M35A3 Oil in Anti freeze

Heavy D.

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Newport News, VA
I just got finished putting a new radiator fan on the truck. I put everything back together and let her run for about 5 minutes, checking for leaks and what not. All was good. After shut down I popped the Coolant reservoir and saw oil. I dipped my finger in it and it seemed like A LOT of oil has gotten in there. There is no way I could have hooked up one of the oil lines to a coolant line right? I have absolutely no idea how pulling the radiator can all of the sudden start this problem. I am hoping somebody here can enlighten me.

thanks
 

Scarecrow1

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If you had it over heat on you before replacing the fan you could have a blown head gasket. That is the only way I know of oil getting in the coolant. Its not likely you crossed the lines or by now you would also have water in the oil pan too.. Good luck finding the cause.....
 

PETE BALLARD

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Does this truck have a cummings diesel? Oil cooler,air compressor and head gasket are all areas where there may be a problem. If i remember right they were also susceptible to holes developing in the cylinder liners if the coolant chemicals become out of balance (electrolysis) the head gasket and oil cooler is probably the most common area of failure
 

porkysplace

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Does this truck have a cummings diesel? Oil cooler,air compressor and head gasket are all areas where there may be a problem. If i remember right they were also susceptible to holes developing in the cylinder liners if the coolant chemicals become out of balance (electrolysis) the head gasket and oil cooler is probably the most common area of failure
3116 caterpiller motor , what ever it is , it's probably not going to cheap .
 

wb9btz

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The surge tank return line carries radiator coolant back to the surge tank from the connection at the right TOP of the radiator. The transmission fluid (15W40 oil as used by the Military) cooler lines (integral to the radiator) come out the RIGHT SIDE of the radiator. If you got the right top and right upper side mixed up you could be putting oil into the cooling system and coolant into the transmission. Check TM9-2320-386-24-1-1, page 358 for correct connections.

If you did get them mixed up, I'd suggest a complete drain and flush of the coolant system and the transmission.

This may not be your problem, just one possibility. Good luck
 

carolinanum1

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I've had bad oil coolers and a bad tranny cooler which pushed the tranny
fluid completely out and fried the tranny. Try obvious first. Do you have a
friend at your local CAT house? They are priceless !!!
Happy Hunting!!
 

Heavy D.

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Thank you everyone for your thoughts on this. I sure do hope all that it is is a crossed line somehow, even though I have examined the diagram in the TM quite a bit. I will take some pictures tomorrow just for the heck of it, so there is NO doubt among all of us that they are hooked up correctly. When I drained the coolant the first time, it looked a little dirty, but not oily. after this last start up it looks simply... polluted.
 

Heavy D.

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Newport News, VA
Coming to think of it, the TOP and TOP RIGHT coolant and oil lines cannot be mixed up. the oil line is attached via a threaded fitting, the coolant line is merely a nipple with hose clamp. There is a "CAT house" about 30 miles away but I am deathly scared to hear any figures. When I was running without the fan the temperature never went above 200 degrees. What exactly is considered overheating for these engines? I will get the pictures up this afternoon, and drain the coolant to re assess.
 

carolinanum1

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I have a 93 m35a3. If you need to compare I can get a photo to you. I always get my free info from the CAT house, just like to pick there brains and just try to narrow down possibilities
 

Heavy D.

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Ok Gentlemen, here is how the lines are attached. As I see it, they are in accordance with the TM. I believe only the oil lines can attach to fittings specifically for the oil lines, so cross contamination is ruled out as far as I can tell. the last pic is a sample in a mason jar that has been sitting for about 20 minutes. It looks to be about the same as it did before, I guess I wasn't paying close enough attention. If it was flooding with oil it would look much worse after 5 minutes of operation. To me it doesn't look tooooo contaminated yet so it leads me to believe it is either A. a minor leak, or B. has just began. At this point I am hoping it is the oil cooler. I have also read that the air compressor could also be a culprit. I am awaiting on a call from a diesel shop about 12 miles away to pick their brain, and if it is a light risk to drive it to them I will surely do it. Does anyone know what the general idea of an overheat temp would be?

Paul


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Heavy D.

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Newport News, VA
Were did the sample come from, bottom drain??Do you have access to a coolant system pressure tester?
I drained around 3/4 of the coolant into a 5 gallon water jug and poured some out into the mason jar. I do not have access to a pressure tester. Is that something you can rent from an auto store?
 

carolinanum1

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Usually have pressure testers at a truck shop. We have a MAC set for several different radiators. Usually the oil comes out last when drained from bottom. Could see about how much total is in the system. What was the mileage and hours on your motor?
 

PETE BALLARD

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overheating temps usually are over 200 degree F when ambient temps are moderate, if operating under load and ambient temp is over 90 degree acceptable temps can reach 205-210 but i would not want to see them any higher. No coolant in the oil? It will turn it grey and milky. You may have to remove the oil pan, pressure up the cooling system and look for the leak inside the crankcase
 

wb9btz

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Yes... I was servicing my A3 this afternoon and looked at those two fittings... I don't see how they could possibly get mixed up accidentally ...so scratch that idea.

I guess my next thought would be if removing the radiator somehow disturbed the internal (to the radiator) transmission fluid cooler and opened up an internal hole, allowing trans oil and engine coolant to mix.

There is also an engine oil cooler on the upper right side of the engine block that allows radiator coolant to cool the engine oil. Maybe that sprung a leak allowing engine oil and radiator coolant to mix. Seems to me that there is one of those for sale on "the Bay". Good luck & may your problem have an easy, inexpensive solution! :wink:

BTW.. Normal operating temperature is 160-230 degrees. I've never seen mine above 180. Seems to me I've read that the truck needs to be loaded and working pretty hard to get much over 180 and the fan will free-wheel until the truck gets pretty hot.
 

Heavy D.

Member
62
3
8
Location
Newport News, VA
Usually have pressure testers at a truck shop. We have a MAC set for several different radiators. Usually the oil comes out last when drained from bottom. Could see about how much total is in the system. What was the mileage and hours on your motor?
True, I will drain the remaining coolant tomorrow and see if there is a difference. The engine "according to the gauge" says 341 hours, and 6,200 miles. I too was thinking perhaps something was broken loose during the jarring of the radiator a little bit. it reached 200 degrees because my old fan (what was left of it) had almost no blade area left after it demolished itself in the water. That being said when it occurred it punctured two tiny holes in the main radiator which was fixed with radiator stop leak in short order...
 
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