Trying to verify the reading of my temperature gauge on my '63. It appears to be running hot according to the gauge, 225 degrees, but never boils over. I've seen one way is to use a IF gun to get this measurement. Using one tonight got various temperature readings when pointing the gun at different locations on the engine, I.E. intake manifold, water pump, theromostat housing, radiator, upper radiator hose and expansion tank. Where does the gun need to be pointed to get an accurate reading of the coolant temperature? Mike #28614
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Re: Checking engine temp on my '63 340HP
Mike - I would think the thermostat housing would be the best point to measure...Craig -
Re: Checking engine temp on my '63 340HP
Mike:
Point it at the base of the temp sender, or the intake manifold, clost the the sender. The sender is sending the temp signal to your gauge, so that is where you should record the temp. The t-stat housing should yield slightly lower readings at steady state.
JoeComment
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Re: Checking engine temp on my '63 340HP
Most of the time I get readings on the intake in the vicinity of the temp sender. Keep in mind the ratio of you particular IR unit. Many of the inexpensive ones have a 6:1 area, so If you are a foot away you are reading a 2" circle. Also, many of the IR thermometers are confused by shiney or reflective surfaces. On my 62 FI car, I cannot get an accurate reading on the intake anywhere. Apparently the bright aluminum interfers with the reading. On this car I have to shoot the underside of the upper radiator hose, just past the thermostat housing.Comment
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Re: Checking engine temp on my '63 340HP
Ed makes a good point about shiney surfaces! Most of the inexpensive guns out there do not have an emissivity adjustment on them and do not read correctly on anything but a matte finish preferably black. The radiator hose adjacent to the Tstat housing is about the best location. After shooting the hose try shooting the shiney brass sensor, you will be amazed at the difference! As was pointed in an earlier post, get as close as possible since the sixe of the measurment area grows as the distance increases.
Regards, John McGrawComment
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Re: Checking engine temp on my '63 340HP
Mike, I am copying what I just sent you via email here so others can read:
Mike - first, the IR gun comment is from others that use them and have posted on the NCRS database. So, not from my own personal experience but the folks here. You can search on IR and find lots of posts. Now, on to your high reading but no puke. Did you change the temperature sending unit? The current ones do give high readings and are not calibrated. I am guessing you may have seen the many many posts about that. There is a NAPA and AutoZone part available by Wells, (I think it is TU5 or TU6 by the Wells number) and this part gives an accurate read. My guess is you are not running hot at all. But with your IR gun, you should see the lower reading at the metal thermo housing, down in the range you expect. Sometimes small blocks, even bored 30 over, will have heat issues in midyear vettes due to cooling, but if you have a good DeWitts replacement in there (not a copper/brass OR original Harrision that is 30+ years old) you should not have heat issues. My 67 L79 is also running hot, it has a 72 date code aluminum Harrison that I am sure is getting clogged and causing my problem, but I bought a DeWitts resto unit to replace it when I get the car back on the road (too many of my cars are crippled right now by resto work!).
My 67 will get to the 215 to 220 and not puke eiether, and mainly with I kick the AC on. I am certain I have an issue with the radiator causing the problem. I also have a 30 over blueprint (I didn't do the work on that one myself, but it looks like a good job from the bottom from what I can tell), and had a great balance job. Anyway, you sould like you may be in the same situation I am on mine, but if you have all new radiator and are on the buildup of a resto job, I would suspect the sending unit if you changed it. Let me know how you make out!Comment
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