Oil in radiator on JCB 185 skid steer

SamJackie

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May 23, 2025
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Hey folks, I am hoping someone can help out, so I recently picked up a JCB 185 Robot skid steer. Mechanically, it runs great, but I ran into a concerning issue, there's oil mixing with the coolant in the radiator. I drained and flushed the system, but within just a few minutes of running, the oil shows up again. I'm trying to figure out how the oil's getting in there. Could it be a blown head gasket, oil cooler failure, or maybe a cracked engine block? Not sure where to start. Has anyone dealt with this before, or have suggestions on how to properly diagnose and fix it?
 
Oil mixing with coolant usually means a blown head gasket, cracked block, or oil cooler issue, you can start with a compression test and inspect the oil cooler first
 
Hey folks, I am hoping someone can help out, so I recently picked up a JCB 185 Robot skid steer. Mechanically, it runs great, but I ran into a concerning issue, there's oil mixing with the coolant in the radiator. I drained and flushed the system, but within just a few minutes of running, the oil shows up again. I'm trying to figure out how the oil's getting in there. Could it be a blown head gasket, oil cooler failure, or maybe a cracked engine block? Not sure where to start. Has anyone dealt with this before, or have suggestions on how to properly diagnose and fix it?
You're right to suspect those three but the most common cause would be the a blown head gasket, especially if the machine has been overheated. A cracked block would be the worst-case scenario and honestly, the least likely unless the machine has been through a freeze without proper coolant. I'd start with a cooling system pressure test and a block test kit for exhaust gases in the coolant. A compression test is also a good idea. If the block test is positive, that points to a head gasket for sure.. if it's negative, then I'd be looking closely at the oil cooler next. Hope it's a simple fix!
 
@SamJackie yeah oil mixing with coolant is serious, I had the same issue before.
check the oil cooler, this is the easiest fix. The oil cooler uses coolant to regulate oil temperature. A failure in its internal seals or a crack can allow the higher pressure oil to seep into the coolant.
You can bypass the cooler by disconnecting the coolant lines and looping them back together. If you run the engine for a few minutes and no oil appears, you have found your problem.
 
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