'Peanut Butter' Gumming Up Camry Could be a Sticky Situation

Dear Car Talk:

My 2015 V6 Toyota Camry has a substance that the mechanics can only describe as "peanut butter" gumming up my heater core, coolant system and now the engine. I have included a picture. So far, no one knows what this stuff is or how it got there.

Any idea what it might be or why it can't be cleaned out after 17 times of draining and flushing the system? -- Amy

Wow. If you can figure out how to get the engine to make some grape jelly, you can start a lucrative lunch business, Amy. It does look kind of like peanut butter. But, unfortunately, it's going to cost you many, many jars of Skippy to fix.

I think oil is getting into your coolant. There are separate passages inside your cylinder head for oil and coolant. And they're kept separate by a complex seal called the head gasket. If that head gasket breaks -- which often happens if the car is badly overheated -- oil and coolant can then mix together. They can go either way. Coolant can get into the oil, or oil can get into the coolant, which is what's happening in your case.

And that's why, despite flushing it out 17 times, it keeps making peanut butter, because new oil gets into your coolant every time you drive the car.

At minimum, you need a new head gasket. You have two of them on this V6 engine, one for each bank of three cylinders. Replacing both of them is probably a $2,500 job. But the news could be even worse. The head itself could be cracked -- which also can happen during severe overheating. In that case, you'd need an engine rebuild or a replacement engine. Which means you'd be subsisting on peanut butter for a while.

There's a slight chance that it's transmission fluid in your coolant, coming from the transmission cooler, which sits inside the radiator. That would be a lucky break. So check that. But I think it's more likely to be a head gasket or head. I wish the news was better, Amy.

My suggestion would be to have your mechanic start by removing the cylinder head closest to the front of the car. That's the easier one to work on. If you're lucky, he'll see a clearly broken head gasket between an oil passage and a coolant passage. And if you want to save money, you can just ask him to replace that head gasket, close it up and hope for the best.

Normally, we'd replace both gaskets, figuring if one has failed, the other might, too. But if funds are really tight, you can take your chances on one of them. If there are no visible head gasket breaches in either cylinder head, then you've got a decision to make, Amy. You can either spring for a used or remanufactured engine or craft a used car ad that includes the words "as is." Best of luck to you.

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