Topic: 40 cooling temp

Dons40	-- 06-01-2016 @ 3:16 PM
	Can anyone tell me the "correct" thermostat temp for a stock 40? Can you also enlighten with the correct pressure (Lbs) for the cap. The 40 I just bought had no thermostats whatsoever. Overheating challenges....
len47merc	-- 06-01-2016 @ 4:12 PM
	Technically 'correct' meaning original? Or 'correct' meaning most effective for your local climate? As I recall Mike Kubarth places 155s in all his '40s. Others in mostly northern climates run 177s-185s. Fwiw, worst case here in central NC, I run 177s in winter and 155s in summer only for the added heat during the winter - the vehicle runs the same approximate highest temp at highway speeds winter or summer regardless of stat rating. It simply warms up more quickly in the winter with the 177s. For the past two years I've run 177s only - winter & summer - never seen actual temps measured with a calibrated Fluke meter thermocouple exceed 195 in the hottest of summer runs at speed or during stop-n-go July 4 parades. Typical temps in the summer run 185-195, winter at speed 170-180 depending upon ambient temps. I run a 4# cap on the '47, but without the EFV8 book on '40s I am not aware what is technically correct for that year in this regard. Reach out to Mike Kubarth (kubes40). If you are having overheating challenges recommend you look first to a clean, free running radiator (versus the obvious) and whether the block is free and clear of debris, mold sand, etc.. Typically have not seen properly operating stats and stat temperature ratings, or no stats at all, as well as pressurized caps or not being the fundamental root causes of overheating issues. Steve This message was edited by len47merc on 6-1-16 @ 4:40 PM
40 Coupe	-- 06-02-2016 @ 4:44 AM
	Ford did not use a pressurized radiator cap in 1940 or 32 thru pre war. I used to run a 3# cap and found with use the top of the 40 radiator would bulge outward and would not return to the proper shape after cooling. The top tank is very large and easy to distort, especially over time and with some minimal pressure. The Ford procedure for correcting over heating has some basic steps before removing the radiator, the procedure is below. The procedure below could have a couple of additional steps added at the end. Have the water pumps rebuilt so they have better water flow. Make sure there is not a leaking head gasket (do a compression check and check spark plugs also look for exhaust gas bubbles in the coolant). Remove the engine heads and replace the head gaskets, make sure they are on properly with the small coolant holes toward the front of the engine block and larger holes in the rear. The last step would be to remove the oil pan and the welsh plugs in the engine block oil pan rail. dig out foundry sand at the rear plugs and flush out especially the rear of the block with clean water. There is usually a lot of sand left from the manufacturing process. The sand does NOT usually cause overheating but can cause some hot spots in the engine block. Good Luck
40 Coupe	-- 06-02-2016 @ 4:46 AM
	Second and final page of coolant Doc.
kubes40	-- 06-02-2016 @ 5:52 AM
	Steve has offered wonderful advice. 155° was in fact the stock thermostats from the factory. I use them in my restorations and have found they maintain each & every car at a good - operable temperature. Keep in mind though, my restorations include proper rebuilding of all components. The engines are boiled out, the radiators re-cored, distributors and carburetors properly rebuilt. If everything is rebuilt properly there is no need for high volume pumps and certainly no need for over flow tanks, check valves, etc. While those things may aid "what ails ya" they are no more than bandages applied in an attempt to mask the true underlying issue(s).
TomO	-- 06-02-2016 @ 7:22 AM
	Don, The advice given above is the best way to solve overheating problems. If you provide more details about your overheating, we may be able to shorten the check list. Is the radiator boiling over or is it just the temperature gauge reading in the HOT range? Are you losing coolant? Does it happen when you are on the highway or just when you are in traffic? Tom
Dons40	-- 06-06-2016 @ 7:22 AM
	Thanks to all for the input. First time "Forum" user and I can definitely see its a great way to tap into the knowledge base for these Early V8's. Here is where I'm at. All hoses replaced and leek proofed. Radiator filled with EG/Water mix. No thermostats. Radiator fins cleaned, radiator inspected and looks fine. With the cap off and engine running fast idle I can see good flow returning to the top of radiator from both upper hoses ( Good flow) Internals of radiator also look fine. Lets talk temp gauge. With ignition on, I have power to the gauge from the Ign switch and 6 Volt across the gauge. In addition, 6 volt out to the sending unit. Maybe someone can explain the circuit to me, as I'm a little unsure how it works. In any case, temp needle never comes off H. reading the bulletin, it implies the gauge needle rests with ign off on H. Once Ign is turned on ( engine cold) the needle should go cold and gradually rise as engine warms. Is this correct description, and if so is the gauge "bad"? New sending unit installed an makes no difference. Checked new and old sending units in warm water, and they Ohm out differently...?
TomO	-- 06-06-2016 @ 8:08 AM
	The gauge and sending unit use a current balance to sense the temperature. Both the gauge and the sending unit with one terminal have bi-metal strips with heating coils. The bi-metal strips open and close the circuit in the sending unit. When the engine is cold, this action takes place less often and increases as the temperature rises. If you have a sending unit with 2 terminals, it is just an open and close switch. When the temperature increases beyond the boiling point the contacts open. To test the gauge, connect the wire from the gauge to the sending uni to ground for a few seconds, with the ignition on. The needle on the gauge should move toward ground. If it does not, either the wire is broken or the gauge is bad. Recheck with a jumper wire from the gauge to ground, to isolate the wire. Do not use teflon tape on the sending units threads. They need to make a good ground to the heads. The motor should have a ground strap from the body to a bolt on the intake manifolds. Tom
Dons40	-- 06-08-2016 @ 2:14 PM
	Back in the shop last night. Temp sending unit is single post. Engine was not running. I pulsed the Ignition in both cases described below. . When I grounded the sending unit, gauge in dash went to C. went under dash, again ran a jumped from Gauge to ground , pulsed the Ignition switch, gauge did not move. Bad gauge? BTW that process of grounding the gauge yields a warm jumper is pretty short order! I realize the car is + ground so my terminology may not be "correct" If the gauge is shot, where can I find one? anyone know?
40cpe	-- 06-08-2016 @ 4:21 PM
	It sounds like when you tested the gauge under the dash you put the jumper on the feed, or hot, wire to the gauge. It should be placed on the other terminal. From your description, I think the sending unit is bad or not grounded to the engine properly. I don't understand the term "pulsed the ignition".
TomO	-- 06-09-2016 @ 7:14 AM
	40CPE is correct, your gauge appears to be good and the sending unit is bad or not properly grounded. I am sorry that I did not make clear that if the test of grounding the wire at the sending unit showed that the gauge was good, you did not need to recheck at the gauge. Check the sides of the sending unit for 12V. If it is present, you have a 12 volt sending unit and it will not operate correctly with your car. Tom
Dons40	-- 06-13-2016 @ 6:47 AM
	Thanks 40 CPE, rechecked the sending unit ground to body and gauge goes to C. Pulled sending unit, gently retapped threads (3/8 pipe tap) and installed new 6Volt ( Macs) sending unit, same thing... gauge will not come off H. There has always been some question regarding engine ground strap on this car. When received, there was a strap attached to dash (Near battery box) but NOT attached to engine. One book I have says engine ground strap runs from Right cylinder head to dash. OK, but I cant imagine they mean cylinder head stud? Wouldn't the torque on that head stud nut be suspect if there was a ground strap between head and underside of nut? If there was a longer cylinder head "stud" where the correct torque could be achieved...THEN the strap was connected, I could believe that. Am I overthinking this? Should I pull a head nut and attach strap and retorque to 45 Lbs ( Cold) current studs don't seem long enough. Is there an alternative cylinder head location? Thanks Group, I appreciate the help...
Dons40	-- 06-13-2016 @ 6:49 AM
	Pulsed the ignition simply means a quick cycling of the Ign switch.
TomO	-- 06-13-2016 @ 7:39 AM
	The ground strap goes from the stud on the firewall to a bolt on the intake manifold. Tom
Dons40	-- 06-13-2016 @ 8:27 AM
	And there you have it. A picture speaks a thousand words....... Thanks Tom. Great looking engine compartment BTW.
TomO	-- 06-14-2016 @ 7:04 AM
	Not mine, I took the photo at the Central National Meet in Auburn, IN Tom
Dons40	-- 06-14-2016 @ 8:54 AM
	Well.... still at this temp gauge issue. With the help of the Photo from Tom, I installed the ground strap ( Where it should have been ) from firewall stud to intake manifold bolt. Still the needle wont come off H. (when the engine is stone cold, but Ign switch is ON.) The wire attached to the sending unit is solid green in color. The wiring diagram shows it to be black. So that I can trace it, can you confirm the wire which goes to the sending unit comes off the Pass side, ( when facing the back of the gauge) The lead on drivers side ( same orientation) has the copper bar attached. I believe I was told the one on the right/Drivers side was the Hot in a previous reply. Thinking about taking a new wire outside the harness from the gauge to the sending unit (temporary) to rule out some harness issue. Good idea?
deluxe40	-- 06-14-2016 @ 10:13 AM
	About 5 replies back you said that when you grounded the wire at the sender the gauge went to C. If that is correct, you already checked the wiring harness. If you do the test again with your jumper going from the connector on top of the sending unit to some clean spot on the engine (rather than the body) and the gauge still goes to C, you will have checked the engine ground strap too and eliminated everything but the sending unit itself and it's connection to ground. In that case, run the jumper from the base of the sending unit to ground and eliminate the possibility of a bad connection between the sending unit and the head. If the gauge stays on H in this latter test, it would mean that you have a second bad sending unit. Not uncommon in my experience. I have had brand new sending units fail right out of the box.
Dons40	-- 06-14-2016 @ 11:52 AM
	Yes good idea. While I now have the ground strap in its correct location, I haven't "checked" in the way you describe. I will,, sending unit to Engine ground. Secondly to check the sending unit body to ground. I too have had Bad/new parts. China cr-p! Thanks DLX40.
RAK402	-- 06-14-2016 @ 8:03 PM
	I have been having an interesting time with repro temperature sending units. While my gauge has worked to some extent (unlike Dons40's) it has been erratic and prone to suddenly jumping all the way to the right/high end, even when the car is not overheating. Wiggling the two contact sensor n the left cylinder head revealed that the inside of the unit was loose in the brass tube fitting. Removing it and taking it apart (ok, it actually fell apart) was even more interesting... Soldered to the to the two contacts and on the inside of the unit was a modern, silicon component (a friend suggested that this was something called a thermistor), not a bi-metal strip (I had hoped the repro part manufacturer had done it right and used an actual bi-metal strip). Inside of the tube was several teaspoons worth of white powder that resembled sugar or salt. I installed a replacement unit (probably the same thing internally) and now have more consistent temperature readings. It was not my intention to derail this thread, but just to point out yet another area where a problem could (and in my case did) occur. This message was edited by RAK402 on 6-14-16 @ 8:54 PM
Dons40	-- 06-15-2016 @ 1:17 PM
	I realize you guys may all be on "Pins and Needles" waiting for the latest. Well.... not likely. Pleased to report the engine ground to sending unit wire made gauge go to C. Confirming the engine indeed now has a good ground. Sending unit (Body or Base) to Engine, and/or to body did not produce the same results. Sending unit is therefore Junk. I bought this one at Macs, and don't really want to buy another one that's no good. Are ther more than one supplier? seems like C&G, Macs< Dennis C, all source from similar places. Any suggestions where to locate, or is this a fluke and I'm sure to get a good one next time.... Thanks greatly to Tom O and 40 Cpe for your "guiding"
TomO	-- 06-16-2016 @ 7:34 AM
	Try Little Dearborn in Minneapolis. They may have an original. Baxter Ford in Lawrence, KS may also have one. Don't blame Mac's, they have to sell the reproduction. There are not enough used Ford ones to go around. Tom
VT/JeffH	-- 06-16-2016 @ 4:28 PM
	Dons40, keep reading what TomO says again and again. He's exceptionally good at helping from a distance! -VT/JeffH
TomO	-- 06-17-2016 @ 7:47 AM
	Thanks for the kind words, Jeff. Tom
Dons40	-- 06-17-2016 @ 9:52 AM
	Joe at Macs was very stand up about the sending unit. I have no complaints...It happens. Will reach out to those suggested. VT, couldn't agree more Tom O is super good from a distance. His direction was simple and straight forward. A genuine resource.. Thanks again. Enjoy the summer, burn some fuel through em...
RAK402	-- 06-27-2016 @ 3:11 PM
	What is actually in the left side (repro) temp sending unit: http://airpax.sensata.com/pdfs/6700.pdf
len47merc	-- 06-27-2016 @ 6:29 PM
	Modern autos and their temp gauges have calibrated us all to think that ~1/3-3/8 deflection of the temp needle indicates 'normal' and it is very hard to get over that when watching one of our flatheads reading 3/4 to 7/8 travel toward the 'H' indicator. When you've time to help yourself get over this paradigm borrow a calibrated thermocouple and digital meter and check your coolant temps at varying gauge readings on the dash (or install your own quality gauge in the glovebox as Old Henry did). For my '47, here's what the results were, validated winter and summer - gauge reading on the left, actual temp on the right, readings taken with the engine running after a 30 minute min drive using then 155 degree (summer) & 177 degree (summer & winter) thermostats: 1/2 or midpoint.......148 degrees Between 1/2 & 3/4..157 3/4............................168-170 Just above 3/4.........177 7/8............................185-190 Between 7/8 & H....195-198 Will your gauge read the same? Doubtful, as these 70+ year old gauges are not precise instruments nor were they meant to be, but the generalization here is what is important. I'm not quite in the '...if it ain't boiling it ain't overheatin'...' mindset yet but am much more comfortable driving the car in the summertime with the gauge at or slightly above 3/4. Took me a while to get used to this but with this knowledge I've kept the 177s in this year's summer and don't feel the anxiety I used to when the gauge barely inches above 3/4 as I know the stats only just opened fully. Makes the summer drives (when necessary - like say, maybe, ummm...driving from Raleigh to Gettysburg in August) much more enjoyable and less stressful. Fwiw when you get the '40 together the way you want. Steve This message was edited by len47merc on 6-27-16 @ 7:24 PM
RAK402	-- 06-28-2016 @ 6:00 PM
	Steve, Great information sir! I have been trying to resolve what is going on with the cooling system in my '40 for decades. One thing that I have found out, is that the left hand , repro temperature probe (the one with two terminals that really is not correct for a 40) goes open at about 185 degrees-giving me the appearance of the temperature running away to a full "Hot" indication on the stock gauge when the car has not actually overheated (about 27 degrees under the boiling point). I will be bypassing it and charting the actual coolant temp vs. what the gauge says, as you have, so that I can finally know what is really going on. I suspect that the engine has not been overheating for all these years when the gauge pegged-I intend to finally find out. This message was edited by RAK402 on 6-28-16 @ 6:08 PM
RAK402	-- 06-29-2016 @ 10:34 AM
	Following Steve's lead, I took the two terminal temperature unit out of the loop this morning, ran the engine at a fast idle in the driveway, logged the actual temperature of the water coming out of the left cylinder head, and came up with the following numbers: 3/8: 140 degrees 1/2: 160 5/8: 170 3/4: 182 7/8: 192 Between 7/8 & H: 198 The engine did show signs of being too warm at 198, so I cooled of the radiator then shut it down (it also lost some coolant at this point). The dual terminal temperature prob was left installed in the left cylinder head and measured with an Ohm meter every few minutes in order to measure the temperature at which it went open. It opened at 182 degrees. If this remained in the system, it would indicate a fully hot condition (gauge pegged to the right) at this temperature, making the right hand sending unit (the one that actually senses the temperature of the coolant for the gauge) useless from 182 degrees on (i.e. 30 degrees below the boiling point). I think the King-Seeley documentation for the original dual terminal unit states that it should go open at 190 degrees-give or take five degrees, so my particular repro one goes open about three degrees under the lower limit tolerance for the original unit. This message was edited by RAK402 on 6-29-16 @ 11:04 AM
len47merc	-- 06-29-2016 @ 11:16 AM
	Cool! (no pun intended) That's gotta give you confidence knowing approximately where you're at on your dash gauge. Steve
len47merc	-- 06-29-2016 @ 12:02 PM
	Am a bit surprised you reached those temps simply by starting it up from cold and letting it idle in the driveway. How hot is it today where you are (ambient temp)? Steve
RAK402	-- 06-29-2016 @ 4:15 PM
	Steve, It was probably around 85 degrees. I know that I should have measured the ambient temperature. It has always had issues with excessive heat (or the appearance of excessive heat) when idling or moving very, very slowly forward (and, of course, it is worse when it is hot outside). This has been over a period of 41 years which has included: three engines, two radiators, two exhaust systems, countless distributors and water pumps (now the new high flow water pumps), etc. At least now I know what the temperature gauge really indicates now... This message was edited by RAK402 on 6-29-16 @ 4:17 PM
TomO	-- 06-30-2016 @ 8:13 AM
	Rak402, The Ford service letters state that the contacts should open at 195 degrees + or - 5 Degrees. Your repro unit is opening 8 degrees below specs. 182 degrees is within the normal operating temperature of the engine. Your cooling system seems to be working marginally. You should not lose coolant at coolant temperature below 200 degrees. I would add Skip's pressure relief valve into the overflow and use a 4# pressure cap to help with the loss of coolant. A nos fan may help with traffic heat problems, but unless you drive in parades, you should not need it. Try changing to 10W 30 oil and make sure that you have 5 quarts in the pan. It may help lower your temperature in traffic. Tom
RAK402	-- 06-30-2016 @ 5:50 PM
	TomO, Thank you very much for the advice sir. This is how the car has been, from a cooling standpoint, since I got it in 1975. I agree that it is marginal at best. My father had a '37 and a '41 when they were new-he told me many times that he never had any issues with overheating, driving in the same climate that I do. The oil I have been using is Dello 15/40. I can change it to 10/30 next time around. Is there any particular brand that you would recommend? I still have the two terminal probe wired out of the system. I may take the one that I have apart and change the electronic component to one that opens at a higher temperature (these are available). I have two of the repro units that have not worked properly, so I have little faith at this point, that a new one would be any better. The electronic part sells for under $10.00, so that I could rebuild it (although I am still not sure what the white powder in the brass bulb portion of the unit was). I drove around in 75 to 80 degree weather today, and the temp never go above 182 degrees, including stop and go traffic, which is somewhat comforting. Do you have a link to Skips pressure relief valve? The fan is the original one that came with the car. From what I can tell from the books/references, it appears to be the correct one for the car. Are NOS ones available? I am also considering looking at one of the new Drake radiators. These are not cheap, but I would finally have a completely new radiator as opposed to a 76 year old, re-cored one (my existing one is quite ugly...). This is the first time that I have had access to a group of people who have a great deal of knowledge and experience with flathead Fords. For decades, all I have heard was "those old flatheads always ran hot," and similar things. There is additional confusion for me, as there appear to be two schools of thought regarding overheating: 1) The coolant does not move rapidly enough, staying in the block too long and leading to overheating. This is what the higher flow water pumps are supposed to correct. 2) The coolant moves too rapidly and does not stay in the radiator long enough to cool off. The coolant is moving too rapidly and the flow should be restricted. It seems to me that #1 is correct, based on what I have read on this forum.
TomO	-- 07-01-2016 @ 8:12 AM
	RAK402, The key number when choosing an oil viscosity is the second number, the viscosity when hot. I like to keep that number at 30 for the flathead and all major oils should meet the specs that were in effect when your car was made. You could use the Delo 10w 30 or Delo 15w 30. The traffic temperature that you are reporting is a good sign. My 40 runs about 170 on the highway and around 180 in heavy traffic. Here is the link to Skips http://www.fordcollector.com/water_pumps.htm Sometimes NOS fans show up on E-Bay. You can check your fan with a piece of paper. Hold it halfway up the radiator and the fan should hold it tight against the radiator. I have no experience with Drake radiators. The price is in the range of a heavy duty recore in the Chicago area. Yours and your block may just need a good cleaning. Several people have had success with draining the system and filling it with vinegar. Let it sit over night and flush and back flush the system. Spray your radiator with Simple Green or another all purpose cleaner, let it work for about 10 -15 minutes and then rinse with cool water. Tom
len47merc	-- 07-01-2016 @ 8:33 AM
	Tom - what temp stats are you running? Just curious. Steve
Dons40	-- 07-01-2016 @ 10:19 AM
	chiming back in on this thread. New Macs temp unit works fine. temp gauge hits 3/4-7/8 but never pegs. which is good. I know all gauges are slightly different, so Ill check my temps ( Actual) and compare to Len47merc. When I changed upper hoses I noticed lots of rust/scale in the heads. If I were to use Vinegar (which... White or Apple Cider) is it best to disconnect and plug water pumps and concentrate only on engine? Im concerned about running Rust/grit through the pump into the Radiator and having it collect in the radiator itself. Fill and flush them separately? Evaporust...good idea in instead of Vinegar? it looks like a beautiful weekend in Wisconsin 80-85 and not a bit of rain..
RAK402	-- 07-01-2016 @ 1:34 PM
	Dons40, Are you running both the left (two terminal) and right single terminal temperature sending units, or just the single terminal on in the left head?
TomO	-- 07-02-2016 @ 8:26 AM
	Steve, I do not run thermostats. I don't drive in the winter, so I have never felt the need for them. Dons40, use the cheapest vinegar you can find. I would fill and flush them separately. Evaporust is a more expensive method, and IMHO not significantly better than vinegar. Wait until you check your temperature gauge before trying to clean the block. You might not be running hot and cleaning could dislodge sediment that will cause you to overheat. In other words, if it is not broke, don't fix it. Tom
misfit	-- 12-29-2017 @ 10:01 AM
	In my 40 I run #180 all year with a 4 lb pressure cap. The radiator top vent is plugged and the vent tube is run from the cap rim to a container. The container has never filled up. It has run good for two years. I live in Co at 6800 feet. Misfit
trjford8	-- 12-29-2017 @ 5:38 PM
	TomO is a living library when it comes to old Fords.
trjford8	-- 12-29-2017 @ 5:39 PM
	TomO is a living library when it comes to old Fords.
TomO	-- 12-30-2017 @ 9:45 AM
	Tom, thanks for the compliment, but is seems that the librarian is on vacation more often than not these days. Tom

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