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Veteran
Posts: 299
 
Location: Rochester, NY | Hi Guys, A few weeks ago, I was on my way home with the DeSoto and I glanced down and noticed the temp. gauge was almost all the way up to hot. I started to panic and thought “well, if it doesn’t go down soon I better pull over/shut down.” Well, thankfully, it went right down to where it normally settles in, which is about a third of the way up. So I figured, it’s due for a coolant change anyway, so I went out and bought a new thermostat and I emptied the coolant and flushed a few times (without a thermostat in it) the temp gauge went up to about an eighth of the way up during that time. Well, now I have new coolant and new thermostat in it. I bought a 165° thermostat and first time out yesterday, it did the same thing as it did originally. Temp went up almost all the way to hot. I was about ready to shut it down and then it quickly came down to about a third of the way up just like it did that night on the way home. What could it be? Thanks |
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Expert
Posts: 3402
 
Location: Chestertown, NY ( near Lake George) | Could be air bound, one possibility. Another is a bad head gasket pressurizing the system., which can block circulation. See if the hoses are pressurized right after starting. |
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Veteran
Posts: 299
Location: Rochester, NY | Shep - 2024-05-08 10:58 AM
Could be air bound, one possibility. Another is a bad head gasket pressurizing the system., which can block circulation. See if the hoses are pressurized right after starting.
Thanks for quick reply Shep. I appreciate it. First thing I did was top radiator off. It took 3 more quarts on top of the 2 gallons I initially put in. That’s a good indication there was some air in there which I’ve seen before…after flushing/putting in new coolant in my other cars over the years. There were no “hard hoses” right after start up. I’ll take it out again/see what happens…fingers crossed. Also: It was many years ago at a car cruise/show…and I pretty much forgot about it until just now. I remember a guy telling me to get a lower pressure radiator cap. I just looked…it’s a 15 lb. Too much?
Edited by furvedere 2024-05-08 11:36 AM
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Expert
Posts: 3402
Location: Chestertown, NY ( near Lake George) | Use what is called for regarding the cap. Check those hoses 1 minute after a cold start. Also try and park the car overnight, with the front higher than the rear, radiator cap off, that should bleed off trapped air if any. |
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Expert
Posts: 4046
Location: Connecticut | Replace the 165 degree thermostat with the correct 180 degree thermostat. 15 lbs is probably right. But check the shop manual to verify. It does sound like there's air in the system, or a blockage.
Ron |
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Elite Veteran
Posts: 659
Location: Finland | I don`t think it is the issue here but 15lbs is too much for me. I have seen strange "sweating" on several cars until I tried with 7 lbs(6?).
!5 lbs is also dangerous for your heater core.
The first thing you checked was the gauge for sure?
If the gauge is in order you would here some bubbling from the system if the meter was up to almost top reading. |
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Expert 5K+
Posts: 8948
Location: WHEELING,WV.>>>HOME OF WWVA | the higher the pressure the higher the boiling point.
http://www.forwardlook.net/forums/forums/thread-view.asp?tid=21724&...
Edited by 60 dart 2024-05-12 1:37 AM
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Expert 5K+
Posts: 9922
Location: Lower Mainland BC | .
I believe that if you check the Factory Service Manual for your car, you will find that the thermostat should be a 185 F one and the rad cap should be a 14 psi relief pressure one.
At least that is what is says for a 58 Chrysler via the downloadable FSM pdf at MyMopar.com
https://mymopar.com/service-manuals/
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Elite Veteran
Posts: 659
Location: Finland | Yes but these are not new cars so with high lbs caps you are in danger for leaks , blown radiators , cores and popped core plugs even. This is what I have experienced , not read.
With the cooling system in order you have no boiling issues with a 6-7 lbs cap even at very high ambient temperatures.
16 lbs and up from that might be causing disaster. |
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Expert 5K+
Posts: 9922
Location: Lower Mainland BC | .
I hear you Ralf. I am running a 7 psi cap on my 56 Dodge with recored rad, repaired heater core, flushed block and NOS water pump. I rarely get much past the middle
of the temp gauge.
Owner's manual
Mine:
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58 DeSoto Cooling Issue
