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Discussion Starter · #1 ·
The oil cooler is built into the radiator right? Is there a specific way of checking the radiator once it's out to determine if it is indeed bad. Could you put air through where the lines hook up to see if it blows through. I'm no expert mechanic so these may seem like silly questions. I just want to be sure before i order something. Any help would be appreciated.
 

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the engine oil cooler is behind the oil filter housing on the side of the block, i don't know about the tranny oil cooler on the autos.
 

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Discussion Starter · #3 ·
Here is my next question. Ive read a couple of archives that people have said when oil coolers go bad they fill your radiator with oil. Is it connected to the radiater, and how? It's taking the oil out of my crankcase and putting it into my radiater under pressure to the point its filling my overflow and not registering oil on the dipstick. I'm just trying to get an understanding of how it ties together and works.
 

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the oil is water cooled. it has a radiator type thing that is in the block. it will get a leak and oil pressure is higher than water pressure.
 

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This is an old engine oil cooler next to a new one . . . .





It is immersed in the engine coolant inside the engine block, behind the engine oil filter mount . ..





Next to cylinders one and two . . .





Cool engine coolant is drawn from the radiator, through the water-pump, and into the block right there where the engine oil cooler is mounted.

That's what cools the engine oil.

NOTE: That same oil cooler location lends itself to warming the engine oil on a cold start-up as during the initial warm-up, the engine coolant thermostat is closed and engine coolant is circulated in the long-block thus bringing the oil temperature up to a minimum. ;)

Unfortunately, oil cooler failure resulting in oil mixing with the engine coolant is not unheard of with the older CTDs. :(

Hope this helps. :)
 

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Discussion Starter · #7 ·
That is exactly what i needed to see. Where does one get a new oil cooler, or is it usually a gasket thing? Or both? Once thats done how do you flush all of the oil out of the cooling passages? Im asking alot of questions, i should stop. Thanks again.
 

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When I have a cooler failure at work I use Cascade dishwasher detergent to clean the system. Drain the coolant out and fill the system with water, while filling with water ad a few cups of Cascade. The cascade works well because it won't get all sudsy.
 

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Discussion Starter · #10 ·
I dont mean to be a goofball here but do you use the cascade and just the pressure from a garden hose or how exactly do you do this procedure? Do you do it after you swap out the old cooler with the new one installed to remove oil residue. Once again im new to cummins and feel like im asking stupid questions. Your help is very appreciated.
 

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no worries about all the questions, that's how we learn. when you get it all back together put the straight water and dishwasher soap in it and run it at least till the thermostat opens to let it circulate for a while. i like to drive mine around a bit, just like BC847 said in another post, grab a cold mt dew and tell the mrs you'll be back in a bit. use the soap till there are no traces of oil, them do straight water a couple of times to flush out the soap, then you should be good!
 

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Discussion Starter · #12 ·
Well today i went ahead and pulled my truck into the garage and removed the oil cooler. Radiator had a bunch of oil in it, the overflow was completely full of oil and the pocket where the cooler goes as well. Does the filter itself usually fail or is it the gasket between the oil filter plate and the oil cooler plate? There was nothing glaringly obvious with the cooler itself. I tinkered with it a little bit with low pressure air and nothing was blowing out anywhere. I may not be testing it right but nothing seemed bad on the cooler. i mean everything had massive amounts of oil in it, seemingly none of the symptoms of a head gasket. Im going to order parts monday i reckon, just wish i new for sure.
 

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if the gasket were to fail you would have an external leak. i was in the same boat as you, oil everywhere. all i can say is i've had one that the oil cooler fixed the problem, and one that it didn't. i wonder if you could take that cooler to a radiator shop and have it tested? if air won't leak through you wouldn't think oil would?
 

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Discussion Starter · #14 ·
I took my oil cooler to the local radiater shop today and had it pressure tested, it was the best bad news ever, they confirmed the oil cooler was toast. On the down side the Cummins cross point in Indianapolis wants 315.00 for a new one, 24.00 for the gasket thats sandwiched between the plates, and 14.00 for the one on the side of the block. I reckon it's still cheaper than a Head gasket and possible machining. At least i have a definate cause. I will just keep my fingers crossed on everything else having no issues for a while.
 

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i think i was around 350 shipped for everything, so that's right in the ballpark. i may take my old one in and have it tested, just to see. glad to hear you found it!!!
 

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I beleave my oil cooler just went south. Filled up my radierior till oil was poring out my overflow. At first thaught it was a head gaskit but now thinking its this. My qusetion is ar the coolers year spasific? ive been finding a lot of used coolers that look newer on ebay. But moast are from 24v's. An my truck is a 12v 94.
 

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Discussion Starter · #18 ·
I ran that option through and you just have no guarantee unless you have it pressure checked, then you ask why are they selling it. I just ponied up the money, went to cummins and got the right one, and they wanted the numbers off the engine.They have switched to a new one, but i dont know if a 24 v will work or not. Im still cleaning oil out of my radiator, i even did the cascade thing. Its almost out.
 

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I Just ran into this deal last weekend. Same exact thing. Mine is a 99 though. Think this is possible? I was on the trail of the head gasket but after reading this i think its the oil cooler now. I just about traded her in the night it happened. NOTHING BUT PROBLEMS....NOTHING IS RELIABLE ONCE MODDED!!!!
 

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Discussion Starter · #20 ·
I would say it's deffinately possable! My truck was not modded in any way, so i didn't think it was a head gasket. My truck has 75k on it, but it set for a long time, and i dont think they kept up on the anti freeze. It's a big decision to just tear into it and pull it out, but its cheaper than the head gasket, especially if its not the head gasket. Process of elimination, i had oil in radiator and overflow, mass amounts not traces. No water in oil, and crankcase oil not registering on dipstick. Pouring oil out the overflow. While i was doing that i went ahead and did the KDP.
 
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