49 V8 Flathead Thermostat - late opening

F

F47

Junior Member
Hello,
I'm new to the forum, and have recently acquired a 49 F47 pickup.
(An F1 to my American neighbours to the South) I live in Calgary, Alberta.
This is my first post. Sorry it's in the form of a question, rather than one of assistance.

I'm hoping someone may have a suggestion that helps solve my brief overheating issue. I noticed the driver's side engine bank seemed to run cooler than the passenger side, so I wondered if there was a thermostat on that side. Upon draining and removing the thermostat housing I found that the thermostat was there, but it had slipped down when it was installed, leaving an open situation. It was obvious by the mark left on the gasket that it had been installed that way.

I replaced the thermostat (on both sides) and made sure it remained in place by using some gasket glue. Now I have the opposite problem with the driver's side, running up to 200 + before the thermostat opens. (160º). I monitored the temps with an infrared thermometer and the head reaches 200 - 210 and then the thermostat opens.
The gauge also gets up to high. As soon as it opens the temp quickly drops down to the normal range and the head temperature pretty much matches the thermostat range.... about 165º

I have checked that it is not in backwards and have also installed a new one, but the problem persists. I have noticed that the temperature right near the housing seems to stay cooler than the rest of the head, so it appears that the thermostat is not getting the high temps nearby. Eventually, it gets warm enough at the top front of the head, thermostat opens and it seems to behave fine after that. I am hesitant to run it much more, as it is reaching an overheat situation, although only for a couple of minutes. Also at this particular time I have straight water with a flush agent in it, so it concerns me a bit more.

I have wondered if perhaps this might signal a water pump issue? I'm not entirely sure how the water pump functions with a closed thermostat. It's curious though as it is the top front of the head that seems to stay cool. It also seems to be an original pump, as it has the oiler cap on it.

I thought of trying to find a 140 or 150º thermostat, but that would be kind of a band-aide solution.

I might add, I drove the truck about 250 miles to my home after purchasing it.
There were no overheating issues, but it did hit the 3/4 mark on the gauge at one point after climbing a long gradual incline of about 10 miles at highway speed (55-60 mph). Aside from that, the temp never got much past the halfway mark. Ideally, I would upgrade the cooling system with new pumps and a better radiator, but I am puzzled by this condition.

Sorry for the long initial post, but I wanted to provide enough clarity and related background info.

I'm looking forward to being a forum member.

All the Best

Wayne
 
Before you do anything else put your thermostats in a pan of water, insert a thermometer, heat until water boils and observe what temperature the thermostats start to open and the temp. reached when they are fully open.

There may also be some numbers on each thermostat that tells when it starts to open.
Lots has been discussed on this topic so you might want to do a SEARCH.
 
Wayne, Welcome to the Barn. Others will tell you which exact thermostat is best to use, but I'll just touch base with a couple thoughts for you.

First, check this thread, on page 2 of today's barn, for methods of securing the stat.
https://www.fordbarn.com/forum/showthread.php?t=258555

Your exact position of the stat can affect how and when hot water actually reaches it, so that's one thing to consider: The problem stat may have shifted position and sees the hot water later than the other stat. The stat itself needs a small bleed hole to assure cold water can exit to bring hot water to it.

Next, a temp of 200ºF is not an overheated engine, especially for the short time it is at that temp. The only problem, really, is if it boils your coolant, (212ºF) thereby exiting your radiator out the overflow. Again, for a short duration, no problem.
 
An F1 should have a pressure cap (3 1/2 to 4 1/2 psi). 200 to 210 is not overheating in my book. On the thermostats, I would go the other direction and run a 180 or 185 (Ford spec was 177-182). 160 in not high enough temp for normal driving. The thermostats operating temperature does not increase engine coolant system temperature, it speeds up the warmup of the system and maintains a minimum temperature. If it is overheating something else is most likely going on. All of this is based on the assumption your engine is an 8ba and you are running a pressure cap.
 
Last edited:
Thanks 19Forty
I had tried the stats in hot water & they just start to open at 160. I think they are fully open at about 175 - 180. Also in response to Alan's suggestion on anchoring the stats, I do not think they are subject to that problem with the 8BA head and stat housing.

JSeery mentions that 200 - 210 is not really overheating, and there is a 4Lb. cap on the radiator, but right at this moment, I am running straight distilled water with a corrosion flush in it. My concern there is that water will boil at a lower temp than 50/50 Antifreeze. The 4 Lb cap helps, but I am also at close to 4000 ft of altitude at my house. The straight water situation is temporary and I will return to antifreeze soon. (And hope my garage furnace stays working until then... about -30C last night)

Essentially, the engine is not overheating...when the stat opens. The puzzle for me is why it is opening late... and only on the left side? The particular area of the head where the water exits to the rad seems to stay cooler than the rest, by about 40-50 degrees. I don't get that.
Before I placed the stat in the correct position, that side ran too cool, due to the always open situation, so overall, there does seem to be an overheating problem, but there is an over-cooling problem of sorts. Now the temp gauge spikes to hot for a few minutes before the stat opens. The head temp near the sender, and pretty much everywhere else exceeds 210, but it's only about 170 at the stat housing at that time. The right side opens about 5 minutes before and functions normally through its cycle. Once the left stat does open, it cools down in about 30 seconds. Then the entire head reads between 165 and 170º with the infrared thermometer, the gauge is at the mid-point and it stays there.

I'll keep pondering this for a bit. Thanks for all your suggestions.
 
Ensure that the bypass hole in the stat is not blocked by the gasket or gasket goo,even run a bigger drill threw it to open up a little. Im only guessing but maybe the water in the neck below the stat is staying cooler for a while , with a small flow past the stat it may get a truer temp and open a bit earlier. Its worth a try.
 
kiwitony said:
Im only guessing but maybe the water in the neck below the stat is staying cooler for a while , with a small flow past the stat it may get a truer temp and open a bit earlier. Its worth a try.
Click to expand...
"Water in the neck below the stat" ?

Thought that this was an 8BA and there is not any "neck " below the stat, just the water chamber of the head.
 
I think that is worth a try, even though there is really no neck. Maybe if there was some flow allowed, the hotter water will reach the stat sooner.

On my original post, I mentioned that I was unsure of exactly what the water pump was doing when the thermostat was closed. I assume it is working, as the engine cools properly when the stat is open, but it appears to be an original pump. A set of updated pumps is in the cards, but whether that would solve this issue is not known by me.

I will try drilling a couple of holes and let you know if it does the trick.

Thanks
 
F47 said:
I think that is worth a try, even though there is really no neck. Maybe if there was some flow allowed, the hotter water will reach the stat sooner.

On my original post, I mentioned that I was unsure of exactly what the water pump was doing when the thermostat was closed. I assume it is working, as the engine cools properly when the stat is open, but it appears to be an original pump. A set of updated pumps is in the cards, but whether that would solve this issue is not known by me.

I will try drilling a couple of holes and let you know if it does the trick.

Thanks
Click to expand...
If you intend to purchase 'Skip's' pumps, as I recall, one of the requirements for the pumps to operate to his standards is that thermostats NOT be installed.
 
Does not a 1949 pickup have a late model 8BA style motor with the removable thermostat housings that hold the thermostats in place against the head? They should not be able to slip out of place. On sbf 289s I've seen the intakes with a thermostat recess and without them. I've seen the thermostat housings with the recess and without them. Only one can have the recess. There are all kinds of aftermarket water necks available for 8BA heads so just make sure your head or your thermostat housing has a recess in it but not both.

Stick your thermostat in the recess. Then you use Gasgacinch sealer on the part with the recess and on one side of the gasket and let them dry until they no longer look wet. They must look like they are not wet or this won't work. When the gasket contacts the thermostat housing it will hold the thermostat in place. The gasket will never slip. I use this method on most gaskets. If you use silicone on both sides of a gasket it can slide right out when you tighten it down. On the opposite of your gasket you can use just a little silicone and I mean just a little! The tiniest bead you can make. It should not be squeezing out when you tighten it up. I like the black silicone best (not the black aquarium silicone) because you don't see it between the parts. I hate engines with blue, orange and red silicone squeezing out all over the place. If the thermostat were to slip out between the head and the housing, and the housing is aluminum, when you tighten it down you will break the housing every-time. The only time I use silicone on both sides is if there are gouges from somebody scraping off gaskets, electrolysis and porous castings. If you have nice machined surfaces then I would use the Gasgacinch on both sides.

You said the thermostats are installed correctly but just to be sure the sensing bulb goes down into the head.

Thermostat selection. A thermostat will only control at what temperature it wants the coolant to start flowing. Its only purpose is to make the engine warm up faster. After it opens it has no control over how hot the engine can get. If you live somewhere really cold a engine might need a 180 thermostat to get up to that temperature. Here in SoCal either thermostat , 160 or 180 is probably not going to make a bit of difference. The engine will reach 180 degrees with either one. The 180 thermostat will just get there al little faster.

I'll tell you a little story about a Toyota pickup I had and my friends had. Those years thay all had thermostats that were going bad at around 60,000 miles and we all knew it. One night on my way home I saw the gauge go to 3/4 on the freeway. I though if it gets any higher I'm pulling over but It never did. The next morning it had a misfire and white smoke came out the tailpipe. It warped that aluminum head that was about three or four times thicker than a flatheads. I have no idea how hot 3/4 on the gauge was? But after that I'm a little leery of an engine getting up much past 210 degrees with aluminum heads.

I also got a batch of bad thermostats one time. I stocked them at work. The new one I grabbed off the shelf was bad. I checked it and in boiling water it would not open. I tried several different auto parts stores with the same brand of thermostat and they were all bad. They must have all been made in the same batch. I bought a different brand thermostat and that solved it.

You guys were talking about heating up the thermostats and watching them open or not open. Our boss at work kept his coffee cup in the breakroom right between the sink and the microwave. When he wasn't there it made a really convenient thermostat checking station. I've seen more fail stuck open than stuck closed.


On this thermostat housing you can see the recess that the thermostat fits in. Sometimes the housings get so corroded you can barely see the recess. Then you need to buy new ones.
 

Attachments

  • housing.jpg
    housing.jpg
    40.5 KB · Views: 15
Last edited:
I kiwitony has the answer.


I didn't think about that little bypass hole. I assumed they would all have that hole, they use to have them. I just looked online and neither Stant or Motorcraft '49-'50 Ford thermostats have the hole?

Here are some photos. A motorcraft with no hole in it. A thermostat with the small hole with the wiggle rivet in it. That's a one way valve that lets coolant flow from the engine to the radiator. Then a couple examples of thermostats people drilled.
 

Attachments

  • 141201.jpg
    141201.jpg
    41.7 KB · Views: 31
  • mar03307.jpg
    mar03307.jpg
    15.3 KB · Views: 35
  • tstatdual.jpg
    tstatdual.jpg
    44.2 KB · Views: 32
  • thermostat-1.jpg
    thermostat-1.jpg
    63.5 KB · Views: 28
Thanks Flathead Fever, and Flatjack 9
I'll try the bleed holes. I tried some more complete replies, but for some reason they would not go out.

I'll report back after the hole drilling experiment.

Regards

Wayne
 
"51 MERC-CT" - Read the title of this thread. This guy has a '49 Ford pickup, thus, an 8BA type engine. While Skip's instructions may be correct for the earlier engines, I agree with Jack that it is "Bad advice" for the later engines. We should really try to keep these discussions on point, otherwise, someone may interpret what has been said in the wrong way, thus causing themselves problems.
 
Last edited:
Flathead Fever said:
A thermostat with the small hole with the wiggle rivet in it. That's a one way valve that lets coolant flow from the engine to the radiator.
Click to expand...

The wiggle rivet or jiggle pin is designed to allow air to vent from the engine to the radiator during a cooling system fill and prevent coolant flow and heat loss during engine operation. We used thermostats with jiggle pins on Diesel engines to improve cab heater performance in the Winter.

I have never heard of anyone complaining of cab heater performance with a flathead; I think adding a hole will eliminate the pocket of cooler coolant at the thermostat.
 
51 MERC-CT said:
Suggest that you both read post #21 in this thread--

The instructions that came with the last three sets of pumps that I had rebuilt by Skip said...."Do not use thermostats in temperatures above 65° with these high volume pumps. In winter or cold temperatures a 160 degree is recommended with a maximum of 180. Do not use any thermostat with an internal opening when fully open of less the 1-1/4" inside. Any restriction or restrictor will impair the cooling with the use of these pumps".

I red post #21 (above). From what I understand Skips pumps they increase the circulation. When the late 8BA cooling system was re-designed they went to smaller outlets on the heads. It doesn't leave as room for a thermostat. "If" those thermostats flow less than the earlier ones they would restrict the flow of Skips pump.


There has been the myth for decades that you need to install washers with a 5/8" hole to restrict the coolant flow. The theory being that it slows the flow through the radiator allowing more time for the radiator to remove the heat. There have been some tests done that refute that myth. I believe the restrictor myth originated from a question and answer in one of the early Hot Rod Magazines. The problem was that in dirt track racing the high rpms circulated the coolant faster than it could flow through the radiator and it backed up and went out the overflow tube instead. The solution was to install the restrictor washers or cutoff every other fin on the water pumps. So unless your going to drive ten-laps around town, at 5000 rpm, with a non-pressure radiator cap you do not want to slow the coolant flow down.
Click to expand...
 
You must log in or register to reply here.
Back
Top