texdave
Junior Member
- Joined
- Mar 28, 2024
- Posts
- 16
- Reaction score
- 11
- Location
- Houston, Texas
- First Name
- tex
- Truck Year
- 1976
- Truck Model
- C25 Suburban
- Engine Size
- 454
Video of engine bay
Details: Stock QJ, stock intake, stock cam, headers, no EVAP equipment (factory), 18-18.5 inches of mercury vacuum at idle
I can’t figure out if the droning/burbling/hissing noise I’m hearing is normal or not. I thought it was a vacuum leak but all the lines in the bay have been replaced or checked out as OK. It seems to originate at or just behind the carb. It is also louder when engine vacuum is higher (idle or coasting).
I recently rebuilt the QJ using Cliff’s performance parts. Ended up with slightly better MPGs and slightly higher vacuum at idle. Could there be a leak on the throttle body or where the carb meets the intake?
Only other place I can think of is the HVAC control unit but the nose is louder in the engine bay than inside so I doubt it.
Any other place I should look at?
Details: Stock QJ, stock intake, stock cam, headers, no EVAP equipment (factory), 18-18.5 inches of mercury vacuum at idle
I can’t figure out if the droning/burbling/hissing noise I’m hearing is normal or not. I thought it was a vacuum leak but all the lines in the bay have been replaced or checked out as OK. It seems to originate at or just behind the carb. It is also louder when engine vacuum is higher (idle or coasting).
I recently rebuilt the QJ using Cliff’s performance parts. Ended up with slightly better MPGs and slightly higher vacuum at idle. Could there be a leak on the throttle body or where the carb meets the intake?
Only other place I can think of is the HVAC control unit but the nose is louder in the engine bay than inside so I doubt it.
Any other place I should look at?
