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When I drove my 72 home it ran from right on 210 to the next hash mark hotter....First question what reading is that next mark....230....?
I did pull over and raise the hood and didn't hear the boiling sound that would indicate it was getting too hot.
About a week later when I drove it up the road a couple of miles I noticed it running on the hash mark to the right of 210 again....I shot the thermostat housing and the upper hose with an IR gun and got readings around 160...The headers read around 400. On my skin it reads around 89.
I remember the guy telling me he had replaced the waterpump and put a new thermostat in it but don't remember what temp he said. He may have put the wrong sending unit in it and that is why the readings are so off....? Or maybe the IR gun is wrong....I just don't want to run the car hot....I think I'll find a nice rubber ball and boil it and then test the IR gun against that....Should read close to 212....Any other ideas....?
When I drove my 72 home it ran from right on 210 to the next hash mark hotter....First question what reading is that next mark....230....?
I did pull over and raise the hood and didn't hear the boiling sound that would indicate it was getting too hot.
About a week later when I drove it up the road a couple of miles I noticed it running on the hash mark to the right of 210 again....I shot the thermostat housing and the upper hose with an IR gun and got readings around 160...The headers read around 400. On my skin it reads around 89.
I remember the guy telling me he had replaced the waterpump and put a new thermostat in it but don't remember what temp he said. He may have put the wrong sending unit in it and that is why the readings are so off....? Or maybe the IR gun is wrong....I just don't want to run the car hot....I think I'll find a nice rubber ball and boil it and then test the IR gun against that....Should read close to 212....Any other ideas....?
Brian
Over the many years I have been twisting wrenches I have found most of the "running hot" problems were the result of using a wrong temperature sender for the gauge. The '68 thru '71's (the "green face" gauge models) used a sender with a peg on it and the '72 and later (the "white face" gauge models) used a "button top" peg.
Here is a pic of what I think is the temp sender unit....It's on the passenger side of the block....It's not the original engine it has this remanufactured metal place siliconed to the block on the drivers side.
I think I'm losing coolant somewhere....I checked the oil and it's not milky looking....I don't see any puddles under the car either....It runs good.
Get a good guage. I was a little concerned about coolant temps in my rebuilt engine. The stock guage was reading over 200. I decided to change out all the guages using autometers.
For the water temp I selected the mechanical version. I tested it out using my digital vom with the temp probe and a pan of boiling water. The new guage and the temp readings of the vom were almost spot on.
Now my water temp runs up to 180' my thermostat opening temp then just sits there. Nothing was wrong with the engine, the guage/sender wasn't accurate.
Reading an article on the accuracy of the stock guages was enlightening. GM wasn't too concerned with accuracy, felt that acceptable accuracy was around 15% of actual temp. So that's a plus or minus swing of around 30'.
That pic of your sender in the right bank is a sender but I believe that one was for the emission ignition system, I forget the name of it, I eliminated it anyway. There was originally 2 senders on my 72, one in the left head, guage. One in the rt head for that emission system.
Last edited by Sunstroked; May 26, 2015 at 12:18 AM.
Thank you for the info....I'll look on the drivers side today....If both are there is should be easy to see which one is going to the gauge by just unplugging one at a time.
the sender usually screws into the cylinder head not the block. If you have milky looking oil you may have a blown head gasket or cracked head do not continue driving the car or you may end up with bearing damage.
I checked the oil again and it is not milky.... The sending unit is on the passenger side head not the block.....I need to be more careful with what I type.
Can anyone tell me what temp the unmarked hash reads....?
I found atleast part of the leak tonight....The large brass plug in the top of the water pump was leaking....I tightened it about 1/2 turn and drove it up the road a few miles and no leak when I got back or after the motor cooled down. The temp went up to just over the 210 mark....The top radiator hose shot about 160 the the thermostat housing shot about 150 and the head where the sending unit is shot about 190....Headers shot about 400....I think the inside gauge may be off by about 20 deg too high.
Do the above numbers seem about right as far as deg spans go....?
Temp readings....?
