I’ve got a 99 chevy s10 pickup, 2.2L engine. I just got my engine replaced by a bunch of idiots, and they didn’t install an exhaust manifold gasket. Being an idiot myself, I didn’t actually look under the hood when I noticed an obvious exhaust leak whilst driving it out of their garage. I took it back to them and they said it was a cracked exhaust manifold. So I went to a junk yard, got a new manifold, went to install it myself and noticed that there was no gasket on the old one. I noticed this before I actually took anything apart. Was there any damage done to the engine by driving it like this?
…and can an exhaust leak make the engine less powerful?
I had to change the gasket on my S10 Extreme for a new aftermarket header. Well to answer your question. Driving for a long period of time with no gasket could have warped the block surface where the manifold bolts on. I would get a new crush gasket and install it. Make sure you torque the bolts to the right value and order. All should be well as i drove for a little while with a leaking gasket.