This is my friend's 2012 Chevy Sonic 1.8 once again.
One of the heater hoses blew last April. I replaced it and a bunch of other hoses, and the thermostat housing. At that time there was a lot of yellowish "mayonnaise" in the cooling system, which I attributed to my friend having added generic antifreeze to the system.
The car subsequently had a leak from a brittle plastic pipe (coolant to throttle body), and before I replaced it, my friend topped up the system with quite a bit of water, which diluted the coolant a lot.
He brought the car over yesterday so we could add coolant before winter. (In the nick of time, as it was snowing today.)
Anyway, I was dismayed to find lots of brown foam in the coolant reservoir. I said "chocolate milkshake" in the title, and that's a pretty good visual description.
I feared a blown head gasket, but was glad that the leakage (oil into coolant) appeared to be one-way only. Coolant into oil could take out the engine quickly, but the oil looked good.
Poked around the 'net a bit, and discovered that there's an oil cooler, which the oil filter housing is mounted on, which tends to fail, causing exactly this symptom.
@14Accent, you've offered good advice on the Sonic in the past. Do you think the most likely cause is the oil cooler? Thank you!
One of the heater hoses blew last April. I replaced it and a bunch of other hoses, and the thermostat housing. At that time there was a lot of yellowish "mayonnaise" in the cooling system, which I attributed to my friend having added generic antifreeze to the system.
The car subsequently had a leak from a brittle plastic pipe (coolant to throttle body), and before I replaced it, my friend topped up the system with quite a bit of water, which diluted the coolant a lot.
He brought the car over yesterday so we could add coolant before winter. (In the nick of time, as it was snowing today.)
Anyway, I was dismayed to find lots of brown foam in the coolant reservoir. I said "chocolate milkshake" in the title, and that's a pretty good visual description.
I feared a blown head gasket, but was glad that the leakage (oil into coolant) appeared to be one-way only. Coolant into oil could take out the engine quickly, but the oil looked good.
Poked around the 'net a bit, and discovered that there's an oil cooler, which the oil filter housing is mounted on, which tends to fail, causing exactly this symptom.
@14Accent, you've offered good advice on the Sonic in the past. Do you think the most likely cause is the oil cooler? Thank you!