PublicMAJ

94' Civic SOHC Vtech motor.

Theres a slight knocking sound when driving. Sounds like it coming from the engine bay/tranny and can sometimes feel it in the floor boards.
1st gear - 2000rpm and above, goes away when shifting until hitting 2ns gear certain rpms
2nd gear - 2000rpm and above. goes away until 3rd gear certain rpms
3rd gear - 2-2500rpm only, then goes away under acceleration but knocks when maintaining a constant speed between rpms
4th gear - roughly 2500rpm knocks staying at a constant speed, goes away when accerating or decel or when clutch engages
5th gear - knocks staying at a constant speed roughly 2-2200rpm, but goes away when accelerating or decel or when clutch engages

I know that my clutch is getting a little weak. but I can also hear the noise when in neutral and reving the engine. In neutral it is fairly constant with rpms, but doesnt get noticably louder. and completely goes away when idleing.

It is possible that the weakened clutch is causing the problem? any other ideas of why its only at certain rpms and not constant through all gears and only sometimes when reving it at idle? Possible heat sheilds or bad tranny gears, syncros?

Car runs and drives perfect. Idles great around 700rpms, no vibration.

thanks

akacoke

its pinging, its a knock. most time for a healthy motor to knock is just cheap gas. fill up at chevron or shell or run 89 91 . happens when the engine begin having a load, which is after clutch engaged.

akacoke

a valve adjustment helps too.

PublicMAJ

I just got the car, I will try and fill up tomorrow with Chevron Premium. Then adjust the valves hopefully on sunday. Its it hurting the motor at all, even slightly?

akacoke

if you dont wanna keep filling up with premium gas, just retard the ign timing for 2 degree see if it helps, it might not be knock, i was just making an assumption based on your description.

to do it , make a mark of your current timing, with the engine running, you just lose 3 bolts holds the dizzzzy, use a paper clip to jump the connector next to ecu under passenger carpet. once you jump it, you will see a check engine light, then go to engine retard it, just a lil bit. and take off the clip engine light will go away

PublicMAJ

I pretty much figured out that the knock is coming from the motor, very minor though. Ill just have to buy another motor, easier than rebuilding, most likely just going to do a B series swap alot sooner than planned,

thanks for the quick answers though

Texas4door

*ignores Vtech by OP *

Hey before you rebuild or replace....
Try running some Seafoam through the intake
If you have alot of carbon on the piston tops, in can increase compression to the point that you need premium gas or have to retard the timing.

Try that before going crazy with the motor, cuz that little motor gets bookoo gas mileage I'll bet (something we could all use atm and in the futire)

PublicMAJ

I filled with premium gas already, didn't change anything. My buddy told me it sounds as if its one of the bearing caps or bottom rod connectors, something in that area.
He said that he can briefly hear it in all gears at all times, just making a different tone because of the load that the engine is on during different gears.

Another strange thing is that in 2nd gear, 60mph Im only running about 3600rpm's??? How is that even possible on my Tach, and Vtec doesnt even kick in.

Go_Race_Your_Self

Is it more of a ticking noise than a knock?

Kev

PublicMAJ

No, it sounds more definate of a knocking noise.

PublicMAJ

I will try and post a video of the noise tomorrow of the engine running and rev'ing it up

akacoke

if its all times its not the pinging, something internal you can hear it with a echo scope, its a very good tool to have. does this noise occur when idling, does the noise goes quicker as you rev?


are you sure youre not in 4th gear?

PublicMAJ

Positive, I'm in second gear.

Noise does not occur when idling, but can be heard when reving it up,