The Ford Barn

vetpenny · 06-11-2018, 07:26 AM

I have a problem with my V-8 pickup running hot. I have no problem starting the truck but it quickly registers H on the temperature dial. If I pick up the speed of the truck it will cool down to about the 3/4 level on the temperature dial and then goes back to hot. Once I shut the pickup off and then try to start it, it turns over very slowly. I see no steam from coming from the radiator. I am thinking maybe thermostats, faulty temperature indicator, water pumps or possibly the starter. I would welcome any suggestions you may have. Thanks for your input.

4dFord/SC · 06-11-2018, 07:36 AM

Suggest you first determine the actual operating temperature with an inexpensive infrared heat gun, e.g., https://www.amazon.com/HDE-Temperatu.../dp/B00QYX6F5G.

tubman · 06-11-2018, 07:38 AM

The first thing you have to know is the actual temperature of the engine. I notice Harbor Freight has the remote infra-red thermometers on sale this week. I think they're $14.95. I have one, and they're invaluable for stuff like this.

EDIT : "Great minds think alike"

drolston · 06-11-2018, 12:00 PM

Did this problem just appear, or has been building?
I assume the water, or whatever, is an inch over the radiator core.
One or both of your thermostats may have flipped from the head outlet up into the hose; common problem.

The slow cranking when hot is probably not related; maybe a cable size, corrosion, or grounding problem.

revkev6 · 06-11-2018, 12:19 PM

like was mentioned already, those heat guns are worth So much for quick diagnosis. I thought I had a horrible overheating problem after I swapped in a rebuilt motor only to find out it was a bad ground on the stewart warner gauge causing it to read about 40 degrees high. I spent an entire weekend swapping parts and such before I broke down and got the IR temp gun and found out my "new" used gauge that I thought wasn't working at all, actually WAS working but hadn't even started registering yet when my other "old" used gauge was already reading hot!

4dFord/SC · 06-11-2018, 12:45 PM

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[QUOTE=tubman;
EDIT : "Great minds think alike"[/QUOTE]

Go Gophers

tubman · 06-11-2018, 12:57 PM

Fred - I did beat you by 4 cents, but even I would go to Amazon rather than saving the .04 at Harbor Freight.

vetpenny · 06-12-2018, 11:36 AM

Thanks for the helpful advice that many of you gave. I purchased an IR thermometer and took the temperature of the engine block and the hoses leading to the engine when the heat indicator on the dash registered H. The engine block temperature was 220 degrees Fahrenheit and the hose temperature was about 140 degrees Fahrenheit. Also after turning the engine off it barely turned over. Can anyone offer any further suggestions as to what my problem may be? Again thanks for your help.

deuce_roadster · 06-12-2018, 11:51 AM

All electrical troubleshooting begins with the battery. If it were me, after the battery checked out under load, I would remove and clean all the cables and grounds and clean and tighten them. I am assuming the cables are proper gauge. If still weak when hot, go through the starter, there are high torque field coils available, check the armature for shorts, turn it and replace brushes and springs. Make sure the bushings are not worn and re assemble. If the solenoid was the problem, I don't think engine temp would make a difference but that is also in the mix. Good luck, post what the problem was after you find it.

tubman · 06-12-2018, 05:00 PM

The temps you are reading suggest to me that you have a clogged radiator. The coolant isn't flowing through it like it should. You should "shoot" the radiator as well. It should be cooler at the bottom than the top. I forget what the drop should be; maybe someone else knows off the top of their head.

vetpenny · 06-13-2018, 09:44 AM

Again thanks for the many suggestions. I have checked the temperature of the block (220 degrees) and the hose coming into the block (140 degrees F). Also I have checked my wire connections which are okay and the battery which is fully charged. Unfortunately it begs other questions. What effect if any does a malfunctioning thermostat(s) have on my problem? Is it possible that my temperature reading on my dash is wrong due a bad sending unit? Why does my starter turn over very slowly once my dash temperature reaches H? Is it due to an engine block that is too hot, in my case 220 degrees F, and/or a starter that is not operating properly?The temperature at the radiator hose coming into the block is 140 degrees while the block temperature is 220 degrees. Is this difference of 80 degrees normal or does it indicate a possible clogging problem in the radiator and/or engine block? I apologize for pinging on you with so many questions but this problem has been bugging me for several years and I am still looking for a solution. Thanks for whatever help you can give me.

1931 flamingo · 06-13-2018, 11:07 AM

" this problem has been bugging me for several years and I am still looking for a solution. Thanks for whatever help you can give me"

Have you pulled your hoses and flushed the block and radiator?? Are the t/stats blocking the flow (if installed). 220 is WAY too hot. JMO
Paul in CT

JSeery · 06-13-2018, 04:48 PM

Are you running a pressure cap? How can the water temp be 220 degrees and not be boiling over?

expavr · 06-13-2018, 08:29 PM

When using an IR gun to check water temperatures I aim it at the hoses. You say the block is reading 220* is that the upper hose or the engine itself? I don’t think its possible to get an accurate indication of the water temp by aiming it at the block. You will be sensing the heat of combustion and the associated residual heat buildup in the heads and not water temperature. The cooling system on the tonner uses Skip’s water pumps, no stats and has the OEM fan shroud on the radiator. The radiator is a recored OEM split design. IR temperature readings at the upper hose can vary from 165*-185* with the lower hose reading averaging 15-20* less.

06-11-2018, 07:26 AM	#1
vetpenny Senior Member Join Date: Oct 2014 Posts: 103	1940 ford V-8 running hot I have a problem with my V-8 pickup running hot. I have no problem starting the truck but it quickly registers H on the temperature dial. If I pick up the speed of the truck it will cool down to about the 3/4 level on the temperature dial and then goes back to hot. Once I shut the pickup off and then try to start it, it turns over very slowly. I see no steam from coming from the radiator. I am thinking maybe thermostats, faulty temperature indicator, water pumps or possibly the starter. I would welcome any suggestions you may have. Thanks for your input.

06-11-2018, 07:36 AM	#2
4dFord/SC Senior Member Join Date: May 2010 Location: Columbia, SC Posts: 1,579	Re: 1940 ford V-8 running hot Suggest you first determine the actual operating temperature with an inexpensive infrared heat gun, e.g., https://www.amazon.com/HDE-Temperatu.../dp/B00QYX6F5G.

06-11-2018, 07:38 AM	#3
tubman Senior Member Join Date: Dec 2013 Location: Minnesota, Florida Keys Posts: 10,316	Re: 1940 ford V-8 running hot The first thing you have to know is the actual temperature of the engine. I notice Harbor Freight has the remote infra-red thermometers on sale this week. I think they're $14.95. I have one, and they're invaluable for stuff like this. EDIT : "Great minds think alike"

06-11-2018, 12:00 PM	#4
drolston Senior Member Join Date: Jun 2014 Location: Williamsburg, VA Posts: 1,627	Re: 1940 ford V-8 running hot Did this problem just appear, or has been building? I assume the water, or whatever, is an inch over the radiator core. One or both of your thermostats may have flipped from the head outlet up into the hose; common problem. The slow cranking when hot is probably not related; maybe a cable size, corrosion, or grounding problem.

06-11-2018, 12:19 PM	#5
revkev6 Senior Member Join Date: Nov 2012 Location: western Mass Posts: 365	Re: 1940 ford V-8 running hot like was mentioned already, those heat guns are worth So much for quick diagnosis. I thought I had a horrible overheating problem after I swapped in a rebuilt motor only to find out it was a bad ground on the stewart warner gauge causing it to read about 40 degrees high. I spent an entire weekend swapping parts and such before I broke down and got the IR temp gun and found out my "new" used gauge that I thought wasn't working at all, actually WAS working but hadn't even started registering yet when my other "old" used gauge was already reading hot!

06-11-2018, 12:45 PM	#6
4dFord/SC Senior Member Join Date: May 2010 Location: Columbia, SC Posts: 1,579	Re: 1940 ford V-8 running hot Sponsored Links (Register now to hide all advertisements) [QUOTE=tubman; EDIT : "Great minds think alike"[/QUOTE] Go Gophers

06-11-2018, 12:57 PM	#7
tubman Senior Member Join Date: Dec 2013 Location: Minnesota, Florida Keys Posts: 10,316	Re: 1940 ford V-8 running hot Fred - I did beat you by 4 cents, but even I would go to Amazon rather than saving the .04 at Harbor Freight.

06-12-2018, 11:36 AM	#8
vetpenny Senior Member Join Date: Oct 2014 Posts: 103	Re: 1940 ford V-8 running hot Thanks for the helpful advice that many of you gave. I purchased an IR thermometer and took the temperature of the engine block and the hoses leading to the engine when the heat indicator on the dash registered H. The engine block temperature was 220 degrees Fahrenheit and the hose temperature was about 140 degrees Fahrenheit. Also after turning the engine off it barely turned over. Can anyone offer any further suggestions as to what my problem may be? Again thanks for your help.

06-12-2018, 11:51 AM	#9
deuce_roadster Senior Member Join Date: Oct 2011 Location: Shelton, WA Posts: 3,800	Re: 1940 ford V-8 running hot All electrical troubleshooting begins with the battery. If it were me, after the battery checked out under load, I would remove and clean all the cables and grounds and clean and tighten them. I am assuming the cables are proper gauge. If still weak when hot, go through the starter, there are high torque field coils available, check the armature for shorts, turn it and replace brushes and springs. Make sure the bushings are not worn and re assemble. If the solenoid was the problem, I don't think engine temp would make a difference but that is also in the mix. Good luck, post what the problem was after you find it.

06-12-2018, 05:00 PM	#10
tubman Senior Member Join Date: Dec 2013 Location: Minnesota, Florida Keys Posts: 10,316	Re: 1940 ford V-8 running hot The temps you are reading suggest to me that you have a clogged radiator. The coolant isn't flowing through it like it should. You should "shoot" the radiator as well. It should be cooler at the bottom than the top. I forget what the drop should be; maybe someone else knows off the top of their head.

06-13-2018, 09:44 AM	#11
vetpenny Senior Member Join Date: Oct 2014 Posts: 103	Re: 1940 ford V-8 running hot Again thanks for the many suggestions. I have checked the temperature of the block (220 degrees) and the hose coming into the block (140 degrees F). Also I have checked my wire connections which are okay and the battery which is fully charged. Unfortunately it begs other questions. What effect if any does a malfunctioning thermostat(s) have on my problem? Is it possible that my temperature reading on my dash is wrong due a bad sending unit? Why does my starter turn over very slowly once my dash temperature reaches H? Is it due to an engine block that is too hot, in my case 220 degrees F, and/or a starter that is not operating properly?The temperature at the radiator hose coming into the block is 140 degrees while the block temperature is 220 degrees. Is this difference of 80 degrees normal or does it indicate a possible clogging problem in the radiator and/or engine block? I apologize for pinging on you with so many questions but this problem has been bugging me for several years and I am still looking for a solution. Thanks for whatever help you can give me.

06-13-2018, 11:07 AM	#12
1931 flamingo Senior Member Join Date: May 2010 Location: new britain,ct 06052 Posts: 9,390	Re: 1940 ford V-8 running hot " this problem has been bugging me for several years and I am still looking for a solution. Thanks for whatever help you can give me" Have you pulled your hoses and flushed the block and radiator?? Are the t/stats blocking the flow (if installed). 220 is WAY too hot. JMO Paul in CT

06-13-2018, 04:48 PM	#13
JSeery Member Emeritus Join Date: Nov 2012 Location: Wichita KS Posts: 16,132	Re: 1940 ford V-8 running hot Are you running a pressure cap? How can the water temp be 220 degrees and not be boiling over?

06-13-2018, 08:29 PM	#14
expavr Senior Member Join Date: May 2010 Location: Hansville, WA Posts: 776	Re: 1940 ford V-8 running hot When using an IR gun to check water temperatures I aim it at the hoses. You say the block is reading 220* is that the upper hose or the engine itself? I don’t think its possible to get an accurate indication of the water temp by aiming it at the block. You will be sensing the heat of combustion and the associated residual heat buildup in the heads and not water temperature. The cooling system on the tonner uses Skip’s water pumps, no stats and has the OEM fan shroud on the radiator. The radiator is a recored OEM split design. IR temperature readings at the upper hose can vary from 165-185 with the lower hose reading averaging 15-20* less.