1999 Mustang GT - possible vacuum leak?

[SVT_MAN]

Hi guys. My name is Adam and I hail from Wisconsin. I'm 20 years old, and I really love Mustangs. Ideally, I would like an SVT Cobra or a newer Mustang, but I'm a undegraduate at UW-Whitewater so I don't have the money for that at the moment (especially the insurance - even with huge good student discounts ).

In any case, I recently purchased a 1999 Mustang GT from my father. He has kept the car in very nice shape, and it has 87,000 miles on it. The 4.6L is plenty stout and it has a K&N air filter / charger kit on it. Sounds awesome, even with stock exhaust. It's a 5-spd.

The reason I am posting is because I am concerned about a possible vacuum leak. My dad never noticed it when he drove it, but I am noticing something weird recently.

1) The car has an odd squeak (mainly when it's cold) in the steering when I drive at low speeds and turn quickly.

2) I have noticed that when I am in neutral (or any gear with the clutch pressed in), if I hit the brakes, the revs drop a bit. As I push harder, they drop slightly more.

3) I noticed that there seems to be a hose connecting the brake booster to the power steering. I was wondering if that might have something to do with it?

4) I remember reading about intake manifold cracks with this engine since it uses a composite. This is my worst fear. I have visually inspected the manifold for cracks, do not see any.


You guys have a lot of experience with these cars and these engines. I absolutely love my car and I plan to do some more changes (Mach 1 grill delete, different rims, perhaps a few engine mods). I just want to know, in your honest opinon what you think it is. Is it a problem?

I've always thought when the RPMs drop and you press the brake it's a classic case of vacuum leak. I did inspect the hoses and didn't notice any loose. If you guys could help me out, that would rock! I'd like to get it fixed ASAP if there is a problem, because I don't want to wreck the motor.

Thanks! Love your site.


Here is a photo of my car:

 

[Superhereaux]

2) I have noticed that when I am in neutral (or any gear with the clutch pressed in), if I hit the brakes, the revs drop a bit. As I push harder, they drop slightly more.

3) I noticed that there seems to be a hose connecting the brake booster to the power steering. I was wondering if that might have something to do with it?

these cars use what's called a Hydro-Boost system, the power steering pump is used instead of a vacuum booster to create the needed brake pressures

when you press the brakes it puts additional strain on the p/s pump, hence the the rpm drop, it's normal


if your intake doesn't look like this it's just a matter of time

btw, YOU'LL KNOW when it cracks

 

[SVT_MAN]

Well, so you're saying that this intake failure is inevitable? That's .. great ?

Well, that makes me 2/2 in lousy things happening tonight. My girlfriend, I mean ex-girlfriend .. my first girlfriend I ever had, in fact .. just dumped me about two hours ago. Shortly after I posted in fact.

So, now that I'm over that (not really, but I feel kinda of helpless about it) ... what do you recommend I do about the intake manifold? Can I install a Bullitt-style intake manifold? I think those are cast-iron and I believe they make a bit more power. Or, what do you recommend?

I really don't want my intake to blow, because, if I'm not mistaken, that can cause all kinds of other problems with your motor. (Can't it screw your heads over too?)

 

[Superhereaux]

what do you recommend?

i'd go with this, the Bullitt intake will cost you well over a grand with the install kit and add little hp. the part that cracks is on the coolant crossover so the material of the intake itself doesn't matter (in fact when you get down to it composite is superior to cast alum. in N/A cars)

i haven't experienced it firsthand ('o2 here and my brother has an 'o1) but from what i can gather the alternator bracket is usually the culprit. look at the design and you'll see why. the new intake has the aluminum crossover as opposed to plastic on the old one.



at your post with the whole g/f thing though

 

[SVT_MAN]

Yeah, I wish I was laughing about the g/f thing ..

Anyway, I was looking at Trick Flow intake manifolds. What do you guys think of those? Honestly, if I lose a couple of horsepower or something, I don't really care that much. I'd rather spend $700 and lose 5 hp than break my bank account with $1000+ bullitt intake ...

Crud, read your post wrong. Are you saying that I can kee the composite intake manifold and just change the alternator braket to an alluminum one? I'm not super familiar with the engine yet. Everything is new to me on this car. I just learned how to drive a stick 3 months ago.

I'm in college and I don't have a lot of money to throw around. Just paid for my tuition. *PUKES* Bank account dropped like a rock.

I didn't have any income coming in all summer because my mom has been very ill with health issues that are unexplained and I had to help take care of her. (I work at an elementary school as a computer tech during the "school year." But, my dad is going to the Mayo Clinic with my mom in October. We're hoping they'll have some advice for us on where to look or get a disgnosis. We're still trying to get her on disability with her work, but it's hard since none of the doctors have a firm diagnosis. She is obviously not doing well when you see her, but they can't figure out why ..

Oh whoops, too much personal info, my bad ... anyway, help on the intake choice would be appreciate. Thanks.

 

[Superhereaux]

Are you saying that I can kee the composite intake manifold and just change the alternator braket to an alluminum one? I'm not super familiar with the engine yet. Everything is new to me on this car.

i circled the location of the aluminum crossover, if your car DOES NOT have this your manifold will probably crack. i couldn't find a pic of an intake with the plastic crossover for a direct comparison

the blue circles are where the alternator bracket bolts to and where i *think* it fails (on the plastic ones)

it's all one piece so you have to change the entire manifold, around $200 i think. hell for all you know your car might already have it

 

[Mustang5L5]

The intake manifold cracking isn't a HUGE deal. I mean more than likely you won't suffer a catestrophic need-a-tow failure with it. You'll just notice some leaking one day.

A replacement manifold is $200 from summit

http://store.summitracing.com/partdetail.asp?autofilter=1&part=FMS-M-9424-P46&N=700+115&autoview=sku

Not a big deal to change. If you want peace of mind, wait til you have a spare $200 kicking around and buy it and swap it when you get to it. You've gone 8 years with the stocker with no probs right? You could go another 8 years with no prob...or it could crack tomorrow.

The brakes are hydroboost. No vacuum. They take power from a combination of compressed gas and the power steering pump, so pressing harder does put a strain on the PS pump. Just make sure your fluid level is fine.

Suspension squeaks are common. Grease/lube your front steering rack bushings bolts. It helps with most of the steering related squeaks.

 

[SVT_MAN]

My family has only owned the car a couple of years. I think 3 now. I have been driving it since the beginning of summer.

Thanks for the info though.


Just went outside to look at my engine. I can confirm it does NOT have an alluminum crossover, so apparently I'm driving a ticking time bomb. I think I'll cross my fingers and wait till next year to replace it. I just made a payment for school and don't have that much money in my account. I don't plan to drive the Mustang this winter, so hopefully I should be okay.

 

[kylebgt]

Hey Adam, Don't stress over the intake deal. If it hasn't cracked yet it probably won't for a while. I live in Davenport, Iowa and mine has held up to all the weather fluctuations. If you notice your rpm's dropping significantly when coming to a stop with the clutch in or shifter in nuetral than your culprit is the IAC(Idle air controller) It basically regulates the idle under various conditions. For some reason they are prone to failure. I have had my rpm's get so low that the car turned off, thats from the IAC going haywire. If it becomes a regular prob drop by autozone and pay $50 for a new IAC, changing it is the simplest thing you will ever do..only two bolts.
How do you like UW-whitewater? I have a couple friends in UWplatteville..real nice up there. I am thinking of transferring to either Western Illinois University or UWP.

 

[2002BLGT]

take off the IAC and clean it with some carb cleaner , if its still acting up afterwards , replace it with a new one from advance or autozone or napa , whoever is cheapest ........also look at the tube going from the mass air meter to the throttle body for any leaks .........

 

[kylebgt]

take off the IAC and clean it with some carb cleaner , if its still acting up afterwards , replace it with a new one from advance or autozone or napa , whoever is cheapest ........also look at the tube going from the mass air meter to the throttle body for any leaks .........

I have never had any luck with this..if anything cleaning it makes it worse. You can give it a try but it is nothing more than a temp fix. These cars are really reliable and what we talked about (intake manifold & IAC) are the two most common trouble spots.

 

[SVT_MAN]

kylebgt: That makes sense. My dad actually told me that he had the car stall on him a few times at intersections while he was idling. I'll run the IAC idea by him and see what he thinks.

He knows a fair amount about cars, but I thought I'd ask around here since you guys are pretty intimately familiar with the engines (since many of you modify them ).

UW-Whitewater is a pretty good school. It has an awesome reputation for its business and accounting programs. Students always score really high on the CPAs around here.

Anyway, I'm actually an information technology infastructure major. It might seem kind of odd that I'm in the business part of the school since I'm in IT, but the thing is - they have a comprehensive program where you learn business alongside the IT angle of things.

Many people don't realize how much IT guys need to know about the business side of running IT programs. For some reason, there's a false conception out there that large scale organizations can buy whatever they want, at any cost, because they rake in such huge profits. Of course, only naive people think that way, but you'd be amazed at how many there really are out there ...

In any case, I really do like the program they have at Whitewater. I actually am living at home to save some costs. I actually commute to Whitewater with my twin brother who just recently purchased a 1998 Mark VIII. We actually use his car to commute out there because the ride of his car is obviously better.

Whitewater is a very reasonable price for the value of education you get. By the way, my girlfriend's (she decided that she was just pissed at me and acting stupid, thank God!) brother actually goes to Platville. I could probably get you an idea about the school if you wanted.


One other thing I wanted to ask:

I am a little disappointed in the ride that the Mustang GT delivers. I've driven V6 Mustangs and their ride is actually pretty comparable to my (now) winter beater, my 1995 Mercuy Sable. That said, I also found the handling on the V6 Mustangs to be more than adequete, and almost the equal of the GT to be honest.

I really don't want to put V6 springs on my car, but I have to say that the GT's springs seem a little stiffer than they're good for. I'm sure the GT weighs more than the V6, so it probably needs higher spring rates just from that aspect. But, the handling of my GT doesn't seem significantly better than V6s, and I feel the ride is pretty poor. Now, I have considered that there might be a weak or bad spring or somthing. I am going to get that checked out. But, I'm just wondering: Does the GT just ride pretty darn stiff in general for all of you compared to other cars you've driven?

And, I was also wondering: Is there a shock and spring package out there that will deliver a better ride without compromising handling? Honestly, I am more interested in making this car ride and handle better than making it fast. I feel 260 hp is PLENTY of power to get me into trouble. I think upgrading the suspension would be a better investment. I don't plan to drag race it because I think that's pretty hard on a car. I'm just mainly using the car as a daily driver that is a lot more enjoyable than my sedate 145 hp Sable

 

[Mustang5L5]

I am a little disappointed in the ride that the Mustang GT delivers. I've driven V6 Mustangs and their ride is actually pretty comparable to my (now) winter beater, my 1995 Mercuy Sable. That said, I also found the handling on the V6 Mustangs to be more than adequete, and almost the equal of the GT to be honest.

I really don't want to put V6 springs on my car, but I have to say that the GT's springs seem a little stiffer than they're good for. I'm sure the GT weighs more than the V6, so it probably needs higher spring rates just from that aspect. But, the handling of my GT doesn't seem significantly better than V6s, and I feel the ride is pretty poor. Now, I have considered that there might be a weak or bad spring or somthing. I am going to get that checked out. But, I'm just wondering: Does the GT just ride pretty darn stiff in general for all of you compared to other cars you've driven?

And, I was also wondering: Is there a shock and spring package out there that will deliver a better ride without compromising handling? Honestly, I am more interested in making this car ride and handle better than making it fast. I feel 260 hp is PLENTY of power to get me into trouble. I think upgrading the suspension would be a better investment. I don't plan to drag race it because I think that's pretty hard on a car. I'm just mainly using the car as a daily driver that is a lot more enjoyable than my sedate 145 hp Sable

You've got to remember your car is almost 9 years old. If those are the stock OEM shocks and springs in the car, then you can almost assume they are ready to be replaced.

Having owned my GT since new, i can tell you they handle quite well ride decent...for a Mustang. As with age though, i have noticed it starting to ride a little rougher, which translates into "hopping" over bumps, especially in turns and making the car feel loose.

Definitely invest in a good spring/shock setup and you will notice one hell of a difference. If you want o save ride comfort, invest in an adjustable shock that way you can set to full soft when you just want to cruise around.

 

[SVT_MAN]

Mustang5L5: Thanks for the advice. Much appreciated.

I guess the thing is: I'm a realist. I realize the Mustang is not going to be as refined as a car with an independent rear suspension, and that is fine with me. However, I think that the car is definitely a little "loose" as you put it. I've noticed that it seems to want to "step out" in corners, and I get a lot of mid-corner axle tramp.

I wasn't sure if that is just normal for the car since it has a live axle (I'm sure some of it is), or if it is just that my shocks and springs are aging and weak.

That said, I'm actually interested in what specifically you think IS a good package? Any specific combinations or brands?

I don't really know what is available, since, as I mentioned, I'm a newbie when it comes to these cars.


I remember from when I was younger (from visting car forums) that many people lowered their cars with Eibach springs. Are Eibachs pretty good? What will offer me the best bang for my buck? I honestly don't care if it's lower or not - the stock ride height, although some people call it a 4x4, doesn't bother me - there are a lot of steep driveways and places where I have to drive the car in the gravel so I would prefer to keep it at its present height actually.

 

[Mustang5L5]

There are a lot of good springs, Eibach, H&R(my fave), Steeda, Ford Racing. You just need to look around and find a stance you like or a spring rate that will give you the quality you are looking for.

I'd go with an adjustable shock as it allows you to custom tailor to the spring you are running. Bilstien, Koni, tokico are good brands.

It's all personal preference really.

I have my heart set on H&R springs and Tokico 5-way adjustables, but that;s me.

Invest in full lenght subframe connectors and caster/camber plates and along with the spring/shock you will have a pretty good handling Mustang.

Skipping in turns is normal for a live axle Mustang, spring and shocks can increase or decrease the effect.

 

[SVT_MAN]

Skipping in turns is normal for a live axle Mustang, spring and shocks can increase or decrease the effect.

Yup. Constant camber is fun


Thanks for all your comments again - truly appreciated. It would be cool if there was a site out there that would allow me to view the stance of the car with different combinations. Maybe I'll have to pitch a marketing plan to places like Tire Rack and use my web skills to pull that off (I do freelance web design).

 

[Superhereaux]

wow this thread sure took a turn


as for suspension, 5L5 is right, the car is getting old and the stock dampers aren't the greatest

for a DD i'd go with Ford Racing B springs and Tokico blues

or

H&R Sports and Bilsteins if you want to spend a little more

both offer a moderate drop and a better ride since they're both progressive style springs

go here for more information and click on the "Live Help" on the top right corner if it's available, the guy knows his stuff

 

[SVT_MAN]

Thanks guys! You rock!

 

[Mustang5L5]

Keep hanging out here and you'll know more about mustangs than anyone should ever know...


At least that's my case...

 

[Superhereaux]

Keep hanging out here and you'll know more about mustangs than anyone should ever know...


At least that's my case...

...and get hit on by dudes, as is your case as well