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bad shake at idle

15K views 28 replies 19 participants last post by  9297oldram 
#1 ·
well since i bought my truck it has had this really bad shake at idle it makes the whole truck shake and the best part is when its in drive gear and im coming to a stop - the front end shakes really bad just before i come to a complete stop and it downshifts into first, it feels to me like there is something wrong with the engine or there might be something wrong with the transmission if anyone can give me some help that would be great!

the truck is a 1990 12v with a 3spd auto 2wd 395,000kms
 
#6 ·
mine does the same except the whole front end thing while stopping. If im stopped, the engine rocks the truck. I think she' idles @ 900 even with the idle screw backed all the way out, i have the fuel screw maxed, 1 turn from run away. But the whole truck shakes while stopped. i have the getrag and 175,XXX miles
 
#9 ·
ya i checked mine aswell they are fine, im taking my injectors out this week to have them cleaned and recalibrated back to stock since the last owner owned it all they did was regular oil changes and nothing else to the truck it probably has never seen new injectors or had any fuel additives in the 395,000 kms it has been drove, so im hoping this helps the truck run a lot better
 
#10 ·
my truck shakes at idle but if i rev it up at all it goes away. it doesn't really shake much but it does make everything vibrate. my front end doesnt make funny sounds. the funny thing is it didnt do it untill i replaced the tranny mounts
 
#11 ·
gen1- does the shake go away when you rev it up? Mine didnt go away, and one of the plunger springs in the head and rotor had broken.

If it clears up above idle, I'd say it's time for new springs anyway. Not a bad job- 1stGen545 has a commplete write up on DTR about doing it.

Good idea to get your injectors cleaned and reset. Most engines need it by 150K mi.

Daniel
 
#12 ·
Raise your idle speed a bit. Mine shook so bad it made my rad leak. You may have other issues. A lot of short tripping may clog injectors leading to a rough idle. However I kind of expected the cummins to idle more slowly than it does. It does not need to rise much over an idle to pull but it can't idle smoothly at as low a speed as some other engines. I will get my injectors reset someday. I get a lot of smoke on start up and I suspect my injectors may need a nudge.
 
#13 ·
minewas doing something similar...

it seemed like it was defueling at idle, and just didnt have the power it used to. i believe my problem was the little boost line that runs from the intake to the top of the pump near the smoke screw. the line was loose at the intake and leaking boost pressure.

I say i belive that was the problem because i also backed off my starwheel 3/4 turn from bottomed out.

whichever it was, it made a huge difference and it idles nice again!
 
#15 ·
Try a valve adjust.
 
#16 ·
i gave up on the shake i just tell every one shes just cold,valve adjust check,8oorpm idal,new motor mounts(drag strip made one a victum) and tranny mount both check,i dont know but if some one has an idea im open
 
#17 ·
my injectors were redone with new nozzles right b4 i bought my truck, got the receipt. It goes away when i raise the R's a little but at idle she rocks back and forth. i tell my friends that its the feel of REAL power lol. I have lots of smoke at start up but, i got pump mods too. It had a smoke haze when i bought the truck at start up just like all the 1st gens do. It had the muffler and the pump was still "a virgin."....till i got a hold of it. I have no idea what it is. It runs strong, very strong. breaks the tire(s) loose on dry pavement at 30-35mph in 4th when the turbo spools, even at 1/2 throttle. I dont know what it could be tho.
 
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#18 ·
well ive done the valve adjustment about two weeks ago, the shake does go away if i rev it up but its got a wierd pop coming out the exhaust almost like a cylinder is missing. but the thing is it feels like it has all 6 running and it doesnt really feel down on power, and it blow out a big cloud of black smoke when i fire it up but i do have the fuel screw turned up
 
#19 ·
My truck does the same thing. its prolly in the pump . somethings unballanced? the older trucks all shaked pretty bad cause the mounts are a lot more ridgid than the newer ones.
 
#22 ·
My 1992 just got new gaskets (front main,,tappet cover, valve cover and intake) so the truck was apart for a while the pump was out, the whole front of the motor was apart after completing my task I put the truck back together the same way it came apart and turns out I was off a few teeth on the pump gear so it wouldn't fire..I finally got them lined up as they were and it fired up but now has a wicked shake while idling and moving around the yard. The motor shakes pretty good there's always a haze of white smoke and I can't seem to figure out what it is. Everything on the truck is stock even the settings on the pump nothing has been messed with at all! The radiator now leaks cause it was rocking so hard the only thing that's not fully together is the turbo side charge piping to the intercooler. Has anyone figured out this issue yet? I'm going insane over this
 
#23 ·
I can't believe you don't have this truck running yet haven't heard back on your post so I figured it was running.

Does the shaking clear up if you give it some throttle? What's the rpm's at idle?

Does it start on the first crank when the engine is cold?
 
#25 ·
White smoke is a good sign of a miss firing cylinder/s which will also give you the shakes.
Are you certain the pump timing is correct?
Could crack each injector line and see which on it is.
Did you have the injector lines off? May have got some crud into and injector. Don't ask how I know!.
Cheers Steve
 
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