Hello, I have a 1998 Civic EX 1.6L Auto. It has 142,000 miles on it. When starting the engine in the cold (now less than 50 deg F), the engine makes a noticeable rattle/knock. After warming up the noise is much reduced. It has been doing this for the last 15,000 miles, and is getting progressively worse. It now sounds horrible during cold start at 32 deg F. I have seen many other posts illustrating this issue, but never with any resolution. Has anyone had this issue, and conclusively found out what the cause is? I have already adjusted the valves (only a few were even out of specification). I am assured it is not the valves, as I have run the engine without the valve cover installed, while listening for the noise. Oil is also definitely reaching the top end. I suspect it is piston slap or a connecting rod bearing. Also, can anyone tell me if connecting rod bearings can be replaced by simply removing the oil pan, as opposed to removing the head to pull the pistons?

Thanks

 

Get a video of the sound and it is a little easier to diagnose b/t piston slap and a bad rod bearing.

 

If you are going to go that far you should just do the whole thing put some upgraded internals.

 

I have a '97 Civic Coupe and the engine knocks between 3 and 10 times either hot or cold while accelerating between 1200 rpm's and 1500 rpm's then it goes away and the car runs fine. Sounds like marbles being knocked around momentarily under the valve cover. Then I stop at a light then take off...same noise at the same rpm's. Smooth idle and good pick-up, just that damn knock Any clues as to what this could be? Thanks.

 

Sorry for really late delay.

Did you get this figured out?
My 2000 LX is doing the same thing?

 

I was just about to open a thread about similar issue, but found this.

I have a Civic '98 LX (Stick) and at about 3K rpm (but never under) the rattling noise is present. Looks like the noise disappears after 3500 rpm. It sounds something like steel ***** in a metal cup or vibrating steel sheet.
I have a bushing on the cat back that needs to be attached, but I am not sure is that the problem. The noise comes from under the engine.

Friend of mine told me that is the main shaft on the manual gear box, probably caused by improper shifting. I bought the car from an old woman. How she drove stick shift I don't have an idea.

So guys, is there anybody that knows what this annoying noise would come from?
Thanx in advance!

 

I took mine car to the mechanic.
He left kept for 2 days or so. He told me that this noise is very common for this generation civics. He told me it's my valves. My lash it set properly. Once they get warm, they expand and work properly. He also suggested that i switch to thicker oil 10w30 or 10w40. Mine does it only when it's cold. He said that i could spend $500-$550 to get it fixed, or just let it warm up for a few min and let the oil flow through.

 

I see, your problem is different than mine because it happens only when the engine is cold. Yes, this probably is the valves, but might be the pistons too, which also expands when the engine gets warm. If it's the valves is not that hard, but if are the pistons sucks.

 

Check the exhaust manifold gasket. What you are hearing is a leak in the gasket there. And when the gasket gets hot and expands the noise goes away. Had the same thing happening. Replaced the exhaust manifold gasket and bye bye noise!!

 

Why would you reply to an 11 year old thread?