lazy motorad 2 1/8" thermostat?

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It is about 4 years old. 195f. Am on a roadtrip now and temp gauge just started reading a smidge higher than normal. Still within accept able range according to factory service manual. Ir temp gun on aluminum radiator maxing out at 192.5f when Temp gauge reads highest. Aiming gun at white gaffers tape next to inlet. Bare aluminum readings are 40 f less. Black sharpied half of tape. No difference between black and white readings. This morning, after a 3 mile drive, temp gauge reading high, but ir gun on top radiator tank indicated t stat had not yet opened. Was 60 f. Another minute idling and it opened and I got 192.5f reading on top tank. Then This fell to 185f short ly after. I know the temp readings are not alarming but am not sure how well they actually represent true coolant temp. Either temp gauge is just reading different. OOrthe engine is running warmer despite cooler ambients. Phone typing forgive structure. 89 dodge b 250 with a 318 and 35k on rebuild. Opinions?
 
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Jack up the front end and run it a bit. Maybe a small air bubble near the thermostat? Can't hurt to try.
 

wrcsixeight

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The gaffers tapei put n top tank allows thei r gun to work pretty accurately. However I have a temp probe for my multimeter ill route fir reading when driving. Put probe on top radiator tank., or t stat outlet?
 
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Originally Posted By: wrcsixeight
The gaffers tapei put n top tank allows thei r gun to work pretty accurately. However I have a temp probe for my multimeter ill route fir reading when driving. Put probe on top radiator tank., or t stat outlet?
Thermostat outlet would be better, top tank would cool off faster due to air moving over it.
 

wrcsixeight

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Ill check both. But first is top tank. Used a dab of arctic silver 5 thermal grease on probe tip. Will not drive again till sundown though. light winds and groundswell. will report back with results.
 
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<span style="font-family: 'Verdana'">If the ambient temperature is 60F outside and you're going down the freeway in clean air, I'd say 195F is too hot. Keep in mind though, I'm comparing those numbers to my Buick which has a tendency to run cool in clean air. At 60F on the freeway, my Buick would be running about 174F coolant temperature which is what it was doing yesterday. The thermostat is a supposed to open at 192F. Buick came factory with digital coolant temperature gauge.</span>
 

wrcsixeight

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Ok ir gun reads on black tape top tank reads about 6 degrees cooler than dmm temp probe, but if I hold ir gun on black tape touching for a few seconds the gap narrows to near nothing. Readings indicate it gets no hotter than 194.5f and start s dropping right after that peak. And swings between 180 and 194.5. Idling it drops to 160f after a few minutes. But dash temp gauge will still read a bit higher than I am used to seeing. I did not do a long drive but I think reading from top tank will be less informing than on intake manifold. Ill move temp probe to base of t stat housing for more data. I cant get ir gun directly on t stat housing with engine running crom unddr hood, but reading from a few inches away indicated few more degrees than top tank.
 

wrcsixeight

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I m not getting good readings with temp probe taped tightly to base of f thermostat housing. Basically at speed it never registers over 97f, then after engine shut down it climbs to 185 while my ir gun on top tank reads same as before and searching for a hotspot on intake manifold near housing with it maxes out at 192.5f I do have a tachometer and a mechanical oil pressure gauge and it is reading same as always. Im thinking the gauge is just reading different than before, but I have no 'before' data. Shortest route home is 500 miles but I got another 11 days to explore. And will rack up well more than that. Perhaps I should carry a new stat and sender and 2 gallons of 50/50 antifreeze. Wouldnt be first time I have changed a tstat on The side of the road. But I prefer to properly dispose of the old
 

wrcsixeight

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Temp probe is a bit short and had pulled out leading to the bad readings yesterday. Rerouted and secured it better this morning. Initial warm up indicated t stat did not open until intake at base of t stat housing read 197.5f. oem Temp gauge was alarmingly high at that point. Radiator was low this morning a quart and overflow tank empty. Previous leaks at radiator bottom tank and timing chain cover stopped visibly, after just one bars leak tab many Months ago. Have not noticed indications that they have restarted. But have not yet inspected closely. Ive been using a 12 psi radiator cap and returned the 15psi one when I notice the higher readings Id rather deal with all issues at the same time when im back home and can easily work on it. I ground up two more tabs and will monitor levels and temps closely. Motorad t stat has a little jiggle valve for purging air. on initial warm up it temp gauge almost always spiked a bit high then lowered to normal. Now it is spiking higher and generally reading higher.
 

wrcsixeight

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Edit. Overflow tank was not empty. I overfilled it. It just ran 161 going down highway at 55 for 15 miles. At nearly 70f and gauge was reading normal again. Climbed to 180 sitting at red light. The bubble theory In The upper manifold appears to have been culprit. Along with a coolant leak that caused it, as all is normal again. Carrying extra 50 50 coolant with me and have 8 more coolant tabs if needed. Digging the digital temp readout. Might have to get something more permanent.
 

wrcsixeight

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Correct the bars leak tabs. Just returned 15 miles into headwind at 65 mph. Gauge read normal. Dmm read 161f and only rises as I slow to stop. Rises to 180 then drops again to 165 170f
 
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I am little surprised that somebody who is paying that close attention to the coolant temperature via scanner is using that type of remedy rather than doing the real fix.
 

wrcsixeight

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Im in the middle of a road trip. Ill attend to a correct fix when home unless temps spike again or major leaks develop before then. I now.got the tools installed.to monitor and some data for comparison.
 
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