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Few months ago our 1999 Escort Wagon (third North American generation, standard 2.0L CVH motor, about 120 000 miles (roughly 200 000 km)) exited the building with a bang. That is, driving down the street loud bang occured, and it died. It was possible to start it afterwards, but it would run really loud, and have no power. It was necessary to rev it really high just to get off the road. If that matters, oil on the dip-stick was clean, with no metal shavings, coolant or any other contaminants.

Now that the weather is warming up, it is time to access the situation, and see if the car can be salvaged. When we took it to the mechanic, they said it was “probably” the piston rod that broke, and it was cheaper to replace the engine ($1500 for refurbished one, with labour included) than to rebuild what was there. I was not willing pay that much to fix 13-year old car we just recently bought for $2000. Also, a friend told me that if the rod broke, it was unlikely it would turn at all.

Later I’ve been told that there is a common problem with CVH engines: valve seat can drop, causing all sorts of damage. It is said that it often happens without warning, but I must admit the car was running rather loud, and was a bit sluggish when we bought it. In the hindsight, we shouldn’t have, but it was otherwise so clean, and well-maintained, I closed my eyes on that at the time.

So, the questions are, where should I begin? Would it be obvious what happened by taking off valve cover and/or intake manifold, or should I remove the whole head? What can I see if I drain the oil, drop the pan, and take a look at the bottom end? Given that it was run at least for two to three minutes afterwards (to get it off the road, and later to check what is happening), would the damage be too extensive (pistons, head and cylinder walls, bent rods), or, at least, how do I determine that? Depending on the extent of the damage, can most of this be repaired without taking out the motor?

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2 Answers 2

Removing the head would most certainly find any damage if it exists. Especially since it still runs, the bottom end is likely intact. You're not likely to find anything by dropping the pan.

Getting a good look at the valves and piston tops would be where I would start. This would involve removing the head to be absolutely sure, but one thing you might try is taking off the intake and exhaust manifolds, and if possible, taking a look in the head at the valves. You might be able to find the problem without removing the head. And if you do have to remove the head, you'd be halfway there. Your saying that it gets much louder points to something wrong with the valves, or between them and the muffler.

It all depends on if you can get a mirror/camera in there and/or if the pathways to the valves are too hard to look into.

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I'm by no means an expert in engine repair, so take this answer more as a starting point than a conclusion.

If the problem is the dropped valve seat, you may be able to determine this by taking out the spark plugs and inspecting the combustion chambers, though I expect this will be very difficult without some sort of specialized tool (automotive endoscope?). Maybe somebody more familiar with this problem could provide some photos for you to look at that would make it easier to evaluate the situation. Otherwise you'll probably have to take off the head, which is a pain, but considering that if this is the problem you'll want to replace the head anyway, it might not be a bad idea.

I don't think there's anything useful you can determine from underneath as to whether the valve seat dropped, but you might need to inspect from below to determine whether there was additional damage such as bent connecting rods mentioned in the article you linked. If it were me, I'd start the search from the top and only bother dropping the pan once I had a good idea what went wrong and whether it might be fixable.

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Yes, from what I’ve read, I might want to replace the head with the one on which valve seats had been taken care off (I do not know what the fix is, but I know it exists). –  theUg Feb 9 '13 at 0:27

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