6.0 diesel acts like no oil pressure when warm.

I have a Ford excursion with a 6.0 diesel. 20k ago I put in new injectors, oil cooler, fuel pump, standpipe, ect. It's now at 170k, and has run fantastic up until this week. Typically it takes 4 secs for the oil gauge needle to rise on start up. It still does but on hot mornings, it may stall before the guage rises. Once I restart, it runs smoothly. Then when driving home last Friday, after 30 miles in Michigan heat, it stalled at the light and no oil pressure on the gauge. It would not restart at all.

I had it towed home, and 3 hours later it started up and purred. I ran it at idle for over a half hour and it sounded great.

Today I started it and it slowly began to fire up, not the roar as usual but a assisted speed up of the started until it caught. It ran well at idle, but lacked power coming off the idle when moving. It did move. I parked it near the workshop so I had access to tools and 110v power.

I have a laptop scanner to get codes, monitor performance, and power balance.

To me it's like it doesn't have enough oil pressure to fire the injectors properly.

Any suggestions? Ideas?

I am trying to figure out a plan as I will start on it early next week.

Thank you for your help.

I am far from and expert on Ford 6.0 engines but I do know that the high pressure oil pump is a failure point on all of the newer powerstoke engines. I would not be running those motor any more until you have found the problem. The failure of the high pressure oil pump can push contaminates into the injectors. So then your looking at additional costly repairs.

That"s why I stopped and asking for comments. The original though by the local garage was that the oil broke down and caused this issue. I have 5k on Mobil synthetic diesel 5w-40 in it. The other thought was that the smooth Michigan roads caused a pigtail to break connection. I went through all the pigtails, and checked the oil.

My next step was to check the pressure relief valve on the low oil pump for sticking, then check the oil filter/refill to see if that area is working properly. Then I was going to pull the IPR to see if there is anything wrong there.

So if anyone has any suggestions or comments, I would welcome them. It is a 2004.5 6.0 (built in Jan 2004) with the old style HPOP (no cover).

I would put a "real" gauge in to see what the actual oil pressure is. The slow oil pressure raise on the factory cluster might be real or it could just be electrical in nature.

I would also pull the oil filter and look for any thing on it.

Does the oil "feel" and smell normal??? The heat these engine run at can cause the oil to break down if they are running too lean/hot.

Just throwing out some Ideas. I am much more familiar with the 7.3 and 6.4 engines. With the issues with the 6.0 motors not many of them are left around here.

My son had pretty much the same problem, ended up being a O ring popped on a dummy plug in the high oil pressure manyfold in the pass side head.

Couple years ago his truck stalled out of the blue on the high way.
The high pressure oil pump had failed.

The oil press gauge is on the low pressure side of the oil system. The high pressure side of the engine is fed oil from the low pressure side. There are multiple things with the high pressure side and leaks, most of them don't affect the low pressure side though. Significant high pressure leaks can cause low oil pressure concerns though. Typically HP oil leaks start showing up on hot engines, and go away or are not as bad on cold engines, reason is the HPOP can pump enough colder/thicker oil to overcome the leak, but cant pump the hot/thin oil quick enough.

Not that you really need to read the actual ICP (high pressure oil PSI), I'm sure you will probably find it to be low, since you have a starting problem. ICP pressure needs to be around 500 PSI for the engine to start. If you can get it to start, look at IPR% it should be somewhere around 30%, if its much higher then it's compensating for a oil leak, especially if you see 85%

Ok, if you read all of that, the only thing I was going to add is checking if you are actually pumping oil. all of this is covered in a video I found. Actually skip what I wrote above and start with this video first since you had injector and oil cooler work done recently. haha.

video here

(quoted from post at 21:53:19 07/03/19) It is a 2004.5 6.0 (built in Jan 2004) with the old style HPOP (no cover).

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I'd say you have a high pressure leak, plugged IPR, or failed HPOP, but there's a few electrical components that can do the same thing. YouTube is full of 6.0 videos. Spend your time watching the ones made by DieseltechRon and you'll find out what you need to do. I don't know anything about the early 6.0-s. There's a couple of cheap test fittings on eBay that you can use to pressurize the high pressure side to find a leak. I'm presently working on a 2005 and decided to RR all known areas that a leak can develop instead of the fitting that leaked. Doesn't take much more time and avoids going back in again.

You don't mention the EGR cooler in your original post. It is known to accumulate sludge. My F-350 had a turbo problem when it was just out of warrantee, and when the local dealer made a friend's 6.0 un-drivable, I elected to take mine to an independent that was highly recommended. He went into great depth with the diagnostics and besides the turbo he replaced the EGR cooler and the plugs/O-rings that bison mentioned, along with the HPOP. I agree that it sounds primarily just like low pressure from the HPOP, but a plugged cooler could be a major contributor. Since that major repair I have had no more problems with mine. I think that it is due in part to it working hard pulling a heavy trailer for 2/3 of the miles that it runs. Also I rarely idle it.

Hate to tell you this, but you have probably had a roller lifter come apart. The needle bearings get sucked through the low pressure pump, chewing it up. Pull the low pressure regulator that is behind the balancer, it may have pieces of needle bearing in it. If so, it is engine rebuild time, the cam is last out and first in on a 6.0 diesel. It is installed from the bell housing side, but there is a flywheel adapter on the crank that won't let the cam come out until the crank is removed. DO NOT REMOVE THE FLYWHEEL ADAPTER, it cannot be reinstalled square and the crank will be junk.

6.0 diesel is the last of the HEUI injected Fords. 6.4 dumpster fire and 6.7 are common rail injected with a high pressure diesel pump.

(quoted from post at 20:04:38 07/03/19) 20k ago I put in new injectors, oil cooler, fuel pump, standpipe, ect. It has run fantastic up until this week. ... on hot mornings, it may stall before the guage rises. Once I restart, it runs smoothly. Then when driving home last Friday, after 30 miles in Michigan heat, it stalled at the light and no oil pressure on the gauge. It would not restart at all. I had it towed home, and 3 hours later it started up and purred.

Today I started it and it slowly began to fire up, not the roar as usual but a assisted speed up of the started until it caught. It ran well at idle, but lacked power coming off the idle when moving.

I have a laptop scanner to get codes, monitor performance, and power balance.

To me it's like it doesn't have enough oil pressure to fire the injectors properly.

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Again, sounds like the classic high pressure leak. Now that I'm awake and have reread your post, buy the leak test adapter(s) and do a high pressure oil leak test after you scan and there's no codes. You can buy the IPR adapter and test both sides at once or buy the ICP adapter and a pigtail to send power to the IPR. Send 12v to the IPR while you're sending pressure through the ICP port, one side at a time. If there's a leak, you will hear it on the side you're pressurizing. Don't energize the IPR more than 30 seconds at a time, leaving a minute or so between test cycles.

The worst thing you said in your original post is you replaced your injectors 20,000 miles ago. If the job was done wrong or the reman injector cheap, your failure is likely under the valve cover. Your IPR is probably not plugged because you've run 20K after repair. Spend some time on YT watching DTR's videos. Do the easy stuff first. Do a pressure test. If no leak, test the ICP, IPR and FICM before you dig into the HPOP. If you want to measure oil and fuel pressure, buy billet caps with test ports. A lot easier than using the factory protocol.

The fact that she stalls or fails to start when hot tells you that you have a leak that the HPOP is unable to overcome. This is supported by the fact that she starts when the oil is cooler and thicker. Your suspicion that you're not getting enough fuel through the injector above idle tells you that you don't have enough high pressure oil to open the injector. Now you just have to figure out why. Forget about the doomsday scenarios. Analyze and work through what's wrong. Fix all known problems in the area you're working in so you don't have to return.

(quoted from post at 05:16:18 07/04/19)
You don't mention the EGR cooler in your original post. It is known to accumulate sludge. ... He went into great depth with the diagnostics and besides the turbo he replaced the EGR cooler and the plugs/O-rings that bison mentioned, along with the HPOP. I agree that it sounds primarily just like low pressure from the HPOP, but a plugged cooler could be a major contributor. Since that major repair I have had no more problems with mine.

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Coolant flows between the oil cooler and the EGR cooler. Sludge (coolant sludge) accumulates in the oil cooler, likely from coolant breakdown. As the coolant passages in the oil cooler plug, coolant flow through the EGR cooler slows. This causes the temperature in the EGR cooler to rise until excess heat destroys the EGR cooler. What starts as a minor leak at first sending coolant into the intake becomes greater until your engine hydrolocks and/or the head gasket(s) let go.