Cylinder head operating temp?

[srimes]

I'm concerned about the cooling system on my 79 70hp chrysler, so I ordered an outboard CHT gauge. Any tips on where to install it? And how hot is too hot? The gauges reads up to 220, but when is it overheating?

 

[Frank Acampora]

Re: Cylinder head operating temp?

Too hot is when the oil starts to burn off the cylinder walls. However, as a rule of thumb, if water will boil off when dribbled on the engine block, it is overheating. (212 degrees)

The engine should be hot enough that it is most uncomfortable to touch and you can't leave your hand on it, but should not burn you with a quick touch
Since internal combustion engines use thermostats anywhere from 130 to 180 degrees, a cylinder head temp of 180 would be considered acceptable.

 

[srimes]

Re: Cylinder head operating temp?

Thank you, that's good to know. I feel better now and doubt it is overheating and will check it the next time I go out.

 

[john from md]

Re: Cylinder head operating temp?

Mine runs about @140* at WOT with a 110* thermostat. At idle and low speeds, the needle sits on the line at the left of the gauge. On these engines, you can always put your hand on the exhaust box. If you have to remove your hand, the engine is not cooling properly.

John

 

[jerryjerry05]

Re: Cylinder head operating temp?

You can buy heat guns that read the temp thru infared light.They also sell melt sticks that come in different temps.Anything over 185 I'd consider looking into.J

 

[srimes]

Re: Cylinder head operating temp?

Finally got to run it with the gauge yesterday. At idle it ran about 140 and at speed it went to about 170, but it's hard to call 'cause the gauge only has 3 marks: 60-140-220. Guess that's good enough.

 

[john from md]

Re: Cylinder head operating temp?

Do you know if you have a 110* or 130* thermostat? Since it is an older engine, it probably has a 110* however, if for some reason it has a 130* then you can put a 110* in and drop the temp down somemore.

John