Hey all,

I have a 91 CRX with a SOHC ZC. Car runs fine great MPG no smoke, no excessive oil consumption, plugs are clean. What is worrying me is a strange metallic rattle on the distributor side of the head/valvetrain. I have checked and rechecked valve clearances and they are all within spec. Oil is clean no metal shavings. Timing is right on as checked with timing light. Oil level is good. swapped distributor with known good one and sound was the same. I don't have a ton of experience with engine internals but checking for anything loose on the cam/rockers I couldn't find anything that would be an issue.


Changing with RPM

At idle



It gets slightly better when the engine warms up but gets quite pronounced at a certain RPM range that one of the videos shows.



Hoping you all can point me in the right direction for things to check or possible causes.

 

Sounds like the bearing inside the distributor is gone. Pull the cap off and look for brownish/red dust. Also with cap off, drawn a fine line across the mounting ear to the cylinder mount for timing reference, take the distributor off the head rotate the shaft and listen/feel..

 

I already tried swapping the distributors but possible they both have bad bearings. Is it that common? I can grab a new one from parts place see if it resolves it.

 

If you see any of that dust inside your distributors, then yes it is likely both bearings are on their way out. If not and they both spin freely and quietly then, I would inspect the rocker assembly very carefully and also check valve clearance.

 

As far as inspecting the rocker arm assembly..
what should I be looking for like what would stand out if they are the cause?

 

Could just look for any obvious wear spots, scorn cam lobe contact pads, broken springs, could have a blocked oil passage somewhere?? What type of oil you use may make it noisy.. Could just be that the heads valvetrain is worn and has a combination of things creating excess clearance. I've heard plenty that just sound noisy and run just fine.. my old d16a6 liked penzoil 10-30.. if you can't seem to find any issues without tearing too much apart, maybe try adding some Lucas engine oil stabilizer to your oil and see if it helps?

 

try doing a valve adjustment. doesn't cost much if you already have a feeler gauge.