Water Pump Replacement

[Synchro909]

Originally Posted by Joe K

Many actually "trim" the impeller fins a bit as it is felt that the flow is entirely TOO FAST - and contributes to issues at the radiator overflow (which is right in the flow path from the pump.)

Credence to this thought comes also in that there was at least one maker of Model A "Aftermarket" pumps who utilized a later V8 type impeller - and a single impeller of this lesser vane did perfectly fine in the Model A application.

These aftermarket pumps are actually probably the first "leakproof" type pump having as they do a ceramic supposedly leakproof seal surface.



The image is an Ebay image so it probably won't last but these aftermarket pumps can be described quickly as "not having a gland or adjustment" otherwise similar to the original Model A pump.

The sleeve front bearing is probably the most undesirable part of this pump.

Joe K

I've heard this one before and believe it to be total BS. For every drop of coolant pumped into the top tank, a drop has been taken from the bottom of the radiator. If the rad is blocked, not much water gets to the bottom tank and the amount pumped is therefore reduced. It self regulates.

[Joe K]

Originally Posted by Synchro909

I've heard this one before and believe it to be total BS. For every drop of coolant pumped into the top tank, a drop has been taken from the bottom of the radiator. If the rad is blocked, not much water gets to the bottom tank and the amount pumped is therefore reduced. It self regulates.

I will not defend my observation except to say the same flow thought follows the use of "thermostats" or "flow restrictors" placed in the upper hose.

Most who use thermostats/restrictors tend to say "My car doesn't boil over with the flow restriction" not realizing that a flow restriction puts "head" at the point where boiling over is most likely to occurs (i.e. the upper hose where pressure downstream of the pump is minimum and temperature is maximum.)

I have considered that a thermostat on a partially plugged radiator MIGHT result in slower flow THROUGH the radiator and cooler water to the engine lower connection, which by itself might limit boil-over - but like the impeller issue I'm not prepared to defend it.

I can see a thermostat on its own merits. There is an optimal "cylinder temperature" for both efficiency of combustion AND wear on the cylinder walls. The reason for a later age placement of thermostats is to take advantage - and to provide a "warmer" engine - which the Model A lacked.

Not unusual during the Model A era AND today in trucking to put a cardboard in front of the radiator in the winter to limit over-cooling.

Still, its funny that an aftermarket water pump might take advantage of reducing flow at the same time that everyone's radiators were becoming "flow obstructed" in a normal radiator life. One's early reaction to repeated boil-overs MIGHT be to replace the water pump - and not address the radiator issue.

It might have even temporarily solved the issue.

Joe K

[shew01]

I decided to do a test fit of my rebuilt water pump, and it doesn’t fit right—it does not go all the way into the head. The previous owner apparently rebuilt the pump (which I purchased with the car), and I’m guessing the impeller is not on the right place on the shaft. What are my options?


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[shew01]

The new (rebuilt) water pump is on the left.



Here is the gap I’m seeing.




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[Joe K]

If the pump spins as it is built (check with the fan on) then you can cut down the nose (center shaft extension at the impeller) so without gasket it fits "tight." The additional thickness of the gasket is about the recommended 0.010 thickness for "fore & aft" movement of the pump shaft.

You don't want to constrain the shaft too tight with either original packing or the "lip seal" of a leakless pump. (Some leakless pumps come "pre-constrained" by the front bearing.)

A little "front-back" movement of the shaft sometimes allows a drip or two to get past the lip seal, but it prevents the lip seal from wearing a groove in the shaft.

Joe K

[Big hammer]

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You’ll need to remove some of the shaft that touches the boss in the head. New shafts are made long so you can fit it to your head.

[Joe K]

The $1 water pump I referred to earlier is now disassembled. It was seized and it took some doing (and a punch and hammer to unscrew the gland nut) to allow removal of the shaft.

The failure mode of the pump was the prior owner simply "tightened up" the gland nut too tight and bound the shaft. The nut was within two turns of "home." Looking at the packing I'm not sure anyone ever added a ring of packing and what is there is HARD.

I'm pretty sure I can remove the packing, clean up the galvanized nut and re-pack. The shaft is probably the best "used" shaft I've seen and even the hyatt bearing at the front appears re-usable as is.

I guess this is a "gloat."

Probably my 8th pump...

Parts ARE an addiction.

Joe K

[shew01]

Originally Posted by Joe K

If the pump spins as it is built (check with the fan on) then you can cut down the nose (center shaft extension at the impeller) so without gasket it fits "tight."

That’s the first time I’ve heard someone recommending cutting the end off. I figured that impeller just needed pressed so that it would be located at the correct distance from the head.

How would you cut it?


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[Joe K]

Originally Posted by shew01

How would you cut it?


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Best would be to disassemble the pump and turn the shaft in a lathe.

Given you likely don't have one, an alternative might be found in holding the entire pump in a vise, and by using the fan, "turn" the shaft while holding a 4-1/2" hand grinder against the end.

This might be laborious - maybe take off a slice using a hack-saw and THEN use the grinder to "fine-tune" the fit (and prepare what will be a metal-to-metal contact surface between the bridge and the pump shaft.)

Blow your grindings off onto the bench or otherwise protect the pump from intrusion (situated rag or create for yourself an "operating theater.")

I can see that one might "measure" between the flange of the pump and the nose - and then measure between the head pump mount flange and the recession in the bridge. A "sharpie" works well to "blacken" the metal surface upon which you can scribe a line with an X-Acto knife to guide your cutting.

It presents problems - but careful cutting and patience is the key.

Rather than "re-press" the impeller (you may not see a "pin" that most use in addition to the press fit) I might choose modify the shaft. The look (pix) it does appear to be the "extended shaft" version. As another has said, commonly supplied this way so you may fit it to your head.

Joe K

[shew01]

Joe,

Hmm… I’m not sure I totally understand. (I am a total novice at water pumps on Model A’s. Under normal circumstances, I’d just buy a replacement, but replacements are out of stock everywhere I’ve checked—Bratton’s, Snyder’s, MAC’s, Mike’s.)

What about measuring the old water pump and cutting the rebuilt one to match the length of the old one? How could I accurately measure from the mounting flange to the end of the spindle that goes into the head? (The impeller is an oddball shape. How would I get around that and get an accurate measurement?)


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[Joe K]

Likely you would have the same issue with a replacement - or maybe the converse - shaft too short resulting in too much forward-back movement of the shaft/impeller. Sellers generally sell what will cover most circumstances and too long is better than too short in that instance.

Your thought to measure an existing functional pump is a good one. Just leave yourself enough to remove with the grinder so you don't "overshoot."

Overshooting can result in a need to "add" metal, or do the "tap & insert for a brass bolt" extension fix. The fix can be performed by having a welder add metal and re-grind.

My measure might be done using a technique called a "bridge gauge" - basically amounting to three blocks of wood set up to "bridge" the impeller. But I have the vernier caliper (with extension) to measure how much bridge the bridge actually bridges. A ruler might work if you're careful.

Joe K

[Joe K]

Harbor Freight sells a cheap 4-1/2" grinder on sale for $9.99. This can be fitted with either the typical "cup" wheel (actually more dishware than teacup) or with a THIN blade (typically 0.040 thick) which will cut a "slice" like a hack-saw. And probably do it easier and more accurately. Both wheel patterns are sold in packs of 5 at HF.

They're not my fave for power tools, but $9.99 (or $14.99 normal) is still pretty cheap for a tool which you don't try to fix if it breaks. And mine is still soldiering along.

Joe K

[Dennisfly]

I'm going through the same process. I'm planning on using a bench grinder to shorten the shaft after the pump is assembled. I will hand finish the shaft end with fine emery cloth after the grind, attempting to get it as smooth and square as possible. The last picture is the collar you can use to control the end play if you grind off too much.

[shew01]

A friend in our club has a lathe, and he plans to help me with it.

I have a vernier caliper, but I don’t know if it has enough reach to measure like you did. Roughly, it looks like my rebuilt pump is about 1/4” too long going into the head.

Measuring is part of my problem. The water pump (for me) is difficult to measure.


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[shew01]

I ordered a collar, and it came in a couple of days ago. At the moment, I can’t get the pump bolted to the head because the large gap between the pump and the head.


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[Dennisfly]

You will need a precise depth measurement from the water pump mounting flange on the head to the the point inside the head where the end of the pump shaft would contact. This should then equal the distance from the pump flange on the pump to the shaft end. Your friend with the lathe will need this to know how much to take off. Or, he could just cut off 1/4"+ and then you could adjust your end play with the collar.


I'm building a spare pump, so my present pump is still installed. I'll remove it to hand fit the spare pump. The picture is the spare pump with the long (not yet shortened) shaft. I anticipate removing about 1/4 inch, so the nominal measurement looks like 2 3/4 plus whatever wear you have in the head. When the gasket is installed this would give you the desired end play.

[shew01]

Originally Posted by Dennisfly

You will need a precise depth measurement from the water pump mounting flange on the head to the the point inside the head where the end of the pump shaft would contact. This should then equal the distance from the pump flange on the pump to the shaft end. Your friend with the lathe will need this to know how much to take off. Or, he could just cut off 1/4"+ and then you could adjust your end play with the collar.


I'm building a spare pump, so my present pump is still installed. I'll remove it to hand fit the spare pump. The picture is the spare pump with the long (not yet shortened) shaft. I anticipate removing about 1/4 inch, so the nominal measurement looks like 2 3/4 plus whatever wear you have in the head. When the gasket is installed this would give you the desired end play.

I’ve looked at this picture about a dozen times, and I think I finally figured out how to measure the water pump. Thanks for posting.


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[Big hammer]

If you just install the pump and measure the gap between the pump and the head plus a little more, remove that from the shaft end,presto

[shew01]

Yesterday, I got the rebuilt water pump installed. I used a little Permatex around the stud that is open to the water jacket, and I used Blue Hylomar on the gasket and water hose to make future removal easier. My wife and I took the car out for about a 10 mile test drive. So far, no leaks. I have some radiator flush in the radiator at the moment. I'll probably take the car out a time or two before replacing that with 50/50 antifreeze.


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