Running out of ideas. Need help with a 1927 Dodge overheating problem.

[Degeraths]

Okay, so here's what's going on and I am hoping that someone here might have some insight into what is happening with my car.

 

I have a 1927 four door sedan. She starts right up, seems to run smooth, but will boil over after even as little as two or three miles of driving. I have flushed the radiator several times and it seemed to help very slightly and a lot of brown water came out, but it didn't solve the problem. Yesterday I drove her to a mechanic shop that I use for my regular cars and had him look at the radiator with his thermal camera while the car was at idle and very hot and it showed pretty even distribution of heat, no cold spots. The temp at the top of the radiator was around 190 and the bottom about 130 or so. So, I don't think it's the radiator.

 

I have asked in other groups and have gotten suggestions that the timing may be off and that can cause overheating, but the engine runs and idles smooth, so it doesn't, at least to my ear seem like a timing issue. There has also been a suggestion that she is running either too rich or too lean, but again, none of the signs of that seem to be present. The plugs are clean when I looked at them (remarkably clean actually) and if memory serves from my younger days of restoring VW's, if a car is running lean then plugs would be white and too rich, black. Neither seems to be the case here.

 

She does tend to backfire when hot and driving. She will sometime have a couple of internal pops when shifting from 1st to 2nd, and then sometimes an exhaust bang when shifting from 2nd to 3rd... and occasionally when I engine brake in 3rd. 

 

I thought that it might be a blown head gasket, but I am not blowing any white smoke at all and there are no bubbles in the radiator water while running. She does lose a LOT of water somehow though, in fact in one drive that was about 12-15 miles it took nearly 2 gallons of water to refill her. There is a small drip leak at the water pump packing nut, but just the occasional drip, nothing that would account for nearly 2 gallons. The radiator cap doesn't fit well and I will see quite a bit of water bubbling out when it gets hot and driving down the road. The threads on the radiator cap are pretty worn and the cap doesn't seem to seat well or seal. 

 

Her stock fuel vacuum system is gone (wasn't there when I got her) and has been replaced by an electric fuel pump with a pressure regulator that I believe is currently set at 1 psi, with room to drop it to .5 psi if needed. 

 

So, I would love to hear your thoughts as to what might be happening to cause the overheating. As I said, she seems to run well, starts easily, in fact when she is warm just a simple tap of the foot on the starter is enough to make her run, so quickly in fact that often times the starter doesn't even come close to a single revolution before she is running. 

[avgwarhawk]

A lot of brown water came out when flushing.   I would think scale inside the water jacket of the engine is the problem.  

[avgwarhawk]

 

[JayG]

You might want to check the water pump. Mine was doing the same thing and when I took the water pump apart the impeller pin had sheared so it was spinning on the shaft.  Ended up rebuilding the pump.  

[Degeraths]

1 hour ago, JayG said:

You might want to check the water pump. Mine was doing the same thing and when I took the water pump apart the impeller pin had sheared so it was spinning on the shaft.  Ended up rebuilding the pump.  

Interesting, that might be something I could try. It seems that the water pump on mine would be pretty easy to remove and take a look at. Any tips on how to repack the shaft? 

[JayG]

Repacking is easy.  Loosen the caps on each end and put new pump sealing rope in then tighten up (but not too tight).  If the problem is with the impeller it is more involved.  And you may find that the shaft needs replacing.

 

Thinking back it might not be a pin but the key that sheared.  

Edited May 19, 2023 by JayG (see edit history)

[Degeraths]

29 minutes ago, JayG said:

new pump sealing rope in then tighten up (but not too tight). 

 

Okay... never heard of pump sealing rope? Is this something I have to make or can I buy it? 

[JayG]

Yes - Myers has it along with any other parts you might need for the rebuild.  http://www.myersearlydodge.com/image.php?ws_page=cooling.php&ws_image=DSCN0689.JPG

 

[Mark Gregush]

Have you checked the timing and where are you placing the timing lever after you start? How is the compression? An engine can still run smoothly even if timing is off or lever is not in the correct position but will overheat the engine. Have you taken the carb apart and cleaned it? Mine was plugged up with fine dust. Even just partly taking it down, you should be able clean with carb cleaner and blow the muck out of the holes. Also, check to make sure the ball check valves at the bottom of the dash pot are moving. 

The backfiring when accelerating tends to make me think it is running too lean or the dash pot is sticky and not free to move like it should. 

Edited May 19, 2023 by Mark Gregush (see edit history)

[Minibago]

The cooling system is not pressurised so the cap sealing is of no consequence.

The pump can be seen operating (or not) by removing the cap and observing the return flow into the header tank.

2 gallons of water loss in 12 miles with no obvious leak does suggest head gasket or a cracked head / block.

Methodical checking of

compression

Valve timing

Ignition timing in retard and advance positions

Fan belt tightness.

 

[Degeraths]

2 hours ago, Mark Gregush said:

Have you checked the timing and where are you placing the timing lever after you start? How is the compression? An engine can still run smoothly even if timing is off or lever is not in the correct position but will overheat the engine. Have you taken the carb apart and cleaned it? Mine was plugged up with fine dust. Even just partly taking it down, you should be able clean with carb cleaner and blow the muck out of the holes. Also, check to make sure the ball check valves at the bottom of the dash pot are moving. 

The backfiring when accelerating tends to make me think it is running too lean or the dash pot is sticky and not free to move like it should. 

The lever is all the way down when started and I move it upwards as my speed and rpm's increase. 

[Degeraths]

5 minutes ago, Minibago said:

The pump can be seen operating (or not) by removing the cap and observing the return flow into the header tank.

 

 

I will say that if I fill the radiator to the point where I can look in the tank and see the water while the engine is running I don't see any noticeable movement of the water at all. There is no flow. Would I easily be able to see the water being moved around by just looking in the fill cap?

[Minibago]

Yes.

If the cap is removed and the water level is above the deflector plate then water movement will be observed.

No water movement will indicate a failed water pump.

[Degeraths]

40 minutes ago, Minibago said:

Yes.

If the cap is removed and the water level is above the deflector plate then water movement will be observed.

No water movement will indicate a failed water pump.

AAAAH HAAA!!!!! Then I think I may have found the problem. I will check again today and make absolutely sure but I think you may have made the winning diagnosis. 

 

In theory, I should be able to drain the water, remove the hose that it attached to the top of the pump and then crank the engine and be able to tell if the impellor is working or not. 

[Minibago]

It would be easier to leave the water in the system, remove the top hose to the radiator and turn the engine on the starter with the ignition off. 
If the water pump is working water will flow from the head return pipe.

 

Credit belongs to JayG. 😊

[Minibago]

Yes, impossible to view the impeller through the pump.

 

 

[Degeraths]

1 hour ago, Minibago said:

Yes, impossible to view the impeller through the pump.

Not the same pump as mine. 

[Mark Gregush]

Yes you could. Barrow one of these: 2.7 in. Color Compact Digital Inspection Camera (harborfreight.com or get the adapter to use your smartphone. 

Edited May 20, 2023 by Mark Gregush (see edit history)

[Mark Gregush]

He got the overheating fixed. What it was: the shaft was turning but the impeller was not. The pin was missing. 

[Minibago]

5 hours ago, Mark Gregush said:

He got the overheating fixed. What it was: the shaft was turning but the impeller was not. The pin was missing. 

Thanks for the update Mark, it is nice to have a solution to the problem.

[nat]

10 hours ago, Mark Gregush said:

The pin was missing. 

     Was the key missing as well?

[Mark Gregush]

32 minutes ago, nat said:

     Was the key missing as well?

Must have been or sheared. Don't recall. 

[22touring]

Minibago wrote: "If the water pump is working water will flow from the head return pipe."

I thought the water pump on a 4-cylinder car sucked water out of the bottom of the radiator and pumped it up the hose that goes into the top of the block near the front (that's what it says on page 44 of my BOI).  When you say "from", do you mean "out of the top of", or "out of the bottom of", Minibago?

[Minibago]

The head return pipe directs water from the block / head back to the top of the radiator under pressure from the rotation of the pump impeller.

No water flow out of this pipe? Pump not working.

So yes, out of is the same as from.