Q: Truck idled, ran rough, fluid streaming from motor

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A very bad knocking noise has developed in my dad’s truck recently. It has that sound as if something is loose. A couple of days ago when I was driving his truck and I got to his house, the truck idled, was running rough, and then the engine almost shut down. There was a stream of fluid pouring from the motor and so I opened the hood and saw that the master brake cylinder lid was loose and the brake fluid was spilling everywhere. Now, the truck has a muted knocking noise when I start it. My dad thinks he changed the oil and put synthetic oil instead of regular 10w-30. So I'm thinking that he did not change the oil and kept the same oil that was in it and just added the synthetic oil. I don't know if this happened or not. He’s a bit forgetful these days. I don't know if that is what would make the knocking noise, or not. Perhaps it is the brake fluid that has gotten inside the cylinder. The oil pressure lights read a bit high and my dad also told me that the truck has stalled coming up their road. Now he has no transportation and I want to fix this for him; he needs my help. We are hoping that it is a simple fix so he won't have to scrap this truck. In your experience, what will fix my dad’s truck?

Hello there, thank you for asking about your car. It’s highly unlikely that brake fluid entered the combustion chamber. The noise also would not be caused by using synthetic oil instead of conventional oil. As for the oil pressure, I’m not sure what your dad considers too high. With the engine fully warmed up, oil pressure should be about 24 psi at 3,000 RPM. To know for certain what’s going on, a professional will need to listen to your vehicle firsthand. A certified technician from YourMechanic can come to your home or office to inspect why your truck is idling roughly and make any necessary repairs.

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