Noisy Vacuum Pump

[permx11]

Does anyone else hear the vacuum pump on their d/a? Mine is a California vehicle.

[MEP]

I don't think the D-max has a vacuum pump. The brake booster is hydralic (from the power steering pump) and the heater controls are probably all electronic. The engine has no EGR valve (like the new 6.0 F#*d does).

[permx11]

The California 03's have egr and a vacuum pump and maybe even a catalytic converter.

[OC_DMAX]

The vacuum pump is only on California GMC/Chevy 2002 and 2003 models with a Duramax engine. These trucks have an EGR system incorporated on the engine and the vacuum pump is part of that system. There is also a catalytic converter in the exhaust system (Although this cat is not the same as on a gas model. From what I understand it is meant to reduce the amount of soot being emitted from the diesel engine).
I hear the same vacuum pump noise on my 2002 Chev that you mention. It sounds kind of like a "puff - puff" noise. The sound is coming from the back of the vacuum pump, out of a vent hole. Thats the best I can describe it.
There was another thread several weeks ago that I replied too that talked about the same topic. So others are inquiring about the same noise. I am not sure if it is normal or if there is something wrong with just a couple of the pumps (yours and mine). I need to stop by and listen to my friends new 2003 to see if the noise is present on his vehicle. I had originally complained to the dealer about this noise, but he was convinced I was refering to the "tick" noise (which was also present at the time). So I just gave up asking about it. By the way, the dealer indicated that the vacuum pump was present to run the A/C controls (he was wrong). This may have been the case in older model trucks, but not on our's.

I hope this helps,
Alan

[Kennedy]

The vacuum pump isn't necessarily noisy, it's the Dmax that is quiet. Much like th eintake noise on an air compressor, the vacuum pump will make noise.

[ 11-20-2002: Message edited by: kennedy ]</p>

[OC_DMAX]

The air compressor analogy makes sense. The noise coming from the vacuum pump spoils the otherwise sweet sounds of the diesel clatter.

The whole EGR system is unfortunate. The only thing worse is that it is going nationwide in 2004.

[permx11]

Thanks for all the replies.

Mr. Kennedy, do you have any idea how much power might be lost to this vacuum pump, egr and cat?

Thanks in advance.

David

[permx11]

I dont think there is any problem with the pump but you can sure hear it over the dmax.

[Kennedy]

Hard telling on the HP loss. Peak numbers on the dyno seemed consistent with Federal trucks, but there may be some off peak diffeences. I've been meaning to experiment with this for a while.

[Oongawah]

Mine does it.