serious overheating issues

94 mustang gt

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Jun 9, 2019
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alright so for a little background with what i have. i have a 94 mustang gt with a top end kit from late model restoration, bbk, cold air intake with throttle body, mishimoto radiator; fan with aluminum shroud; thermostat; radiator hoses, bbk off road x pipe, new water pump. before i replaced all the cooling components i was having some serious overheating issues. engine was getting so hot the coolant was vomiting out of every hole it could find its way out of. i couldn't find the issue to save my life so i just replaced everything that i thought could cause overheating issues. still no luck, so now im thinking it could be the ccrm. my engine is running super lean and i only get about 20 minutes of drive time at about 60 mph before my temp gauge is past "normal." on top of that my a/c only runs on max and blows through my defroster vents by the windshield. once i replaced everything with the mishimoto stuff and new water pump the car stopped vomiting all the coolant but still runs super hot in about 20 minutes of drive time.
 
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jrichker

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An air dam deflector is standard equipment on Fox body Mustangs, but may not be on SN 95's. The deflector is mounted below and in front of the radiator. It serves to help direct airflow so that the radiator gets the maximum airflow through it..

The vacuum that controls the heater vents probably has a broken or missing vacuum line.

The following are diagrams courtesy of Tmoss & Stang&2birds

HVAC vacuum diagram
Mustang_AC_heat_vacuum_controls.gif


See the following website for some help from Tmoss (diagram designer) & Stang&2Birds (website host) for help on 88-95 wiring; http://www.veryuseful.com/mustang/tech/engine/ Everyone should bookmark this site.


TFI module wiring for 94-95 Mustang GT
http://www.veryuseful.com/mustang/tech/engine/images/Mustang-94-95-IgnitionControlModule.gif

Complete computer, actuator & sensor wiring diagram for 94-95 Mustangs

Complete computer, actuator & sensor wiring diagram for 91-93 Mass Air Mustangs

Complete computer, actuator & sensor wiring diagram for 88-90 Mass Air Mustangs

5.0 wiring diagram for Fuel Injectors, Sensors, and Actuators

Ignition switch wiring

O2 sensor wiring harness

Vacuum diagram 89-93 Mustangs

HVAC vacuum diagram

TFI module differences & pin out

Fuse box layout

Mustang 5.0 Lights and Radio schematic, by TMoss:
http://www.veryuseful.com/mustang/tech/engine/images/mustangFoxLights-Radio_diag.gif

87-92 power window wiring

93 power window wiring

T5 Cutaway showing T5 internal parts

Visual comparison of the Ford Fuel Injectors, picture by TMoss:

Convertible top motor wiring http://www.veryuseful.com/mustang/tech/engine/images/mustang88VertTopMotorCkt.gif

Engine mounted fuel injector harness

Location of the TPS, IAB, and the 10-pin connectors on a 5.0, picture by TMoss:

Starter circuit

Alternator diagram for 94-95 Mustangs.
 

Dan02gt

10 Year Member
Mar 2, 2003
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Greenville, NC
Have you checked the oil for any water and the coolant for oil? It could have blown head gasket.

Also your AC blowing out the defrost could be vacuum leak or a bad vacuum seloniod for the diverter. I would check the vacuum lines first and if they are OK all the way to the seloniod then check it out too. It should be behind the radio/Hvac controls.

A vacuum leak would also make the car run lean.
 
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94 mustang gt

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Jun 9, 2019
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Have you checked the oil for any water and the coolant for oil? It could have blown head gasket.

Also your AC blowing out the defrost could be vacuum leak or a bad vacuum seloniod for the diverter. I would check the vacuum lines first and if they are OK all the way to the seloniod then check it out too. It should be behind the radio/Hvac controls.

A vacuum leak would also make the car run lean.
well i would assume i dont have a blown head gasket because i just got the new top end kit with new gaskets and havent driven over 50 miles with it but ill check the oil. from what i can see with the coolant is there is no oil present.
 

90sickfox

I didn't really have an issue with the stink...
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There was a problem documented with badly designed aftermarket water pumps recently. What brand did you use ?
 

nickyb

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Apr 3, 2009
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Did you burp the system?,does it run hot at idle?what temp thermos ?do you still have mechanical fan?,if electric does it work prperly?try idling it with rad cap open and check coolant flow.
 

LILCBRA

10 Year Member
Dec 6, 2005
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This link can help. The quote is taken directly from the linked page and corresponds to what you've said. There are a number of factors to consider, but given the information provided I'd say make sure your car's tune is good and go from there.


"A proper air/fuel mixture will help your engine run cool and to its full potential. Most overheating issues related to air/fuel ratios are the result of a lean mixture, which causes the cylinders to run hotter."
 

Mstng93SSP

You have a nice rear end there Dave.
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Nov 29, 1999
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If you just did the top end kit, and are having these serious overheating issues I suspect you might have the head gaskets on wrong. If the head gasket is on backwards (where it says "front" is on the back of the head/block) you will overheat as the water passage will be blocked. Did you do the top end kit or a shop?
 
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FastDriver

My dad had a bra
SN Certified Technician
Sep 5, 2001
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Temperature sensor? Also, does the temp go up when you turn the lights, fan, and other electrical things on? Pretty common in foxes. Not sure about yours.

I have a top end kit (GT40X heads, EdelbrockPerformer intake, & a cam. Radiator looks stock, but new-ish with a stock clutch fan. It run above normal, but nothing to be concerned with.
 

RioRed95Cobra

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Apr 7, 2017
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well i would assume i dont have a blown head gasket because i just got the new top end kit with new gaskets and havent driven over 50 miles with it but ill check the oil. from what i can see with the coolant is there is no oil present.
Mileage means nothing. I installed new HG's and blew em out in 5 minutes.. all it takes is your timing being off and you not hearing it. Pop.

That, or you didn't burp your cooling system and have tons of air in it.. that would do this. Did you let the car warm up, radiator cap off, let thermostat open, then add water/coolant til full, and let it bubble itself out any air?

If not, you have an issue there i'd bet along with others.

Also what dude up there said.. the head gaskets usually say "front" on them, and in this case, that's absolutely WRONG.. if you put them both on this way you block off the water jacket hole on the front of the block/or rear depending which way you did it backwards, lol. That will def. do it, too.

Who put all this on?
 

96pushrod

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May 15, 2018
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Also what dude up there said.. the head gaskets usually say "front" on them, and in this case, that's absolutely WRONG.. if you put them both on this way you block off the water jacket hole on the front of the block/or rear depending which way you did it backwards, lol. That will def. do it, too.
What? The head gasket is supposed to block off the fwd coolant holes to force water into the rear first.

Like so:

629617



@94 mustang gt you see that tab on the fwd end? You should see it sticking out between the head and block with everything together, at least if you used a felpro non-MLS gasket.

Here's one I just put together, the tab is circled in red.

629618
 

RioRed95Cobra

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What? The head gasket is supposed to block off the fwd coolant holes to force water into the rear first.

Like so:

head gasket direction 2.jpg



@94 mustang gt you see that tab on the fwd end? You should see it sticking out between the head and block with everything together, at least if you used a felpro non-MLS gasket.

Here's one I just put together, the tab is circled in red.

image1 (3).jpeg
Just went through this on my stroker. The gaskets I bought both said "front".. I put them on not even thinking anything. You should flip one over to allow even water flow throughout.

One has to be flipped over with felpro's.
 
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96pushrod

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Just went through this on my stroker. The gaskets I bought both said "front".. I put them on not even thinking anything. You should flip one over to allow even water flow throughout.

One has to be flipped over with felpro's.
By “flipped over” do you imply that you shouldn’t be covering up the forward water port on one side of the engine? Because this is not true.
 

RioRed95Cobra

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By “flipped over” do you imply that you shouldn’t be covering up the forward water port on one side of the engine? Because this is not true.
Not at all. All i'm saying is when you put it "front" on both sides, one ended up backwards. Felpro's do this.

You have to flip one over to make it right. Not sure which brand you used, but this is very common because people put them on saying "front" on both sides like people saying here, and it's simply wrong. Felpro's will be backwards if you do that.
 

96pushrod

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Not at all. All i'm saying is when you put it "front" on both sides, one ended up backwards. Felpro's do this.

You have to flip one over to make it right. Not sure which brand you used, but this is very common because people put them on saying "front" on both sides like people saying here, and it's simply wrong. Felpro's will be backwards if you do that.
:suicide:
This is completely wrong. Whoever told you this has no idea what they’re talking about. You really think every sbf head gasket manufacturer has gotten it wrong for all these years?

It’s not rocket science: “front” goes on the front of the block.
 

RioRed95Cobra

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:suicide:
This is completely wrong. Whoever told you this has no idea what they’re talking about. You really think every sbf head gasket manufacturer has gotten it wrong for all these years?

It’s not rocket science: “front” goes on the front of the block.
I should post pictures. In fact there are threads on the corral about this.. I just looked at em.. again. Lol.

But ok. Even your own resident stangnet nerd jrichker said the same thing.

I had to do this very same damn thing, and yep.. my car runs amazing. Guess i'll await the kaboom.. lol.
 

96pushrod

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Go ahead and show me a thread where jrichker - or anyone except you, states one head gasket should have the “front” stamping facing the rear of the engine.
 

RioRed95Cobra

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Go ahead and show me a thread where jrichker - or anyone except you, states one head gasket should have the “front” stamping facing the rear of the engine.
Felpro gaskets are marked "Front" on the end that goes towards the front of the engine. It insures that the coolant passages are properly aligned for best coolant flow. That means on one side of the engine, the word "Front" will face the engine block. On the other side of the engine, "Front" will face the cylinder head.

Right from his mouth. I had to flip mine over. Again, there are threads about this on the corral, lol.