vibrations at idle, with new engine mounts.

[legolyle]

For a long time I've been trying to chase down vibrations I get through the entire chassis at idle. It is very noticeable.
The car idles fine at ~700 RPM like it should, but I can feel vibrations in the seat, and all the stuff in the car vibrates as well (coins, etc). However, if I run the A/C the shaking all but dissapears (for the *most* part) as the idle hops up to 900-1000 rpm.

First thought is of course, engine mounts. However, I replaced the mounts when I rebuilt the engine 15k miles ago, and it's idled like this since day one. Visually inspecting the mounts, they seem fine.

At this moment, I'm stuck thinking the engine mounts are just shoddy. Junk from the auto store, not Toyota, and thus not doing their job properly, but I sort of find that hard to believe. Beyond that though, I'm not entirely sure. Any input? Think it's just the engine mounts?

In addition to this, on deceleration at around ~4k RPM, I can feel similar vibrations through the car at any speed.

I have other ideas as to what it could be, but, wanted to get some input here first

 

[GrimJack]

Dead front damper pulley?

I doubt it's the mounts, even my solid mounts don't shake stuff in the cabin.

 

[legolyle]

I actually checked that out before I threw it back on the engine, and it seemed fine, it also never did this before the rebuild. To be sure though I'll pull it off this week and take a second look at it. Is there a way to check it while its on the crank?

Aside from that, something else I more recently thought it could be is the alternator, or, related. The alternator doesnt seem to be charging at idle, thus voltage is ~12volts at idle. Think that could effect the idle quality significantly?

 

[GrimJack]

I don't think the alternator could do that. Maybe if it was actually torn up inside, but even then, it seems like it should just slip the belt.

I don't know of a good way to check the damper. If it's the original one that came with the car, it's almost certainly toast by now, the rubber hardens over time, and it stops damping. I picked up an ATI unit for mine.

 

[legolyle]

Well, for the alternator I meant more along the lines of a crappy spark at idle = possible crappy idle but, the battery should have a good enough charge to accommodate that should it not? 12 volts vs 13-14 volts should be within the design tolerances, and shouldn't cause it to idle rough I would assume.

I doubt thats the issue though. The damper sounds more it. I'll probably order one in the next few days then. Don't want this thing breaking off in the engine bay or somesuch eh...

My worst fear, is that the engine internals weren't properly balanced (or the flywheel was screwed up) somewhere along the line by the machine shop. However, from my understanding, if the internals were out of balance, the vibrations would be there at all RPMs (and worse at higher ones), probably the same with the flywheel.

Anyway, thanks for steering me in (what is hopefully) the right direction!
I'll report back with the results.


edit:
[strike]also, I just wanted to ask...I see in a few threads the stock bolt needs to be machined down. Anyone have any more info on that? Is there anything I should be aware of in mounting the ATI on there? I'd like to have the car back up and running asap (my DD), thus, if I go and find out it needs to be machined down on a Sunday....XD[/strike]
edit edit:
Nevermind, found it all on here after a bit more searching. Gotta machine the bolt flange down to fit, not too bad.

 

[GrimJack]

Ya, keep in mind that bolt is really hard steel, so machining it is a bit of a bitch.

 

[legolyle]

haha yeah, a little late for that XD
went and bought a new bolt from Toyota and machined it down yesterday morning, I went at it way too fast at first, one edge of the tool was totally destroyed by the steel within just a few passes. That stuff is seriously hard. It almost destroyed another edge going at it in significantly smaller passes too, cheap tool...supposed to be getting the damper in today, should have it on there before the weekend.

 

[legolyle]

well, I'm sitting here with hands covered in crap, and a good nights work done, got it all installed.
I really wish I could say it was all better, but it's the same. It feels exactly the same. Reading through the manual for the ATI damper it says it may be out of balance until the engine reaches 2000 rpm for the first time with the damper installed, at which point it should work...So...did that, took it all the way to 3000 (while in the garage), and it still idles like crap, the whole car vibrates. I can feel it in the seat, coins rattle, all of it. It didn't help at all, not even a little.

Right now, I'm really hoping if I take the car for a drive it'll settle in, think that'd help?
But, I'm done for the night...

If it isn't the damper. It has to be one of only a few things:
-something out of balance, could the flywheel be the issue? or, engine internals? If engine internals were out of whack, would that not be present at all RPMs? If the flywheel was out of balance, would it be the same way?
-shitty spark at idle because of the going-bad alternator. I'm just not sure if this would/could cause the whole car to vibrate like it does. Obviously, a misfire or some such could do it, but, I should be able to hear that. I hear nothing. Or, nothing I recognize. Thus, I just don't think this is the problem.
I'm going to hook up a charger to the battery while the car is running to bring the voltage up on the system, see if it helps, I dunno why I didn't try it long ago. But, I doubt it'll do anything.

 

[legolyle]

So, drove the car some today and it hasn't gotten any better at idle.
It's too early to say for sure, but, I *tried* to see if the vibrations still occured at 3k rpm while driving (I said 4k in a previous post, I meant 3k) and I couldn't feel any at ~3k rpms. When I get to take it back on the highway tomorrow I'll check and see if it was just a one time thing or what. But, if it wasn't a one time thing, then that means the vibrations at 3k are gone, leaving me with just vibrations at idle.

Is it possible the transmission mount could be sending vibrations through the chassis? I mean, it's weird it's only at some RPMs, but I would still think it could be a cause. I'm going to have to pull the engine here in the next few months to change out the rear main seal, so I'll probably have the flywheel checked for proper balance while I'm doing that.

 

[GrimJack]

Well, there are only a few possible culprits, because at idle, and stopped, there are only a few parts that rotate. You're going to have to go through the basic steps of troubleshooting, eliminating one piece at a time.

Does the clutch have any effect? If so, it's something in the clutch or tranny.

Have you tried replacing the ignition components? Plugs, wires, borrow an igniter and set of coilpacks, maybe something on yours is too damn weak.

I'd try it without any belts, to eliminate any of the accessories on the front of the engine. Mostly because fixing those is easier than anything else.

Then, I'd pull the tranny and flywheel and try it again. If that fixes it, there's something wrong with the flywheel. If that doesn't fix it, you've checked everything external to the engine, so it must be something *in* the engine, which is going to suck.

 

[legolyle]

took it for another drive today, I want to say that it used to feel much worse at around ~3k rpm, and it feels more smooth now. Rather, I should say, ~3k RPM no longer distinguishes itself from any other point in the RPM range whatsoever. I also want to say the idle feels, ever so slightly better, but I think that's wishful thinking.

yeah, I've sorta already gone through some of that. I replaced the spark plugs about a week ago, no effect. I checked the wire's resistances, all of them were well within spec (should I still worry about the wires? They do seem pretty old...). I replaced the coil (GE) a while ago because it showed out of spec, with another used one within spec, didn't help (or effect much of anything). I also replaced the distributor cap and rotor with new ones during the rebuild. I haven't looked at them since, but because the idle has been so bad since the beginning, I doubt the problem lies there. Now, I totally forgot about the igniter, that's next on my list now. I'll take a quick look at the tranny mount tonight, and try it with no belts.

So, first thing, no belts. Good tip, thanks.

Now, I want to do the flywheel asap, I wish I had more time...I'll need to set aside some weekend for it.
If I pull the tranny, the engine wont have any support at the rear, is that not a bad idea? Or, will it's two mounts hold it up fine?
If need be, I'm thinking you could theoretically hook the tranny back up with no flywheel/clutch cover and it'll all be fine yeah? Just to keep the rear of the engine supported.
Additionally, with no flywheel, will any new vibrations be introduced? Or, should I be okay there?

 

[GrimJack]

The two mounts in the front are plenty when there's no tranny attached. I've started these sitting on a wooden frame with nothing attached, not even a radiator.

No flywheel shouldn't matter - these are supposed to be neutral balanced for each part, you don't need the entire rotating assembly like some engines.

 

[legolyle]

alright, and yeah, I just wasnt for sure
Havent had time to check anything else yet, hoping to check some more stuff this weekend and get the flywheel off in the next two weeks
however, I realized, without the flywheel, I cant exactly start the engine. Got any suggestions for that?
I was thinking you could probably use an impact wrench with the right size socket on the front, but, I doubt it could get it up to speed in order to start...plus, I dunno how safe that is, honestly.