My first post here. Bought a cheap 2001 F350 with a 7.3, just over 245k miles on it. Was not running when I bought it. Didn't start, and oil in coolant.
It had a LOT of oil in the coolant... previous owner didn't know much about cars, trucks, engines in general I guess.
Long shot but someone may recognize my name from NASIOC, a Subaru forum. I race my Subaru Impreza on the road course as a hobby and have built it up in my home garage over the past few years. 295 slicks, roll cage, sleeved motor, big turbo, 600awhp from a 2.5L
Anyways, I bought the truck cheap, didn't mind doing work to it and I think I'm pretty good with tools so I had a go at it (first diesel engine). I cleaned the engine down, did an oil change twice to flush everything. Cleaned the oil cooler and changed the o-rings and gaskets, new de-gas tank, etc. Pulled the valve covers off, put new ZD-11 glow plugs in, new AP injector o-rings, new glow plug relay, flushed the coolant system like 4 times with simple green, and like 10 times with water, it currently has RO/DI (reverse osmosis de-ionized) water in it (RO/DI unit for my reef tank).
Fired up right away (glow plug relay was dead before). Drove the truck around, runs very smooth, good power, no smoke, nice idle, no oil in the coolant anymore. Also popped the oil filler cap off and this motor has ZERO blow-by. I was so amazed that the original motor in this thing has 250,000 miles on it almost and I put the filler cap on the filler neck upside down and it barely even moves.
Now to the bad part, I was driving it the other day, about to put ELC coolant in it and noticed that the coolant level was low. Checked dipstick, oil level is high. Loosen drain bolt to oil pan and like 4 litres of water was in there.
I drained the water out of the pan, added water back into coolant tank, truck drives fine... no oil in coolant with truck idling for over 30 minutes. I think that rules out the oil cooler being bad? With truck hot, coolant pressure is up of course, turned off the truck, came back a few hours later when cold and the coolant tank is completely empty. Drained into the oil pan again.
What do you guys think it is? Cavitation problem? I am going to pull off the water pump this weekend to check the front cover as I've read around this part can develop pin holes from cavitation if the cooling system is not maintained properly (which I doubt the previous owner did).
I don't think it's the injector cups? I don't have fuel in my coolant or oil in my fuel (checked fuel bowl when changing fuel filter).
I also don't think it can be the oil cooler anymore since there is no oil going into the coolant when engine is running? However I can see coolant bleeding off into the oil cooler when engine is off since coolant pressure will be higher when engine is off and hot...
Pin hole in the block? I really hope it isn't this. Haven't done a compression test on the motor but since the truck has like zero blow by maybe we can rule this out...
Once I pull the water pump I'll look at the front cover... if it's good I will have to drain oil, remove oil filter and pressurize cooling system to see where coolant leaks out from I guess.
Any insight to the problem guys? I have pretty much done all the research I can.
250k miles on stock 7.3
Oil cooler o-rings/gaskets changed
New injector o-rings
New glow plugs and relay
New oil and filter
RO/DI water in coolant system
No external oil or coolant leaks
No smoke from tail pipe
No blow by whatsoever
No oil in cooling system
Coolant level stays relatively high with engine running
Coolant bleeds off into oil pan when engine is off and hot after a few hours
Front cover? Cavitation? Injector cups? O-cooler problem? Pin hole in block? Head gasket? Cracked head?
I have been driving the truck around for about 120 miles total now with straight water in the cooling system. Is that enough mileage to cause a cavitation issue that quick?