Cooling System Design Flaw

[Bob Bidonde]

I am amazed by the number of faulty pre-1949 coolant system designs because basic fluid mechanics dating back to 1738 were not understood.
That is, the maximum flow will always occur where the resistance to that flow is the least.

[J Witt]

Nice illustration, Bob. Has anyone measured the head temperatures and at least the outside cylinder wall temperatures? This would be easy to do with one of the IR probes that are handy these days.

John

[mshmodela]

I measure mine after almost every drive, I've seen little difference cylinder to cylinder... One the the head the hottest is the #4 near the exhaust... head temps at the spark plugs are all. about the same. One might guess that once the engine is up to operating temperer, the block itself in addition to the water reaches a steady state temperature, regardless of the flow...

[JoeWay]

I have a photocopy of an article in the MAFCA Restorer by Ed Rossig, titled "Analysis: Model A Fan and Water Pump". I wrote "11-4" on the copy, which I think meant the July-August 1966 issue (I made these copies about 30 years ago). In it he presents some charts listing "temperature measurements at various engine locations" taken after running different fans. Temps are remarkably close. #1 is usually coolest, and #2 runs close to #3 and #4.

The May-June 1978 Restorer had an article by Paul Moller subtitled "Nothing ever happens on no. 1 cylinder". In it he described a modification consisting of a copper tube from the water inlet to the back of the block. I did this when I installed the stock head on my rebuilt engine in about 1987 before I put the body back on the chassis. But I when I went to put on a high-compression head, I found that the fittings interfere with removal of the throttle control assembly. I had to raise the front of the body to get the throttle assembly off. I left the bypass tube off and plugged the block when I put it back together.

Joe

RossigCooling.jpg

MollerCooling.jpg

[40 Deluxe]

What about the vast majority of other engines where the coolant flows into the FRONT of the block and exits the FRONT of the head, even on straight eights? Why doesn't the coolant just circulate around the front cylinder or two?
Answer: Head gasket design. The holes for the coolant passages are small at the front of the engine, restricting flow, and large at the rear, allowing more flow. So if the engineers sized the holes right, flow would be equal at each cylinder.
On many engines, the head gaskets can be installed backwards and the bolt holes will line up, but the coolant passage openings are reversed and will starve the back cylinders and the engine will overheat. Seen it happen!

[burner31]

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Good picture Bob, never thought of the flow in that way.

[BRENT in 10-uh-C]

Originally Posted by burner31

Good picture Bob, never thought of the flow in that way.

Well, in theory it seems believable however that really is not totally factual. First off, the pump does not have the ability to "draw" water. It only has the ability to displace it. Because it moves the water, there is a void which is filled by surrounding water in the jackets.

In addition, try this little experiment. Fill a large drinking glass ½ full of clear water and place a straw in one side of the glass. Next fill a pitcher with a mixture of water and food coloring. As someone is gently sucking on the straw, begin pouring the colored water from the pitcher into the glass. Does all of the colored water go directly to the straw, -or does the colored water blend into the entire glass of water?

It is also worth noting that there is a deflector at the inlet that was used on some cylinder cases (engine block) that directed water towards the rear of the case. Also remember there is a cylinder case deck and cylinder head deck with small passages that this water must traverse through before it reaches the water pump.

[BILL WILLIAMSON]

#4 cylinder on Datsun 210's would get SO hot, valve seats fell out & usually scored #4 piston.
Temp gauges installed in Model A's should be in the rear of the head, to monitor the HOTTEST SPOT, "might" save an engine! ! Study the rear of a head for the SPOT to drill, in the left side, about 2 1/2" or so, from the rear of the head.
Chief ALWAYS located them there & he knew his SHIT, & he taught me all his TRICKS, that worked well.
Bill W.

[marc hildebrant]

I suspect that the engineers at Ford studied the design of the cooling system for a long time before they made the cars. Also, the Model A's had quite a number of changes as they were built.

While the picture in the posting is a nice graphic, I do not believe that the actual operation is as shown.

Marc

[1937pickup]

Originally Posted by BRENT in 10-uh-C

Well, in theory it seems believable however that really is not totally factual. First off, the pump does not have the ability to "draw" water. It only has the ability to displace it. Because it moves the water, there is a void which is filled by surrounding water in the jackets.

In addition, try this little experiment. Fill a large drinking glass ½ full of clear water and place a straw in one side of the glass. Next fill a pitcher with a mixture of water and food coloring. As someone is gently sucking on the straw, begin pouring the colored water from the pitcher into the glass. Does all of the colored water go directly to the straw, -or does the colored water blend into the entire glass of water?

It is also worth noting that there is a deflector at the inlet that was used on some cylinder cases (engine block) that directed water towards the rear of the case. Also remember there is a cylinder case deck and cylinder head deck with small passages that this water must traverse through before it reaches the water pump.

You must be talking about Model A water pump. While pumps have problems on the suction side the discharge side is pressured. Once a pump is primed, from the suction side, it will move liquid. One exception to this is a diaphragm pump which will move liquid from the suction side without much problem. Now a pump will have a problem on the discharge side when there is a lot of head pressure. I don't see any of these being an issue with a Model A water pump. Based on the radiator being full, the block "burped" the water pump will be primed and moving water under pressure.

[Pete]

Yes, the stock configuration has design flaws.
It was a product of cost marketing.
The Ford flathead V8 of later years had the exact same problems.
Here is a solution that has worked well for us for over 60 years on race engines and modified street engines.

[Gold Digger]

I remember some older IH truck engines had what was called a "recirculating tube" that slipped inside the engine block. They were thin metal with a lot of holes in them and was made in a tapered configuration that slipped in easy and rust took over and was hell to get out. There was other engines made to use this type of water circulation. When they rusted partially out they over heated and not many people could figure out what was wrong.

[BILL WILLIAMSON]

Originally Posted by Gold Digger

I remember some older IH truck engines had what was called a "recirculating tube" that slipped inside the engine block. They were thin metal with a lot of holes in them and was made in a tapered configuration that slipped in easy and rust took over and was hell to get out. There was other engines made to use this type of water circulation. When they rusted partially out they over heated and not many people could figure out what was wrong.

Yep, Golden One,
Chrysler Corp used that type tube on their Flathead engines, after hot tankin' the block, rebuilders would pull it out, with a LOONG wire hook! It was technically called a "WATER DISTRIBUTION TUBE". Replacements were sometimes made of BRASS!
Bill W.

[garyaodell]

Back in the early 60s I modified 59ab block with distribution tubes, removed every other vain from the water pumps and installed 180* thermostats; This was a bored and stroked engine of 297 cubic inches. I was able to drive this 48 Ford around Portland Or without a fan and it never over heated

[Kahuna]

Some old book that I've got showed a long tube that was inserted into the water jackets behind the pumps on a flathead V8.
I never understood how it worked or how it was installed and kept in place

[blgitn]

Originally Posted by BILL WILLIAMSON

Yep, Golden One,
Chrysler Corp used that type tube on their Flathead engines, after hot tankin' the block, rebuilders would pull it out, with a LOONG wire hook! It was technically called a "WATER DISTRIBUTION TUBE". Replacements were sometimes made of BRASS!
Bill W.

My Hudson has one. It's brass colored.

[Bob Bidonde]

The water pump is in the wrong place in the cooling system. The pump should always have an adequate coolant supply, pressure heads at the inlet and outlet, and would have this if it were in the lower radiator hose. The supply line to the pump would need to be larger than the outlet line (perhaps 50% larger).

The attempt by Ford to steer flow with a diverter at the water inlet in the block is not a sound design. The diverter is evidence that Ford became aware of the flow issue at the back of the engine. Again, this shows a lack of understanding fluid mechanics. The diverter has a local effect, and be of some benefit to Cylinder 3.

Regardless of what the surface temperatures are, the evidence (gasket burnout; cleaner running plugs) is clear that Cylinders 3 & 4 run hotter internally. In my opinion, surface temperatures are subject to higher heat transfer rates because of the liquid (conduction) and air cooling (radiation & convection) effects. Thus the surface temperatures are not an accurate indication of what occurs in the head and block at Cylinders 3 & 4.

I have a suspicion that micro-boiling may be occurring in the head at Cylinder 4.

A better design, but not the best idea is to move the water inlet:

[redmodelt]

My understanding of the Model A is...it is still a thermal siphon system and the water pump is an assistant to that. Bet H. Ford would have left it off but modern cars all had one so it was put on to help market the new car.

[Kevin in NJ]

I think you got it all wrong.

I bet the Ford engineers were well aware of the water flow in the engine.

They also knew the system they used did the job. If they wanted a more complex system they would have done it. The reason why they did not is because they knew this lower cost system would do the job.

While today we might have a different perspective on the engine and its use, when they designed the engine things were different. Fuels were different, oils were different and coolents were different.

What we are certain of is the engine when properly built runs. It runs great and goes for 50,000 miles with the 'poorly' designed cooling system.

To me the Model A community seems to fixated on thinking about the design flaws and needing to fix them with modern things. We forget that the car was wildly successfull as built. The car was a staple car known to just keep running and take abuse we could not imagine today. With all this abuse cars were known to run for decades with almost no maintence.

The Model A was carefull engineered to be simple, economical, and strong. During the engineering process I am certain they looked carefully at the efficiency of different methods of moving the water around the block. What we have today is clearly good enough to do the job and likely met a price point for manufacturing.

[mrtexas]

Originally Posted by redmodelt

My understanding of the Model A is...it is still a thermal siphon system and the water pump is an assistant to that. Bet H. Ford would have left it off but modern cars all had one so it was put on to help market the new car.

The Model T was a thermo siphon system. Not the large radiator tubes on a Model T. Model A radiator is a modern system.