Grinding sound

madmikeismad

madmikeismad

So mad
Joined
Dec 19, 2009
Messages
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In park or drive or neutral, doesn't matter, my truck makes a rough, almost grinding sound at 1000rpm, and only at 1000rpm. You can feel it in the floorboards too.

Any ideas?
 
Yup, but as soon as I go over or under 1000rpm, the noise/feeling goes away.

Also may be of relevance: Today when I put it in gear, the TC (goerend if it matters) locked up and stalled the truck. Did it twice, and then went back to normal and drives fine again.

But the grinding sound is still going.
 
My truck made grinding sound when the TC bolts were loose. Didn't find out the reason soon enough, so had to replace both TC and flexplate.
 
Mostly it was around 1200rpm. Sometimes there was no sound at all and sometimes noise was there from idle to 2000rpm. I didn't rev it higher than that.
 
I was going to suggest the same thing. The FSM calls for 35 ft lbs, and I add some red loctite as well.
 
A harmonic of a wave is a component frequency of the signal that is an integer multiple of the fundamental frequency, i.e. if the fundamental frequency is f, the harmonics have frequencies 2f, 3f, 4f, . . . etc. The harmonics have the property that they are all periodic at the fundamental frequency, therefore the sum of harmonics is also periodic at that frequency. Harmonic frequencies are equally spaced by the width of the fundamental frequency and can be found by repeatedly adding that frequency.
 
The flexplate wiggles a little as it spins. If the converter bolts are loose, and you're at the right RPM to make the wiggle happen just as the bolt is spinning by a low clearance portion off the block/tranny adapter, it'll rub and cause the vibration.

A simple way to check the bolts is remove the two 10mm bolts and inspection/access cover on the passenger side below the turbo and just right of the exhaust downpipe & auto tranny dipstick. There is a round plug that gives access to the flywheel teeth when using a barring tool and just to the right of that is a 2" cover plate with 10mm bolts. Remove the cover and then slowly rotate the engine via 7/8" socket on alternator nut. There are 6 total 5/8" bolts that mate the torque converter to the flywheel. Rotate the engine slowly till a bolt comes into view and check that it is tight. Then rotate the motor another 60* about 5-6 turns on the nut and you'll see another converter bolt come into view. Repeat the process 6 times. If all the bolts are tight, the problem obviously elsewhere.
 
I checked the bolts today, everyone was as tight as the day I put them in there. What else can cause that vibration? I can feel it through the whole truck. I could even feel it under the hood when I played the throttle by hand on the side of the pump.

BTW Big Blue: I just use a short prybar and turn the TC by prying against the bellhousing, then I can reach up and feel when another bolt comes around without moving back and forth to the alternator, and back under the truck 100 times.

Also, I can't turn it by alternator nut on this truck, the belt just slips on the pulley. does this mean my tensioner arm is bad? Would that also explain the incredibly loud screech when I shut the truck off?
 
To rotate the motor with the alternator nut, you have to turn the motor backwards. Looking at the front of the motor, turn the alternator nut counter-clockwise. The belt shouldn't slip in this case.
 
Maybe down on one cylinder. Cylinder leakage testing?

What does your vibration damper look like? Like it is meant to?

Fuel leaks anywhere?

Pump barrels in the locations they have always been? Any extra scratchmarks around the boot in pump mating surface?

Pulsing smoke at idle? Or when it shakes and shudders?

Boost leak?

...just to give you ideas here.
 
JariV said:
Maybe down on one cylinder. Cylinder leakage testing?

Not sure

What does your vibration damper look like? Like it is meant to?

I'm checking that when I get back from work next week. Thanks

Fuel leaks anywhere?

Nope

Pump barrels in the locations they have always been? Any extra scratchmarks around the boot in pump mating surface?

I haven't touched the pump except for fuel plate and afc. Barrels don't turn on their own do they? I didn't notice any scratches, what could cause them?

Pulsing smoke at idle? Or when it shakes and shudders?

Nope

Boost leak?

I don't think I make enough boost to say so at 1000rpm. And I don't think I leak any at all anyways. (except a little at the gauge, sometimes it hisses :)

...just to give you ideas here.
Click to expand...

Thanks.
 
Nick said:
To rotate the motor with the alternator nut, you have to turn the motor backwards. Looking at the front of the motor, turn the alternator nut counter-clockwise. The belt shouldn't slip in this case.
Click to expand...

Tried that, she wasn't budging. I just turned it by turning the tc with a short prybar on the teeth. A lot easier and faster.
 
One more thought:

What if one of your auxiliary brackets has cracked? I've also seen some cracked alternators. Not in my ride but there's been a couple of OEM alternators here in Finland that have cracked. Or loose bolts in the brackets / auxiliaries?
 
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