Hey guys. Is it normal for engine to vibrate at idle? I've replaced the mounts and I don't notice the vibration from inside the car anymore. But engine itself is still vibrating. I did valve clearance adjustment and it got quiet and smooth. But vibration is still there. No matter what I do.

-Tried replacing spark plugs. Tried NGK platinum and iridium. Neither stopped the vibration.
-Replaced plug wires, distributor cap, and rotor. Still vibrate
-Flushed the radiator and put the coolant in following the procedure. Still vibrate.
-Adjusted the ignition timing to 12* as specs. Still vibrate.

What is causing this vibration to the engine? Is it because it's old? My other car with D15B7 doesn't vibrate at all.

 

Hmm. No answer?

 

Does it idle low?

 

^my guess too, low idle


op, fix your sig...it doesnt make sense

 

No. Idle at around 700 RPM. Engine is just vibrating.

 

Fixed.

 

Any ideas?

 

did you change all the motor mounts?
you use oem mounts or polys?

 

OEM mounts. Changed 4 of them. I couldn't change the one in the back of the engine that is connected to the firewall. When I bought the car, it came with 2 polys. One for driver side upper and one for transmission. Inside the car was vibrating a lot. So I switched to regular mounts and inside the car is now quiet and stable. Engine is still vibrating noticeably.

 

Did you verify idle speed with an aftermarket tach? OEM tachs are notoriously unreliable, especially at low RPMs. Also, check mechanical/ignition timing.

 

I have not verify the idle speed. I get around 700 RPM on OEM tachometer. I will check that. My mechanical and ignition timing are set at 12* as spec. I've confirmed it in another thread.

Although, can a small difference in idle cause the engine vibration? If so, I will adjust the idle again.

 

Ok. Thanks to you guys, the problem has been somewhat fixed. I adjusted the idle. While I was adjusting, I heard a very low hissing sound coming from radiator cap. Turned out it was leaking and car wasn't getting enough coolant. So, engine was struggling. I replaced the cap, bleed the system and re-adjusted the idle. Now, engine doesn't visually vibrate anymore. There's still vibration when I touch the engine but I'm just gonna assume it's normal since the engine is 170k mileage and 16 years old.

Who knew just a 100 RPM makes this much of a difference....

You can close the thread now if you want, mods.

Edit: I should have mentioned that my initial idle was 600 and not 700. I couldn't really tell since I was using OEM gauge. Now, it's slightly higher. About 100 RPM more.

 

Yep, 100 RPM can make a huge difference, especially with our little four bangers. Glad you got it figured out.