1990 Fox Problems Help Needed

change the water pump

Does it have enough coolant in it? The temp sensor will read air temperature inside the cooling system in the absence of coolant. If your engine is beginning to overheat, it will definitely run bad.

Spray those damn H2O bolts with PB buster well before you start trying to loosen them, and be very careful when you start to apply pressure.. They are notorious for breaking. Autozone and Oreillys have some of the bolts/studs in their help section. Wire brush them clean and I put antisieze on the the bolts, as you will be doing this again in the future lol. Also make sure the mating surfaces are squeaky clean. I always throw in a bottle of H2O pump lubricant as well as two bottles of purple ice. While you are at it, throw a new stant 180 thermostat in their and check the hoses. No sense draining the coolant and doing this twice.

Check the lower hose while you have it apart.
It can be soft to an extent, so long as it has a spring inside it.
No matter the condition, if it doesn't have a spring, and you intend to keep the hose, put a spring in it while you have it apart!
That is the suction hose from the radiator, and without a spring inside the hose, it can start to suck shut and heat up the engine.
If I don't have a spring handy, I will make one out of a hanger or whatever I have around.
A hose sucking shut can take out your head gaskets quick.
Changing head gaskets on the side of the interstate due to a soft lower hose is no fun. Ask me how I know.

ratio411 said:

Check the lower hose while you have it apart.
It can be soft to an extent, so long as it has a spring inside it.
No matter the condition, if it doesn't have a spring, and you intend to keep the hose, put a spring in it while you have it apart!
That is the suction hose from the radiator, and without a spring inside the hose, it can start to suck shut and heat up the engine.
If I don't have a spring handy, I will make one out of a hanger or whatever I have around.
A hose sucking shut can take out your head gaskets quick.
Changing head gaskets on the side of the interstate due to a soft lower hose is no fun. Ask me how I know.

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You changed head gaskets on the interstate?

gearheadboy said:

You changed head gaskets on the interstate?

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For real! That takes dedication.

Take a cardboard box, & turn it upside down. Count the number of bolts that hold the water pump on, don’t forget to count the 4 funny looking studs too. Poke a hole in the box for each bolt/stud. Arrange the holes in a circular formation, and mark the box at the 12:00 point. When you remove a water pump bolt, put it in one of the holes in the box according to where it came out of the water pump. When you are done, all bolts will be arranged it the exact same order and position that you removed them from the water pump. That makes re-installing them easy, no wondering where does this bolt go.

A long shank tap should be used to chase the dirt & corrosion out of the original threads before you reassemble everything. Cleaning the threads will help prevent the bolts from seizing next time (yes, there will be a next time).

A word about the links, if they don’t work, do a search on the part number (P/N). MSC updates their catalog regularly, and the pages may change, but the part numbers don’t.

Long shank 5/16” taps

http://www1.mscdirect.com/CGI/NNPDFF?PMPAGE=267 5/16” pulley tap, 6” shank P/N 04801189 price $18.91

OR second choice, will not clean all the bottom threads unless you grind the end of the tap.

http://www1.mscdirect.com/CGI/NNPDFF?PMPAGE=266 extension tap, 6” reduced diameter shank P/N 04701181 $21.37

Use lots of antiseize on the bolts to protect them from corrosion and make them easier to remove next time.

See http://totallystainless.net/totally.html for replacement stainless steel bolts. Last time I checked, they didn't have the studs. Nice folks, very into cars of all types. They have all kinds of stainless fasteners for almost every car. The prices are very reasonable, less the $10 for the water pump kit without the studs.


The studs are a Motormite item available at your local Advance Discount auto Parts store.

Motormite Water Pump Stud Kits for Ford, Lincoln and Mercury cars and trucks w/3.8L, 4.6L, 5.0L, 5.8L.



Part Number: 23744

Copied from Noobz347

Water pump bolt sizes
*All bolts are 5/16"-18

Water pump:
4 bolts - 3 1/4"
2 bolts - 4 1/4"
2 bolts - 1 1/4"
1 bolt - 2 1/4"

Additional timing cover bolts:
2 bolts - 2 1/4"
2 bolts - 2 1/2"

These are measure from underneath the head to the end of the bolt and NOT from the top of the head. Just the shank.

If you are still having performance problems after you do the water pump, steam from the leaking pump can condense on the wires and inside the distributor cap. Clean the inside of the distributor cap and the wires with a good spray of WD40 and wipe it down..

Still having problems after that, dump the codes.

Dump the codes: Codes may be present even if the Check Engine Light (CEL) isn't on.

Dumping the computer diagnostic codes on 86-95 Mustangs

Revised 26-July-2011. Added need to make sure the clutch is pressed when dumping codes.

Codes may be present even if the check engine light hasn’t come on, so be sure to check for them.

Here's the way to dump the computer codes with only a jumper wire or paper clip and the check engine light, or test light or voltmeter. I’ve used it for years, and it works great. You watch the flashing test lamp or Check Engine Light and count the flashes.

Post the codes you get and I will post 86-93 model 5.0 Mustang specific code definitions and fixes. I do not have a complete listing for 94-95 model 5.0 Mustangs at this time.

Be sure to turn off the A/C, and put the transmission in neutral when dumping the codes. On a manual transmission car, be sure to press the clutch to the floor.
Fail to do this and you will generate a code 67 and not be able to dump the Engine Running codes.





If your car is an 86-88 stang, you'll have to use the test lamp or voltmeter method. There is no functional check engine light on the 86-88's except possibly the Cali Mass Air cars.



The STI has a gray connector shell and a white/red wire. It comes from the same bundle of wires as the self test connector.

89 through 95 cars have a working Check Engine light. Watch it instead of using a test lamp.



The STI has a gray connector shell and a white/red wire. It comes from the same bundle of wires as the self test connector.


WARNING!!! There is a single dark brown connector with a black/orange wire. It is the 12 volt power to the under the hood light. Do not jumper it to the computer test connector. If you do, you will damage the computer.

What to expect:
You should get a code 11 (two single flashes in succession). This says that the computer's internal workings are OK, and that the wiring to put the computer into diagnostic mode is good. No code 11 and you have some wiring problems. This is crucial: the same wire that provides the ground to dump the codes provides signal ground for the TPS, EGR, ACT and Map/Baro sensors. If it fails, you will have poor performance, economy and driveablity problems

Some codes have different answers if the engine is running from the answers that it has when the engine isn't running. It helps a lot to know if you had the engine running when you ran the test.

Dumping the Engine Running codes: The procedure is the same, you start the engine with the test jumper in place. Be sure the A/C is off, and clutch (if present) is pressed to the floor, and the transmission is in neutral. You'll get an 11, then a 4 and the engine will speed up to do the EGR test. After the engine speed decreases back to idle, it will dump the engine running codes.

Trouble codes are either 2 digit or 3 digit, there are no cars that use both 2 digit codes and 3 digit codes.

Your 86-88 5.0 won't have a working Check Engine Light, so you'll need a test light.
See AutoZone Part Number: 25886 , $10




Alternate methods:
For those who are intimidated by all the wires & connections, see Actron® for what a typical hand scanner looks like. Normal retail price is about $30 or so at AutoZone or Wal-Mart.

Or for a nicer scanner see Equus - Digital Ford Code Reader (3145) – It has a 3 digit LCD display so that you don’t have to count flashes or beeps.. Cost is $30.

gearheadboy said:

You changed head gaskets on the interstate?

Click to expand...

Yeah. My lower rad hose was sucking shut, and I didn't know it.
I-10 between Slidell, LA and Diamond Head, MS. 6 hours from home.
Hitched to the parts store to get the gaskets.

ratio411 said:

Yeah. My lower rad hose was sucking shut, and I didn't know it.
I-10 between Slidell, LA and Diamond Head, MS. 6 hours from home.
Hitched to the parts store to get the gaskets.

Click to expand...