An overheating question-the 3rd update 10/2/13

[700rpm]

I've had a ticking sound when the car is first started and cold. I suspected a tappet or possibly piston slap. I had (and still have) 55#-58# compression on all four cylinders. I pulled the engine in March of this year and tore it down. It had a lot of carbon buildup around #3 and #4, and the exhaust valve seat for #3 was especially blackened and not crisp around the edges. It had non-adjustable lifters, and only three of the valves (intakes) looked like they were reusable. Four pairs of the valve guides showed evidence of wear and leakage (all exhaust guides). I removed the pistons, took up on the mains and rods (rear: .003, center: .0015, front, .002; rods: #1 .0015, #2: .0015; #3: .002, #4: .002); I did not have to actually take up the rods; they were already set to those clearances. The center main lost about a 1/4" triangular chip out of one edge when I lifted the cap, but no cracks. I put in five new valves and ground them in, four new sets of guides, all new adjustable lifters, and set the clearances at .011 for intakes and .014 for exhaust. I replaced the timing gear (with a .005 oversize gear) and the distributor drive shaft. The cam lobes and distributor drive gear looked good with no appreciable wear or pitting. All of the crank journals and crankshaft gear were also in good shape with no pitting or noticeable wear. The wrist pins seemed to my amateur eye to be tight, but I didn't remove them or otherwise test them.

There was some blackening on #4 cylinder, but none of the cylinders showed evidence of scoring; there was no lip at the top of any of them. The block is .100 over. I did not observe any cracks in either the block or the head, though I did not have it magnafluxed. One head stud had been installed crookedly, and most of the others would not come out, so I lived with that. When I put it all back together, I still had the ticking sound, so I'm pretty sure it's piston slap.

In June I ran 3 gallons of vinegar in the cooling system for 500 miles, then ran the kerosene/detergent/water mixture for about 100 miles. I then back flushed and forward flushed till I got clean water, and a lot of rust and scale and gunk came out.

Prior to all this the engine did not overheat. Afterwards, but before flushing, I began to experience minor overheating on steep climbs. I've got my timing to a gnat's eyebrow, so I know that's not a factor, though my spark lever position may be. I had serious overheating on the trip over to Bend and on the Grand Tour. I had removed my front license plate and repositioned my spark lever to where I thought I had it solved, but still had some overheating problems returning to Portland.

What might be causing this overheating, given the above measures? Would .100 over make the engine prone to overheating? Could there be a crack in the block I missed? If the head wasn't completely flat, could there be a hot gas leak into the water jacket? Where should I start to look?

[Greg out west]

Hi Ray,


You said you backflushed,,, was that just the block or did you do the radiator too ? I'ed go back & redo the block & Radiator (backflush).


The Model A cooling system is pretty simple & not going to overheat unless something "plugged" or broken.One time I broke a fan belt. As long as I kept moving the motor didn't over heat..The thermosyphon worked !!!


Greg out West

[Tom Wesenberg]

Does the engine overheat and then boil out the coolant, or does the coolant go out the overflow pipe and then the engine overheats. Lately my coolant went out the overflow pipe until the engine overheated, so now I have the radiator out again. I found my drier sock filter has disappeared and when I turned the radiator upside down more rust flakes came out. These rust flakes block some of the tubes and cause the coolant to go out the overflow pipe.

I'm going to try compressed air in the side port to see if I can blow out some more rust flakes. I'm also going to borrow an inspection camera to see if I can get a look inside the rear of the coolant chamber. After that I plan to run pure white vinegar again for another 30 days.

[Mike V. Florida]

IF one were to have a crank that was oval due to wear and the bearings were adjusted on narrower side, it is possible that the bearings would be tight on the wider side of the oval thus overheating.

How many miles have you driven with this problem (overheating)?

[H. L. Chauvin]

Hi Ray,

Humble opinion:

FWIW:

Manuals recommend several causes for overheating like timing, brakes too tight, spark plug heat range too hot, lean carburetor, wheel bearings too tight, low tire pressure, clutch slipping, engine too tight, or maybe even Model A owner's underwear three (3) sizes too small LOL ..................... however:

Appears most of the time overheating is cause by the radiator coolant not flowing fast enough because of either a defective thermostat that is not opening, or the radiator tubes are partially clogged with water pump grease and/or cast iron engine rust flakes.

After checking out everything else, maybe concentrate on the radiator.

Hope this helps

[700rpm]

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Greg: Both engine and radiator were flushed back and forward.

Tom: The coolant (water) boils out as the engine overheats. I don't use socks or thermostats, it's all completely stock.

Mike: I've driven the car about 500 miles since the overhaul.

Henry: I did just relube the water pump, but with water-soluable grease. I also changed to 3X plugs. Maybe they're too hot? That seems unlikely, since they're supposed to be factory specs.

[Purdy Swoft]

A tighter overhauled engine will run hotter.Did you measure piston ring end gaps? Too close ring gaps makes for a tighter fit between the rings and cylinder walls, especially at the lower part of the cylinders. If its not freezing in your area, I would run straight water in the radiator at least until danger of freezing. Water runs much cooler, especially in a fresh tight overhaul.What head gasket did you use. Some head gaskets are only good for an overbore of .060 . With larger over bored engines, the head gasket will overhang the cylinder bore and cause a ticking sound. The copper clad Felpro 7013C gasket is good for an over bore of over .125 I'm not sure what other gaskets work with large over bored cylinders.

[1931 flamingo]

I think I would go back in and re-verify the timing gear is lined up correctly. FWIW
Paul in CT

[700rpm]

Purdy: I didn't change the rings out; the gap is unchanged, and I re installed them with the gaps properly offset. I'm running water, which is running clear and clean. I don't know which head gasket I used, but the pistons are beveled at the top, and the ticking seems to occur only between #3 & #4. The gasket is copper-clad.

Paul: I was very careful about that installation, but it's worth rechecking. Though the timing seems right on: the car starts on the first turn when warm, second turn when cold. Good strong power in all speed ranges.

[tbirdtbird]

1. Radiator can still be plugged regardless of all you have done. The bottom tank is all but non-existent and thus crud can build up into the tubes easily. I would have a rad. shop check it over. There are few orig. rads out there that I would trust. A re-core may be in order; rad shop can tell.
2. u say timing is spot on but how did u determine this ? I know all of the manual ways to time, but if there are issues it is time to bring out the timing lite and see exactly what is going on. a few degrees can make a huge diff in these cars
3. Did the head gasket get replaced? Did the old one look blown?
4. .100 over will not cause your problem
5. a ton of engines have been torn down for a noise that was just piston slap. Just Listen to any GM motor from the 70s and 80s
6. If exhaust gas is getting into the water jacket it will overheat for sure. Due to the baffle in an A rad, you cannot check for bubbles. You can get a tester at auto parts stores to check for exhaust gas components in the rad to check for this.
7. get an infra-red temp gun and let the car idle and watch the temp climb by aiming at the rad. inlet pipe. Look at the ground for water coming out the overflow. If water starts coming out the overflow before your water reaches 212* then exhaust gas is pushing it out. Fill the rad as full as you can before starting this test.
A parallel question to this is how long does the car have to run and at what speed before water starts pushing out. If running a fairly short time with very little load before water starts pushing out then be suspect of blown head gasket.
I diagnosed 5 blown head gaskets this summer.

[Purdy Swoft]

You mention that you are sure about the timing but not sure about the spark lever.I've driven mine with full advance when running at speed for over fifty years. I run the ones with brumfield heads the same way.The thing is not to lug or you will need to retard the spark or down shift or both. You will do more harm in high gear at low lugging speed than you will at wide open throttle. All the talk in the owners manual about spark usage pertains to driving on trail like roads with sand beds like it was back in the day. The engine will lug if hills are approached at slow speed and require more use of the spark to cushion out the knocks and bucks as the engine lugs. The more the lever is retarded the hotter the engine will run

[700rpm]

tbird: I timed it like I have timed A's for 50 years, so I'm pretty sure it's where it should be. I did replace the head gasket, but whoever put the old one on used some kind of super sealant and the gasket was destroyed trying to break the head loose, so I don't know what its condition was, but the car did not run hot with the old gasket. I suspect it may be the new gasket and/or a warped head that was covered up with the superglue used on the old one. Good to know about the .100 over. I'll run test #7. Thank you.

Purdy: I ran my tudor at full advance for about 20 years before I finally destroyed the babbitt and before I was told about the 9:00 position; that's where I'm driving all my cars now; I was running at about 8:00 at highway speeds (for me, that's 45 mph), and that caused some serious overheating. When I went back to 9:00 it calmed down some, but still steamed up on the hills. I try not to lug the engine, but it's got the full stock flywheel so it should be able to take some lugging, though I wasn't lugging it on the hills in high gear.

[tbirdtbird]

let us know how you make out.

[700rpm]

A local fellow suggested it might be a bad manifold gasket, which would allow excessive heat to affect the outer side of water jackets. My manifolds have been machined together, so I know they're right, and I don't have any excessive exhaust noise, but what does the Ford Barn court of opinion think about this theory? This is a pretty easy thing to inspect, but I'm still looking for opinions and suggestions before I start tearing things down.

[tbirdtbird]

I think that is a bit of a reach. In any event you need more diagnostics....

[1931 flamingo]

For the price of a headgasket I'd try that next, a GOOD copper one with coppper spray. Ck head and deck for flatness. FWIW
Paul in CT

[Purdy Swoft]

If you remove the fan belt, you could crank fhe engine and rev it under the hood while you felt for exhaust leaks, If the water pump was making the ticking sound , it wouldn't do it with the belt off. If The manifold is getting hotter than normal, that could mean points gap too small or timing too retarded. With the same rings, the engine shouldn't be that much tighter. Does the car have a recent brake job that hasn't quiet worn in. this would make the car harder to propell and it woiuld run hotter. I'm only guessing.

[H. L. Chauvin]

Hi Ray,

Sounds like you have already patiently checked other possible overheating causes:

A. Ignition timing OK; &,

B. You have rotated each wheel after lifting same to verify all (4) wheel bearings & brake bands are not too tight; &,

C. See no bubbles in coolant under radiator cap when is engine running; i.e., no hot exhaust gases going into cooling system; &,

D. 3-x plugs naturally not the cause of overheating; &,

E. No manifold exhaust leak; &,

F. Whatever else you already checked & did not mention.

Maybe try this quick & easy process of elimination:

1. Engine Too tight: Remove (4) plugs & crank engine first with hand crank -- Why? You have enough experience to "feel" the force required to rotate a Model A engine & to notice "if" something is too tight.

2. Ticking Noise: With plugs removed, hit starter & rotate engine rapidly to see if you can hear your clicking noise -- if yes, disconnect fan belt & listen again just in case it is the water pump, if not, possible piston slap? Go to step 3.

3. Piston slap: Start engine while engine is cold & hurriedly disconnect one spark plug at a time & reconnect such that the engine is always running on (3) cylinders. If ticking stops upon disconnecting only one (1) plug, stop engine. Remove this plug & squirt about (4) good large oil can squirts of lubricating oil on top of this cylinder & wait about 60 seconds, then re-start engine -- if no ticking within first minute of running, this cylinder has the piston slap -- if ticking continues, no piston slap.

After all of the above, & other subsequent suggestions, it may be possible that the vinegar attacked your first layer of loose grease, & loose rust flakes & exposed the second layer of grease & loose rust which is separating & circulating.

Eighty (80) years is a long time for Model A's, vintage tractors, old hit & miss engines etc. to build up fine "layers" of rust & grease.

Victor Page's Model A book recommends what was used in the 1920's & 1930's for cleaning blocks & radiators, , i.e., caustic soda, (Lye).

When a Lye solution gets hot with engine heat, it can remove rust, paint, & even knock the skin off of a crocodile in a few seconds -- but it is very dangerous to use.

Food canning plants also used to use Lye years ago to peel sweet potatoes -- in a few seconds a raw sweet potato was skinned.

I used to use Spic & Span for radiator cleaning -- do not know if it is as strong as it used to be.

Lately I use POR 15 Marine Clean to clean radiators -- sold a Snyder's.

Hope this helps.

Let us know what else you find.

[H. L. Chauvin]

Hi Ray,

Humble opinion:

FWIW:

I used caustic soda years ago to clean some metal for industrial painting.

But just in case anyone would ever even consider trying Mr. Victor Page's Model A vintage radiator & engine block cleaning method with caustic soda, maybe one could imagine possible results from a simple test like this:

1. Imagine pouring pure vinegar on a lettuce & tomato salad; & even imagine letting the delicate salad sit in pure vinegar for a week in the refrigerator to see what happens to the salad.

2. Next, imagine making a new lettuce & tomato salad & imagine pouring caustic soda on the salad to see if you notice any difference in the chemical reaction from that of the vinegar -- this caustic soda worked as a cleanser; but it is potent & is to be used with only with extreme caution.

[TerryH]

You mentioned that you flushed the radiator, but in my opinion that will not always totally clean it. My Model A had the radiator flushed and boiled out by the original owner, but it still overheated some going up hills. Another friend recommended pulling the radiator and having it rodded by someone who knew how to do it properly. I did that, and was told there was a total of about 20 tubes totally clogged up. He was able to clear almost all of them, and the car now runs without ever overheating. I would sure double check on this..........