Engine/Transmission (1994 - 1998) New noise after tabbing KDP and adding gauges

[Johnstra]

I hear something that sounds like a bad bearing under load after tabbing my KDP and adding gauges. It's not loud, but it definitely holds my attention. I'm wondering if drilling/tapping for my pyro probe is to blame. I did this one just like I did my 03, I just drilled it with the engine running so all the chips flew out of the hole. I did tap it with the engine not running though. I still get good boost, a little over 20 with everything stock.



What do ya'll think? Anything else I need to check out? Seems I remember hearing about some people complaining about the EGT gauge transformer making noise, but I don't think that's what I'm hearing



Appreciate any suggestions.



-john

 

[Johnstra]

. . bump. .



Anybody?

 

[Joe G.]

Have you found where it's coming from? Might try using a hose to listen at different places. The only thing I can think of that you may have disturbed that can make a noise is the crank speed sensor on the front of the engine. Is the clearance right on it?

 

[Johnstra]

I can only hear it going down the road... can't do it in the garage. I checked the speed sensor. Its clearance is ok and it's not dragging on the vibration dampener.

-john

 

[Joe G.]

Can you make it do it if you put the truck up on axle stands and run it in gear?

 

[Johnstra]

I'll try that tonight. I adjusted the speed sensor some and will be driving around today, but I don't expect that's the problem.

Thanks, Joe. I'll update when I know more.

-john

 

[biggy238]

Check the turbo just for the satisfaction of knowing it's not bad.



If you put a hole in the firewall for the gauges, did you seal around it? You could just be hearing something inaudable before through the new hole.

 

[Johnstra]

biggy/Joe - What all can I do to check my turbo. I pulled the air intake and checked the shaft for play and movement. It has no play and turns freely with no contact anywhere. Turning the blades on the turbo offers a little more resistance than I expected, but I've never turned one by hand and don't know what is normal. No driveability issues though... normal stock power, nice turbo whistle... just the annoying sound.

 

[Johnstra]

I'm still stumped on this sound. It comes on like a switch at 1500 RPM. I can't locate where it's coming from because I can't hear it with the hood up and it's barely noticeable if not loaded pretty well. Climbing the mountain home is when I really hear it. I tried raising my rear wheels and listening for it with the wheels turning, but it's just too quiet that way to draw a bead on it.



To my ear it sounds like a turning metal metal part just brushing against something, but I've been fooled before. The turbo seems healthy. I put my screwdriver on it and don't hear anything that sounds bad.



I don't mind noise as long as I know what it is, but this is driving me nuts!



Any ideas?



-john

 

[Joe G.]

I really don't know, but I wonder if it is RPM dependent or MPH dependent. That would locate it to engine or drive train. Try running it with the trans in 2nd.

 

[Johnstra]

It's definitely engine. 1500 RPM with trans in any gear. I can hear it in neutral; it's just very hard to hear.



How much sound can the fuel lines make? Wondering if I could be hearing something pump related.

 

[Gene Arnold]

Johnstra,

You sure can get noise from any metal line. When you were drilling and tapping it is possible that you moved some metal line until it "grounds out" against the body and amplifies a sound. I had this very thing happen on my old 6. 3L Chevy. Turned out to be the brake line to the trailer brake controller. Moved it a fraction of an inch away from the firewall and all was back to normal. Just retrace your steps and see if a steel ine is touching the body where it shouldn't. Hope your problem is something that simple.

Gene