well, last night my girlfriend and I figured out the spagetti mess of vacuum lines and electrical connectors and got ready to fire up the Trooper for the first time since its been out of comission due to a cracked head.

our initial attempts had me worried but i quickyl realized by the backfire through the intake i had dropped the distributor in with the timing marks lined up (another words TDC #1, but on exhaust rather than compress). I was 180* off, quickly rectified the problem and tried again.

This time, the trooper started up and sounds very mean i might add. either i have a big exhaust leak that i'm missing, or the Delta cam adds a lot more 'throaty' sound to it.

Now the problem... what i noticed almost immediately is the engine has a horrible shuttler. like the motor mounts are made of jello. any slight rev of the engine (even up to about 1200rpm) and the vibrations are transferred to the trooper and the car starts shaking. there is no way it could be driven or even rev'd like this, the engine what shutter itself apart in no time. So i quickly turned it off and haven't started it since. it sounds fine (other than a noticably deeper tone) and idles fine, doesn't act like its not firing on all cylinders or anything, its just there is way too much movement from the motor.

So i need your help, what should i be checking? obvisously it wasn't this way when it last ran with the old damaged head. I have a hard time believing anything in the bottom end was hurt, but maybe thats a little presumptive.

These were my initial thoughts:
- could ignition timing cause this? i haven't put a light on it yet, but it idles and otherwise sounds normal.
- what about valve adjustment? possibly caused from overtightening a valve? i don't think so, but just an idea.
- harmonic balancer? seemed ok when i examined it, do i need to reseat it? replace it? could it cause vibrations this bad?

then whole engine acts like its horribly (and i mean horribly) out of balance. what could this be?

Any insight would be greatly appriciated. thanks guys

-Rob

May or may not be helpful info:

One time I was resetting the timing on my engine after I removed and replaced the distributor, and the first time I started it up was interesting. The engine was bucking and shaking and there were high pitched hissing sounds to the point I thought I had forgotten to tighten/install something and seriously damaged my engine by starting it. I was seriously concerned I had destroyed something by the noises it was making. Sounded like as if I had changed the oil with 2 lbs of beach sand.

I adjusted the distributor by "feel" then timed it up with the light and had no problems. So my vote would be time first, then be concerned if it doesn't fix the problem.

I'd also hypothesize that a "way out of timing" 4 cyl would idle rougher than the same timing on a 6, since there are less rotational mass to even out the ignition.
^^^^^^^^^^^^only a SWAG though, could be incorrect.

Did you check the bolts that hold down the rockers to the head?A couple were loose on the head I had to put on...
found it when i took it apart to lube and set valve clearance.......valve clearance was set by a factory monkey
with a big forearm.
I also say put a light on it.If timing is way advanced it could be fireing far enough ahead of topdead center to cause
a bad vib/shutter.
Good luck

Bansil

yea, i installed the rocker assembly/cam caps since we put a delta cam in this. I torqued down those nuts to the recommended 14-17 ft/lbs IIRC. I'm sure they're tight (well, at spec at least).

As far as the timing goes, i haven't put a light on it yet and will do so as soon as i go to my shop to pick my light up, but the part i find strange is the engine sound/idles completely normal. It does run "rough", it runs fine, it just shackes almost uncontrolabley. Best way to describe it is its like its running with no balancer.

Thanks for the opinions guys, if you think of anything more, definitely let me know.

-Rob

Oh yea, the other thing that crossed my paranoid mind today is... what if we hydrolock'd this thing on its own radiator fluid and tweaked a rod? possible? i know the bottom ends are tough, but how tough? there was a huge amount of coolant leaking into the combustion chamber from the cracked head. Are rods likely to bend enough to cause this sort of vibration? or do they typically just break and send parts flying instead?

-Rob

Can't help you with this, Rob, but guys are right. Check the timing, it can do some realy freaky stuff.

You still have a spare block laying around, right?
I just hope it's in a better shape than the head was (in case you need the parts from it).

Just a question, did you change the timing belt or re-used the old one?

i'm sure you've checked, but i've crossed a couple of wires more than once when working on my 2.6, and it'll do exactly as your described.

you know, you're right, i do! <img src="/forums/images/graemlins/smile.gif" alt="" /> but when we removed the head from it, mostiture has taken its toll, things are pretty rusty and funky, to the point your old engine wouldn't turn over then i tried. but could be a possible source for pistons/rods if it comes to that.



reuse. the belt appeared in good condition and was an aftermarket one so it had already been replaced once. with the extra money we've already put into this project and still might have to put, i'm trying to keep costs down to the vital things that need to be replace. I'll come back in a year or two and do the timing belt again, no problem, i think i could do that rather quickly now.

-Rob

thanks rufus, i'll check on that tonight. i'd rather eliminate whats easy to check first, before getting back involved in this thing.

-Rob

I would second the plug wire idea. I remember when I first got my 88 I did a pretty good tune up and that included a new cap and rotor new plugs and wires. When I tried to start it no go. The Haynes manual isn't right when it came to the plug wires on mine. I had to look at the cap and run the wires that way. Something to check.