Oil mixed with coolant
When removing my coolant cap, it covered
with milky engine oil. I google this issue
and found that the most common solution
replacing the heads gasket and oil cooler. I
replace both of them, then flush the
coolant and refill it again but still facing the
same problem. So any suggestions?!!
(2010 camaro L99)
Hmm, do you have an automatic? If so did you check the transmission fluid color and level? That might be mixing with your coolant.
Yes, I do. But the trans fluid in normal level. I'm pretty sure that is engine oil. Also I notice today that the engine oil pressure goes down.
Is the oil on the oil dipstick milky as well! Pressurise the cooling system with a cooling system pressure tester and start the engine. See if the needle on the gauge of the tester bounces. If so, it's a head gasket. If not I'd suspect the intake manifold gasket. HTH. -Jim
The oil in normal condition not milky.
Maybe try flushing out the cooling system again using a chemical cleaner. Perhaps you didn't get all the oil out with the first flush. Was the oil on the dipstick milky before the head gasket replacement? If so, you'll want to change the oil again. That could be the pressure drop. HTH. -Jim
The oil wasn't milky before I replaced the head gasket. I've changed the oil since I flushed the radiator. About a chemical cleaner, could you provide me with a chemical name?!
Prestone Super Flush or Prestone Fast Flush are both very good products. HTH. -Jim
The radiator cleaning is done but the problem still the same. Also, the oil pressure goes more down and sometimes the engine heat goes up to the extreme level.
Ok, pressurize the cooling system, engine cold, with a cooling system pressure tester. Once pressurized start the engine. See if the needle on the pressure tester's gauge bounces. If so, head gasket is blown into the cooling system. If not, revisit the intake manifold gasket. That may be leaking internally. Now you're absolutely certain it can't be the transmission cooler inside of the radiator? What has me puzzled is the oil in the crankcase isn't milky. But with the oil pressure drop, the overheating , and oil in the cooling system, to me, says head or intake gasket. No excessive water condensation out the exhaust? HTH. -Jim
Hey Jim, There is a written at radiator cup says 20 psi /140 kpa ,so I pressurized the cooling system to 20 psi, then started the engine as you wrote and tester gauge still the same (20 psi). About engine overheating, after cleaning up the cooling system, the overheating problem is gone and the oil pressure rises until the engine warm up. Moreover, the oil at dipstick is at the same level. I don't think that the cooling system or engine oil are crossing the intake manifold. There is no water consideration getting out from the exhaust.
Well, that's all good news! Oil pressure will drop some as the engine warms up and the oil thins out. Since the pressure test passed, the oil in the crankcase isn't milky, and you have no excessive condensation from the exhaust the engine itself must not be leaking internally. Have you looked at the transmission fluid, as mentioned before, and is there an oil cooler in the radiator? Or maybe a power steering fluid cooler incorporated in the radiator, if it's a hydraulic power steering system? -Jim
Yes, the cooling system also contains transmission cooling system but the trans fluid color is red. So I don't think it's a trans fluid. On the other hand, engine oil got yalllow color. I'II try cleaning cooling system again. Thanks a lot Jim,
You're welcome. Glad to help. Please keep us posted! -Jim
BoEbrahim —what was the problem and what was the solution
This problem was shown after camshaft replacement. I pull out the engine and took the block to machine shop. I found that the block cylinder surface wasn’t straight. After fixing this issue, the oil pressure goes to normal level and there isn’t oil mixed up with coolant. Hope this info is helpful.
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