Greetings all, This is my first post concerning my recently acquired 1996 F250 XLT, RWD,7.3 diesel, 130K miles.
Background - bought truck last week. Truck has been off road for at least 5 years, sitting. PO indicates that
truck will start but seems that not all cylinders are firing. Started up truck for the first time 2 days ago. Before attemping
to start truck - the fuel bowl was cleaned and new filter installed,oil level on dipstick appeared to be excessive, maybe 1 gallon or more overfilled, oil was black.
Fuel pressure gage was attached. Truck would fire with minimal cranking maybe 2-3 seconds,and run quite roughly for 2-3 seconds, then quit. Eventually was able to get truck to idle
, very rough, and was able to rev to 2800 rpm. Did smooth out some at the higher rpms.Fuel pressure was between 40 and 60psi. Shut off truck and checked oil, oil was now milky grey.
I think oil was floating on coolant in oil pan. When running minimal blowby observed out oil filler cap, also no white smoke out exhaust, no residue in tailpipe.
Guessing that oil cooler may be leaking coolant into oil, removed oil cooler today, and pressure tested to 30 psi, no leaks. Replaced orings and reinstalled.
In the process of adding coolant back into engine, through radiator, on the 3rd gallon I noticed continuous small diameter coolant stream out oil pan(plug was removed).
I have no experience with the 7.3, however my gut says cracked block or head, head gasket? The continuous coolant volume passing thru oil pan seems to be more that what a crack could allow to pass,
but don't know for sure. What would the possibilities be causing the coolant leaking into oil pan ? Thanks in advance.

 

Could always check cylinder compression. Possible there's an internal crack or hole. I have an engine on a stand in my shop that externally looks good but the inner wall of a cylinder is completely cracked.

If it's a steady stream as you suggest, no amount of radiator stop leak is gonna help 🤔

 

with coolant running into the oil pan that easy, i'd start by finding a running engine as that's one heck of a crack

 

I believe these have freeze plugs inside the head/valve area. Could be one of them rotted out or not sealing right

 

Front cover may be eroded as well behind water pump. If this is the case, engine removal and at least partial diassembly is required anyway.

Lots of places water can get into the crankcase.

 

Update: Removed oil cooler and it seems that outer(smaller) Oring of the end of heat exchanger that mates with front housing fell off during reassembly. This allowed a direct path for coolant to flow into crankcase. So yesterday when coolant was added back into radiator and level in block rose to sufficient level to exit front housing coolant port and migrate into port for oil return. Reassembled correctly this time.Now coolant does not mix with oil and this seem to have solved my original coolant into oil pan issue. The rough running was also fixed with new cps and connector cleaning and bleeding high pressure fuel port on regulator.

 

Thats awesome it was a pretty simple solution.

Thanks for the update!

 

I have been through something like this before. Fast forward, spoiler alert, I ended up not having a horrible problem but a much minor fix. In my case a saw little bit of oil in my coolant. Went to fix oil cooler o rings. Assembled it and installed. Ran truck, seemed fine running for a few minutes. Started my oil change and at the end of draining I saw coolant. Freaked out! Went through every emotion and heart break. Head gasket, front cover, etc!! I looked at my coolant again and saw a much larger amount of oil in it this time after the small amount of run time. Reached out to the forum and common answer was cracked somewhere in block, oil only can enter the coolant not other way around due to the higher pressure on oil side. Yes I understood that the odds of it being a major issue was high. But….

what had happened in my case was the spring bypass at the oil cooler head was faulty. I found this out by removing the oil cooler again and saw the bypass was broken at the rear head mount to block. This is where the block heater is.

So in my case, how unlikely a scenario I had, turned out to be a blessing. Of course, the work that followed flushing the oil/coolant, replaced rear head of oil cooler, new oil cooler tube and rings, etc, took several days. But luckily it was not a cracked block. Drove it 50 miles and changed oil/filter again. Refilled with cheap oil, ran it a couple hundred more miles, drained and no coolant. Then added new filter/oil with the good stuff this time.

now is that what is going on with yours, I don’t know. But there is a slim chance that it may be. This happened several years ago and truck is good today and haven’t had cross contamination on either fluid change since.

 

WHITE95PSD, thanks for revealing another trouble zone with the oil cooler. In my case it was a oring that fell out during reassembly. See my update post 2 posts before yours for details.

 

Hahaha. Funny when I replied the recent posts didn’t show for me. Otherwise I would have not replied in the fashion I did and look like a goof.

Will I’m happy it was the oring rather than valve. Expensive to replace that rear head where the valve is located.

The flushing process is so time consuming! I ended up buying a new coolant reservoir as I could not get the oil residue out.

I was so rattled when I had the coolant coming out of my pan. The oil cooler rebuild can be tedious with the rings and replacing both front and rear gaskets. I thought about researching a way to bypass this system and use an external oil cooler mounted at the front so I don’t have to rely on these orings and mitigate the cross contamination when they fail. If that is even possible 🤷‍♂️

 

oil cooler on these work better than oil to air, just like the rad does more for an auto trans than external cooler

 

thanks for confirming!