coolers get re-sealed when a visual inspection of the outside of the cooler body shows oil sludge covering it, and possibly even dripping onto the ground. That would be the two seals towards the more middle part of the cooler where the header parts end and the cooler body begins. There are two internal seals toward ends of the cooler body that separate oil and coolant, and they can fail, mixing oil and coolant, but this seems to be less common than the external oil seepages. Good idea to jump on it when you notice the external seepage so it doesn't get to that point.

Before switching to that ELC, did your truck have green coolant in it and did you check the engine serial number? Reason I ask is because some older engines specifically were not advised to switch to ELC because it could do something with the injector cups. Make the sealant go bad or something. How does the oil dipstick look? Any signs of water contamination in the oil?

I'd be curious to hear you jump the starter relay or disconnect the 42 pin and crank it over cold.

 

5.If oil cooler leaks, oil will show up in your cooling system overflow tank. Here's why. Oil pressure is considerably higher than cooling system and oil will be forced into water first. Believe me, you DON'T want that. It turns your water into a thin silly putty that will take you days to wash off.
6. With >250K, I would replace it. It's not difficult, it's not expensive, and an ounce of prevention is worth a pound of cure.

 

Thanks for the organized replay Based on your info and other replies, it sounds like my first step is to maybe perform a pressure (maybe vacuum) test on the cooling system. I found some tools on HF website that should help with the job, as well as some YT videos. The more I think about it, I think a vacuum test would be best or maybe just go ahead and pull the cooler. I'm afraid if I pressure the system with the engine off, I'll push coolant into the oil system. In fact, I'll be checking if there's any sitting at the bottom of the pan today before starting the truck. I just hope my system doesn't turn into .

 

You are very welcome!! I try my best to be thorough, maybe too thorough. Takes me too long to get back to everyone. I always try to do research before replaying with more questions. Hell, I'm supposed to be mowing right now, but it was driving me nuts that I hadn't responded to anyone.

As I mentioned in my reply to udsuth, I may skip the testing and go ahead and pull the cooler. I'm not driving the truck because of this and don't want to create more issues.

I'm running Rotella T6. I've had to run the blend (T5) a few times due to not being able to source the full synthetic, but I've always run the T6 as long as I can remember. What's your line of thinking here?

 

I am glad you brought this up. This really had me POd after I finished the coolant flush. I chocked it up to the hydrocarbons eating away at the plastic and it probably being cheap plastic, but now you got me wondering. The screw cap rubber gasket completely detreated too, so I put the old one on for now. I'll do some more research on this later once I resolve the oil contamination issue.

Btw, big Volks fan. Had an '05 Jetta TDI that was amazing until an elderly lady pulled out in front of me. Luckily I was able to maneuver fast enough to keep from T-boning her dead on and hurting anyone, but the Jetta was trashed. I just bought a '15 Audi Q7 TDI off my dad. It's really growing on me. There's just something about those TDIs. I maybe reaching out to you in the near future for some upgrade advice on the Audi.

 

I'll see what I can do regarding the video. Not sure what y'all are referring to. Can you enlighten me? I kinda here a unique sound just before it turns over, but idk if that's what y'all are referring to or what it would indicate.

All glow plugs were replaced back in May of 2023. I think it's mentioned in the video, but maybe I forgot to add it. While I was on Paternity leave, I replaced all glow plugs, UVCH, and checked the torque on everything. This is when I also did the full coolant flush and replacement of degasser bottle.

 

Unfortunately I am not sure what coolant it was running. Before I learned about the ELC and the damages to the water jacked sleave from cavitation when running improper coolant, I was probably running some basic green coolant from the auto parts store. This also has me worried I may have a pinhole in a cylinder somewhere.

I did not check the engine serial number. The mfg date is 05/99 on the tuck door sticker. I will be checking for water or coolant in the oil today and try to get back to y'all this evening or tomorrow. I will also try to get a recording with the 42 disconnect, but as I mentioned earlier, I am supposed to be mowing and getting yard work done... Too much 💩 to do and not enough time.

 

It sounds like there might be a fluctuation in the cranking speed of the starter, a kind of rhythmic fast, slow, fast, slow. It happens so quick before the engine fires it's hard to be sure. I barely caught it, and probably only because I'm kind of an idiot savant of engine noises. Well full time idiot and occasional savant might be more accurate. If that is what I think I might hear, it can be caused by low compression on 1 or more cylinders. Which doesn't automatically mean the end of the world, but would be something to investigate before throwing a bunch of money at a motor that's got bigger problems.