So I recently bought a new pickup, just like every other guy who has a problem with their first diesel I need advice. It is a 1993 F-250 factory turbo 7.3 idi, has a zf5 and 189K. I have had it for three days. Today I decided to do an oil change, everything looked fine, but then I checked the coolant, it is a dark grey sort of milk color, but more dark. It also was very sludgy, according to the guy I got it from, he had a professional mechanic replace the oil cooler about 6 months ago, should I trust he did the installation right, any ideas would be greatly appreciated! Also, the motor was hot when I first got to check it out so I couldn't check the coolant.
Oil in Coolant, need advice!
- Thread starter longbox93
- Start date
Darrin Stephens
Call Her Facetious
Having any over heating problems? That could be a sign of a bad head gasket. If not I would say it's the oil cooler leaking coolant into the oil.
- Darrin
- Darrin
No, the motor doesn't get excessively hot. I have read a lot on this, but nobody reports the coolant being sludgy like mine is. Is that what oil in the coolant looks like? I would have thought it to be more milky, thanks for the reply too.
Darrin Stephens
Call Her Facetious
I can't recall anybody saying anything about coolant being sludgy when oil got into it, but I'm not the most experienced with this problem. Hopefully a member with some expertise with this problem will reply to your post soon! 
- Darrin
- Darrin
IDIoit
MachinistFabricator
its not a headgasket.
coolant pressure exceedes your oil pressure.
so if it was a gasket problem, you would have water in your oil.
i would say that your coolant is overdue for a change.
drain it, fill it with straight water. run it for a day.
then flush again. ive seen people actually putting oil in their coolant...
people do the strangest things.
dont sweat it until the problem happens again.
read, i mean READ the stickey threads.
those are the threads at the top of the forum page.
when youre done with that, crack open a beer or 5, put 3 of them down quick, then enjoy the tech articles.
you will find about everything in there from recommended coolants, to cool little mods you can do to gain power, and make your beast more reliable.
coolant pressure exceedes your oil pressure.
so if it was a gasket problem, you would have water in your oil.
i would say that your coolant is overdue for a change.
drain it, fill it with straight water. run it for a day.
then flush again. ive seen people actually putting oil in their coolant...
people do the strangest things.
dont sweat it until the problem happens again.
read, i mean READ the stickey threads.
those are the threads at the top of the forum page.
when youre done with that, crack open a beer or 5, put 3 of them down quick, then enjoy the tech articles.
you will find about everything in there from recommended coolants, to cool little mods you can do to gain power, and make your beast more reliable.
IDIoit
MachinistFabricator
welcome to the forum, now put your vehicle in your signature so we know what youre working with in future threads.
C_Luft
Full Access Member
The sludge could be from the previous owner not doing a good coolant flush after the oil cooler was replaced and the left over oil that got into the cooling system made its way to the top of the radiator. And or they mixed different coolant brands and that can look like sludge if there is oil present.
79jasper
Chickenhawk
^Got in backards buddy. Oil pressure exceeds coolant pressure. Say 40 or so psi vs about 12 psi. But coolant pressure stays built up longer than oil pressure when you shut it off.
Oil into coolant usually won't sludge up. Normally it'll settle at the top of the radiator.
Could be someone changed the water pump and didn't use sealant on the bolts that pass into the timing cover = coolant in oil.
With the oil cooler can get oil into coolant while running, as oil pressure is higher than coolant pressure. But then you shut it off the coolant can push into the oil system.
Could be they didn't flush the cooling system.
So I would start by flushing the cooling system. Put in all new coolant. Get the fleet charge concentrate. Need about 4 gallons, get 5 to be safe. Also pick up 5 gallons of distilled water. Pour in one gallon of water per one gallon of coolant.
Some use cascade dishwasher soap to flush the system. You'll need to pull the block drains. One of the flush kits can help, but not necessarily needed.
Might as well throw in a new thermostat while you're at it.
Also, is it using any oil?
Sent from my SM-T537R4 using Tapatalk
Oil into coolant usually won't sludge up. Normally it'll settle at the top of the radiator.
Could be someone changed the water pump and didn't use sealant on the bolts that pass into the timing cover = coolant in oil.
With the oil cooler can get oil into coolant while running, as oil pressure is higher than coolant pressure. But then you shut it off the coolant can push into the oil system.
Could be they didn't flush the cooling system.
So I would start by flushing the cooling system. Put in all new coolant. Get the fleet charge concentrate. Need about 4 gallons, get 5 to be safe. Also pick up 5 gallons of distilled water. Pour in one gallon of water per one gallon of coolant.
Some use cascade dishwasher soap to flush the system. You'll need to pull the block drains. One of the flush kits can help, but not necessarily needed.
Might as well throw in a new thermostat while you're at it.
Also, is it using any oil?
Sent from my SM-T537R4 using Tapatalk
IDIoit
MachinistFabricator
i was speaking in the headgasket area. true that constant oil pressure is higher than the coolant pressure.
but when youre talking about an area with oil only pressureised with crank case pressure.,,,,,
blah blah, yea i know im an idioit... just look at the ******* name
I have only had the truck for a few days, but I can say that the oil level was fine on the dipstick and the truck had a service tag where the previous owner went past by about 700 miles. He said the truck didn't leak any oil which was a lie lol, but the oil level was fine. I got it just a little North of Seattle and I live by Salem, about a 240 mile trip and everything ran fine.
79jasper
Chickenhawk
Ah, yeah. In the head gasket area, yes.
Sent from my SM-T537R4 using Tapatalk
Sent from my SM-T537R4 using Tapatalk
PwrSmoke
Full Access Member
Best idea is to flush the cooling system, maybe more than once or twice, running the water with a very mild flushing compound for a day or so before draining. After that, when it seems to be clean, fill with water and a rust inhibitor only, observe, and see if more appears. If not, after an appropriate period, refill with SCA-laced coolant, go forth and make some black smoke.
With no clear direction, always start with the least expensive step. Potentially, leaking oil cooler seals can put oil in the cooling system and coolant in the oil almost simultaneously. When the engine is running, oil pressure is higher and oil goes into coolant. Shut the engine off and the reverse happens. I have never faced this problem with my own truck (though I have resealed the cooler, plus decades of professional wrench twisting experience) and the best approach is the a calm, methodical and measured one. Step by step. Start with the most likely and least expensive answer (unless another answer comes out to bite you in the ass) and work your way down the list of possibilities in order of likelihood and the evidence presented. Otherwise, you are running around, stepping on your crank and making it just about impossible to pinpoint the problem and make a pinpoint repair.
The most likely answer is that whoever did the cooler repair did a poor job of cleaning out the cooling system. There are increasingly more dire possibilities that you'll have to work your way thru if the oil continues to appear. It isn't unknown for seals to be damaged while resealing a cooler, so don't necessary discount the idea of tearing the cooler apart again.
I have found small oil cooler leaks in other engines by draining the oil when the engine is really warm. Then move the oil pan out of the way and place an empty one there, put the cooling system under pressure with a pressure tester and keeping it pressurized for a long time. On a good cooling system, it should hold pressure for a long time and only very slowly leak down. If you have a cooler leak, the pressure will drop more quickly and eventually water will dribble down into the pan and out into the pan.
With no clear direction, always start with the least expensive step. Potentially, leaking oil cooler seals can put oil in the cooling system and coolant in the oil almost simultaneously. When the engine is running, oil pressure is higher and oil goes into coolant. Shut the engine off and the reverse happens. I have never faced this problem with my own truck (though I have resealed the cooler, plus decades of professional wrench twisting experience) and the best approach is the a calm, methodical and measured one. Step by step. Start with the most likely and least expensive answer (unless another answer comes out to bite you in the ass) and work your way down the list of possibilities in order of likelihood and the evidence presented. Otherwise, you are running around, stepping on your crank and making it just about impossible to pinpoint the problem and make a pinpoint repair.
The most likely answer is that whoever did the cooler repair did a poor job of cleaning out the cooling system. There are increasingly more dire possibilities that you'll have to work your way thru if the oil continues to appear. It isn't unknown for seals to be damaged while resealing a cooler, so don't necessary discount the idea of tearing the cooler apart again.
I have found small oil cooler leaks in other engines by draining the oil when the engine is really warm. Then move the oil pan out of the way and place an empty one there, put the cooling system under pressure with a pressure tester and keeping it pressurized for a long time. On a good cooling system, it should hold pressure for a long time and only very slowly leak down. If you have a cooler leak, the pressure will drop more quickly and eventually water will dribble down into the pan and out into the pan.
IDIoit
MachinistFabricator
icanfixall
Official GMM hand model
Welcome to the forum. My suggestion is to flush out the cooling system. Many ideas how to do this but removing the block drains on goth sides is a must to get all the crap out. the passenger side block drain is hard to reach without contacting the hot side of the battery feed to the starter. That line is always hot with 2000 amps ready to melt any wrench or screw driver. Best to remove both battery negative or positive cables before working there. Please install block drains like found on the bottom of most radiators. then you just reach up and open them much easier than a wrench is. Some like using Dawn dishwashing liquid for dishes in the sink. Not the stuff for automatic dishwashers. Dawn breaks down the oil faster than any other out there. Its safe to use and drain to the gutter too. Most automatic dishwasher detergent is caustic in nature. Thats why it clean so well.. Us plain tap water for the flush. Flush with a cleaner twice. Then as posted refill will water and rust inhibitor and run it. See if any oil collects again. Most of the oil will collect in the recovery tank too because its floats up into the pressure cap area and it pushed over. Watch the tank for oil too. Its simple to remove the tank and drain it too. If no oil shows up on say 200 to 500 miles drain the tap water and rust inhibitor and add only distilled water and coolant. There are several good coolants to choose from. Be careful to only buy diesel rated coolant. Distilled water has no minerals in it that drop out clogging up the radiators and its non conductive too so no electrolysis.
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