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My Ford Explorer

What does it mean when your vehicle puts out a big puff of smoke from the tail pipe. i just replaced the radiator because it was running hot and the radiator had a bad leak. it has been running really rough and sputtering like it wasnt getting enough fuel. i checked the oil on the dip stick and it looked fine but when i looked at the cap on the place where you add oil it had a milky white look to it. am i totally screwed?

The overheating may have been related to a blown head gasket (or two).

I strongly suggest that you have a compression test and a leak-down test performed in order to see if you have blown a head gasket. If there is coolant in the motor oil (as possibly evidenced by the milky look on the oil filler cap), it could mean that you have blown a head gasket, and coolant is migrating into the motor oil. Since coolant is not a lubricant, this situation can quickly lead to bearing damage. (Translation–BIG bucks)

On the other hand, if you have not been very good about changing your oil, the milky look to the oil filler cap could just represent bad maintenance. What is this vehicle’s maintenance history?

What year Explorer and engine option? I have a 2000 model with the SOHC 4.0L V6. This model has aluminum heads and plastic intake manifold. If your truck overheated, a cracked or warped intake manifold is also a possibility. A leak in the intake can cause these problems, too.

I agree to get a leak-down test and compression test. This tests the integrity of the combustion chamber. If these test results are good, then check vacuum integrity to see if there is a problem with the intake.