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Cooling question for Sprint
#1
Ok......I have been working with the cooling issues for my Sprint this summer. It sat for 4 years with never having been driven. (351c 4v Q code, Cobra Jet)

When I first got it, it drove perfectly with no over heating. Then after awhile it would over heat all the way to the H on the temp gauge. I opened the petcock valve and nothing drained......I took the valve out and not even a drop lol. I poked it with a screw driver and that loosened it up and it drained. I have flushed it perhaps 5 times with a radiator flush and at least 20 times with straight water. It drives around town and does fine now until: 1) I turn on the head lights and the temperature goes up instantly....then back down soon as the lights are turned off. I tried it 4 times, each time it did the same thing. It also heats up when I hit higway speeds. Other than those two....it doesnt over heat. I am only filling it with water at this time. Any thoughts? Thank you

[Image: 33vc6z8.jpg]
Vehicles: 1972 Sprint Sportsroof CJ
2011 F-150, Lariat 4x4, Super Crew
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#2
Check your grounds, you might have a bad ground.

Steve



[Image: 25yvyp3.jpg]
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#3
Yeah, the headlight issue is almost certainly a bad ground. You can test this easy. While the car is not running and after sitting for a while, turn the key to the ON position without starting it. Check the temp. Turn on the headlamps, if the guage jumps up you almost certainly have a bad groud. Very often this is the body ground. So take a large wire and attach it to the negative battery and then a good body ground point, like one of the three shock tower bolts. This is easy to do with jumper cables, just use one side.

If you see the temp guage drop back down you know it is a body ground, if it doesn't then it is the ground for the guage or guage cluster.

The 'at highway temps' might be the same problem for a different reason. Perhaps the ground is heating up and not working as well after driving at highway temps or, very possibly, it is a different problem all together.

Solve the first one and then see if the second is still happening.

'Mike'
73 Convertible - 351C/4V CC heads/4bolt/forged flat tops/comp 270/rhodes/mallory unilite/tri-power/hookers/glasspacks/c6/3.50 limited slip/Gear Vendors/Global West sub frames, strut rods and shelby style traction bars/ Rear sway bar/tilt steering (not original)

Pics of modifications included in:
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#4
Is it actually over heating, puking coolant from the over flow or cap, or is the gauge indicating over heating when the engine is not really over heating? Do the other gauges read correctly? The gauges have never been known for their accuracy. The headlight switch and dimmer switch are in the circuit that powers the "voltage regulator" on the instrument cluster that in turn powers the gauges. I would check/reseat the connections at the two switches to see if anything changes. The fact that the gauge moves upscale with the headlight on is puzzling. There are checks described in Volume 3, Part 33-40 of the Ford Shop Manual. I hope you find an easy fix. Chuck
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#5
c9zx;33017 Wrote:Is it actually over heating, puking coolant from the over flow or cap, or is the gauge indicating over heating when the engine is not really over heating? Do the other gauges read correctly? The gauges have never been known for their accuracy. The headlight switch and dimmer switch are in the circuit that powers the "voltage regulator" on the instrument cluster that in turn powers the gauges. I would check/reseat the connections at the two switches to see if anything changes. The fact that the gauge moves upscale with the headlight on is puzzling. There are checks described in Volume 3, Part 33-40 of the Ford Shop Manual. I hope you find an easy fix. Chuck


Thank you VERY much. I do have the manual. I will find the problem! I know the original problem was rust or something in the cooling system. I could see thousands of tiny flakes floating around. Now I think (knock on wood) I have most of it out of the system. It has never over heated to the point where the system blows its top. I am careful not to get too far from home as I dont want to damage the car. Having said that......the car didnt feel "that" hot lately even though it pointed close to the H. I will try the suggestions posted here. Since its inexpensive I will change out the sending unit again too.

The good news is she runs very very well. Thank you!

[Image: 33vc6z8.jpg]
Vehicles: 1972 Sprint Sportsroof CJ
2011 F-150, Lariat 4x4, Super Crew
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#6
Hey! How are you!?
I've been to some similar misaleading problem with my temp a while ago too... If the guy are saying it most certainly is the ground the go for it!
Although if were you ill take the coolant system and as you are concerned about it, do it everything and you'll end up driving the car more confident...
I did that... My car overheated because of a bad timming but as i were on that subject i ended up renewing the hole system... I cleaned the rad and the water cavities of the engine with a 10 minute running product, i changed the waterpump (mine was still the original one), changed the temp sender along with new a clean wire harness, new thetmostat, pipe and gasket, even new rad and heater hoses (i had 3 of 4 original ones still)
It didnt cost me that much and now i know the cooling system is all brand new Smile
It is one of the most important systems and you just need to be sure it is in mint condition! Smile



Damián Cool

[Image: 120x45bk1ani.gif]
Vote For 7173Mustangs.Com Every Day!
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#7
Thank you Damian! I think a new wiring harness/gauges may be in the future. I just now got back from taking the Sprint out. We drove around town and then out on the highway. I drove her for about 40 minutes or so and did get up to 65 mph for a long way. It never heated up once!!!

I dont know if everyone will recall but I have the issue where I get the engine RPM noise in my radio. I can hear in the radio as the RPM's go up. I turned on the headlights and the noise increased in the radio greatly andddddd the temp gauge started going up. So I kept lights and radio off: Zero heating issues! My radio is an AM/FM radio....the AM does not work at all. I wonder if there could be a ground problem in the radio? SInce my Marti report shows this Sprint should be an AM radio only I will take the radio out and put in a correct AM. Thanks for everyones help!

[Image: 33vc6z8.jpg]
Vehicles: 1972 Sprint Sportsroof CJ
2011 F-150, Lariat 4x4, Super Crew
  Reply
#8
There is a radio noise "choke" (small coil) that is an integral part of the "voltage regulator mounted on the back of the main instrument cluster. The noise in the radio can also be caused by someone installing old school solid core spark plug cables, or missing hood to cowl ground "tongue". The ground for the voltage regulator comes from spade connector on the mounting ring for the cigar lighter. The ground for the radio is the radio mounting bracket bolted to a stud on the back of the radio, it is just a slide in pressure fit. The very good news seems to be the engine is not really getting too hot. Keep at it. Chuck
  Reply
#9
c9zx;33044 Wrote:There is a radio noise "choke" (small coil) that is an integral part of the "voltage regulator mounted on the back of the main instrument cluster. The noise in the radio can also be caused by someone installing old school solid core spark plug cables, or missing hood to cowl ground "tongue". The ground for the voltage regulator comes from spade connector on the mounting ring for the cigar lighter. The ground for the radio is the radio mounting bracket bolted to a stud on the back of the radio, it is just a slide in pressure fit. The very good news seems to be the engine is not really getting too hot. Keep at it. Chuck

Chuck a sincere thanks! I did not know any of that....gives me a great place to start. I love this site! Thank you!!

[Image: 33vc6z8.jpg]
Vehicles: 1972 Sprint Sportsroof CJ
2011 F-150, Lariat 4x4, Super Crew
  Reply
#10
There is a body to engine 'ground strap'. They get old, get broken, get rusted. Did you try creating your own battery to body ground? This may solve all of your problems.

The negative battery cable goes to the engine. There is a ground strap that takes the ground from the engine to the body. Most everything else from the drive train is isolated via rubber bushings.

'Mike'
73 Convertible - 351C/4V CC heads/4bolt/forged flat tops/comp 270/rhodes/mallory unilite/tri-power/hookers/glasspacks/c6/3.50 limited slip/Gear Vendors/Global West sub frames, strut rods and shelby style traction bars/ Rear sway bar/tilt steering (not original)

Pics of modifications included in:
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