Running hot, I think.....

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williaml

williaml

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Mar 15, 2012
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Location
Ringwood NJ
1965 Dodge Dart 225 slant 6

Re-built engine
new water pump
new thermostat
Radiator cleaned

I have been noticing that around town the temp gauge shows a little hot. As soon as I get on the interstate the gauge goes all the way over to the right pegging in between the last mark and second to last. Today I had the radiator boiled out and it went from 10.9 gallons per minute to 18.8 gallons per minute. That radiator should be around 20 gallons per minute so it is operating fine. I install the repaired radiator and same thing happens. Does anyone think it is the sending unit? Thermostat? with the re-built engine I also put on a new waterpump. Any ideas?


Thanks as always.
 
I would first put a proper water temperature gauge on there to see what the temperature actually is. The stock gauge is just an indicator and sometimes isn't working correctly after 40 years of service.

If you want to check it on the cheap I'd put a new radiator cap on it that has a little temp gauge built in. You could also check the temp with a Infra-red temperature gun if you have one, just point it at the top and bottom rad hoses to see what temp you are running.
 
You'll never know what the water temp is without installing an actual gauge.
The hash marks on that original instrument mean nothing, especially now that it is very old.
 
Did you put in genuine Chrysler T-stat & Water pump?? I've seen many an aftermarket t-stat cause problems. When it's showing full hot, Feel the upper and lower Rad hoses. They should both feel real hot. +1 on checking with a known functioning test gauge.
 
Try an extra ground wire from the block to fire wall. that worked for me on the same problem a few years back.
Also I find that my 225/6 at correct idle just does not move enough air especially at long L.A. stops. After a lot of tests etc. I found that a big toe on the pedal [about 20-40 rpm] helps. -Ken
 
I also just discovered that I ordered the incorrect T-Stat I ordered a 195 degree one, that would allow the water to heat up an additional 15 degrees, does that make a huge difference?
 
Even if you did have a 15 degree change the tempature gauge shouldn't go up that high or in that case act like it is. I would do what the others suggested get a tempature gun or reader and look at what it reads on the engine after awhile. It sounds like a bad gauge.
 
especially since I don't see smoke or antifreeze pouring out of the thing.....
 
Temp spec for a thermostat is only relevant to when it opens It wouldn't effect operating temp on the high end.
 
You might also want to check the lower radiator hose. I had an instance with my old car several years back where the lower hose was collapsing because it didn't have the reinforcing spring in it. I grabbed one out of an old hose that was laying around. That was a small block, I don't know if the /6 is the same.
 
I switched out the thermostat from 195 to the 180 degree one. I think the thermostat was restricted in some way. With the 180 degree thermostat the car is running cooler. I will take it out again tomorrow just to make sure.

Thanks to all who read and responded...

Regards
Bill
 
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