In your description of the engine being damaged-is it: turns over and refuses to start or won't even do anything when you hit the key to start. Is the engine locked-up
I want to know what, they told you what the Cat did to the engine. Give us a description is to what's happening causing it to be dead or whatever.
We need to know this before we can continue-we cannot fix your problem if we don't know what's the actual problem. Is it mechanical/fuel/ignition give us something to work with.
They told you the engine is damage because they found fuel in the crankcase-they hinting on a washed-up cylinders that won't hold compression. It might be the case-Get a compression and a leakdown test to confirm that.
About something crawling back to the engine, even if you put a Marble between the exhaust manifold and the C/Converter it will never make to the exhaust port its a one way direction deal even during the valve overlap it won't go in.
Totally clogged-up catalytic converter will prevent the engine to breath In the automotive theory they call it Volumetric Efficiency-How well the engine breaths. Like us humans we inhale and exhale.
Thursday, April 26th, 2007 AT 9:17 PM