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Unread 08-21-2011, 04:26 PM   #1
turbogus
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How HOT is TOO HOT?

Since I got 'Betty' (AMC 360 w/3 row rad, 17" electric fan, stock CJ shroud, FlowKooler water pump 180* thermostat) I've gotten two senders for the 'idiot gauge' that resides in the Speedometer cluster from NAPA (likely Echlin) and, having a secondary Auto Meter mechanical temp gauge with it's sender inserted into a water jacket in the intake manifold I noticed yesterday that 210* = fully pegged Speedometer cluster temp gauge. Ambient air temperature was running between 95 -100*

HOW HOT IS TOO HOT?



I've been reassured a couple of times now that 210* is just fine but what with that 'idiot gauge' reading (with both senders) I remain somewhat dubious, the last 80 miles yesterday I was watching all my gauges like a hawk and, after letter 'er cool down overnight I might have detected a new drip oil leak in the aft part of the motor. Saying my not so unusual road side prayers, (My Mom always said "Never underestimate the power of prayer) Betty ran out fine and got me home. Better not be that damm rear main seal, again

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Unread 08-21-2011, 05:02 PM   #2
yahwhy
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the new engines are designed to run warmer than the old, 210 is not that bad but I would try an keep under that, theres something making it run warmer what it is ?, might try some water wetter, they say it can drop temps by 10-15 degrees
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Unread 08-21-2011, 06:21 PM   #3
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210 ain't bad. your thermostat is not opening untill 195, and climbing, so 210 is not far away. myself i don't like to see 220. 180 degree thermostat will knock off 15 degrees at the gitgo.
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Unread 08-21-2011, 07:22 PM   #4
lanecj5
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Jeeps tend to run a little warmer than others.My 258 cj5 sticks on 190* and stays there.210* may be normal for a 360...I personally do not know.I would think 190 to 200 would be better,maybe go to a 180* thermostat.210* is just to close to boiling for me.My oppinion,Thanks Mike
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Unread 08-21-2011, 07:29 PM   #5
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Quote:
Originally Posted by lanecj5 View Post
210* is just to close to boiling for me.My oppinion,Thanks Mike
If it was straight water and not under pressure, then yes, it would boil at 212*. Add 50/50 mix and the boiling point goes up to ~ 223*. Now pressurize it in the rad (16 psi) and that boiling point goes up to ~ 260+*
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Unread 08-21-2011, 08:04 PM   #6
EngChase
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FSM for 1980 states the 195* thermostat begins to open at 195 and is fully open at 219* +/-3*. So 210 is not out of the question.
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Unread 08-21-2011, 08:06 PM   #7
MoC
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Originally Posted by trader View Post
210 ain't bad. your thermostat is not opening untill 195, and climbing, so 210 is not far away. myself i don't like to see 220. 180 degree thermostat will knock off 15 degrees at the gitgo.
How will a 180 degree thermostat knock of 15 degrees?? A 180 degree thermostat just means that water will start circulating 15 degrees quicker, it has nothing to do with the running temp.
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Unread 08-21-2011, 08:39 PM   #8
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If that was true there wouldn't be different temp range thermostats.
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Unread 08-21-2011, 08:39 PM   #9
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Mine, 304, no shroud, factory 4 blade fixed fan, new 3 core, and 180 thermostat. It runs 180 in 95 degree weather over 20 MPH. 15 to 20 MPH, and sitting at stop lights, it climbs to 190 and no higher. I wondering if your electric fan has enough CFM.

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Unread 08-21-2011, 08:44 PM   #10
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If that was true there wouldn't be different temp range thermostats.
Really ??
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Unread 08-21-2011, 09:26 PM   #11
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I would bet your particular electric fan solution is not pulling enough air through the radiator to cool the engine properly. I had this problem. I was running the flex-a-lite 575 dual fans and they just couldn't keep the engine cool enough for me. 220-235 degrees was much too hot for me. I replaced it with a 7 blade mechanical fan from a Wagoneer, a fan clutch, and the proper shroud for the 304 and my operating temperatures reduced dramatically. Around town it is 185-190 and if I drive on the freeway in over 100 degree heat it creeps up to about 200-205 but never higher. Once I exit, it cools right back down. I don't want to swear off the electric fans, but I do believe not all of them are created equal. My 304 is also fuel injected, which I believe may run a bit warmer than traditional carb.
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Unread 08-22-2011, 05:31 AM   #12
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Quote:
Originally Posted by EngChase
FSM for 1980 states the 195* thermostat begins to open at 195 and is fully open at 219* +/-3*. So 210 is not out of the question.
Assuming my '78 is comparable and the PO put an OEM equivalent thermostat in there, this would mean my stock temp gauge wouldn't move much from cold to running temp. I measured the temp of the hoses at 190* or so with an IR gauge. I see the needle move an 1/8" or so after it warms up. I never was sure how to know if the thermostat was good, short of replacing it. It seems to have a lot if needle range left.

Sound reasonable?
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Unread 08-22-2011, 05:37 AM   #13
Erik719
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Originally Posted by CALOcruiser View Post
I never was sure how to know if the thermostat was good, short of replacing it.
You have to remove the thermostat from the Jeep. Place it in a glass container full of water. Heat the water and use a thermometer to read the tempature of the water when the thermostat opens.

I guess you would go through this as part of troubleshooting, but for all the work involved you may as well just replace the thermostat.
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Unread 08-22-2011, 06:39 AM   #14
CALOcruiser
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Quote:
Originally Posted by Erik719 View Post
You have to remove the thermostat from the Jeep. Place it in a glass container full of water. Heat the water and use a thermometer to read the tempature of the water when the thermostat opens.

I guess you would go through this as part of troubleshooting, but for all the work involved you may as well just replace the thermostat.
Thanks. That's in line with what I was thinking. My real question is whether I even have reason to be concerned.

It just seemed odd to me that the temp gauge would read so far on the cool side. Most thermostats I've had in the past were setup to run in the middle of the gauge when operating in normal range. However, based on some of the previous posts, it seems likely I'm running on the cool side of the range where the thermostat opens and maxes out. If I'm running at 190*, then the thermostat is barely open and the needle shouldn't move much if the range goes to 219* or so. I don't have a cooling problem right now. I just want to be able to detect it when I do.
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Unread 08-22-2011, 07:05 AM   #15
trader
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Quote:
Originally Posted by MoC View Post
How will a 180 degree thermostat knock of 15 degrees?? A 180 degree thermostat just means that water will start circulating 15 degrees quicker, it has nothing to do with the running temp.

that is right. but if the cooling system is up to it, then starting at 180, it may never get to 195. it has nothing to do with the too hot problem, but everything to do with the numbers.

most people think of the thermostat opening to cool, which is true, but the main purpose of the thermostat is to let the motor heat up to an efficient temp.
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