Thanks Karthief and 93SSP. A little more info and answers to your questions, bear with me for the long explanation. Trying to be as thorough as possible:
Yes, can feel the vibration at idle and while revving engine slowly. That's how I narrowed it down to the 1300-1400 RPM range. After listening/feeling closely today, I think the vibration is there even at lower RPM's, from idle all the way up to 1400 RPM. It's barely distinguishable from regular engine vibration, but it is there. It becomes severe between 1300-1400, and then goes away completely once the engine goes above 1500. It mainly comes through the steering column and wheel, you can actually see the wheel vibrating when it happens. But I can also feel it coming through the body a little, if I hold my hand on the door panel when it's happening. Again today, I revved the engine slowly with the throttle while looking and feeling around in the compartment, and couldn't see or feel a vibration in there aside from typical engine feel.
It's definitely more noticeable when I first start the car in the morning. This morning, I went for a drive down the street to the post office, then looped back a mile-plus on the freeway. So the engine was warm when I got home, and the vibration had gone away a bit but was still there.
Engine runs smooth, no misses or rough idling etc.
Regarding motor mounts, they were replaced shortly after I got the car a couple years ago. I then went to a different mechanic to do the harmonic balancer earlier this year. When that didn't make the vibration go away, he suggested the motor mounts be changed, even though he could see nothing wrong with them. He did say they were metal mounts, not poly or rubber. According to him, the vibration wasn't there when the engine was lifted and running off the frame, which is why he thought they might be the culprit. He was going to order new mounts to swap out and see if they made a difference but we didn't get around to it. Would mounts be causing this issue only at RPM's below 1500? I would think bad mounts would have the motor shaking even worse at higher speeds, not allow the vibration to go away. Or is it because the engine is turning so fast that the metal mounts would be fine at higher speeds but lack any sort of dampening at lower speeds when there's more time, however small, between revolutions?
In addition to the leak in the PS pump/rack area, I should've also mentioned that when I opened the pump reservoir, the fluid looks like chocolate milk and smells off. Not burnt, just off. I assume that definitely indicates a worn pump or bad seals somewhere. When I had the oil changed a couple months ago, they said the PS fluid was low and topped it off for me. They also said there was a transmission leak, but I've seen no sign of one before or since, so they probably confused ATF from the PS with the transmission.
Also, I'm not experiencing any other steering/control issues. No excessive play in the wheel at any speed, no pulling, it'll stay true if I take my hands off the wheel. There was a brief moment last year I think where it was almost like the PS lost power while I was slowing down or braking, and it did pull hard to the right, but it came right back after I gave it some gas - never happened again after that.
Lastly, as I mentioned previously, the PO had the front end lowered a couple inches. There were also no rack limiters installed. He had to stop me from rubbing the tires when I was cranking the steering and driving it the first time. So I had a rack limiter put in on each side, same time the motor mounts were done a couple years ago. I've also read that lowering the front end without installing a bump steer kit can damage the tie rods and/or rack, so I'm guessing there's at least something wrong there, but no mechanic said anything about those components, unless they failed sometime after that.
So question is, I guess, could the vibration actually just be bad motor mounts (even though they're newer), and the steering leak/pump/rack issues if any, are just a coincidence? Are there specific mounts you'd recommend be swapped out the next time I take the car in? And I will probably have them closely examine the PS pump and rack, or just replace both at the same time.
Only other variable is the vibration going down once the engine is warm. Will a hot engine vibrate less than a cold one since everything has been moving around awhile? And if it's at all related to the PS pump/rack, then I can see how if they're failing, they work better once the fluid has a chance to circulate.
Thanks for any suggestions/feedback!
s and giggles, take the serpentine belt off. Maybe it's the p/ s pump?oh and if so flush that beach , before you replace it.
