Subliminal

So, my engine vibrates. At idle it shakes the truck a little. At low RPM driving, it's ok. In the middle of the RPM band it vibrates the floor, gas pedal and steering wheel. With the pedal all the way to the floor (3200 spring installed) it vibrates TERRIBLY.

I've done motor mounts and it helped but didn't solve it. One of the bolts was really loose, so that definitely helped, but it definitely still has issue.

I adjusted my valves a while back and it didn't make any difference. Would poorly adjusted valves make any vibration?

I replaced my injectors to no avail...although I ended up with bigger injectors, so that's ok.

I was thinking it'd be nice to put on a fuel pressure gauge to check, but for the cost, I could just replace my lift pump...would a faulty lift pump produce vibrations?

I want to pull the belt and check and make sure it isn't an accessory or the fan.

Anyway, I'd appreciate any ideas anyone could throw my way.

Trebor

I'd check for something in the rotating assembly such as a missing bolt or two on the clutch pressure plate, a loose pressure plate, a partially disintegrated clutch disk, or a loose or cracked flywheel. Did you use a torque wrench when you changed over to the Getrag set up? Also, is the front balancer/pulley tight?

Subliminal

I'll have to check the front balancer/pulley...that's a good idea!

The flywheel was surfaced and balanced and then pulled and re-rebalanced. The PP and clutch have a few thousand miles on them (at most) now, as they were brand new parts during the swap.

I did not use a torque wrench, but I did tighten them good and used loctite.

Thanks for the reply!

thrashingcows

I would definitely pull the belt and run the motor...that will eliminate any accessory that might be causing the vibration.

KD93

Bad vibration dampner? Did this just happen, or was it when you redid your tranny? I was thinking it may be the drive shaft is clocked wrong, but that wouldn't be it if it just started.

mhuppertz

To vibrate at idle it would have to be something of weight. I would agree with the idea that it might be a missing clutch pressure plate bolt.

Subliminal

While I guess that isn't impossible, I find it highly unlikely. It did this before and after I re-pulled my tranny (about 1k after the swap) and the bolts were all there when I pulled it and then I reinstalled with Loctite, and no change since then.

Very frustrating...probably end up being why I unload this truck eventually...or kill myself.

mhuppertz

Does the flywheel have any weights welded to it? Did this start with the tranny swap?

Subliminal

It did start with the swap.

The flywheel didn't appear to have any weights added to it, but it did have a few spots where it'd been drilled for weight reduction.

When I got it all together, I noticed the vibration, so after a little while I tore it back apart and took the flywheel and the PP in to be balanced. They checked out again (different shop), so I kind of concluded that they weren't the problem...although if I do rip it apart again, I'm going to run it with just the flywheel, then add the pressure plate and run it again...

I just don't really look forward to tearing it apart again. I was REALLY hoping it was motor mounts, as I did just let the engine hang on them for a time...but nope.

Trebor

Maybe also look for a shiny spot on your exhaust pipe caused by it rubbing the frame or body.

mhuppertz

Very odd. I wonder if it is something completely unrelated to the tranny swap, just coincidental, like your pump having issues.

mhuppertz

Clutch in or out at idle change anything?

Subliminal

Nope, doesn't seem to make a difference...clutch in, clutch out, clutch in with tranny in gear...

It could be totally unrelated, which is why I was thinking of just throwing a lift pump at it. Right around this time I ramped up the pump and also put in bigger injectors.

DevilzTower

If we're going to talk the fuel route ... could be:

1. Clogged fuel filter - can't get enough fuel - causing a misfire
2. Air into the lines (small crack that sucks more air with more vacuum, i.e. higher rpm)
3. etc

When you put in the injectors and ramped the pump, you put significant added strain on the fuel system with both those mods ...just food for thought

Subliminal

Right. I realize this, and that's why I've been trying to go through the fuel system a bit.

The fuel filter is new within the last thousand, and there was no change in running when I changed it out.

I DID bend the lines a little bit when I was doing the injectors, but didn't notice any leaks..not sure really how to proceed with the fuel line.

Funny thing...I can crack injectors all day long and fuel will spurt all over the place but the engine seems to run the same, regardless...