Vacuum sucks (Or lack thereof) when cold

[undefined0000]

Well I've been noticing a lower vacuum when I start the car cold. about 12inhg, but it increases as I drive it more. to about 16inhg. Ideas? I have a tiny leak in shaft seals, but I woulnd't think that would change with temperature.

 

[007jimmy]

Well I've been noticing a lower vacuum when I start the car cold. about 12inhg, but it increases as I drive it more. to about 16inhg. Ideas? I have a tiny leak in shaft seals, but I woulnd't think that would change with temperature.

Sure the temp will affect it. As the seals and metal expand due to the heat, the leak would get slightly smaller and when its cold everything contracts.

 

[habitatguy187]

Could also be actual compression increasing as the car warms up (piston rings). That's why it's always recommended to do compression tests warm.

 

[007jimmy]

Could also be actual compression increasing as the car warms up (piston rings). That's why it's always recommended to do compression tests warm.

Understandable, but i lose vacuum as my car warms up. Not stock cams.

 

[undefined0000]

Alright, was just making sure im not crazy. Thanks for the input.

 

[habitatguy187]

Understandable, but i lose vacuum as my car warms up. Not stock cams.

Startup idle? Rpms are higher while the tb heats up, which raises vacuum slightly.