I've recently picked up a new noise. At idle the engine buzzes. It sounds like the vacuum pump running but coming from the engine (the vacuum pump is not running while this noise is happening). This noise could also be happening while I'm driving too but the RPMs bring up the engine noise so I can't tell. Nothing looks out of the ordinary and I haven't done anything different that would give me any direction (no off-roading). It was just there one day.

Anybody had anything similar that can point me in a direction?

The truck doesn't seem to be running any differently (right now), just the buzzing. I just want to catch it if it's going to become something serious. An ounce of prevention is worth a pound of cure (not to mention the towing bill!).

Thanks for any help.

 

id say you going to have to do some investigating.
see if you can get somone to slowly rev up the engine while you listen around, and see if it changes with rpm's..
did it get colder by you in a recent time?
and is is doing it when fully wormed up?
it miht be an injector, rocker arm, TC, list goes on...

 

We've had a heat wave and it's actually gotten a little warmer down here.

It does it even after it's warmed up. I've driven home 30 miles and I can still hear it. I'll pop the hood and take a look around while the turbo's cooling down and I can't seem to pinpoint it. At first I thought my dressing cover was rattling (it's only being held on by one bolt, the other one rusted and I broke the stud off trying to remove it). I was hoping for an easy and quick fix, but it was not to be. Looks like it's time to dust off the fingers and have at the search function again....

 

bumble bee in the cab..open a window..

 

well. getting rocker arms tighten its free, as long as you have TQ wrench,
how loud is the buzzing?
maybe its your Vacum pump? if you have ESOF maybe leaking vacum line? just a guess.
is it doing it only with engine running? or with the key on too?
just trying to help....

 

Only does it with the engine running.

Already had the ESOF leak/frozen hub combo (to the tune of almost $1000) so I'm well versed in vacuum pump ops (I'm too old to get out every time I want to lock the hubs otherwise I would have jumped on the Warn Premiums). It's definitely not the vacuum pump.

How hard is it to get to the rocker arms? I've got an in-lb (and ft-lb) torque wrench.

The buzzing is noticeable, very much like a loose dressing cover vibrating...

It doesn't seem to be having any operational effect (loss of power, smoke, rough running, leaks, etc...) but I want to cut this off at the pass if it's going to mushroom into a real problem...

 

its not that ad, you have to remove your valve covers, so airbox, and all pipes for the intercooler have to be removed, its a 1/5 day job if you didnt do it before.
ill see if i can find the specs on injector bolts and rocker arms TQ ...

 

here you go
rocker arm pedestal bolts to 20 ft-lbs
lower injector hold down bolt to 120 in-lbs

 

BTW you can reuse you VC gasket, so no expenses there....

 

LMAO at Ron.... do you have this happen to you ? hahaha

 

Thanks for the specs! It seems to only do it at idle. Granted, it's like trying to pinpoint a noise on a garbage truck once you start revving it, but it sounds like it's coming from the top of the engine at idle. When the fuel pedal is released and the engine approaches idle is when the noise seems to re-initiate. I'll have to set aside some time to climb on top and check the torques. My wife will be thrilled! At least it's just time and beer, no parts money...yet.

 

Subscribing......I have a similar buzzing. Hopefully this will fix yours and then I will know what to try first

 

Here is a picture from Chris

 

Thanks for the pic! I was wondering exactly which bolts I was going to be torquing and you read my mind...thanks.

 

One of my frustrations is always that once the problem is solved, the OP doesn't post the results for everybody to see and learn from. I'm not going to be that guy!

So I finally had a day (yesterday) to open the hood and have at it. In addition to the routine stuff (oil/filter change, rotate wheels, add washer fluid), my primary goal was to have at my engine buzz. By the time I was done I had collected a pile 1/4" and 3/8" ratchets, sockets, swivels, wobbles, and wrenches to get the job done (oh yeah, and 2 torque wrenches for ft-lbs and in-lbs). What I thought was going to be 3 hours turned into 6 hours. Some of this was due to trying to keep too much crap from falling into the exposed engine components with the valve covers removed, and most of it was me trying to get my freakin' arms/hands/fingers to every bolt. Seriously, who designes this anyway?

Anyway, everything was straight forward (albeit not conveniently placed) to do.

I removed all the interference (intake filter and tube, both batteries, driver's battery/air box, both CAC tubes). The shop manual calls for removing both heater hoses too but I wasn't about to bring my cooling system into this to complicate things further. The hoses really don't pose much of anything more than a nuisance anyway. I removed the valve covers (be sure to remove the oil filler tube on the passenger side otherwise it is going to be VERY difficult to get it in/out). I checked the torque on the rocker arm pedestal bolts (20 ft-lbs) and only one moved ever so slightly. When I checked my lower injector hold down bolts (120 in-lbs) they were all loose. All of them! Some turned as much as 1/2 turn before reaching required torque. I put the valve covers back on (10 bolts per cover) and torqued them to factory spec (the shop manual says 98 in-lbs for the driver's side and 96 in-lbs for the passenger's side). I found that odd that each side had a different torque for the valve cover bolts (I also verified that both were for the 7.3L). I put everything back in and fired it up, and viola, no more buzz!

Thanks for the help (and the picture!). I never knew about these bolts walking out until I posted about the buzz. I would say it was free but it cost me a few knuckles, cuts and scrapes (all part of a good day's work!).

Also, when I was in there I had planned to do the quarter trick for the harnesses, but they were one solid plug and not loose, so maybe the crappy connector is just on the earlier models.

Thanks again for all the help. It solved my problem.