This is going to be long winded, and i apologize in advance.
I just bought my first diesel recently, '97 standard cab powerstroke w/ZF5. 170,000 miles and had been all stock until the PO, within a year, put a 4" exhaust and a TS 6 position chip on it. I got the truck for an extremely good deal and couldn't pass. He was selling cheap because it had "blown head gaskets". Along with that, it had another issue. It was mixing oil into the coolant, from which he told me the oil cooler had gone bad. He replaced the oil cooler but told me he didn't know if he got it together well enough because he didn't press it back together. His reasoning for determining a blown head gasket was water in the oil. So, knowing i was buying a project, i took it.

I have a buddy who is a diesel mechanic and we did some tests. Come to find out, it did indeed have a cracked injector cup. I went ahead and replaced those and drove it for a weekend. Went to the lake and noticed a decent oil leak coming from the oil cooler. Figured i could make it 2 miles to my home. Got 1/4 mile down the road and she ran out of oil (enough to shut down the injectors) and i immediately shut it down and towed it home. once home, pulled the oil cooler and sure enough it had a broken o-ring. replaced that and now the truck has a slight knock. It runs rough and is hard to start, but i'm kind of assuming its because the injectors still haven't bled all the air from the system after running them out of oil? and through this, i noticed i still am getting water into my oil. I check the dipstick, and there doesn't appear to be any water in the crankcase, but if i pull the valve covers off, there is still the milky sludge everywhere on top of the head and in the valve covers, and the end of my tailpipe has a liquid residue in the bottom of it.

My main questions being, could i still be looking at a blown HG? Even though we had found a bad injector cup and wrote that off at the coolant in oil?
And what might be the source of this newly found knock?

Sorry so long, I'm very new to this diesel stuff and looking for help. Not new to these 90's trucks in general though. Any help is greatly appreciated.

 

After the truck sits overnight, pull the drain plug carefully and see if water comes out before oil. How fast does your water level drop?

The knock could be an injector, but if it has had a lot of water in it you could have also wiped a bearing or more out. Headgasket failure on a stock truck is not very common, but anything can happen.

 

If have to wonder if the stress from water and running the truck out of oil could have spun a bearing. How long will a truck run off the hpop reservoir oil

 

He won't hurt the bottom end it will die like it did first. The injectors get starved from the top end running short and it dies.

Running rough and hard to start is from starving the top end of oil. You got air in the system. The knock could be an injector, but I would like to hear if you find any water in the pan.

 

When it ran out of oil, it started misfiring badly and suddenly my gauge lost pressure. When i got it home i still drained maybe a gallon of oil out, so it didnt run dry. Just enough to quit firing injectors. Ive only put maybe 50 miles on it since the cups, and ive changed oil twice. (Once changing the oil on its own) both times it appears to be no water. If i top off the the degas bottle, and drive for ten miles, the bottle will be empty again. It also pressurizes the degas bottle and pushes coolant out.

 

is the truck running hot? run engine and look in the degas bottle if its bubbling while the truck is running your getting compression gases into the coolant. this will push coolant out when the engine gets hot. the milky stuff on top could just be condensation from heat cycles not sure where you live but if it gets kinda chilly at night it wouldn't surprise me depending on the amount that's up there.

 

The PCM will shut the motor down with low or no oil pressure. The motor should be OK, I did it once losing all my oil until it shut down and all is good. Good luck with the other problems.

 

If your degas bottle is being pressurized you either have an injector cup leaking, head gasket is blown or holes in the cylinders from cavitation. If you already had 1 injector cup that was cracked there could be more ( did you replace them all?). The only way to pressurize the coolant system like that is to have combustion gasses getting into the coolant system.

One other possible theory for the knock, you could have hydro-locked a cylinder that the coolant leaks into. When the engine is not running the coolant will enter the cylinder and fill it up. When you go to start the motor it will pressure the coolant up too much and can bend a connecting rod. I hope that is not the case but definitely possible.

 

The motor does get hot if i run it a little hard. And it hasnt gone below 80 degrees here since ive had the truck. But if i take the oil cap off the valve cover while its running, and put my hand over it, my hand gets wet from steam. Its straight steam.

 

I replaced all 8 cups. And the motor actually did hydrolock once when it sat for a couple days. I didnt push my luck and just pulled injectors and GPs and cylinder #8 was the culprit. Full of coolant. But it didnt knock til the oil ran dry. Knock actually comes from what sounds like the top of cylinder 3 or 5. Which would confirm the knocking injector like suggested above.

 

I should add that the knock sounds more like a tick or tap. Not a deep knock. If that makes sense.

 

He's loosing coolant...

I doubt an injector cup... He'd have diesel in the coolant if that was the case.

Since you had coolant in cylinder 8, that defiantly points to a HG, Head or block issue.

Maybe I've missed stuff in the thread, but that's what I get out of the information I've read.

 

The injector cups seal in two spots with green locktite, one on each side of the water jacket in the head. A crack in the cup in the area of the water jacket will put diesel in the coolant. But if the lower seal is not sealed right it will leak coolant and allow combustion gasses into the coolant system. There will be no raw diesel in the coolant system in this instance.

He said all 8 cups were replaced, so a crack is unlikely but one might not be sealed well.

 

I took my sweet time cleaning each bore and putting the cups back in, making sure they were all in right. Doesnt mean they are i guess, but im confident they are okay

 

They are probably fine, I was just explaining to williamub that there doesn't have to be diesel in the coolant with a cup leaking.

I think your only option at this point for the leak is to pull the head and see if its the head gasket, it most likely is. That sucks man!