I Have a 1988 Mustang GT 5.0, I'm having a bad vaccum problem but do not know which hose is damage. When I first purchase the car I was having this problem and took the car to Ammco and paid 1,300


Asked by Jun 09, 2015 at 01:10 PM about the 1988 Ford Mustang GT Convertible

Question type: Maintenance & Repair

Now the car is doing it again, when I press the brakes the
car idles up and brakes are really hard to push. Also the
car losses pressure and will not drop into second gear.
the transmission is in great shape and jus put in 3 years
ago can anyone help me???

6 Answers


Sounds like your brake booster took a dump, leaking too much vacuum, it can cause a transmission up/down shift problem. So check all you vacuum hoses, that you can do yourself, look for any cracks, splits or disconnects, if your don't find anything then seek professional help.


I found two lines that was broken but they are plastic, could that have and affect on it?




The small plastic lines usually feed things like the heater controls, emission components, transmission modulator, ect. They can have an effect but are most likely not your real problem.

Best Answer

Is the break booster something hard to get to?


It is the big cylinderical can that is in the rear of the brake master cylinder, the real problem is getting to the four nuts that hold it on up under the dash, but other than that it not too horrible.

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