Crazy Overheating Problem. Need Help

[GrapeApe318]

This just started Saturday while driving. The temp usually stays around 220 with the AC on while cruising but now if I get the temp to 220 it will shoot up to 240. Once it gets to 240 I shut it off or it will climb to 260. If I have a cold engine and start driving normal without getting the RPM's or the temp up above 200, everything seems to be ok but thats with the AC off. If the temp gets above 200 then it will at some point shoot up to 240 quick. I can have the heater on and it blowing hot then all of a sudden it blows cool and as soon as it blows cool the temp climbs to 240+. The top hose will be hot but the bottom hose will be cool. Both hoses will be tight as a blue tick on a yard dog. I also noticed the top left side of my fan is blowing really hot air but the rest of the air around the fan is much cooler.I have replaced 2 thermostats and put the burp pin pointing up. Yesterday I jacked the front end way up, topped of the radiator, cranked the car up and turned the heat on full. I kept topping of radiator as needed and the temp stayed at 180. I turned the AC on and it stayed at 180. I let the car idle for 20 mintues while the front was jacked up. Let the car down and drove to town. I noticed the temp got up to 240 as soon as i got to down. It took me 3 hours to get back home. I stopped at the lake a few times and kept pouring water over everything until the temp got below 180. then eased it home fime. What am I missing???

1995 Mustang GT 5.0 (302ci.) Stroked to a (331ci.) and SUPERCHARGED
TKO 500 Trans with a SPEC stage 3+ clutch kit (1000 miles on new clutch).
CUSTOM TUNE with 3 programs and dyno of 481 RWHP & 486 Torque on low Tune
502 RWHP on high tune. Third tune is for emissions. This car can pass a texas emissions test.(tuned by Murillo Motorsports in San Antonie, TX)
Forged Eagle crank, connecting Rods & ARP Balanced with Molly Rings and JE --SRP Pistons.
GT-40X Heads,
High RPM Springs,
Motor sport 1.6 Roller Rockers,
Stainless Valves
Vortech S-trim V2 Supercharger 10 psi.(capable of 14 psi)
F303 cam,
42 psi. Injectors,
T-Rex fuel pump
Full MSD 6AL-2 Digital Ignition system with 2 stage rev limiters,
Cobra Intake,
65mm Throttle Body,
90mm SCT 2800 Mass Air meter
Shorty Headers,
Bassani x-pipe,
High Flow Cats
Flow master exhaust, 50 series
K&N air filter,
3.73 Gears,
Speedo geared to matchTKO 500 Trans.
B&M Short throw shifter & Knob,
Anderson ford motorsport power pipe
Mishimoto All Aluminum 3 core Radiator
Tube Flex lite electric Fan,
Summit high volume water pump & oil pump
Ford Racing Pedals,
Glow shift Blackout LED Elite 10 Color Gauges, (5)
Triple pillar pod with Tac, Air Fuel, Boost.
Double dash pod with Oil pressor, Water Temp.
Eibach 1 ¾"lowering springs,
Functional side scoops to keep rear tires cooler.
4 wheel disc braks with cross drilled and slotted rotors
Weld aluminum weels with 275/50/15 Nitto 555R's on rear
Xenon complete body kit
Cobra R hood True Cal
Saleen SR-351 wing,
Halo smoked LED Headlights,
96 Cobra smoked tail lights

 

[GrapeApe318]

Also, Saturday after I got the temp way down to 160, I was able to drive 20 miles home with no problem. Then about 45 minutes later I left the house and trove for about 45 minutes with not a single problem. I even got on it a few times. Went to lunch and about an hour later I went back to my car and drove probably 3-4 miles and the car started overheating again. This is an intermittent issue. There is no water in the oil. Last night I bypassed the heater core and it made no difference.

 

[Chythar]

Our engines have two temperature sensors: one that the computer reads (the ECT), and one that feeds the dash gauge (the CTS). You need to figure out if one or both of them have failed. The higher-end code readers can read PIDs, one of which is the current ECT reading. If you don't have a high-end code reader, you can measure the voltage coming off of the ECT and CTS, but I don't know offhand what the proper values are.

If the ECT has failed, its values will fluctuate wildly. When this happened to me, my computer thought the car was still cold and it threw more fuel in to warm up the engine. This gave me bad gas mileage and the engine was always on the edge of overheating.

 

[5.0 Ford Guy]

The heater blowing cold air is a sign coolant is not flowing. How old is your radiator? Does it have a lot of lime scale build up?

 

[GrapeApe318]

the car runs great and doesnt seem to be flooding. The top hose is hot and the bottom hose is cool soI don't think it would be a sensor. its more like something is blocking the flow. I have flushed the radiator a couple of times but there has not been one drop of trash or rust or metal that I have seen. The radiator is a couple of years old but it appears clean. hen I first open the radiator its about a half a gallon low so I top it off. Crank it up and it drops some. I can see the water squirting in the radiator and it bubbles so it has somewhat flow to it. It doesnt appear to be a hose collapsing either. I'm stumped.

 

[Wicked50Chris]

my suggestion is to get the system flushed by a radiator place. They will put pressure in it, so its way better than you doing it yourself. I had this type of problem years ago and it was perfect after the flush. I know you did the thermostat, but do it again, this problem could be a faulty thermostat. They are cheap enough. I would start here first. Then if the flush/thermostat didn't fix it, then it might be your pump. Just my 2 cents. Good luck bro. Let us know what happens, so the next person with the same issue can get the info.

 

[88stang88]

I wouldnt keep driving much until you fix this issue but it seems like it should be on the cheaper end of things. I would definitely replace the thermostat again...I have run into bad batches where you get two or three faultys in a row from the same parts store. My advice is go to another store bc they wont have the same batch. If still does this after replacing thermostat I would check and make sure you dont have a clog in your radiator or buildup in the heads. You can run a hose thru your upper hose and see if your getting a good flow coming out from the bottom hose. If you do not want to deal with the mess I would take it somewhere that does the flushes regularly and not valvoline.

 

[88stang88]

Good news it seems like your gauge is consistent with your coolant temps tho. Whenever your heat stops blowing and starts blowing cold air is a sign your overheating, be careful with aluminum heads and running it hot, believe it or not you can warp those heads pretty easy running hot not even overheating,I found this out the hard way. My 95 GT had this issue alot and I kept replacing parts in a pattern and you will get super irritated. My end result was a set of warped trickflow heads and a block that was severely damaged from overheating cycles.

 

[Wicked50Chris]

yes i agree, DON'T GO TO Valvoline. They do everything the cheapest and fastest way. They reuse some oil. When you go for an oil change, its 75% new oil, and 25% used. I had a friend that worked there, and i heard the stories. As you know, cheap and fast isn't always the best route. I actually just came in from changing my thermostat. There was nothing wrong with it, but its one of my anal things i do. I change the thermostat every 12 months, regardless if working fine or not. I also change fuel filter at same time. That will be tomorrow. Thermostats and filters are cheap enough, and they are very important.

And yes, its true, aluminum heads warp, even when you don't overheat. I had a set of aluminum heads warp and i didn't even overheat.

 

[5.0 Ford Guy]

Ok, did I read this right and you said your radiator bubbles? That is sometimes a sign of a blown head gasket. I don't want to get you all worried, but if you are seeing bubbles like a blow gun is blowing air in your rad and you can hear these bubbles you might want to do a compression check. Not seeing oil in the water and water in the oil is never a sure thing that you don't have a blown head gasket. You could have a gasket failure between a water jacket and a cylinder where no oil is getting mixed with the water. This would explain where the water is going, and the overheating. A compression test will show this.

Stay away from Stant thermostats. Robert Shaw thermos are the way to go. Way more accurate, and never once has one failed me. Do some research on the Stang forums. I am really surprised nobody has mentioned them yet.

 

[toyman]

the car runs great and doesnt seem to be flooding. The top hose is hot and the bottom hose is cool soI don't think it would be a sensor. its more like something is blocking the flow. I have flushed the radiator a couple of times but there has not been one drop of trash or rust or metal that I have seen. The radiator is a couple of years old but it appears clean. hen I first open the radiator its about a half a gallon low so I top it off. Crank it up and it drops some. I can see the water squirting in the radiator and it bubbles so it has somewhat flow to it. It doesnt appear to be a hose collapsing either. I'm stumped.

It appears your answer is here. If you need or can add a 1/2 gallon of coolant the the overfill bottle is being drawn down to the point air is being sucked into the system every time the engine cools. Ensure the overflow bottle always has liquid coolant in it. Air pockets in the engine become steam pockets. That would account for those rapid and erratic temperature changes.

 

[GrapeApe318]

The overflow tank has an aluminum screw on cap and about a month ago the o-ring broke so I went to the local parts stores and the closest one I could find was a little big so I don't feel it seals properly. I bought a good fit yesterday and will see what it does this evening. Maybe it was sucking air in. Im dreading a compression check and the only thing thats keeping my hopes from being a head gasket is that the top hose from the radiator is hot and the top of the fan only on the upper left corner is hot but the rest of the fan is cool when its overheating but when its sitting at 180 - 220 the air is warm all around the fan. I can crank it up and let it idle for 20 minutes with the AC on and it wont get above 190 but once I drive for a few minutes the temp will get up to 220 slowly. If I get on it any then the temp will get up tp 240 and it takes getting temp below 180 for it to quit overheating. I can watch that gauge go up from 220 to 240 as quick as the speedometer goes up when I get on it. There are times I can get on it though and nothing happens. Nothing seems consistent.

 

[WhiteCobra95]

I hate to say it, but that sounds exactly like a head gasket leak to me. You build a pocket of air or exhaust gas in the cooling system which will allow the coolant to turn to steam in that spot and read really high on the temp sensors. However, the thermostat needs to be in contact with a liquid to open. Since the stat is at the highest point in the system, the air pocket will find it’s way to the stat and then the stat won’t open. That’s why the car will run normal until a point, then you’ll see large rapid increases in the temp measurement. This is really bad because the engine is actually overheating and the radiator isn’t being used in the cooling system. If you keep driving or give it some rpm, sometimes you get lucky and the stat will eventually open, then you’ll see an instant drop of the temp gauge to something like 180 or even 160.

When this condition happens and you park the car, chances are that the thermostat eventually gets hot enough to open, purges out the air bubble, and then the car works fine for a drive cycle or two until you build up another bubble in the system. This is why it’s somewhat intermittent.

The quick fix is to pull your stat and drill a small hole at the 12 o’clock position on it’s main plate. That provides the coolant flow with a small bypass to push the air bubble through. However, this is just prolonging the car’s usefulness until the head gasket completely lets go.

To confirm the head gasket or worst case, a cracked head/block, you should do a coolant system pressure test with a tester from a local auto parts store. Crank up the pressure to around 14 or 16 psi and see how long the system holds pressure. You don’t want the pressure to drop too much or too fast. If it’s bad enough sometimes you can even hear the leak if you do the test in a quiet area.

You can also do a leakdown test, but my experience has been that the leak has to be pretty big before it shows up as leakdown. If it’s already that bad then usually the spark plug on the leaky cylinder looks like it’s been steam cleaned where the others come out tan or black depending how you’ve been driving. (White smoke out the exhaust is another sing that you're burning coolant, but you need a good sized leak before it really shows.)

 

[GrapeApe318]

Oh wow. Well I guess my next question is, does anybody want to come help me change a head gasket??? LOL JK. I just hate this because I moved away from where my shop was and now have nowhere besides my driveway to work on it.

 

[5.0 Ford Guy]

You may get lucky and it just be air in the system. But I would do some tests to make sure.

If it is a head gasket, make sure you have your heads checked that they aren't cracked or warped. Otherwise you may waste a lot of time replacing a gasket only to have to do it again.

 

[GrapeApe318]

right on. I appreciate everybodys help

 

[toyman]

The overflow bottle MUST not be sealed. Stock is plastic and vents to the atmosphere. It's correct name is "degas bottle". As the name implies, its purpose is to allow air trapped in the cooling system to be expelled. Head gasket failures on NA cars are not that common. If you really suspect that there is a kit that tests for exhaust gasses in the coolant. Don't pull the heads before doing that test.

 

[88stang88]

Head gasket failutes on NA cars are not that common.

I disagree with this statement. I have seen my fair share of people with blown head gaskets on our cars. They are the weak point in a cooling system for a reason, to prevent further damage to everything else.

I do agree run a pressure test before ripping heads off but it definitely has the potential to go out.

The problem I hope you don't have however is a warped head. Aluminum overheats easy and warps even easier.

If you end up pulling the heads make sure to get them checked out and resurfaced.

 

[5.0 Ford Guy]

Read his first post Richard. His car is supercharged

 

[toyman]

OOPS

But I still think it's premature to conclude it's a head gasket issue without supporting tests.