How hot is too hot? (1 Viewer)

[Millardo]

Searched many threads but came up empty...

The factory Temp gauge sits at about the 1/3 position once my 3/72 FJ40 comes up to temp. But it seems like/feels like the engine is running HOT to me. Like don't dare touch the top of the radiator hot.
I added an over flow bottle with this engine rebuild, not a drop flows into it. The radiator is filled to the filler neck.

What should normal operating temp be on this 1F, and what is the easiest way to check for true temperature.

Including a picture as I always do. Non related, a photo of a radiator isn't that fun.

Thanks in advance.

 

[FF LC FREAK]

If you searched, you probably came up with the fact that the factory temp gauge is little more than an idiot light. You really need to put in a mechanical gauge to see where your temp is sitting, especially if you are worried about it. With that said, normal operating temps are whatever temp your thermostat is, on up to about 210*F. My stock gauge sits just below the middle of the gauge at 190*.

 

[byrd_hntr]

I always think I'm running hot too but I think it's because my truck dumps heat into the cab even with the heat off. Especially on the drivers side. My feet always feel like they are on fire during a long drive.

 

[Millardo]

If you searched, you probably came up with the fact that the factory temp gauge is little more than an idiot light. You really need to put in a mechanical gauge to see where your temp is sitting, especially if you are worried about it. With that said, normal operating temps are whatever temp your thermostat is, on up to about 210*F. My stock gauge sits just below the middle of the gauge at 190*.

Yes I realize the limitations of these factory gauges. The stock gauge in a '72 doesn't have numbers, just a Cold and a Hot. I would say mine sits just below middle as well, as it had for the 15 years I drove it before the restoration.

Also, I removed the Thermostat because I thought maybe it wasn't opening. What would be a good way to see if I'm getting good water circulation, AND check the true temp, with out getting a separate gauge.

It just seems hot to me.

 

[Millardo]

I always think I'm running hot too but I think it's because my truck dumps heat into the cab even with the heat off. Especially on the drivers side. My feet always feel like they are on fire during a long drive.

Mine did the same until I dumped the header and went back to the stock exhaust. That exhaust header was right under me feet. HOT

 

[myquestoyota]

Get an infra red temp gun from Amazon for $25, it's really handy when barbecuing or smoking as well.

 

[Fast Eddy]

If you searched, you probably came up with the fact that the factory temp gauge is little more than an idiot light.

P-shaw. It works fine and is proportional to the actual temp. If you get the infrared thermometer, you can "calibrate" it in your head, or go all crazy and pull the gauge and put a calibrated sticker on it.

Check the temp of the lower and upper radiator hose. You should see something like 200 degrees at the lower and 180 degrees at the upper hose.

 

[Millardo]

Get an infra red temp gun from Amazon for $25, it's really handy when barbecuing or smoking as well.

Of course! Great idea. Thank you very much!

 

[Millardo]

P-shaw. It works fine and is proportional to the actual temp. If you get the infrared thermometer, you can "calibrate" it in your head, or go all crazy and pull the gauge and put a calibrated sticker on it.

Check the temp of the lower and upper radiator hose. You should see something like 200 degrees at the lower and 180 degrees at the upper hose.

Ahh, now we're getting somewhere. I will order an infrared thermometer in the morning! Always wanted one anyway, and now I have an excuse

I will report my findings. I'm hoping to prove the old factory gauge correct.

 

[steffan]

In the mean time just go to Walmart and get a simple cooking thermometer - you can tape it to the radiator etc. couple bucks and you'll know immediately. The IR ones can vary a lot depending on the material/ color of the surface your reading

 

[FF LC FREAK]

Get an infra red temp gun from Amazon for $25, it's really handy when barbecuing or smoking as well.

For $4 more, you can get a 3 gauge set from Amazon that will tell you your coolant temp, battery voltage, and oil pressure - http://www.amazon.com/Sunpro-CP8218...771533&sr=1-4&keywords=auto+temperature+gauge. I'm not saying a temp gun isn't handy, but why wouldn't you want to monitor your engine all the time?

P-shaw. It works fine and is proportional to the actual temp.

As long as you know what that actual temp is! That's the problem. Sure, you can get a temp gun to read the temperature at normal operating temperature sitting in the driveway, but what happens when you pull a long hill on a hot day and the needle starts rising? Do you know what the temp is at the 3/4 line? At the upper limit of the gauge? 230*? 250*? My point is, if you get an actual gauge, you don't have to guess. A gauge with numbers is way cheaper than putting in a new head gasket and getting the head and block decked.

 

[Millardo]

In the mean time just go to Walmart and get a simple cooking thermometer - you can tape it to the radiator etc. couple bucks and you'll know immediately. The IR ones can vary a lot depending on the material/ color of the surface your reading

Good idea, I have a couple of those in the drawer.

 

[Millardo]

For $4 more, you can get a 3 gauge set from Amazon that will tell you your coolant temp, battery voltage, and oil pressure - http://www.amazon.com/Sunpro-CP8218...771533&sr=1-4&keywords=auto+temperature+gauge. I'm not saying a temp gun isn't handy, but why wouldn't you want to monitor your engine all the time?



As long as you know what that actual temp is! That's the problem. Sure, you can get a temp gun to read the temperature at normal operating temperature sitting in the driveway, but what happens when you pull a long hill on a hot day and the needle starts rising? Do you know what the temp is at the 3/4 line? At the upper limit of the gauge? 230*? 250*? My point is, if you get an actual gauge, you don't have to guess. A gauge with numbers is way cheaper than putting in a new head gasket and getting the head and block decked.

I see your point, and in any other circumstance I wouldn't think twice.
In my case, there are no long hot hill pulls, or anything else of the sort.
She's a princes that simply gets driven to local "cars and coffee" events. Or a Sunday drive up the coast for a milkshake. This Saturday we drove our greatest distance yet, 48 miles round trip. Total mileage of 183 miles since restoration completion May 1, 2012.

So my point is, I just want to bring the needle up to the just below half, where it always lands, and see what the temp is...
Saturday, after 48 miles, I thought "Wow, this baby is HOT", which lead me to start thinking about it.

 

[byrd_hntr]

Mine did the same until I dumped the header and went back to the stock exhaust. That exhaust header was right under me feet. HOT

Im running stock exhaust. But I can see where a header would make is seam hotter.

 

[ColonelMustardFJ40]

I added an over flow bottle with this engine rebuild, not a drop flows into it. The radiator is filled to the filler neck.

Do you have the correct radiator cap. Overflow tank require a cap with a check valve such that the coolant can move between the radiator and the overflow tank.

 

[77mustard40]

Echo the heat gun. I felt I was hot as well after driving for more that 20 or so miles at a time. Got the gun, went for a long drive some of which was at highway speeds and found I was running 10 - 20 degrees above the thermostat's 180 rating.

Thermostat was new and everything else was checking out so I went after my fan clutch. Ended up taking it apart, cleaning it out and refilling with new and heavier silicon oil (6,000 CST). That was the trick, I haven't budged off the 1/3 mark (180 degrees on my truck) since I fixed the fan clutch. Trick, if your rubber gasket comes out of its channel in the clutch housing, put it in the freezer so it doesn't expand to the point where you can't get it back into the little channel again.

 

[myquestoyota]

Did you replace or flush your radiator during the resto? I have to drive a long ways to get my needle above the 1/8th mark since I installed the new OEM radiator from beno. And it sure is purdy.....

 

[DSRTRDR]

in OEM configuration, a '72 did not have an overflow bottle

there should be fluid in the overflow - do you have a leak somewhere ?

 

[Millardo]

Do you have the correct radiator cap. Overflow tank require a cap with a check valve such that the coolant can move between the radiator and the overflow tank.

Good question, I will have to give it a look. It's the same cap that has been on it since 1990, and I have never given it a second thought. I only started scratching my head about this whole thing because I feel like its running hot, and I was surprised to not see any overflow into the reserve bottle that I just added after the rebuild.
I will check it out this weekend, thanks!

 

[Millardo]

Did you replace or flush your radiator during the resto? I have to drive a long ways to get my needle above the 1/8th mark since I installed the new OEM radiator from beno. And it sure is purdy.....

Yes, flushed it, and had it pressure checked. All good.