230 coolant temp after shutdown


IHC in the early to mid-fifties.

Rusty Driver
Rusty Driver

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Post Sun Jun 13, 2021 9:01 am

230 coolant temp after shutdown

So it was recommended to me on here to swap out the 160 thermostat for either a 180 or 192. I put a 192 in last weekend. Truck runs good and the temp floats between 190-200. Yesterday after shutdown I monitored the gauge and it crept up to 230. And it wasn't a hot day by any means. Cloudy and 80. Is this 230 too high after shutdown? It wasn't pressurizing out of the radiator.

Golden Jubilee
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Post Sun Jun 13, 2021 9:16 am

Re: 230 coolant temp after shutdown

nrowles wrote:So it was recommended to me on here to swap out the 160 thermostat for either a 180 or 192. I put a 192 in last weekend. Truck runs good and the temp floats between 190-200. Yesterday after shutdown I monitored the gauge and it crept up to 230. And it wasn't a hot day by any means. Cloudy and 80. Is this 230 too high after shutdown? It wasn't pressurizing out of the radiator.

When coolant stops moving it absorbs the heat in the engine. With electrical gauge you will not see this because it shuts down when the key is off.
Having said that, I doubt your gauge is reading accurate. a non pressurized system with 50/50 antifreeze and water will boil around 226 deg, at 230 you should see boiling. If just water is used 212 will boil in a non pressurized system. These are sea level pressures, the boil point goes down with altitude.
If coolant in the engine exceeds the thermostat setting it should open and coolant will slowly thermosyphon out the top of the engine to radiator and back through the bottom hose keeping the temp below boiling even with the engine not turning.
If you see a huge rise in temp when shut down, I would suspect poor heat transfer to the coolant in the block. IE the block has rust build up in the coolant side of the casting, preventing the coolant from doing its job.
REMEMEBER: the thermostat only sets the MIMIMUM temp the engine will run at, it has no effect on the maximum.
EDIT correction boiling point of 50/50 is 223 not 226. Hum, found both numbers listed on the .net so don't know which is correct.

Rusty Driver
Rusty Driver

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Post Sun Jun 13, 2021 10:48 am

Re: 230 coolant temp after shutdown

Ok. It’s a mechanical gauge though, not electrical.

Golden Jubilee
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Post Sun Jun 13, 2021 11:01 am

Re: 230 coolant temp after shutdown

Yeah, I understand that, but my point is why you will not see a rise on most vehicles.
You mechanical gauge can not be reading 230 deg (accurately) if it is a non pressureized system, the liquid would be vapor at that temp. SO your gauge is not reading correctly and as I said a large increase points to a system that is loaded with rust, poor heat transfer.
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Golden Jubilee
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Post Tue Jun 15, 2021 1:05 pm

Re: 230 coolant temp after shutdown

I'm questioning why you'd run a non-pressure radiator cap.

If you ARE running a pressure cap, you have a pressurized system. The standard cap should be around 6-7 pounds.

The info I found online is that a 50/50 coolant/water mix with a 7-pound cap will place the boiling point at about 243 degrees F.

In which case, 230 degrees F is nothing to worry about, as long as nothing is leaking.
My posts contain my own opinions...your mileage may vary, void where prohibited, objects in the mirror may be closer than they appear, and alcohol may intensify any side effects.

Rusty Driver
Rusty Driver

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Post Thu Jun 17, 2021 6:41 pm

Re: 230 coolant temp after shutdown

I likely worded that wrong. There isn't coolant coming out the overflow tube is what I meant.

Golden Jubilee
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Post Thu Jun 17, 2021 6:57 pm

Re: 230 coolant temp after shutdown

Well it may be I mis interpreted and sent things down the wrong road.
As long as coolant doesn't boil, there is no overheating. The sharp rise suggest there is heat in the cast iron not making into the coolant, and when flow stops, the block temp rises.
If you feel an need to address it, I would pull the core plugs and flush with water and air to drive the rust out.

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