I’ve got a 2000 7.3 PSD, and when I start it up, it seems like the oil cooler leaks oil until it warms up. My question is, does this look like diesel or oil in my coolant? The oil looks clean, so I can’t tell which one it is—just some fluid that’s separating with the coolant. The top part looks like clean coolant, and I don’t see a film over it, but I’m not sure what it is.
It will smell like diesel if it is in fact diesel. Pull the cap off and stick your nose in there to sniff it.
If it smells like diesel, it’s the injector cups.
If it doesn’t smell like diesel and is in fact oil it’s the cooler o rings.
@Kai
I wanna say it’s oil it smells weird idk what antifreeze smells like but I don’t think it’s diesel ykwim
Dior said:
@Kai
I wanna say it’s oil it smells weird idk what antifreeze smells like but I don’t think it’s diesel ykwim
Diesel smells like the fuel in the tank.
Old antifreeze smells like rotten fish, fresh antifreeze will smell sort of sweet almost like syrup particularly when it’s warm/ hot. You can usually taste hot antifreeze when you smell it as well.
Had this happen on my 6.0. Ended up being the oil cooler
Is the contamination on top or bottom.
If on top- smell it, see if it smells like diesel. Injector cup failure usually pushes fuel into the cooling system, as the fuel pressure is higher than cooling system pressure.
If on bottom- still smell it, but try to notice if it smells like oil. A ruptured oil cooler will let oil flow into the cooling system, for the same reason as stated above.
It’s probably your cooler. And it’s oil. When it’s diesel it keeps its smell and it quickly overflows the cooling system.
You have to take apart your oil cooler and put seals at minimum but you won’t till you take it apart.
@Shiloh
I got you that’s what I’m hoping for I have new o rings and gaskets
Way to clean for an oil cooler rupture IMO. When was the last coolant flush?
Frost said:
Way to clean for an oil cooler rupture IMO. When was the last coolant flush?
I somewhat flushed it when I replaced degas bottle. The old one had this same stuff but barely any sitting in the bottom, I siphoned it out and put it in a 2L to see what it was. It looked like coolant and then water separated kind of. Flushed a bunch of brown sludge out of the radiator and put the new reservoir on, ran it for a few days popped the hood to check something and noticed how it is in the pictures.
I just got this truck a few weeks back, every time I check the oil it looks like clean oil so I don’t know. I’ll go get some more pics in a bit.
It’s got 421k miles and is just now getting the attention it deserves lol
@Dior
If it’s brown and foamy looking like a milkshake it’s engine oil, you’d know if it was diesel fuel it’d be a strong smell. Hopefully, it’s just the oil cooler o-rings that have just deteriorated. Oil coolers on 7.3’s are pretty easy and simple to remove and reseal. There are 4 o-rings: 2 black, 2 greenish, and then the 2 metal rubber gaskets for the front cover and block. Drain the oil and make sure it’s just oil coming out. Drain the coolant out of the RAD and there’s a plug on the block, a 1/4" plug on the driver side right behind the back of the oil cooler upper one I believe. Usually, those oil coolers will leak oil because the o-rings get hard and brittle and start cracking, or they leak coolant at the metal rubber gaskets, usually the one that seals to the front cover. 7.3 oil coolers themselves are usually pretty bulletproof, but hopefully, that’s all it is. If not, possible a blown head gasket, cracked head or cavitation which these are very rare or hardly ever happens for these slow heavy beast machines.
Water is heavier than diesel. Is it on top?
Day said:
Water is heavier than diesel. Is it on top?
I want to say the coolant is on top, fluid on bottom is a little murky, the oil on dipstick is clean fluid so I can see it not being straight up milk ykwim
@Dior
Oil or diesel would be floating because they’re less dense than water. But, the coolant is miscible with both water and hydrocarbons which is why you’ll get the milkshake when a head gasket goes or the transmission cooler fails to keep the separation. The action of the water pump circulating the coolant would be enough to agitate and mix the two normally separate fluids into an emulsion (all emulsions look milky). Go buy a cheap turkey baster and pull a sample of it from the bottom of the overflow and see what it smells like or take it to your mechanic.