engnie vibration only when hot.

[galant651]

the past couple days my vibrations have been getting worse. at first start up it runs great, hardly any vibrations, even after 5 to 10 minutes it still drives great, only a small amount of vibrations, but after driving for at least 30 minutes, when coming to an idle, i get a very strong vibration from the motor, seems like its the bottom end but i cant really tell. anybody have any ideas?

 

[GEDengineering]

Do you have the balance shafts? If so my guess it that they are out of time, when they are it creates a very strong vibartion like the engine has a large aftremarket cam shaft.

GED Engineering

 

[galant651]

i dont have balance shafts. why would it only cause a vibration when hot? and i do have hks 262 cams.

 

[DynastyLCD]

is the idle higher when cold? do you notice the RPM changing when you note this vibration?

with a higher idle, it can mask the lope of the HKS cams, then when it warms up and comes down to 900 or so, the lope could be be more noticeable. just a thought!

 

[prove_it]

Check your timing and oil pressure. If your still curious, run a compression test and post the results.

 

[SouthCaliVR4]

I would also take a close look at your plug wires, A richer mixture (IE; Cold motor) will be easier for the ignition to fire & then a miss develops as you go into closed loop. Just a thought.

 

[galant651]

i know timing and spark is all good. and i know its not the cam lobe cause it only started the other day and cams have been in for a year or so. should check oil pressure just to be safe the. the wierdest thing is driving to work it did it. but driving home from work it didnt do it. the mits tech i work with said the harmonic balancer could possibly do it. any thoughts on that?

 

[prove_it]

It could, but I would think it would be more consistent if it was the balancer.

Is it rough when in gear driving, or is it present will at a stop idling?

 

[galant651]

i feel like every now and then i get the same vibration while driving. i think i might have figured it out though. i had a intercooler pipping that was rubbing on the radiator, but ill know if that was it for sure in a couple days.

 

[theevozero]

Heat changes a lot of things. I see weird stuff like that every day. If it was the balancer, you might be able to observe it. If it was something touching a related engine part, you would probably hear a annoying rattle too. I would be more inclined to do a cylinder balance test, or compression test. A misfire would be really noticeable.

 

[gvr4ever]

Visually check the harmonic balancer. That was kind of my first thought. It has some sort of rubber core that acts as a dampener. It might be hard enough cold, but getting soft when warm.

I thought they usually just failed and separated, but maybe you are getting some sort of advanced warning.