It seems my truck has some yucky brown stuff on the oil cap. It doesn't sound as powerful as it used to and not enough p

[sholomar]

head gasket is fine. It comes from short, infrequent trips that don't warm the engine all the way up. Grand Am did this when I had a 1.5 mile commute that did not warm up the engine. Since moving with my commute being 2.5 miles, it no longer occurs.

[ukrkoz]

Originally Posted by CALGUY

It's head gasket changing time.


Bob

Yep. It's water+oil frappe. Oil gets into coolant and is milk shaked into this condition by water pump fins. As Bob says - gasket time.
Of course, unless it's a VW, as dealer stood firm it's "normal" for VW engines. So my son got rid of his wife's VW as dealer refused to do anything about it.

[Retriever]

For those who are sure that it is a case of a breached head gasket, I have to say that while that is a possibility, it is far from being a sure thing. I can recall the exact same situation with one of my cars, many years ago. I knew that the problem couldn't be short-trip, local driving or extended oil change intervals, as I drove the car 26 miles each way on my daily commute, and I faithfully changed the oil every 3 months.

In my case, it turned out to be a gunked-up PCV valve, and this may prove to be the case with the OP's vehicle also. However, the major cause of this problem is short-trip, local driving, coupled with extended oil change intervals. Alternatively, a cooling system thermostat that stays open and allows the engine to run too cool is another possibility.

Can the OP please tell us about his usual driving patterns, and also about this vehicle's maintenance schedule? We need to know how often the oil is changed--in terms of both elapsed time and odometer mileage--along with a description of how the vehicle is driven on a regular basis.

[J Baustian]

Originally Posted by Reyesj

It seems my truck has some yucky brown stuff on the oil cap. It doesn't sound as powerful as it used to and not enough power. The truck is a 4.6 Liter V8 F-150 with Manual transmission. What could be the problem?

I strongly recommend you take the truck out for a 30-40 mile drive, working the engine hard, getting the engine good and hot. That should remove the condensation that has turned the oil such a nasty color.

Or, you can change the oil and filter now. Then, in the future, when most of your trips are short, go for one longer drive every week or so, to boil off that moisture.