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TR6 TR6 overheating

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R_Lyle

R_Lyle

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My '72 TR6 seems to be having a problem with overheating all of a sudden. I replaced the radiator and flushed the cooling system about six years ago and have not had any trouble with it till now. All of a sudden the car temperature gauge has been above the middle setting and heading for the red. I figured it was way past time to flush the system so I drained the block and the radiator and refilled with water. I ran the car only to find the problem got worse. So I removed the thermostat and filled with water again. Now the temperature stays slightly higher then the middle of the gauge and as soon as I close the heater valve it climbs to near the red. I flush the system several times and remove several hoses to flush some more. Still the temperature rises above the middle of the gauge. The only part that I can think that may be faulty is the water pump since I have never changed it in eight years of owning the car. Any advice would be great.
 
well could the sending unit be bad? I probably would run the car, take the cap off the radiator,slowly with a towel, or leave the cap off and stick a thermometer in and see what the water temp is.
 
Being an optimist I would also think first of an incorrect gauge reading... due possibly to a faulty sender or a faulty voltage stabilzer (though the latter would make you fuel guage wanky.

If oyu can beg, borrow or buy an infared thermometer you can quickly tell what is going on. In addition to checking the temp at the Tstat housing (or wherever the sender is) you can also measure the temperature drop from the top of the radiator to the outlet to see if it is doing it's job.

Anything's possible, but every water pump failure I have had either sang to me or gave me a bath (i.e. squealed or leaked).
 
Don't waste a lot of time on this issue. Purshase
an IR heat gun and you have a valuable tool.

I carry an infrared temp pistol in the trunk of
the TR6 at all times. The IR gun was one of the
first tools I purchased when I began to rebuild
this car. The radiator blew up the 2nd day
we owned the car..

You can test many things with an IR gun. get one-
they are cheap.

/bcforum/images/%%GRAEMLIN_URL%%/iagree.gif

d
 
I forgot to mention that I did replace the temperature sensor, that screws into the water pump housing, about five years ago. I also replaced the voltage stabilizer at the same time and the temperature was always just below the middle of the guage. The water pump does not leak and does not make any noise which makes this issue rather confusing. I'm thinking that maybe rust ate through the blade on the water pump so it's not pushing much water. What's an IR temperature pistol and where might I buy one?
 
If the ground connection is going south on the sending unit you can have this problem. Take it out, clean the threads on the switch and the block and reinstall to be sure.
 
Ignition timing off can cause the engine to run hotter than normal. I had a 69 AH sprite and on a long road trip from Maryland to Florida it started to run hotter than normal, after changing the thermostat and water pump with no change I finally got home and was able to set the timing. Problem solved..
 
Frank,

You are correct. That can become an issue if the timing is retarded too much. Advancing, unless carried to an extreme condition, does not cause any overheating issues.

In most cases, the owner will complain of a gradual or sometimes sudden loss of power if the distributor works itself loose in some manner.
 
And Sears and Roebuck.


Quick eyeball. Lower the water level in the radiator appx. 1/2 inch below the neck.

Start the car with the cap removed, Accelerate the motor and see if the water is moving in the radiator. If it isn't I suspect your assessment of pump problem is on the right track. Might also check the temperature of upper and lower radiator hoses when warm.
 
Sometimes you can get a big air pocket that won't leave the head. some people drill and tap a hole on the thermostat housing to ensure all air can be blead from the system. If you removed the thermostat then this should not be the case. Did you test the thermostat ( cold water,boiling water)?
Rob
 
Quick scan of eBay and I see those IR temperature sensors are under $25. That's a good idea RonMacPherson I think I will give that a try to see if the water is moving in the radiator. I accidentally damaged the rubber diaphram on the heater shut off when I was back flushing so I'm waiting on a new one. I also have never set the timing on the car so I probably should just check that in case. It just seems so odd given the temperature has been on the low side ever since I had the radiator re-cored and now it hovers on the over heating side. The only thing I messed with lately is the speedometer (odometer stopped working) when I was trying to get it out of the dash. I can see the wires on the voltage stabilizer but I did not disturb them as of yet (I can't get the gauge out of the dash).
 
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