now somebody please tell me whats going on here.. i have an 86 ford 6.9 4-speed. one day i was driving and noticed the engine overheating so i pulled over and checked the water.. there was oil in the radiator.checked the oil.. way over full and chocolate milk.. got it towed home and i thought surely its the oil cooler, pulled it off, tested it for leaks and checked out good so i checked the aluminum housing for leaks and warpage, and it was good. put new o-rings and gaskets on it and made sure the bolts were torqued to spec and changed the oil and coolant thought surely i did something good.... nope same thing when it sets overnight, oil in the bottom of the oil pan, start it up and let it run for 30 mins oil in the radiator. the motor runs like a champ.a swiss clock.. i have heard of one or the other, but not both same time. has anyone had this happen to them?

 

WOW. I'd venture to say that there is a problem with the oil cooler. the oil pressure is 50 psi and the water is 10 psi. the oil pressure wins and this is how the oil is pumped into the radiator. the water in the crankcase is another problem and might be from head gasket or cracked head or even cavitation (pin holes in the cylinder walls). I hope i didnt pee on your parade with this info, but I wanted to give you places to look.

 

When you say you tested the oil cooler for leaks, did you have it pressure tested on a testing fixture? If not, either end or the center section could be leaking only at operating pressure.

 

i still cant see why it runs so good it couldnt be a head gasket or cavitation.. i thought these things made a motor run poorly as well as having the other symptoms, i put pressure on the cooler and let it sit overnight, still had 120 psi. the next morning

 

Did you pressurize the whole cooler, or just the coolant side, or just the oil side? To check for internal leaks, you must pressurize only one or the other.

 

As far as a blown head gasket affecting performance, it all depends on where it is leaking at.

I had a cracked block, let oil in water, water in oil, ran great till you shut it off.
Then the water filled a cylinder and hydrauliced the motor. Pulled glow plug and blew the water out of the cylinder, replaced the glow plug, started just fine, ran great.

But with water in the oil I know it would not go very far at all till it would have locked up. That would have occured as soon as the oil pump started pumping water where the oil was supposed to be.

 

i ressurized the water side only, 120 psi, what is max water pressure in these....like 15 psi there is no water getting into the cylinders, it has to be a cracked block, the 6/9's were rone to cracking i have heard, this crack is just in a weired spot i guess between an oil passage and a water passage, would international really put these so close together??? probably so... i guess i will just run er' till she blows and put a 460 in it or a CUMMINS

 

You don't know it is a cracked block, it could still be a head gasket, and one way or another it still may be the oil cooler. (Although I agree, it should have leaked with the test you did). I have also heard 6.9's are prone to blowing head gaskets, but I haven't had one go bad. Could be that just because these engines live so long, they eventually have problems, and people think they are then prone to it.

 

you know, i think you are right, they do seem to run forever, people dont give them enough credit for what they are, i have seen these trucks go through hell and back many times and live through it time and time again, i guess ill pull the motor out and give it a valve job since im pulling the heads anyways and put new gaskets in it, still a good truck, hell, the 7.3 i drive now has 330,000 miles on it and still runs like a champ, i want to put a turbo on it, but can't seem to find the right erson to help me with bending pipes for it and stuff, either that or i will put this motor in my jetboat i am thinking about, "i have it posted under diesel jetboat" pipes would be way easier in a boat, more room, plus i think the 6.9 would wind up faster which is what you need in a boat.

 

has this ever hapened to anyone before? i thought i'd bring up the thread again to see if anyone has new input. i fired the truck up just the other day, been setting for a few months and with a little ether and a hot battery, she fired off like she was still warm and purred like a kitty cat. i just fired it up. didn't check anything, but i still can't see why theres water in the oil and vise versa. i guess i will have to mess with it some more.

 

Did you ever change the head gaskets? That is where I would start. Pull those heads and look, it may be something simple or not.

 

6.9s blow headgaskets all the time, I bet its that. Mine ran fine, until I turned it off, now it wont start.

 

Really? All the time?

 

this one fires right up ,there is NO water in the cylinders!!! i promise, i guess i just got the oddball one. im just gunna take the motor out and all apart to see if i can find anything worng, i will tell ya'll when i find out.