Bought a 5L, have some questions.

Hey everybody, great site here, glad to be a part of it.

I just bought a 91 GT. It is currently leaking coolant right at the bottom of the water pump. It's a slow leak, maybe a couple drips every 5 minutes of idling. I've read that the waterpump gasket is a pretty common failure point, I plan on replacing the entire water pump and flushing the system, just to be safe. Are there any tips or tricks on this, or are there any good write up threads? A service manual was included with the car (can't remember the brand, has a red LX with it's hood up on the cover), is that a reliable tool to use? I also have an SHO and I know the printed service manual for that car has a few things wrong.

Something else I noticed is that the alternator isn't providing a charge at idle. The voltage will read 12-12.2V at idle put if you just touch the throttle it will jump right to 14V. Alternator belt is tight. Any ideas?

Also, the fuel pump it very loud. When the car is running you can always hear the fuel pump from the back of the car. Is this something I can do? I'm assuming the tank needs to come down, but I'm not sure. I'll keep reading around.

Thanks very much for the help!

Here she is...

IMG_4008.webp
 
Car looks great. the water pump is a pretty straight forward repair but be careful with the bolts they are prone to snapping in the timing cover due to corrosion. when I did mine I soaked them down a few hours before hand with pb blaster and then I would back them out slow,then turn them back in then back them out and keep doing that and it worked. I then used a wire wheel to get all the white powder corrosion of the threads and shanks of the bolts and used a thin coat of never seize when I reinstalled them. These cars are kinda known for having to refill the oevrfill tank a few times before it levels off after doing a coolant drain. replace your stat while you are at it.

The fuel..it could be the brand of pump if it has been changed, some can be loud or it could be on it's way out. they can get loud when they are getting near the end stage but not much you can do really. I'm sure others will chime in but have fun :nice:
 
Does the car have underdrive pullys? If so that can cause a low idle voltage. I have a tiny alternator pulley to help spin it faster and charge better at idle.

On the water pump, like greensvt21 said be careful of the bolts and I would recommend replacing them when you do the pump, you can pick up a set at Advance for a few bucks they have them in the help section. After you refill it with antifreeze make sure to run it with the radiator cap off to "burp" the system of air. Have a bottle of antifreeze ready to pour in when you do that.
 
I'm unsure about the underdrive pulleys but I don't believe so.

Another (very very amature) question, when I was under the car last night I saw the oil pan had 2 drain type bolts. One facing the front of the car and one at the back, lower end of the pan. I'm assuming you use the lower one towards the rear of the car to drain the oil, but I was wondering what the one upfront was for. Also, are there any drain bolt gaskets/washers that need to be changed? If so, can they be purchased at the dealership?

Thanks!
 
Your describing a dual sump oil pan. You need to drain the oil from both plugs since the oil that gets caught in the front sump cannot reach the back sump when draining. I have the same results with my stock fox alternator as yours. ~12 VDC at idle and ~14 VDC when driving.

I just put a water pump on my fox about a month ago, it was easy. Just follow all of the suggestions provided above and you'll do fine. Just from personal experience, I would loosen (NOT remove) the bolts in the water pump pulley before removing the belt. This is easier than trying to hold the WP pulley and take loosen the bolts once the belt is off. For re-assembly, put the pulley on the snout and hand tighten the bolts in the pulley, install the belt and then tighten the bolts in the WP pulley.
 
Interesting. Is this a factory oil pan, or an aftermarket one? I will try and snap a picture and post it up tonight to be 100% sure what I'm talking about.

Also, this would lead me to believe the car would need to be level to drain all of the fluid out. I can't see much fluid coming out of the front drain hole if the front is in the air.
 
I'm going to attempt to be helpful :D

Hey everybody, great site here, glad to be a part of it.

I just bought a 91 GT. It is currently leaking coolant right at the bottom of the water pump. It's a slow leak, maybe a couple drips every 5 minutes of idling. I've read that the waterpump gasket is a pretty common failure point, I plan on replacing the entire water pump and flushing the system, just to be safe. Are there any tips or tricks on this, or are there any good write up threads? A service manual was included with the car (can't remember the brand, has a red LX with it's hood up on the cover), is that a reliable tool to use? I also have an SHO and I know the printed service manual for that car has a few things wrong.

Its very straight forward, try to remember where the longer bolts go because its a pain in the ass if you have to guess, other than that just pop it off, clean off the gasket and replace it. probably dont need a new pump but it wont hurt anything, just make sure you get the stock replacement and dont mess with reverse rotation and all that. :nice:

Something else I noticed is that the alternator isn't providing a charge at idle. The voltage will read 12-12.2V at idle put if you just touch the throttle it will jump right to 14V. Alternator belt is tight. Any ideas?

Stock alternators suck, thats just how it goes. If it bothers you, do some research on a 3g swap.

Also, the fuel pump it very loud. When the car is running you can always hear the fuel pump from the back of the car. Is this something I can do? I'm assuming the tank needs to come down, but I'm not sure. I'll keep reading around.

They are loud in every fox ive ever been in, more sound deadening would be helpful but you get used to it. you need louder exhaust :D

Thanks very much for the help!

Interesting. Is this a factory oil pan, or an aftermarket one? I will try and snap a picture and post it up tonight to be 100% sure what I'm talking about.

Also, this would lead me to believe the car would need to be level to drain all of the fluid out. I can't see much fluid coming out of the front drain hole if the front is in the air.

Its the stock pan, confused the hell out of me when i first got my car also.Good luck
 
Here's another simple question I just thought of... Where is the windshield washer fluid filler? I don't believe I saw one under the hood last night, but the sprayer works... I've also got a picture of my engine bay on my phone and can't spot it here either...

Cheers
 
Dont go off the stock gauge, put a multimeter on the battery with the car running and check voltage. 12V is not normal, your alternator isnt charging the battery at that voltage.

As far as the water pump goes, its straight fowards, the repair manual will help you out. Just be very careful when take out the bolts because they like to rust and snap. Dont use air tools on them if you have any. When removing the bolts I like to give it a rocking motion back and forth to loosen it up. If they are giving you a tough time you can try tapping the bolts and heat.
 
Dont go off the stock gauge, put a multimeter on the battery with the car running and check voltage. 12V is not normal, your alternator isnt charging the battery at that voltage.

As far as the water pump goes, its straight fowards, the repair manual will help you out. Just be very careful when take out the bolts because they like to rust and snap. Dont use air tools on them if you have any. When removing the bolts I like to give it a rocking motion back and forth to loosen it up. If they are giving you a tough time you can try tapping the bolts and heat.

i got a v6 water pump off with a hammer once :D

this is of course, not recommended...ever
 
Welcome to the 5.0 world!

I can suggest a good repair manual by CHILTONS called "Ford Mustang 1989-93 Repair Manual", with the following id number on it: (8253) 26606. It focuses on your specific car and has lots of good info in it. The Haynes book covers cars back into the mid 80s and there were lots of differences there. Also, the Chilton book is a lot thicker. As far as these books go, it's definitely worth having.

I too own a '91 and have for many years. The fuel pump has always made a noticeable whining sound (but I never hear it oven my pipes!) and still works fine.

A few years ago my alternator output failed and I had to swap the alt. The stock system in my car has always worked good. Be totally sure that you don't have a larger aftermarket underdrive pulley on your alt. (I know it was mentioned before).

The two oil drain plugs are normal.

I have always found the parts for my car (stock) to be very affordable.
 
normal out put of the alternator should be 13.5 -14.5 volts. If you had an aftermarket voltmeter gauge when the motor is running it will read 14 to 14.5 volts on the gauge. a fully charged battery should read around 12.6v. The 75amp alt in our cars really does suck and I'm sure yours has seen better days. It sounds like it's possible one of the diodes in the rectifier failed, it will still charge but at roughly 2/3rds it's normal out put. another problem although not has common is one of the stator windings failed which would cause the same problems as the diodes. you should also check all the wires for corrosion, poor ground, alt body ground,etc.