Help! Horrible Engine Knock

[chinzoo]

I have a 1987 Honda Accord LX - carbureted

When I merged into traffic on my way home it suddenly made a horrible loud clunk/knock type noise. The noise is sort of like sparkplug knock or dieseling, but much louder/deeper and it is in a definite rhythm. I let off of the gas and the noise immediately stopped. As soon as I gave it gas again the noise continued. I checked my gauges and everything was fine. There were no smells of antifreeze or anything burning up. Nothing was leaking from the engine and there was no smoke or water coming from the tailpipe. The car also sounded absolutely normal, unless I was giving it gas. I was only a couple of miles from home so I let the car coast home giving it as little gas as possible.

After getting it home we found that the noise completely disappeared when we removed the plug wire from the third cylinder. My husband pulled the valve cover and adjusted the valves. A few of the valves need a little adjustment, but not much. When he was hand cranking the engine there was no binding or friction present and everything on top was fine - nothing looked out of place. He drained the oil and everything looked fine - no pieces of metal etc.

Are there other tests to help us narrow down the problem a little more? The manual says it could be a rod, bearing, pin, etc. We are trying to figure out if we can rebuild/replace the problem without pulling the engine. We live in a Condo and have an Association watching us, which makes it impossible to pull the engine.

We rebuilt the head about three years ago and have not had any problems since. There has been red dust present in the distributor cap for some time, but the car has continued to run smoothly - until now. I know I am reaching, but is there anything special about/relating to the third cylinder? Any input would be greatly appreciated!! I hate to think she is down for the count. I really like the little piece of junk.

Thanks!

Jodi

[SteveDX89]

All those things listed in the manual are possible. I had bearings go bad and I got some really bad knocking as well. Get an oil pressure check. If it's low, your bearings are most likely fried. Otherwise, you're gonna have to take the engine apart to find the problem. You can do it with the engine in the car from underneath but it will probably make it twice as difficult. If you have any family members or friends with garages that will let you use them a little while would be ideal.

[Oldblueaccord]

All those things listed in the manual are possible. I had bearings go bad and I got some really bad knocking as well. Get an oil pressure check. If it's low, your bearings are most likely fried. Otherwise, you're gonna have to take the engine apart to find the problem. You can do it with the engine in the car from underneath but it will probably make it twice as difficult. If you have any family members or friends with garages that will let you use them a little while would be ideal.

Steve's %100 right its most likly a rod bearing. Could, down and dirty ,take the oil pan off and just change that bearing its pretty easy under the car.

Pulling the plug wire is a good test for that.

wp

[FyreDaug]

My sunfire did that when it blew both times. It would knock real bad when your producing power. I spun #1 bearing once and the second time I threw #2 through the block. Both of them having the same symptoms. Get that fixed ASAP, do not drive it until its fixed. You dont want a rod through the block, thats an expensive fix

[AccordEpicenter]

i def think its a rod bearing, probably spun. If thats the case... id just get another short block or an entire motor