vacuum leak

[{Mr Crabs}]

Hi all
whats the key to finding vacume leaks when if first put my 1G in my celica i seemed to have signs of a vacunme leak,and i found not one but three leaks with each leek found the 1g ran more normal.But now when started cold the 1G humps two or three times,but idles fine once started. On a further note project car no 2 runs fine when cold but once hot it shows signs of a leak also.
Any help?

[celicaboy_2000]

Im probably talking out of my arse but could it possibly be the idle speed control unit sticking? Anyhow keep posted to what you find.

Matt

[TC1600]

Vacuum leaks aren't the only thing that will cause a miss. The first one (stumble when cold until running) could also be a leaky injector or the beginnings of a blown head gasket. Check for a puff of smoke when starting, black smoke could show a leaky injector, or blue smoke could show leaking valve stem seals (which could also cause one cylinder to act like that).

Number 2, check plugs and leads, they can show a problem hot but be ok cold. That too could be head gasket and water getting into a cylinder when the coolant is pressurised. To check, pressurise the cooling system (with a pressure tester for eg), then remove the plugs and crank it over. If there is any coolant getting in, it will shoot out the spark plug hole. (note, don't stand over the engine when doing this )

Good luck, hope this helps.

[BradW]

Number 2, check plugs and leads, they can show a problem hot but be ok cold. That too could be head gasket and water getting into a cylinder when the coolant is pressurised. To check, pressurise the cooling system (with a pressure tester for eg), then remove the plugs and crank it over. If there is any coolant getting in, it will shoot out the spark plug hole. (note, don't stand over the engine when doing this )

Good luck, hope this helps.

Also, when doing this make sure to disconnect your injectors. You don't want fuel squirting in there and pumping out the spark plug hole.

[craigy]

aerostart is a good way too find vaccuum leaks. use the little tube and squirt it wherever air may be escaping. If you hit a leak the idle will rise for a second.

[TC1600]

Also, when doing this make sure to disconnect your injectors. You don't want fuel squirting in there and pumping out the spark plug hole.

Usually you won't get enough fuel being injected for it to be a problem, but yes, it is good practise to disconnect injectors whenever you are intending to crank the engine but not start it.

[{Mr Crabs}]

Hi all
I do get a bit of blue smoke on start up when cold but only if the car has been sitting for a long time (6 or8 weeks). shows signs of condensation under oil cap on short runs but no water in the oil or oil in the water.Will replace the leads though they are only 3 years old if i still have a problem its off with it's head!

Thanks case