My Mazda5 has had a smell like oil burning in the engine compartment since I got it. The valve cover gasket was definitely leaking, so I swapped it out, and it appears to have stopped the leaking. I am still getting the smell when I am stopped for more than a few seconds. The car has been driven less than 200 miles since the gasket replacement, so I am wondering if it could still be residual oil on the cylinder head burning off, or is there somewhere else on the engine that can leak oil onto a hot spot and cause it to burn off? If it is just residual, any ideas on how long it'll take to stop smelling?
I'm planning on getting it on jackstands over the weekend for an oil change, but would like to know if there is anything I should check while I'm under there. It doesn't appear to be leaking any oil, but I haven't pulled the undertray yet.
Ours soaked the insulation on the firewall and took a while to burn out
I'd suggest a thorough degreasing to make a potential leak easier to find.
Dusterbd13-michael said:
Ours soaked the insulation on the firewall and took a while to burn out
Now you’ve got me wondering. Ever since the gasket swap, the smell changed a bit. Still smelled like burning oil, but also had a bit of an organic burning smell, too. Rodents have been in the engine compartment at some point, and used firewall material for nesting under the engine cover. I wonder if the firewall insulation has some oil soaked in and the are nut shells trapped behind it. Will definitely be looking closer once I am under it.
Before you do the oil change:
Find a clean, dry section of driveway/garage.
Put the car on jackstands high enough to easily visualize the under side of the engine compartment.
Run the car until the fans come on, at least.
Inspect for fresh oil droppings.
Etc.
Rog
boulder_dweeb said:
Before you do the oil change:
Find a clean, dry section of driveway/garage.
Put the car on jackstands high enough to easily visualize the under side of the engine compartment.
Run the car until the fans come on, at least.
Inspect for fresh oil droppings.
Etc.
Rog
To add to this use a big piece of cardboard or craft paper. Put a reference mark to something on the paper like the front bumper or the leading edge of a wheel well. You can then slide it out and place it on top of the motor and get an idea where the leak is looking from the top. Not perfect as oil will run down things but it will get you in the general area where you can start looking. This also keeps the floor cleaner.
Got under the car. Lots of oil all over the back of the block, but back to looking under the hood, it is still dry around the valve cover mating surface where I cleaned it. Fired it up, let it warm up some, and I can't see anywhere that would be leaking oil so widely, unless there's an external head gasket failure, but I doubt it. There is a bit of oil on the exhaust manifold flange where it does not mate to the block and is away from the exhaust pipes.
I strongly suspect the valve cover leak was worse than I thought, and had been going on for a while. I'm betting as the engine heats up residual oil is flowing onto hotter parts of the engine and exhaust, and burning off. At this point, I'll get the oil changed while it is on the stands, and just keep driving it, and hope the oil burning smell goes away eventually.
