Driving on the Interstate the other day, doing about 80MPH. Sudden loud THUMP and the engine started running very rough. Got it in neutral and slid over to the shoulder. Engine died. I got out and popped the hood and there was smoke everywhere, and a horrible burning-rubber smell. For a minute I thought the engine was on fire. Looked under the car and it looked like the seams had split on the cat, and dark grey smoke was pouring out the sides of the converter. A mix of oil and coolant was pooling in every nook and cranny on the back (intake) side of the engine. Tried VERY briefly to crank it and got a horrible clattering sound. Didn't do THAT again! Had the car trailered home.

Went out and did some preliminary checks. Plugs looked ok, no impact indications. Timing belt looks to be intact. Accessory belts are ok. Lots of oil sprayed across the underside of the intake manifold and the firewall. One rocker arm on cylinder one intake side has about 1/4" of play in it. VERY disquieting. None of the others show that kind of play.

The question now is, what did in fact go wrong, and is it worth my time and money to even try to fix it? My first speculation is exhaust failure leading to blockage and backpressure resulting in a blown head gasket? This is a 2001 Accord in not-pretty cosmetic condition, with call it 274k miles. What's the collective opinion? Is it time to retire the old road warrior and accumulate another Accord?

 

Start with a compression test i think, at least see whats happening across the cylinders.

You may very well find yourself having to pull the head anyway for proper diagnosis though, at which point you will be doing the headgasket anyway. Im sure rockauto has head gaskets cheap enough so that wont be a major cost for parts, but a MAJOR cost if paying a shop to do it. You seem pretty handy so is it something you can a attempt a DIY on?

 

If it was mine, I would remove the plugs, turn the engine over by hand and see if I could identify the source of the clattering noise. I get the feeling whatevers making that noise is probably going to tell you what happened.