Spookygeek

I had a shop do a timing belt change on my 2001 4cyc Accord and when I got the car back it was running fine with the exception of a great deal more vibration making its way into the cabin. After numerous trips back they finally told me I was just too picky and to go away. Now a year later I finally have some time to dig into this on my own and I think it may be that they did not correctly set the harmonic balancer. The car seems to idle ok, but as revs go up vibration increases. Other than the vibration the engine pulls just fine. It used to be a fairly smooth ride, now its just annoying. Any thoughts?

Thanks,

-Brent

wed3k

if the F23 is like the F22, there is a belt for the balance shafts in the engine. if those are slightly off then there will be a vibration.

Another thing is if they didnt use a jack for the driver's side motor mount and let the engine sag. it will bind up the other motor mounts.

the harmonic balancer is set via keyway so you cant put it on wrong.

hondamark35

that shop shouldn't have charged you for labor because they didn't seem to know what they were doing...

sounds like they couldn't get the balance shafts lined back up. you may not even have a balance shaft belt.

the general rule is, any I4 engine over 2L will have a noticable vibration twice the speed of crank rotation. to counter act this vibration two balance shafts, one on either side of the crank meet each pulse of the vibration with a near equal pulse in the oposite direction. the two cancel out and everything is smooth.

when the timing belt was replaced, the belt that spins these shafts was also removed. as you can imagine, if they are not put back in time to meet the pulses (or they aren't timed together) there won't be much of a canceling effect. also if the belt isn't put back they're just dead weight and again not eliminating vibration.

Spookygeek

So is there a keyway on the harmonic balancers for a 2001 4cyc or is it possible there were installed incorrectly and just need to be realigned?

hondamark35

really the term "harmonic balancer" would refer to a weighted pulley bolted to the front of the crankshaft. end goal is the same, but balance shafts are a bit different.

here, i'll add some visual insight...
balance shafts removed from motor
view balance shaft location with oil pump removed from block (central is the crankshaft, front balance to the left, empty bore next to the oblong oil port is the rear shaft location.)
large pulley at the crankshaft, medium is the rear balance shaft pulley, and smallest to the left is the front balance shaft.

as you can see the pulleys are just like timing belt cogs. they have a small timing belt that turns them. they must be lined up with indicator marks on the oil pump housing when the crank is at TDC and then the belt can be installed.

so, technically yes there is a keyway on the front balance shaft. but it's just for the pulley to fit on.