2004 vacuum leak is my guess

Joined
May 7, 2022
Thunderbird Year
2004
Has 69,000 miles on it - very good condition- garage queen - after sitting for a couple days when I press on the brake pedal before starting the pedal is hard, but once I start it the pedal goes down normally as it should. I suspect it may be losing vacuum from a line or could be the brake booster is bad. Another reason I think there is a vacuum leak I’ve recently noticed the idle is a little higher also there’s a very slight roughness in the idle. A bad brake booster would not affect the idle right?
Thoughts please
 
Joined
Jul 19, 2022
Thunderbird Year
2004
A vacuum leak will affect the idle an easy test is to crimp or disconnect and plug the vacuum hose that goes to the power booster.
If the idle goes back to normal and the engine is running smooth then most likely is a bad brake power booster.

A word of caution while doing this test do not attempt to drive the vehicle.
 

biddle

Forum Moderator
Staff member
Joined
Mar 9, 2003
Thunderbird Year
2005
Has 69,000 miles on it - very good condition- garage queen
Thoughts please
Remember you could drive the distance of the diameter of Earth 8.5 times in that many miles and the car is closing in on 2 decades old, not to mention engine coolant is barely under boiling temperature.
 
Joined
Nov 3, 2007
Thunderbird Year
2002
Get you one of these smoke machines, will help show any leaks. With our T Birds 20 years old many
rubber parts are drying out, and or cracking.


Moderator note- post links to products, not screenshots.
 
Last edited by a moderator:
Joined
Jul 15, 2022
Thunderbird Year
1960
Has 69,000 miles on it - very good condition- garage queen - after sitting for a couple days when I press on the brake pedal before starting the pedal is hard, but once I start it the pedal goes down normally as it should. I suspect it may be losing vacuum from a line or could be the brake booster is bad. Another reason I think there is a vacuum leak I’ve recently noticed the idle is a little higher also there’s a very slight roughness in the idle. A bad brake booster would not affect the idle right?
Thoughts please
The booster doesn't hold vacum all the time unless the engine is running . When you apply the brake without engine running what you're feeling is non power brake .
 
Joined
Jul 15, 2022
Thunderbird Year
1960
The booster will hold vacum for a period of time change the one way vacumn booster valve cheepest part . It can cause a leak down . I don't think a booster will hold vacumn forever you need to find out whats normal .
 
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