Totally Stumped for 3 days...

[MAXLLY]

Got the truck up and running no catastrophies.

I have a long list of things to do but ONE item has me stumped, I'd like the groups input.

After the truck reaches operating temp i have a "hard buzz" not from the night before... emitting from the truck.:rofl:

Memmer when the chevy power steering pumps (70-80's) used to go bad? They had a vibration and a hum/howl to 'em when parked at idle? Thats the noise i have. VEry simliar to a hard tire buzz at 50-60 mph with an aggressive tire. Nothing at idle, no noise when the wheel turns, at RPM only, driving down the road it is linked to belt or motor speed. Doin' 50-55 MPH i slip it in to nuetral... it follows rpm to 1000 and quiets down, back in gear... noise is back.

I had Mike L drive it, not the converter or the flex. Could the CP-3 be overspeeding? restriction? premature pressure? Mine has a little jiggle to it, it isn't smooth running at idle. Anybody here running the new oil pump? Does it carry a hum to it?

Any idea???? I've been stuck on this one for 3 days and i can't get it. If i could touch parts while driving down the freeway it'd be fixed. :rofl:

James

 

[dmaxvaz]

I also have a buzz that i cant find either, it is like at 1000-1200 rpm. I have given up trying to find it

 

[NJ_LLY]

You can touch parts at highway speed if you put it on a lift. Just a thought.

 

[Diesel power]

cp3's wont make that noise, PS pumps will, so that may be the issue...

vaccum pump maybe??

 

[JOHNBOY]

cp3's wont make that noise, PS pumps will, so that may be the issue...

vaccum pump maybe??

The regulator on the CP3 can and will buzz loadly. This is very common in trucks with excessive lift pump pressure.
I figured a tuning guru like you would know that.

Max did you try reming the Belt and seeing if it still made the noise. Did you check your alternator. I had one lose a bearing after sitting for a while.

 

[TheBac]

New or old waterpump? Sounds like the buzz Gasuout was talking about with the "new" GM pumps. Gears dont mesh properly.

 

[sweetdiesel]

vaccum pump maybe??

Where is that?

DPR oil pump doesnt make noise on my truck James

 

[duramax-rob]

Have you flushed the p.s. and booster system? Just a thought.

 

[TrentNell]

Where is that?

DPR oil pump doesnt make noise on my truck James

i dont know if all trucks got them but i do know if you have a egr you got one if i remember from the gm breakdown its passenger side driven by belt towards the mid to bottom of motor .

 

[SmokeShow]

does it only buzz with a load on it, i.e. going down the road at RPM? or will it buzz if you free-rev it in park or neutral?


it's a little costly but if it needs a load on it, you could put the truck on a dyno, load 'er up and watch/feel/listen with the hood open???

 

[MAXLLY]

I'll start this morning with belt removal.

I didn't flush the power steering system or hydro, it was removed during build so it was inadvertanley flushed.

Its a loaded buzz, nothing at idle, nothing when cold. Repalced the valley regulator with a LBZ reg to match the wing pump.

Its mechanical as 3 tunes hasn't changed it.

 

[MAXLLY]

does it only buzz with a load on it, i.e. going down the road at RPM? or will it buzz if you free-rev it in park or neutral?


it's a little costly but if it needs a load on it, you could put the truck on a dyno, load 'er up and watch/feel/listen with the hood open???

IT's tougher to feel when under load, as soon as you back out of it you feel it (like a bad power steering pump). I thought i found it... My exhaust exits through the side of the bed. As the run time increases and it gets hotter... the 4" piping grows!! Almost 1/2" in 8', i didn't think it would grow that much.

Still got the buzz. Somebody else mentioned i need to rotate my motor mounts where they mount to the frame? (the 2 larger bolts stacked one over the other 4-5" long) I don't memmer those holes being oblong allowing a "saddle" movement of the engine from fender to fender?

Can anybody refresh on the holes?

 

[IdahoRob]

I know if any part of the exhaust hits even the fender liner, you will get an awful buzz in the cab. What I do to find the noises is, use efi and the dvt in the scan tool and bring up the idle rpm's until you start feeling/hearing it and walk around the truck. My biggest buzz is from the black bumber cover rattling.

Just a thought.

 

[Fingers]

Any engine/exhaust part that comes in contact with anything on the truck without a dampener will buzz. I have a heat shield that manages to touch the driver's side up-pipe when I am in reverse and under certain loads. PITA to find till it did it long enough to see the rub mark. Plenty of clearance when it is sitting on the lift though. I would not have thought they touched.