Help! I know nothing about cars and have been trying to research my problem. For many miles, I have complained periodically of what I thought was a bad muffler (noisy, kind of mild vibration on acceleration) and the engine not running smoothly, and lack of heat.

Since then, my records show that they have replaced what looks like cylinder #2 and spark plugs. Also, the catalytic converter (they said that was the bad muffler-like noise). Also, they replaced the thermostat to fix the heat problem.

Still, it runs funny--sounds like a bad muffler, not good with giving heat at times, keeps losing coolant (no visible leak). They replaced the radiator cap, I think, hoping that would stop the coolant leak. It never runs well for long. Runs better when they add coolant. They have said they hope part of the old catalytic converter did not break off and ruin engine.

Now they say one cylinder is not working. It runs funny again and it sounds again like a bad muffler (noisy/vibrate) and rides rough. They say it will be expensive to take the engine apart and I probably should get a new engine at my expense since I have 112K miles.

My dealer says this should not happen on a 5 year old car and is rare. They tried to get Nissan to pay (declined) since they said this is not fair.

There have been lots of recalls on this car. Some people have posted that a design flaw with the car causes the pre-cat to break off or something and that small metal pieces get sucked into the engine and ruin it.

Does anyone have any insights? I am so upset and would appreciate any thoughts you might have. Thank you.

Sorry to be the one to tell you but it sounds like you've got a blown head gasket...