Pat 12 gets a nose job

[Phil Waterman]

Hi Tony

I've look at the radiator with an IR gun to see the change in temp across the radiator, left to right and up and down on both sides of the radiator (You can only do this on the test stand without the fan mounted) fairly consistent readings left to right. and a good 20F-40F degree delta from top to bottom, moderate airflow from a fan.

Reason I thing it is trash and crap in the water jacket, is when I removed the water pump and look in there was an acorn. Then when I started pushing a tube probe into the block and head with vacuum attached kept getting sandy or rusty grit out of the block.

I've got the radiator mounted on the test stand with the 235 engine so tomorrow I'll start doing some run tests with airflow and see if I keep getting a good delta temperature drop across the radiator.

Will say one thing about 235 it has hydraulic lifters and boy is that a quiet engine without a fan mounted. The loudest think is the mechanical fuel pump which I've bye past for an electric one.

One thing I am going to check is the thickness of the radiator as compared to the Pattern 13.

With the 235 or the 216 I have noticed one thing you need to have a bypass from the thermostat housing down to the pump housing because modern thermostats don't have enough bypass to allow the hot water to actually get to the thermostat to get it to open. Also these engines I think originally had 140F thermostats which are no longer available the lowest being 160F.

On the test stand I have one temperature gauge reading the normal position at the rear of the block and another in the pump housing reading the return temperature. Then I use the IR gun to read the temp at the top of the radiator and the bottom.

If this radiator doesn't work I'll order a aluminum hotrod radiator.

More to follow.

Cheers Phil

[Tony Wheeler]

Very interesting post Phil. I had similar issues with my F15A when I first put it on the road. It was mid summer and the radiator kept boiling. I tried four different radiators before I found one that worked satisfactorily. Some of them worked on the flat but they boiled uphill. There's a long hill near my place where I could test them, using a digital thermometer probe in the top tank. The one that worked best has been recored at some stage, with the usual thin core seen on recored Ford CMP radiators. The others had the original "tropical" core, which is much thicker, having an extra row of tubes across the front.

Naturally I examined each radiator before fitting them. The tubes appeared to be clear, insofar as I could see them through the filler cap hole. I tested them for leaks by plugging the bottom outlets (using small lemons off my tree) and filling with water, and when I removed the plugs the water gushed out under gravity, which would seem to indicate no major blockage.

In the course of this radiator swapping I decided to test the flow through the system, by running the motor with the top hoses disconnected and the radiator level maintained via a 3/4" garden hose from the tap (there are no thermostats in this motor). I don't know how much it's supposed to flow but it sure pumped out a lot of water at around 2000 rpm. It gushed out in front of the truck through both hoses and the garden tap was flat out keeping up. The water pumps are brand new and have the improved impeller design, ie. helical vanes instead of the original straight vanes.

Based on these tests I'm satisfied that the radiators are all clogged to varying degrees, despite appearing to drain quite rapidly under gravity. Your IR gun may pick this up, although if the tubes are randomly blocked I suspect it may not, as there are multiple rows of tubes which may average things out from side to side. Also if they're all partially obstructed, or most of them, the effect would be the same. I guess that could result from small particles of rust lodged in the tubes, or perhaps a coating of residue internally, although chemical flushing should remove that if done properly.

One thing I've noticed is that the recored radiator has much larger tubes than the original ones, which are flat and thin. Obviously these would be far more prone to blockage/obstruction, and would also flow much slower. On the other hand they allow more airflow, which is also a factor in cooling efficiency. However if you look at modern radiators you'll see they have large diameter tubes, so I imagine these are an improvement.

That said, we know these CMP cooling systems worked in hot climates during the war, often in heavily loaded trucks grinding up long hills at full throttle. I'm told Fords had a reputation for boiling sometimes and Chevs were preferred in this respect, so you shouldn't haven't any boiling problems in New Hampshire with the stock Chev radiator, even on peak summer days. Which brings us back to your present problem!

Let's consider the physics. Boiling is caused by one thing and one thing only - insufficient heat loss through the radiator. Heat input is determined solely by the rate at which fuel is being burned. It can't be increased by blocked water jackets, because they're not generating heat energy. Only combustion gases can introduce additional heat energy to the coolant, via a leaky head gasket or cracked head. Blocked water jackets may cause overheating of the surrounding metal, but they can't add heat energy to the system. All very obvious of course but worth covering nonetheless, as it helps us to focus on the real problem, namely heat loss rather than heat gain.

Heat loss occurs through the radiator and is a function of coolant temp and flow rate, cooling air temp and flow rate, and heat exchange surface area. We're not concerned with cooling air temp and flow rate, and we've fixed the coolant temp at say 170F, which leaves only coolant flow rate and heat exchange surface area. If all the radiator tubes are clear, then the heat exchange surface area is maximum, so the problem has to be insufficient coolant flow rate. Obviously if the radiator tubes are clear it has to be in the block! It seems unlikely that all the water jackets could be so badly blocked as to restrict coolant flow rate sufficiently to boil, but if the acorn was restricting the flow out of the water pump it could conceivably be the problem on its own. At that point in the system the effect on flow rate could be similar to a partially closed thermostat. Not having seen its position I'm unable to judge.

Alternatively, if some of the radiator tubes are blocked, then obviously the heat exchange area is reduced proportionately, and also the flow rate. That's the usual cause of overheating, however there's usually no acorn in the block to consider! Of course, it could also be a combination of these factors - acorn, partially blocked radiator, and badly blocked water jackets. If that's the case, then the radiator may be adequate with the new motor after flushing, and it won't be subject to subsequent blockage from crap in the block. Whatever the case I'd persist with the Chev radiator myself, even if it needs recoring.

I look forward to future instalments. My blitz mate down the road is putting a 235 in his C15A project so I'll post some pics when he gets to that stage.

Cheers,
Tony

[Phil Waterman]

Hi Tony

Interesting thoughts on cooling issues, takes a bit of careful thinking to nail down the causes and issues. Agreed with what you are saying but still trying to figure out what is going on with my Pat 12.

Concerning flow testing, when I did the water pump conversion on the 261 engine before putting it my C60S actually did flow testing both with the stock 261 water pump and with adapter plate and the 216 water pump.
261 eng water pump 03.jpg
Set up the engine test stand with a large tank at level of the standard radiator so the water came out the top outlet and dumped into the tank with 22 inches of standing water in the tank same as the radiator. Of course with the thermostat installed the flow rate is control by temp and RPM. Results with the two water pumps came out almost identically so it probably the thermostat throat that controls the flow rate. The at 500RPM flow is 2-10 gallons per minute at 1000RPM flow rate is 8-20 gallons per minutes.

After two hour long test cycles to day with the 235 I'm getting strange results. I have two water temperature sensors one in the normal location at the rear left of the block and the other into the water pump housing. At 500RPM the engine seems to stablize with the rear reading 170F and the return reading 150F good 20 degree delta for the radiator. But when you bring the engine up to 1500RPM rear is reading 170 and the return is reading 170. To further confuse things though at 1500PRM the water going into the at 200-210F (read with IR gun) and returning at the bottom of the radiator 198-175

The other thing that was going on during these test was the air temperature in the shop went from 74-80F.

I knew there was a reason normally do engine testing and break in running in the winter heats the shop up nicely.

Will have to figure out how to display the data so you can take a look.

Cheers Phil

[Bob Carriere]

When you're hot you are hot.

How can you tell if it is the engine that is being overheated by a plugged passageway or the radiator that is not flowing in all tubes.

I would try to test the radiator with a known temperature water going in and measure the delta.... actual drop in water temp..... and by this I mean off the engine completely...... but may be cheaper to run it to the rad shop to have it boiled out and the tubes rodded which means taking(unsoldering) the top and bottom tank off.

On the engine...... without taking the engine apart.... would it be possible to remove the water pump, all frost plugs, temp sensor and drain petcock and flush and fish in there with a coat hanger and/or pressure washer until all that flows out is clear...?

How worn out are the impeller blades on your water pump..... I have seen even rebuilt pumps with very eroded impeller blades.

Can the engine be run with no rad but with a garden hose with controlled flow X amount of water volume and measure water temp going in and going out at various RPM...... hard to simulate load on the engine without some braking device on the output shaft......

On the other issue raised by Alex...... in the Chev parts manual dated Jan 1941 they list the cowl as a separate part from the ARCH BARS...... and the cowl is common to all sizes of cab11/12...... on the other hand they also list the ARCH BARS right and left ( confusing because to us restorer they are all the same once welded to the cowl angle iron) and shows that the arch bars are all the same part number for RH and LH for all C15, 15a,30, etc. size trucks....BUT the C8 has a separate part number which would reflect it own peculiar BAR shape due to the different frame, steering configuration, etc.

I have two sets of C15a spare arches at the barn ....... I could not find any numbering on them at all.... mind you all are rusty.

Phil .....US radiator makes an aluminium rad that is a copy of the cab 12 and includes the off set 90 degree filler tube.... only issue with the AL rad is you will need special coolant compatible with AL...... U tube has a few clips on their manufacturing process and they sell regularly on EBay.

Good luck.

Bob C

[Grant Bowker]

Originally Posted by Bob Carriere

US radiator makes an aluminium rad that is a copy of the cab 12 and includes the off set 90 degree filler tube.... only issue with the AL rad is you will need special coolant compatible with AL......

Given the high percentage of recent vehicles with AL radiators, and the low percentage with brass, it seems it would be hard to find coolant on the shelf that is not AL compatible. I will have to check next time I'm in and auto supply shop. Plain water might be more of an issue for dis-similar metal corrosion but unless we want to drain the system annually, we won't have that problem.

[Tony Wheeler]

Originally Posted by Phil Waterman

Results with the two water pumps came out almost identically so it probably the thermostat throat that controls the flow rate. The at 500RPM flow is 2-10 gallons per minute at 1000RPM flow rate is 8-20 gallons per minutes.

After two hour long test cycles to day with the 235 I'm getting strange results. I have two water temperature sensors one in the normal location at the rear left of the block and the other into the water pump housing. At 500RPM the engine seems to stablize with the rear reading 170F and the return reading 150F good 20 degree delta for the radiator. But when you bring the engine up to 1500RPM rear is reading 170 and the return is reading 170.

Phil, you won't detect any delta once the motor speeds up with the thermostat open, because the water passes through the radiator far too quickly to cool down measurably. At normal flow rate it's only in the radiator tubes for an instant, you'd need quite sensitive equipment to measure the temperature drop from top to bottom. The cooling system relies on the huge volume circulating every minute, so it only needs to cool down a few degrees through the radiator.

We can do a rough calculation based on your 8-20 gallons per minute result at 1000 rpm, choosing say 16 gallons per minute, which is 16 x 3.8 = 60 litres per minute = 1 litre per second. I don't know what the total volume of all those skinny tubes would be, but if we estimate it to be 1 litre, then the water passes through in 1 second. It just won't cool down much in that time, esp. stationary with modest fan rpm. Different story at idle when the thermostat is closed and you're only getting 2 gallons per minute flow. That's 8 times slower, which means the water spends 8 times longer in the radiator, ie. 8 seconds by this calculation. That would account for your 20F delta at idle.

Of course, the delta will also be greater at speed when you're getting maximum airflow. We can do a rough calculation based on a CMP at cruising speed, let's say 50 HP engine output. Petrol engine efficiency is about 25%, which means there's another 150 HP being lost in heat. About half goes out the exhaust and half into the cooling system, which means the radiator is operating at 75 HP (x 0.746) = 56 kW. That would heat your workshop nicely Phil, and it also explains why the engine cover gets so bloody hot!

56 kilowatts = 56 kilojoules per second, and since the specific heat of water is 4.2 kilojoules/kilogram/degree Celsius, and a litre of water = 1 kilogram, the delta will be 56/4.2 = 13 degrees Celsius. However...that's based on our 1 litre per second figure, ie. 16 gallons per minute, which applies to 1000 rpm. If the flow rate is 3 times higher at 3000 rpm, the delta will be one third, ie. 13/3 = 4 degrees Celsius. Also, if the volume of all those skinny tubes turns out to be 1/2 litre, the delta will be halved, ie. 2 degrees Celsius.

It's a fascinating experiment you're running Phil, I don't think I've ever seen it done before, and it gives a lot of insight into how cooling systems work, esp. the thermostat. We tend to think they're only for cold start up, but in fact they're constantly varying the flow rate. It would be interesting to set one up in a perspex tube instead of the housing, so it could be seen operating. It would also be interesting to have a delta gauge on the dashboard, I'm not sure what earthly use it would be but the same could be said of vacuum gauges!

[Phil Waterman]

Hi Tony

Your giving me some interesting things to think about with this which is making it into both an interesting test but a quest for more information. I'm rethinking my testing logic and data collection methods. One thing for sure next test will set the Go-Pro Camera to capture the engine instrument panel through the whole test. Need to move it closer to the instrument panel this next time, so the gauges are easy to read.

vlcsnap-2014-06-24-17h46m17s34.jpg

At the end of your post you said " It would be interesting to set one up in a perspex tube instead of the housing, so it could be seen operating. It would also be interesting to have a delta gauge on the dashboard, I'm not sure what earthly use it would be but the same could be said of vacuum gauges"

Your comment about being able to see the thermostat in a prespex tube how about thisl
Clear View.bmp

Here is their web site https://coolviewthermostat.com/ not sure I want to spend that much for a single test but it would provide an interesting diagnostic tool. I just check and they have one that fits 216 https://coolviewthermostat.com/products/chevy-products/ and they have ones that fit the Ford Flat Head.

Here is the first round of data collection for this test
Test Data June 20 2014.JPG

I'm going to do one more engine flush on the radiator tomorrow then do another round of testing.

Bob, your thoughts on cleaning are running along with mine. I did back flush the radiator with it upside down but surely did not reach the flow rates my flow test (on the 261 at 1000RPM) showed of 20GPM. Had thought about mounting the radiator upside down running the engine but with no way of catching any trash that might come out decided that might be counter productive.

One of the things that running the engine from cold to full hot showed was the value of the coolant recovery tank over a Half Gallon of water goes out into the tank and is drawn back in as the engine cools.

Cheers Phil

PS In the 1990s worked on a couple of large Co-Gen setups for hospitals we were using 545 Cat engines which put out a lot of heat at full power, the system was recovering the heat from both exhaust and from the cooling systems and using the heat to heat the hospitals. As owners rep on the project part of my role was to make the various engineers and suppliers explain how the system and components worked. If they could not explain it they generally did really understand it themselves.

[Tony Wheeler]

Originally Posted by Phil Waterman

I'm rethinking my testing logic and data collection methods.

Phil, I think what you're doing is fine. That's really good data you've collected, it tells the whole story when it's plotted. You can see the thermostat opening at t = 10, then the radiator works perfectly for the next 20 minutes at idle, but when you increase the revs the engine temp starts to soar, giving every impression it would boil if you continued. Perhaps you could let it go a few minutes longer next time and see if it boils. It can't hurt the motor provided you switch off immediately.

09-12-1949_06531-Aanrijding---Flickr---Photo-Sharing!.jpg

There's only one improvement I can think of for this test regime, and that would be a coolant flow meter. It would be very useful to know what the flow rate is doing in response to RPM increase, because it would tell us if the radiator is partially blocked. The temp graph doesn't tell us much there, because although it shows a huge drop in delta when the revs increase, which indicates greatly increased flow rate, it doesn't mean a great deal if the baseline flow at idle is being restricted by the thermostat. We need to know absolute flow, not relative flow, and only a flow meter can tell us that. They're dirt cheap nowadays, eg $57 US for 1.5" diameter: http://www.aliexpress.com/item/Free-...572166866.html


On the subject of flushing radiators, I recall using a kit back in the '70s which had a tyre valve on the hose fitting, the idea being to introduce a burst of air into the backflush flow to help dislodge particles. I don't know if it's still done that way but it makes sense to me. However I only used it in a servo for routine servicing, so I don't how effective it would be on a problem radiator. I haven't had much luck clearing blocked radiators over the years, despite using some very savage chemicals at times. Last year I put a whole bottle of phosphoric acid in a blitz radiator and left it for a month! It was bright green when I emptied it out but when I stuck it back in the truck it made no difference. You'd think by now there'd be a chemical on the market specifically designed to dissolve that brown stuff that clogs radiator tubes. Unfortunately it seems mankind has yet to come up with a way to unblock long skinny tubes except by poking things into them. In that respect we don't seem to have progressed beyond the monkey poking sticks into ant holes.

I was amused by the Coolview thermostat, I thought only someone like me would think of something so weird! I love it as a dress up item and it would be very instructive to see a thermostat working, however apart from that I don't really see the value. My query would be replacement thermostats, ie. do they sell the thermostat separately or do you have to buy a complete new unit.

Look forward to your next data set Phil.

[Phil Waterman]

Hi Tony

Your graph came out giving more information than mine because of the way you ordered the data to be graphed. Did you have to type all this data back in because or did you capture from the picture? (Will add a photo of location of measurements)

Well this afternoon, did flush the radiator with radiator cleaner, because of the right angle filler neck you can not see in to see if it really cleaned. But what came out was nearly clear. The engine had been hot tanked when it was rebuilt so it was clean inside.

As to air burping radiator while flushing, yes I did this when back flushing the radiator upside down. Shop vac to what would be the in pipe water to the out pipe and a flex tube fed in through the drain cock hole with the engine upside down ran the water at full tap flow in and kept moving the flex tube in and out of the tank so that it would move the stream of bubbles around no crap came out.

Ran the engine for nearly an hour today. Air temp in the shop when I start was 80F/26C (hot day here) very quickly the shop air temp jumped to 90F/33C. Ran the engine for 30 minutes with the cleaner in then 30 minutes with drain out and cold tap water going into the top tank to make up what was coming out to clear the flushing agent out. Running the engine at 2000RPM it climbed to about 190F and on the water jacket sensors and about 205 on the top tank with IR gun, but no higher.

Interesting to watch the temp gauges with the engine not running but the blower fan still on the engine continues to circulate, thermosyphoning causing good circulation. (to insure some flow with the thermostat fully closed I have added an 1/8" hole to thermostat body.)

Was going to do more testing but by then I was pretty well cooked standing around in the hot air blast coming through the radiator.

Think the next step will be to finish the conversion of water pump from the low mount position to the high mount to match the original fan location.



More details on pump swap from doing it on the 261 http://www.canadianmilitarypattern.c...ifications.htm

Looking at these photos, it reminds me that I need to check the pulley sizes back to the original engine on the Pat 12 engine just to be sure that in the process of swapping out the original unusable 216 engine for the one that is in it now that I didn't in inadvertently mess up both the water pump and fan speed.

Ah the mysteries of CMPs.

Thanks everyone for taking time to read this thread and add thoughts and suggestions.

Cheers Phil

[Alex van de Wetering]

On the other issue raised by Alex...... in the Chev parts manual dated Jan 1941 they list the cowl as a separate part from the ARCH BARS...... and the cowl is common to all sizes of cab11/12...... on the other hand they also list the ARCH BARS right and left ( confusing because to us restorer they are all the same once welded to the cowl angle iron) and shows that the arch bars are all the same part number for RH and LH for all C15, 15a,30, etc. size trucks....BUT the C8 has a separate part number which would reflect it own peculiar BAR shape due to the different frame, steering configuration, etc.

I have two sets of C15a spare arches at the barn ....... I could not find any numbering on them at all.... mind you all are rusty.

Phil, Bob, once again thanks for all your comments and ideas regarding the arch bars. And what a coincidence that you were right in the middle of arch bar replacement, Phil!!

My main question was how to tell a C8 arch bar assembly (trying to find a suitable name here for the weld assembly of the three parts....) apart from a C15A one....or a Ford one for that matter. As usual such a question results in an interesting query.....with new questions arising along the way....what's the difference between Ford and Chev?. Is there a difference between cab 11 and 12......what's the difference between the C8 and other Chevs?
My intention was to find out if the arch bar assembly in the yard at LWD parts was from a C8.... and possibly a suitable replacement for mine...which is pretty rusted. Dirk and Stefan were very helpful as always and it was enjoyable to talk about the hobby. Sadly for me the assembly they had available proved to be from a Ford, so I have decided to try and repair my rusted example.



Maybe this info is useful for others, otherwise it might be the dullest info ever posted

- Ford vs Chev Arch bars....the Chev RH arch bar has an extra bend/bulge, to give some extra space for the pedals. I guess Ford's don't need the extra clearance (?), as they lack the extra bend.

- The cowl as mentioned by Bob is listed in the Chev parts list with a Chev part number, as well as a Ford number, so I presume the cowl is the same for all(?). I don't have a Ford parts list here, so I can't check if all Fords used the same....nor can I check if the F8 used different arch bars (compared with F15 F30 etc.) as seems the case with Chev.

- I have to check Phils pictures closely, but the parts list seems to suggest the cowl is the same for the cab11 and 12. Usually there is a mention of "before serial...." if there is a part difference between Cab 11 and 12....or a mention on using up old stock, before using the new part(number), but that doesn't seem to be the case here.

- Also interesting.....in the Chev parts list you will notice that it takes 2 bolts and nuts less to assembly the fenders on a C8, compared with it's bigger brothers......so, could that be a way to tell a C8 arch bar assy from the others?

- The fender itself are definitely different in width between a C8 and the sisters....we compared my C8 fender to a fender of the F60H....wow....a considerable difference!



Phil, please keep the pics of your work coming....never dull....always useful! good luck with the engine.

Alex

[Bob Carriere]

Hi Alex

I have mixed and matched parts from both cab 11 and cab 12.... they all interchange. Except for some minor adjustments between the cab 11 engine cover lid and the cab 12. For example I have transplanted a cab 12 brace to my cab 11 to make the nose stronger...less saggy !!!. Took some sheet metal from the inside alligator cab 12 nose piece to replace sheet metal torched by the previous owner.... and arches are absolutely the same.

The C8 has the cab sitting lower on a civvy frame therefore the bends would have to be different to join the regular sheet metal to the civvy C8 frame.

It's amazing what you can fix with patience, a MIG welder and a back up copper plate.

Phil

After looking at your data chart...... would an oil cooler for the engine be part of your solution..? they now have an oil spin-on filter with a thermostat that will cool the engine ONLY when required..... and you can use a double PH 8 spin on for approx. 2 more liter of oil.

Have you considered installing side panels on your engine stand to simulate the engine compartment air flow and large fan in front of the engine.........

Interesting read.

[Phil Waterman]

Originally Posted by Bob Carriere

Hi Alex

...

Phil

After looking at your data chart...... would an oil cooler for the engine be part of your solution..? they now have an oil spin-on filter with a thermostat that will cool the engine ONLY when required..... and you can use a double PH 8 spin on for approx. 2 more liter of oil.

Have you considered installing side panels on your engine stand to simulate the engine compartment air flow and large fan in front of the engine.........

Hi Bob

Strange you should mention Oil Temps as part of the equation. When I was testing the 261 engine prior to putting it in I ran some long test on the engine stand hour plus one of the things being checked was the inlet and outlet temp of the oil filter that was mounted in the airstream from the fan.

What I was testing for was oil pressure drop as the oil and engine temp went up. You will notice that there is a significant delta temp across the filter from the cooling area of the big spin on filter.

261 oil pressure to temp.JPG

Once the engine was installed with the longer lines to and returning from the filter and the filter mounted lower more down in the airstream under the truck the delta got even larger. The cooling effect on the oil means that you have to drive the truck pretty hard for at least an hour to get the oil temp and the engine temp to equalized. If the outside air is much below 70F it never does, which means the valves can only really be adjusted in hot weather.

As to adding an oil cooler/ oil warmer wonder which would be better an air flow cooler or one that runs through the bottom tank of the radiator? But will over cooling the oil just add to the problem of vapor condensation in the oil not getting boiled out? Or is the internal air temperature through which all the oil must travel at some point get high enough to boil of the water vapor. But maybe that is why they have the thermostatically control oil cooler?

Now as to adding side panels to the test stand, that will raise a whole another set of study questions. I do know that if you run the Pat 13s with out the front side shield it makes the cab a lot hotter. Managed to over heat the driver (me) on the recent long convoy I think because didn't have the drivers side shield installed. The guy riding with me used the IR gun to read the foot well temps and the drivers side (no shield) was 20F higher than the passengers side (with shield) now how much of this was also the air spaces around the pedals I don't know. Since have fabricated a two piece drivers side heat shield which is easy to instal and remove for service and I put rubber flaps around the clutch pedal which is inboard of the shield.

Now to Tony's comment on delta on the radiator at full throttle, believe he is absolutely correct if the radiator is at all undersized. If the radiator is big enough there will be a delta change and should be a delta. There is also the obviously, as Tony points out, a speed through the radiator at which fluid is moving to fast for heat exchange to take place. This gets into the problem of no thermostat no flow restriction may make an over heating problem worse. With the CMPs though I don't think we are at that point because the top hose is so small.

This afternoons work will be to use a radiator flush and do another long engine run to see if the temperatures change.