noise on 99 K2500 suburban

March 15, 2005

I have a 1999 K2500 Suburban with the 7.4L engine. Sub has approx 62,000 miles on it. Just recently I began to notice a loud "vacuum leak" sound coming from the front passenger footwell area. I notice it mostly when the vehilce is cold but it is there more or less all the time. When I start up the sub and place it in drive the noise becomes very noticible. Then upon acceleration the noise becomes even louder and the sucking or vacuum noise increases as more throttle is applied. To me it sounds like a large vacuum leak under the dash in the area of the passenger footwell. It did not use to do this and my friend has the same suburban and his is completely quite. My local mechanic told me it was the air intake and the fact that I was using a K&N filter. Over the weekend I took the air intake box out complelely and just installed a paper filter to the inlet duct. I drove it and the noise was still there so I at that point made the conclusion that it was not related to the air intake.

Can you help me figure out what this is ???

TIA

LeeR

99-2door · March 15, 2005

Do you have vacuum brakes or the hydroboost? Sometimes the vacuum boosters can make quite a bit of noise.

And since you said it was the passenger side, there are a few things thee too.

The rubber boot for the antennae lead could be loose.

The seal around the wiring harness on that side (beneath the water bottle) could be damaged or loose.

The AC/heat box could be cracked and letting air in on that side. Happens a lot. Does it also let cool air in on the passenger's feet?

March 15, 2005

It does not have a brake booster so I assume they are hydralic brakes.

It sounds like it is coming from behind the plastic cover that goes over the "wall" just in front of the door adjacent to the floorboard (there is a color matched plastic cover there -----

too much noise to be the antenna gromet

had it check the other day for exhaust leaks they put it up in the air and NO leaks

I dont notice any cool air that comes in and I moved all the HVAC controls around as I was driving it but no change.????