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#2564550 - 10/15/18 05:52 PM Is this 440 running hot?
magnumautoresto Offline
member

Registered: 06/28/13
Posts: 66
Loc: LaSalle,IL
A customer brought me a 1970 Three Hundred with a recently rebuilt 440 engine that he thinks is running hot. Aftermarket digital temp gauge with a sending unit mounted in the factory location shows 235 to as much as 250 degrees. Installed a mechanical gauge in the plug on top of the water pump housing and it also shows the same reading.
My infra red temp gauge shows 185-205 at the sending unit location. It also shows top hose in the same range and lower rad hose about 40 degrees cooler. You can watch the temp rise and fall with the opening and closing of the thermostat which to me shows that it is not that hot or the thermostat would stay open.
Engine shows no signs of being that hot, starts easily when warm without touching gas pedal and idles perfectly, no ticking or smells like a warm engine, etc. No excessive underhood heat when you open the hood either.
Replaced water pump just to be safe, thought maybe impellers were slipping or bad in some way.
So, is it really that hot? and if not, why does the gauge read that high?
Any help or suggestions would be appreciated. I am out of answers.

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#2564576 - 10/15/18 06:37 PM Re: Is this 440 running hot? [Re: magnumautoresto]
ahy Offline
master

Registered: 01/22/07
Posts: 7642
Loc: IN
235 to 250 water temp measured in the correct location and verified with two gauges is quite hot. Too hot. 200 to 205 rolling and maybe 220 at a long stop might be typical or OK.

Infrared guns are a rough approximation... the factory location measures actual water temp which is what matters.

Next question is why is it so hot? Is it like that at idle? How about going down the road at speed? A few more specifics on radiator/fan/shroud setup would help diagnose.

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#2564611 - 10/15/18 08:03 PM Re: Is this 440 running hot? [Re: magnumautoresto]
Pacnorthcuda Offline
I Live Here

Registered: 11/19/07
Posts: 19277
Loc: Kirkland, Washington
I don't think the gauges are totally ruled out yet. Has the mechanical gauge been verified in other applications?

I know it's a long shot but....

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#2564653 - 10/15/18 09:36 PM Re: Is this 440 running hot? [Re: magnumautoresto]
magnumautoresto Offline
member

Registered: 06/28/13
Posts: 66
Loc: LaSalle,IL
I am not convinced that it IS running 230-250. If it was really that hot wouldn't it be puking out the rad or hard starting?
Rad is factory looks to be in good condition, recently serviced but do not know for sure, factory shroud, fan halfway into shroud, clutch fan.
Mechanical gauge is new...have both hooked up at same time. Both read same, machanical just a little slower to register.
Car pretty much shows slow climb to this temp weather sitting in shop or driving in town,or up to 45 -55 mph.

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#2564681 - 10/15/18 10:42 PM Re: Is this 440 running hot? [Re: magnumautoresto]
65Fury440 Offline
mopar

Registered: 03/09/13
Posts: 467
Loc: Spring Hill Fl
If it is really running that hot, would the thermostat really be cycling?

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#2564689 - 10/15/18 11:01 PM Re: Is this 440 running hot? [Re: 65Fury440]
poorboy Offline
master

Registered: 01/19/03
Posts: 6474
Loc: Freeport IL USA
Originally Posted By 65Fury440
If it is really running that hot, would the thermostat really be cycling?


Not if it were functioning correctly. I would change the thermostat on the chance its sticking closed, but if its really that hot, it shouldn't be closing at all. I'd replace the thermostat before I would replace the water pump.

Two different gauges reading the same temp is pretty likely accurate. I suppose you could always check it with another gauge, but what do you do if that one reads differently? Which ones do you believe? Maybe you should add an oil temp gauge, that would let you know if the motor was really hot or not.

240 is hot enough to damage a motor. Gene

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#2564702 - 10/15/18 11:33 PM Re: Is this 440 running hot? [Re: magnumautoresto]
magnumautoresto Offline
member

Registered: 06/28/13
Posts: 66
Loc: LaSalle,IL
Took thermostat out and checked it before I did anything. infra red gun shows temp climb to 190-195, drop 15-20 degrees and repeat. To me that is an indication thermostat is functioning properly...
I agree 240 would cause damage, but the fact that I can repeatedly shut off and restart the engine without touching the accelerator and engine does not turn slowly makes me think it is not that hot.

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#2564814 - 10/16/18 11:37 AM Re: Is this 440 running hot? [Re: magnumautoresto]
moparx Offline
Dreaming of implants

Registered: 09/03/03
Posts: 9493
Loc: north of coder
how "new" are the gauges, and are they quality ones, or just basic aftermarket units ? there is a super wide range of quality out there today, so just because two gauges read the same, doesn't necessarily rule out anything. at 240*, an engine may not smell warm or be hard to restart. lots of new stuff run 215* thermostats, and run all day at 230* or so.
are there any other signs of high temperatures, such as pinging or paint discoloration ?
the right coolant mix, plus a good pressure cap, will prevent boil over [puking]up to 260*.
beer

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#2565026 - 10/16/18 05:38 PM Re: Is this 440 running hot? [Re: magnumautoresto]
magnumautoresto Offline
member

Registered: 06/28/13
Posts: 66
Loc: LaSalle,IL
Digital gauge is an Auto Meter, mechanical gauge is a Quickcar,company owner by Lane Automotive in MI. Both in the $125 dollar range.Auto Meter is about 1 year old and was bought to check if car was hot.Only has a idiot light from the factory. Quickcar was bought 2 weeks ago to check other gauge.
180 degree thermostat.
I have used 3 different infra red guns, all show about same. Never above 210 and cycle temp with opening and closing of thermostat.
No Pinging, runs excellent. Paint on valve cover did come off but on top of valve cover not side by exhaust manifold, but is not discolored from heat, just looks like poor prep( no primer, just bare metal below)
So, my question still is, is it really 235-250 degrees? Are gauges wrong or gun wrong?

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#2565063 - 10/16/18 06:48 PM Re: Is this 440 running hot? [Re: magnumautoresto]
a12rag Offline
top fuel

Registered: 04/23/07
Posts: 2139
Loc: Calgary, Alberta Canada
When I drove my 70 300Hurst to the "first" pacific nationals in vegas - middle of august !!! I had the AC cranked to max and temp gauge was reading 225-230F running down the Interstate at 75mph. No detonation, no pinging, no coolant pushing out the rad/rad cap. I do remember it climbing up going up the hills, to 250F . . .but again, nothing other than higher temps, once got to top and going down, temps back down . . . But hey, it was 120F in Vegas - who has a car show on blacktop then ?????

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#2565102 - 10/16/18 08:12 PM Re: Is this 440 running hot? [Re: magnumautoresto]
Challenger 1 Offline
Too Many Posts

Registered: 02/05/05
Posts: 28304
Loc: Cincinnati, Ohio
Originally Posted By magnumautoresto
Digital gauge is an Auto Meter, mechanical gauge is a Quickcar,company owner by Lane Automotive in MI. Both in the $125 dollar range.Auto Meter is about 1 year old and was bought to check if car was hot.Only has a idiot light from the factory. Quickcar was bought 2 weeks ago to check other gauge.
180 degree thermostat.
I have used 3 different infra red guns, all show about same. Never above 210 and cycle temp with opening and closing of thermostat.
No Pinging, runs excellent. Paint on valve cover did come off but on top of valve cover not side by exhaust manifold, but is not discolored from heat, just looks like poor prep( no primer, just bare metal below)
So, my question still is, is it really 235-250 degrees? Are gauges wrong or gun wrong?



IMO and you know it and your customer knows it's running hot.

Got to know more to be able to start guessing.

I think stock as close as you can get it best for mopar cooling. Sounds like your customer car cooling is stock. If so...

What about timing and fuel mixture? I bet that baby is lean making heat.

I have been to Vegas 3 times with my triple black 340 challenger with AC. It held up good all week idling in 90 minutes of vegas traffic at 5 PM and 115° in July. We took the car there 3 times and drove it a lot always around 110-115 day and night.

I lean it out before going out west from Cincinnati including Vegas. I have experienced first hand the difference fuel mixture makes cooling since I have changed my jetting a lot over the years while driving the car all over from the mountains to San Francisco within a couple days of each other.

What I learned from those Vegas trips was how much better having overflow container was than not having one. Without one I could sit there in traffic and watch my temp gauge go up and down as the thermostat opens and closed. It never overheated or even come close. It ran hotter than at home though.

The second time back I had a factory original overflow on it. It helps keep your radiator a little fuller and gave me more cooling capacity. The thermostat was not opening and closing as often and the gauge stayed just a little bit cooler. Same temp and conditions and the exact same car.

I also had the same car up and down pike peak 3 times, one time it was 95° in July going up that steep hot thin air mountain. The old mopar was leaned way down in the carb with extra timing and made it up that hill just fine. Sounded like motor boat motor at the top and would not spin the tires in the gravel at the top the air was so thin.. Was another ultimate test of my cooling system.
When I went to start my car on top of pikes peak it sounded like someone stole my spark plugs the motor turned over so fast because of thin air.
Stock does the job, I use a clutch fans and shrouds and all seals in place under the hood to direct all air through the radiator on both of my cars. The other one is 6 pak 440 that I have idled around at the Woodward Dream cruise for over an hour at a time in August. Won't brag about bonneville, 95° and 120MPH.


It was crazy hot.

In Out burgers, got to have a good cooling system in July in Vegas to do the drive through because every time I go there it takes a long time I guess because it is all made fresh.
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#2565121 - 10/16/18 08:49 PM Re: Is this 440 running hot? [Re: magnumautoresto]
Y3 70 BEE Offline
super stock

Registered: 01/04/07
Posts: 893
Loc: Badham Co.
40oz of Colt45 in radiator

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#2565178 - 10/16/18 11:14 PM Re: Is this 440 running hot? [Re: magnumautoresto]
ozymaxwedge Offline
super stock

Registered: 09/04/15
Posts: 1051
Loc: Australia
Straight water with one bottle of Redline Water Wetter.
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1971 Barracuda

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#2565452 - 10/17/18 02:54 PM Re: Is this 440 running hot? [Re: magnumautoresto]
zrxkawboy Offline
super stock

Registered: 04/22/07
Posts: 901
Loc: SD
Readings from an IR thermometer can vary from actual temp depending on the color and reflectivity of the surface bring measured. http://support.fluke.com/find-sales/Down...vityexplanation
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#2565512 - 10/17/18 04:49 PM Re: Is this 440 running hot? [Re: magnumautoresto]
BigBlockMopar Offline
master

Registered: 01/22/03
Posts: 3405
Loc: The Netherlands
I recently had an aftermarket temp gauge in one of my cars go 'nuts' above 190-200 and up to 230, while the engine still was purring at 180-190 (IR-measurement).

Flushed and acid treated the radiator to remove some scaling and now the temps are around 170, or 185 with long idling.

You can always also check an IR-tempreader by pointing it at boiling water.
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#2565544 - 10/17/18 05:48 PM Re: Is this 440 running hot? [Re: magnumautoresto]
magnumautoresto Offline
member

Registered: 06/28/13
Posts: 66
Loc: LaSalle,IL
A few interesting ideas mentioned here that I will try. I talked to my engine builder to get his take on it. He also said do not rule out bad gauges. Also suggested a few things, try a meat thermometer in the radiator cap hole while running and see what it says, he puts a rag over whatever he is using is IR gun on and lets the heat warm the rag as the paint can reflect the guns beam and not give accurate reading, Also suggested checking timing as mentioned in your replies.
Thanks for any suggestions and keep them coming. I welcome them all!

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#2565561 - 10/17/18 06:11 PM Re: Is this 440 running hot? [Re: magnumautoresto]
Challenger 1 Offline
Too Many Posts

Registered: 02/05/05
Posts: 28304
Loc: Cincinnati, Ohio
I'd spent less time trying to take measurements and trying to justify it and more time making changes to find, fix the problem. twocents
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#2565757 - 10/17/18 11:57 PM Re: Is this 440 running hot? [Re: magnumautoresto]
4406bbl Online   content
super stock

Registered: 01/20/03
Posts: 1110
Loc: Nebraska
Thermometer in radiator is what I do, always works.

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#2565801 - 10/18/18 06:39 AM Re: Is this 440 running hot? [Re: magnumautoresto]
steve70 Offline
super stock

Registered: 12/02/11
Posts: 715
Loc: MA
I just had a very similar situation in my 71 Charger R/T 440. Temp gauge went above hot when driving but looked OK at idle. You could see the temp gauge move a little when the thermostat opened but as soon as I started driving it would climb to over hot. A laser temp gun showed everything was good and there was about a 30-40 degree drop from the top hose to the bottom. We checked the gauge by unplugging it and then grounding it and the gauge worked fine. My friend decided to run a ground from the coil bracket to the body and surprise everything worked great. I removed the battery and harness ground on the radiator support, cleaned it and reassembled and everything works perfectly now.
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1971 Charger R/T 4 speed-Mr Norms
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