HELP SHE'S OVERHEATING AND NOBODY CAN FIGURE OUT WHY

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DROVE UP TO ATLANTA LAST WEEKEND AND AROUND NORTH JACKSONVILLE MY STANG STARTED TO OVERHEAT. THIS IS SOMTHING SHE NEVER DOES. I PULL OVER AND REMOVE THE THERMOSTAT REPLACE THE COOLANT AND BOOM NO CHANGE.THIS WILL PROBABLY GO QUICKER IF I JUST SAY WHAT I HAVE ALREADY TRIED EVEN THE HEAD MECHANIC AT MY SHOP IS TOTALLY STUMPED

CAR INFO: 1966 MUSTANG 200, IGNITOR IGN, WEBER 38DGES, PORTED POLISHED ORIGIONAL HEAD..STILL WORKIN ON THE "78"
HEAD. ALL OF THIS HAS BEEN THE SAME FOR QUITE SOME TIME NOW SO ITS NOT LIKE A MOD CAUSED THE PROBLEM

1 CARB AND TIMING ARE IN CORRECT ADJUSTMENT

2 ENTIRE SYSTEM WAS FLUSHED VERY VERY THUROUGHLY

3 NEW THERMOSTAT

4 NEW LOWER RADIATOR HOSE

5 PULLED THE HEAD, GASKET WAS FINE BUT REPLACED IT ANYWAYS OF COURSE.

6 SWITCHED TO "DEX-COOL" APPROVED COOLANT

PLEASE HELP IM AT MY WITS END AND AM ACTUALLY CONTEMPLATING SELLING HER FOR THE FIRST TIME AFTER ALL THESE YEARS. I MEAN THIS IS WHAT I DO FOR A LIVING AND I CANT EVEN FIX MY OWN CAR. :cry:
 
First question: was it a gauge reading or a real overheat?

Second question: Is the radiator new or old and plugged up?

Third question: what's the water pump doing? You can test it by putting some water in the radiator (below the full level) and then turn the pump by hand to see if it moves water.
 
RADIATOR APPEARED PRISTINE WHEN I REMOVED IT TO FLUSH THE SYSTEM. ITS A 5 YR OLD 3 ROW AND THW WATER PUMP SEMMS TO BE FLOWING ALTHOUGH IM REPLACING IT ON MONDAY ANYWAYS
 
i think one of the most common things that comes up with cooling problems is the radiator cap... are you using the one that came with the car? or a new one? if it's old, try snagging a new one, it might work it out, if it gets old, the spring sometimes will not release the excess heat causing a pressure cooker effect
good luck
 
I seem to remember reading about the lower radiator hose collapsing if it did not have the spring type reinforcment in it. Maybe your new lower hose is a cheapo that is causing this odd problem.
 
1. Good point about insuring there's a spring in the lower radiator hose.

2. Just because the radiator "appeared pristine" doesn't mean it's not blocking coolant flow through it. You can't see what's in the tubes by looking at the top of them. Get it flow tested to know for sure.

3. Which water pump do you have? Does it have a stamped sheet metal type impeller or a cast impeller with a backer? The stamped sheet metal type impellers have been known to cavitate, althoug it's not a common problem.

FYI for asa67_stang - When radiator caps get old and the spring gets weak they won't hold pressure. So your system runs at say 6psi when it, and the coolant, needs say 12psi. Remember - coolant under pressure has a higher boiling point than at atmospheric pressure. :wink:
 
I think Phil mentioned the one thing that is always over looked, Flow. It is the simplest part to remove, two hose connections and four bolts. Remove it and find a shop that can check the "Rated Flow at Rated Pressure".

Good luck, Ric.
 
makes sense that the spring would get weak, but i'm 94.89742% certain that i've read elsewhere on this site about the caps not letting the pressure vent, wish i could find the thread
 
Check the gauge and sender first.

Look at the thermostat again. Get a good Stewart or Robertshaw unit. Forget the cheap junk. It's not worth the few buck you save. Make sure its installed facing the right way with the temp sensing unit toward the engine. 160 or 180 degree.

Replace the cap. Get a good 13lb cap and add a recovery system.
 
A defective cap could prevent releasing when the pressure exceeds the rated capacity of the cap.

However, a weak spring will vent before the system reaches optimum pressure (my 6psi vs 12psi example). This effectively lowers the boiling point of the coolant.

I've seen a chart somewhere on the 'net that shows the relationship between system pressure and boiling point, but darned if I can find it now. :?
 
there we go, sounds like what i remember reading
sorry for the confusion, was tired when i wrote that post, all this being on leave and partying takes it's toll on a person!!
 
THANX FOR THE IDEAS YALL BUT THE OBVIOUS STUFF HAS BEEN DONE THE CAP IS ABOUT THREE MONTHS OLD AND I REPLACED IT BEFORE THE OLD ONE WENT
'PREVENTIONT IS A GOOD THING" SO I PUT THE OLD ONE ON AGAIN AND NO CHANGE. I ALWAYS USE PREMIUM PARTS BECAUSE WHAT I PAY AS LIST IS STILL LESS THAN A CHEAP ONE AT RETAIL AND BESIDES THIS IS THE SECOND NEW THERMO. THE HOSE IS QUALITY AND NOT CLOSING AT SPEED I DONT THINK. THE NEXT STEP I AM GOING TO TAKE IS HAVING THE RADIATOR ROD AND FLUSHED. I JUST REMEMBERED THOUGH WHEN I DID THE WATER PUMP LAST TIME I HAD TO USE A CHEPO ONE BECAUSE NOBODY HAD ANYTHING BETTER IN STOCK. I HAVE BEEN TOLD THAT THE IMPELLARS ON CHEAPO ONES CAN START TO SLIP. THEN AGAIN LIKE I SAID IT SEEMS TO BE CIRCULATING QUITE WELL
 
Have the flow checked first, before the "rod and flush". The radiator should flow so many gallons per minute at a set PSI. The flow check is usually free and could save on labor for the rod out.

Good luck, Ric.
 
8) also be aware that mixing the dexcool and ethelene glycol can cause heating problems as well as the two coolants are not compatible. the only way to change over is have the block and head completely flushed out, and then switch over. even small amounts of mixing causes problems. just out of curiosity, why did you switch to dexcool, when gm is telling car owners to switch away from it?
 
BECAUSE IM A SUCKER FOR MARKETING AND COLORFULL BOTTLES. OOOOOOOOOOOOOOOO-SHINEY BUT YES I FLUSHED THE HECK OUT OF IT IVE SEEN THE TWO MIX IT PRODUCES A SUBSTANCE THAT I CALL SCHMUTZ.
 
I replaced everything and it ended up being the radiator. But before that, Like jack said, check your gauges. Make sure your sending unit is working. Also, get a mechanical tempurature gauge to hook up and get actual temperature readings from that, not your dash gauge.

Slade
 
When you pulled the head and replaced the gasket, did you look down all the cylinders and look for any discolorization or blueing? Quite possible you have a cracked block. I have seen them extremely small but there. You won't even see much water loss or vapor in the exhaust.
 
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