Dear Dave,
There’s an oily spot on the driver side floorboard of my Class C RV. There’s nothing under the mat so it must be coming from above. Nothing on my shoe after driving. It does not appear that the brake pedal piston is leaking. Help! —Bill, 2013 Coachmen Freelander 19CB
Dear Bill,
Your Coachmen Freelander 19CB is on a Ford E350 cutaway chassis similar to this clipart I received from Coachmen several years ago.
How to determine type of fluid
From what I can tell by the photo you provided, the cab floor of your rig is the standard rubber membrane type. The dark color makes it difficult to determine what the fluid is. With any engine fluid leak, I start by placing a piece of cardboard or large white paper underneath the affected area. The color of the fluid will help determine what it is and hopefully identify where it is coming from.
Red would be transmission fluid, clear or light brown would be brake fluid, and antifreeze could be either green or orange, depending on the brand. Water would be clear and oil would be either a bronze, if it is recently changed, or dark in color.
Place the cardboard or paper on the driver side floor and let the engine run for a period of time. If this happens every time you drive, it should show up pretty quickly.
If nothing shows up at idle, you will need to drive it to simulate airflow coming from underneath. However, since you indicated there was nothing under the mat, you should be able to see a stain.
Another area that I would look at is the engine cover or “dog house” directly next to the stain. If you have a valve cover leaking or other “spray” coming from an engine component, it could be shooting through the seal between the dog house and the floor. Take the cover off and see if there are signs of the same fluid on the inside cover. Once you identify the color, you can start to pinpoint the origin of the leak. It could be a bad heater core leaking antifreeze, or water coming through the engine compartment during a driving rain.
PS. Check to make sure the dog or cat isn’t sleeping there!
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He might also be able to smell it and look on the ground for any signs of engine leaks. I have no idea how their power steering is designed, is it possible it might be coming up the steering shaft…??? (Smell test would verify the dog/cat theory too!!!)
Thank you for the investigative help, Dave! Not sure that I would have independently arrived at your suggestion. But I am decidedly unhandy. 😉 Have a great day and safe travels!
The power brakes on the E350 is probably a hydro boost system that uses pressure from the power steering pump to give the driver power brakes. The seal on the shaft of the unit is leaking.