Engine off balance
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Engine off balance
Hey everyone, I’m having some vibrating/shaking issues with my truck. It’s a 96 with the 5.0 and I haven’t been able to find anything obvious that’s wrong. It’s almost like something is off balance and the symptoms go on at idle, high rpms and low rpms, under load, without a load, all the time. I kept getting codes for a lot of ignition issues but I fixed all those and cleared the codes and nothing else came back. My rear fuel pump went out around the same time that this happened but I’m not convinced that the two issues are related. I checked the harmonic balancer and tried moving it with the belt off and it didn’t budge. I was told there is a rubber bushing on the balancer but seeing that the pulley didn’t move at all would i didn’t think it was bad. I checked all my other pulleys and the only one that would move was the power steering pump pulley but it would only move in and out of the pump about a 1/4”. I’m replacing my fuel filter to rule out bad gas clogging the filter, I’ve changed out my plugs and wires and have a new distributor cap and rotor. Has anyone had any problems similar to this?
Lead Driver
Joined: Oct 2016
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From: Houston/Sugar Land
Hey everyone, I’m having some vibrating/shaking issues with my truck. It’s a 96 with the 5.0 and I haven’t been able to find anything obvious that’s wrong. It’s almost like something is off balance and the symptoms go on at idle, high rpms and low rpms, under load, without a load, all the time. I kept getting codes for a lot of ignition issues but I fixed all those and cleared the codes and nothing else came back. My rear fuel pump went out around the same time that this happened but I’m not convinced that the two issues are related. I checked the harmonic balancer and tried moving it with the belt off and it didn’t budge. I was told there is a rubber bushing on the balancer but seeing that the pulley didn’t move at all would i didn’t think it was bad. I checked all my other pulleys and the only one that would move was the power steering pump pulley but it would only move in and out of the pump about a 1/4”. I’m replacing my fuel filter to rule out bad gas clogging the filter, I’ve changed out my plugs and wires and have a new distributor cap and rotor. Has anyone had any problems similar to this?
Fleet Owner
Joined: Oct 2005
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From: Kentucky
At any time during previous repairs did you check the base timing? If so, did you have to adjust it more than a few degrees?
If neither above apply then check the base timing, SPOUT removed. If it appears the base timing is significantly changed then that is an indication the outer ring of the harmonic balancer has slipped. This could be the cause of your vibration.
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I’ll try to check that this week. I haven’t checked the timing yet because I don’t have a timing light but I can go buy one and check. I’ve never messed with the harmonic balancer but it doesn’t seem to hard to take off if I need too. Is there anything else that could cause the timing to just go off?
The u-joints are all under a year old and are in good conditions. I’ll also check the motor mounts
The u-joints are all under a year old and are in good conditions. I’ll also check the motor mounts
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One more important thing I forgot to add. Last weekend I let my truck sit all weekend and cranked it up Monday morning. the problem just went away and the vibrating/shaking stopped. But it came back again less than a week later
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Valve covers off, measure how much the rocker moves as the motor turns over.
I would do the compression test first.
I would do the compression test first.
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Cargo Master
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From: Laramie, WY
This is an OBD-II truck right? 1996 F-150? Do you have any codes? If not, how far have you driven since resetting them? They often won't come back right away.
Slipped balancer would likely not trigger a code and would shake. A misfire would shake, but tend to smooth out with higher rpm (especially unloaded), should be easily seen by the PCM and trigger a code. So, slipped balancer would be my best guess too.
Slipped balancer would likely not trigger a code and would shake. A misfire would shake, but tend to smooth out with higher rpm (especially unloaded), should be easily seen by the PCM and trigger a code. So, slipped balancer would be my best guess too.
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It is an OBD-II. The only codes I received in the past couple of months have been with the secondary air injection system. Since resetting them I’ve driven 500-1000 miles. I’ll check the timing and see what it’s set at. If the balancer slipped, is it better to replace the balancer or adjust the timing to compensate? I’m thinking that if it slipped once then it could slip again and throw the timing off again but I’m not too sure
Fleet Owner
Joined: Oct 2005
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From: Kentucky
But given your other recent statement:
This is a clue your problem is not the balancer because the vibration will not and come, it's always going to be there.
FTE Chapter Leader
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From: Central Mississippi
Wish you had written down exactly what these were.
More Turbo
Joined: May 2008
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From: Arkansas
Just a thought here. My diesel gives the same symptoms when it is running out of fuel. Fools me every time, feels just like a 'miss'. My suggestion is to check your fuel pressure at the rail and also the time it holds its pressure.
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So, you got it going ok, it sat a week, then when you restarted, same deal? You may have moisture accumulating under your distributor cap. I had a 74 Chevy long time ago, if it rained, it would run like a dog and miss, if it even started. All went away with new cap. To test, next time there's a lot of humidity or I guess you could try garden hose, if it does it, take cap off, dry it out good with hair blow dryer and see if any difference.