Hey, so I recently bought a K10 Micra with the 1.2 carbed engine. Lately I've been noticing a whistling sound everytime I lift off the throttle, which tends to disappear after about 30 minutes of driving. I'm guessing it's a vacuum leak, but I figured I'd ask here in case anybody else has had similar issues. If it is a vacuum leak, would replacing the vacuum hoses be a suitable solution, or would I have to do something else? Sorry if this is a stupid question, I'm very new to owning and working on cars ??
Vacuum Leak??
- Thread starter KillaWall
- Start date
Hi K - I've just joined this group because I've bought a 1988 Micra, (K10) which had severe vaccum leaks, and the carb was 'adjusted' to try and make it run reasonably.
- Basically, if you have a leak the engine will run slower,... but may6 try to compensate for the leak (running weak - more air than fuel in the Air:Fuel ratio),... these two conditions will make it 'HUNT' or ebb & floe like a tide between lower revs & higher revs.
- A vaccum guage is a good tool to gt to the 'nity-gritty' of fine tuning,... but EYES, EARS & SMELL can get you a long way. It's a reiterative process.
- SUSPECT all vaccum tubes/sleeve connectors, as 'leaky', 'split' or 'perishesd',... You can check most of these WITHOUT starting the engine - they should be a tight push-fit - replace first. NOTE: check the rear of the manifold ( near the bulk-head) -there is a vaccum port/connection which can have multiple branch off points,... this can be LOOSE ( unscrewed) by as little as a 1/4 turn and air will get in past the threads,... snug up ( as much as posile but not over tight) and pllace a few drops of (liquid) super-glue while the engine is just started. - If there was a leak there the revs will increase as a leak is sealed.
- Generally, if you block or open a port/tube you will hear the difference. You can SMELL any richness in fuel mix,... like when a CHOKE is on. - If the mixture is too (low) lean,. the engine will run hotter (over all) or sooner.
.
PLUG the leaks (replace tubes & connections) as you go,... and reduce rev-stop to normal IDLE speed.
NOTE: If the carb has been replaced,... there could be a gasket leak or distorted, ( due to excessive torque) this can be checked by spraying carb cleaner on the gasket areas while the engine is running,... the 'liquid' will seal the leak temporarily,... and a change in edle revs will be noted.
.
Steve Mac
- Basically, if you have a leak the engine will run slower,... but may6 try to compensate for the leak (running weak - more air than fuel in the Air:Fuel ratio),... these two conditions will make it 'HUNT' or ebb & floe like a tide between lower revs & higher revs.
- A vaccum guage is a good tool to gt to the 'nity-gritty' of fine tuning,... but EYES, EARS & SMELL can get you a long way. It's a reiterative process.
- SUSPECT all vaccum tubes/sleeve connectors, as 'leaky', 'split' or 'perishesd',... You can check most of these WITHOUT starting the engine - they should be a tight push-fit - replace first. NOTE: check the rear of the manifold ( near the bulk-head) -there is a vaccum port/connection which can have multiple branch off points,... this can be LOOSE ( unscrewed) by as little as a 1/4 turn and air will get in past the threads,... snug up ( as much as posile but not over tight) and pllace a few drops of (liquid) super-glue while the engine is just started. - If there was a leak there the revs will increase as a leak is sealed.
- Generally, if you block or open a port/tube you will hear the difference. You can SMELL any richness in fuel mix,... like when a CHOKE is on. - If the mixture is too (low) lean,. the engine will run hotter (over all) or sooner.
.
PLUG the leaks (replace tubes & connections) as you go,... and reduce rev-stop to normal IDLE speed.
NOTE: If the carb has been replaced,... there could be a gasket leak or distorted, ( due to excessive torque) this can be checked by spraying carb cleaner on the gasket areas while the engine is running,... the 'liquid' will seal the leak temporarily,... and a change in edle revs will be noted.
.
Steve Mac
