Vaccum leaks! Where-to and how-to.
Vaccum leaks! Where-to and how-to. Recently i've been getting shitty gas milage. I've done everything to troubleshoot the problem(oil change, fuel filter, seafoam ect. ect.)
I think i have a vaccum leak somewhere, I can hear what sounds like it, but for the life of me i cant find it. Ive done the parts cleaner spray trick, and the idle gets a little messy, but it was only because it got sucked through the intake.
What are the normal problem spots or other ways i can find the leak/s?
Thanks!!
I think i have a vaccum leak somewhere, I can hear what sounds like it, but for the life of me i cant find it. Ive done the parts cleaner spray trick, and the idle gets a little messy, but it was only because it got sucked through the intake.
What are the normal problem spots or other ways i can find the leak/s?
Thanks!!
The MAP and the lines back there are a good place to start. Also the PCV system and around the throttle body. You can use water to test for vacuum leaks (the water temporarily seals the leak) but carb cleaner works better. I have seen guys use incense to see if the smoke gets sucked in also. The problem is that a lot of the engine is under the cowl and it makes it harder than a typical old school car.
use a can of carb spray cleaner.. just spray a little around each area where you suspect the leak. If you find a leak, the RPM should raise or stablize a bit and then return to the idle as before.
areas to check..:
MAP
Vacuum lines (Purge valve, HVAC and Brake booster lines.)
injectors o-ring/fuel rai/intake
Intake to Head seals
Throttle body
PCV
EGR port
Good Hunting.. let us know if you find a leak or it turns out to be something else.
areas to check..:
MAP
Vacuum lines (Purge valve, HVAC and Brake booster lines.)
injectors o-ring/fuel rai/intake
Intake to Head seals
Throttle body
PCV
EGR port
Good Hunting.. let us know if you find a leak or it turns out to be something else.
Also, get a piece of 3/8" inside diameter (more or less is OK) a couple of feet long. Hold one end up to your ear (touching) and use the other end to try and localize the source of the hissing/leaking sound. This is a rudimentary "mechanics stethescope" and I've used it successfully before.
Actually buying a mechanics stethescope is a pretty valuable tool because it can allow you to listen to bearings while the engine is running (with the transducer attached to the hose) and use it as an acoustical tube too!
Steve
Actually buying a mechanics stethescope is a pretty valuable tool because it can allow you to listen to bearings while the engine is running (with the transducer attached to the hose) and use it as an acoustical tube too!
Steve
With the car shut off, remove the vacuum line from the brake booster check valve. Find someone who smokes (usually found huddled outside office buildings and restaurants here in NY) and blow some smoke into the intake. Look for the rising cloud. Snap On sells a machine that will do this for you for $3000 if you want to be politically correct...
Johnny
Johnny
Also, get a piece of 3/8" inside diameter (more or less is OK) a couple of feet long. Hold one end up to your ear (touching) and use the other end to try and localize the source of the hissing/leaking sound. This is a rudimentary "mechanics stethescope" and I've used it successfully before.
Actually buying a mechanics stethescope is a pretty valuable tool because it can allow you to listen to bearings while the engine is running (with the transducer attached to the hose) and use it as an acoustical tube too!
Steve
Actually buying a mechanics stethescope is a pretty valuable tool because it can allow you to listen to bearings while the engine is running (with the transducer attached to the hose) and use it as an acoustical tube too!
Steve
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Hmm, some good advise! Not only am I a smoker, but i do have a normal stethoscope(EMT).
I'll start with the list, does anyone have vaccum line diagrams? Also, where is the MAP sensor located exactly?
areas to check..:
MAP
Vacuum lines (Purge valve, HVAC and Brake booster lines.)
injectors o-ring/fuel rai/intake
Intake to Head seals
Throttle body
PCV
EGR port
Thanks!
I'll start with the list, does anyone have vaccum line diagrams? Also, where is the MAP sensor located exactly?
areas to check..:
MAP
Vacuum lines (Purge valve, HVAC and Brake booster lines.)
injectors o-ring/fuel rai/intake
Intake to Head seals
Throttle body
PCV
EGR port
Thanks!
The manifold absolute pressure sensor is at the rear of the intake manifold (near the firewall) and points upward. If you don't have a good manual (preferrably a GM factory manual) it's a good time to get one if you are going to do some of your own work or simply want to understand your vehicle better. Also, I turned up a number of vacuum diagrams by just doing a search.
Steve
Steve
Among the ones already listed, try the accordian. Thats all of the areas where there could be a leak. As for your gas mileage problem, what about tire pressure, plugs and wires, and air filter?
