yeah, that's right, it's a metallic clanking/rattling sound coming from the gear case/front of the vacuum pump. just started rather suddenly tonight on the way home. only makes noise when it's idling, in gear or neutral makes little difference, get a driving load on the engine or even just rev it past 1200-1300 and the sound goes away. got my stethoscope and poked around on the engine with it running and the very loudest it ever got was right on the front of the vacuum pump, could hear it all over the cover but definitely loudest right there. also there's now oil leaking out of where the pwr steering pump goes into the vacuum pump.(a brand new leak, I park on concrete and know if it leaks or not)

anyone had this happen?? now about two or three months ago the power steering pump drive gear sheered the two little tabs off, the tabs on the vacuum pump side seemed to be okay. put a new gear on the pwr steer side and the new seal and everything's been fine.

i'm going to pull the steering/vacuum pumps off tomorrow and see what's going on, it clangs pretty dang loud, my mom came out of the house after i drove up to see if it was my truck making that noise

if anyone has any ideas or info i'd appreciate it. looks like i won't be towing the boat to lake shasta next week and i'll be riding my new '97 motorcycle for a while, hope it doesn't rain any in the next few months.

 

Sounds like you are on the right track. After having a recent failure in that location it would be very suspect for this noise problem. Good luck

 

could it be the dreaded KDP?

 

a few reasons i'm hoping its not the kdp, i was told by the guy i bought it from that the timing cover dowel pin had been fixed; the timing cover is not leaking oil anywhere and the sound is coming from right off the front of the vacuum pump, it's amazing how well you can pinpoint a sound with a stethoscope, i bought one from sears for a couple bucks several years ago and it has been invaluable.

anyway i'll pull it apart today, with all the noise it's making i will find something detrimental, unfortunately. AAAAH!

 

After having the previous owner of mine tell me the same thing, and finding out the hard way that it hadn't been fixed, I'd suggest that you look into it ASAP.

 

thanks for the optimism jeremy!

okay so i pulled the vacuum pump gear out and found a few small pieces/flakes of metal on that gear, looked inside from the back with a mirror and didn't see anything unusual. can I just pull the front cover off the gearbox? is anything going to fall out or spring out at me??

 

Pull the cover...nothing will fall out.....at least nothing is supposed to.

 

got a chance to pull the front cover off, found nothing. the KDP HAS NOT been tabbed like the guy said had been done so I ordered the tst kit.

I still want to find what was making the noise! drained the oil out into a clean container and ran my hand all over in there, found no metal. Now I'm wondering if it could be the injection pump?

When it was running I got my stethoscope(with about a 12" welding rod-sized rod on it) and the noise/clatter was the loudest on the very front of the vacuum pump and also on the injection pump, not much noise on the timing case itself(though you could still hear it). wondering if there's noise actually from the engine that's just making it through the gears to the inj/vac pumps or if it's in fact the inj pump. AH! should i take the injection pump off and have it checked?? It's a 180 pump by the way.

 

and it was idling a little slower than usual and a little rough. still accelerated normal, went to 35psi just fine...
i'm confused.

 

alrighty. i was a little off on my diagnosis. regardless, the front cover needed to come off for the kdp. apparently the noise was being transmitted through the crankshaft and into the timing gears. I bumped the starter over a couple times with the cover off and my dad standing up fron listening with me. first time we heard the clatter pretty loud, tried a few more times and figured out that it always rattled a few more times after i'd let off...pulled the trans cover for the tq converter and a couple of the ears are broken off!! apparently the guy that had my trans work done(that I bought the truck from) got the budget job 30k miles before i got the truck and put 55k more. the converter's got paint flaking off of it too.

so it looks like my truck will finally get a Goerend Brothers converter! for christmas...
um, i'll be driving my ol' '96 GMC 1500 4x4 that i sold to my parents and my '97 GSX-r750 for a while.

is there a club for going through black smoke withdrawals?!?!?

 

Glad you found it, too bad it wasn't a cheaper/simpler fix.

For future reference a loose dowel pin sounds just like dragging a stick across a chain link fence. I knew one guy who put up with this noise for several hundred miles without damage to the case before taking the cover off.
He was very lucky.