Water pump question

[Caman96]

Well Said!

But who said it?

 

[Schurkey]

Was only to point out that they weren’t rolling off the same assembly line.

But having descriptions of "grey iron" for one, and "cast iron" for the other doesn't mean they're different. Just that someone wants you to think they're different.

But who said it?

Post revised to make that clear.

 

[Caman96]

But having descriptions of "grey iron" for one, and "cast iron" for the other doesn't mean they're different. Just that someone wants you to think they're different.

Post revised to make that clear.

Again, I posted that in response to this comment:

I am inclined to believe it came off the assembly line right next to the $50 part.

It has a different casting number. However, grey iron is a lower grade.

Just that someone wants you to think they're different

I think it’s reasonable to assume it’s a different part(different casting # and material for one).
The main point I’ve tried to make is that while I don’t think it’s $100 in quality better, and not sure how I could make that any clearer, I do believe it’s of some level a better part. So, we can agree to disagree on this point!

 

[Vanishing Point]

There seems to be a difference in the metallurgy!​

What is Grey Cast Iron?​

Grey cast iron (a.k.a. gray iron castings) is a type of iron found in castings known for its grey color and appearance caused by graphite fractures in the material. Specifically, what makes grey iron “grey iron,” is the graphite flake structure that is created during the cooling process from the carbon that is in the component.

Grey iron is a result of both the materials used and the process used to cast a part. In other words, the properties of the grey iron will change depending on what materials are melted together to pour into the mold as well as the process that is used for casting (it is primarily the cooling part of the process that defines the characteristics of the cast part versus other parts of the process.).

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Grey Iron Magnified to Show the Flakes of Graphite
If you use a powerful microscope you can see the graphitic microstructure that makes grey iron so easily identifiable. In a grey iron casting, you can see little black flakes of graphite. These flakes cause fractures and cause the material to have a grey appearance. The mechanical properties of grey iron are controlled by the size and shape of the graphite flakes present in the microstructure and can be characterized according to the guidelines given by the ASTM.

There are more pounds of grey iron castings produced every year throughout the world than any other type of casting. Just about every manhole cover is from grey iron and the disc brakes on your car are most likely grey iron as well. Other common uses for grey iron include:

• Gears
• Hydraulic components
• Automotive suspension components
• Plow shares
• Pumps
• Linkages
• Stove parts
• Steering knuckles
• Tractor parts
• Valves
• Truck suspension components
• Other truck parts
• Wind turbine housings.
• Weights and counter-weights
• Machinery bases

The popularity of grey cast iron components (gray iron castings) is because grey iron is one of the cheapest types of iron castings to produce. It has acceptable ductility, tensile strength, yield strength, and impact resistance for most applications. Grey Iron is also excellent in its ability to dampen vibrations making it ideal for machinery bases and as well as many housing applications. Grey iron has high thermal conductivity meaning it moves heat more easily through the metal.

A final benefit of grey iron castings is its ability to withstand thermal cycling well. Thermal cycling is where the component goes back and forth between warmer and colder temperatures. While thermal cycling can create stress and premature failure in some types of metal castings, grey iron has proven to endure the strain of thermal cycling quite well and not stress as easily.

While grey cast iron has less tensile strength and shock resistance than most other castings or even steal, it has compressive strength that is comparable to low- and medium-carbon steel. These mechanical properties are controlled by the size and shape of the graphite flakes present in the microstructure.

What are the Material Properties vs. Casting Processes?​

Material properties come from the makeup of the materials present. Some of the materials are added to the iron for strength while others are added to improve castability (affecting melting temperatures, etc.). The properties of all metals are also influenced by the way they solidify during cooling. If you change the cooling process, you automatically change the structure of the metal in its final state. How the cast part cools can be affected by how the metal is introduced into the mold, the pouring temperature, and the process and speed of cooling. One of the difficulties in making a quality casting is to account for the way a part will cool in different parts of the mold, accounting for both thick and thin areas of the mold.

What is the Composition of Gray Cast Iron?​

Just like all cast iron parts, the primary component of Grey Iron is going to be the iron (no surprise there, right?). Just like most other cast irons, it also has 2.5–4.0% carbon and 1–3% silicon. If you look at Chart 2 you will notice that the composition of the iron is very close to other common cast parts, but with a little more phosphorus.

Iron Family	Gray	Ductile	CGI	Malleable	White
Carbon	2.5-4.2	3.0-4.0	2.5-4.0	2.2-2.8	1.8-3.6
Silicon	1.0-3.0	1.8-3.0	1.5-3.0	1.2-1.9	0.5-2.0
Manganese	0.15-1.0	0.1-1.0	0.10-1.0	0.15-1.2	0.15-0.8
Sulfur	0.02-0.25	0.01-0.03	0.01-0.03	0.02-0.2	0.02-0.2
Phosphorus	0.02-1.0	0.01-0.1	0.01-0.1	0.02-0.2	0.02-0.2

[1]

What is the Microstructure of Grey Cast Iron​

Grey iron has graphite flakes entwined with the rest of the structure. Unhardened grey iron is “fragile” compared to other cast metals. The graphite flakes create areas of weakness in the metal where fractures can begin that will split the metal. This propensity to fracture is why grey iron has low tensile and impact strength. Yet the graphite flakes are what create great wear resistance because as friction occurs the graphite acts as a lubricant. The graphite structure also has great vibration dampening properties because the structure created by the graphite flakes helps cancel out vibrations.

Classification of Grey Iron Classes​

In the United States, the classification for grey iron is usually set using the ASTM International standard A48. ASTM A247 is also commonly used to describe the graphite structure. Grey iron is grouped into classes which correspond with its minimum tensile strength in thousands of pounds per square inch (ksi); (i.e. class 20 grey iron has a minimum tensile strength of 20,000 psi (140 MPa)). Other ASTM standards that deal with gray iron include ASTM A126, ASTM A278, and ASTM A319.

Class 20 grey iron has a ferrite matrix and a high carbon equivalent. Higher strength gray irons, up to class 40, have lower carbon equivalents and a pearlite matrix. To get grey iron above class 40 requires alloying to provide solid solution strengthening. Grey iron can also be heat treated which modifies the matrix giving the cast iron greater strength. Class 80 is the highest class available for grey iron and it makes the iron have high tensile strength but low impact resistance because class 80 parts are more brittle.

Standard Specifications​

Below is a reference chart of other ASTM standards affecting grey iron.

• ASTM A395 & ASME SA395: ferritic ductile iron pressure-retaining castings for use at elevated temperatures
• ASTM A439: austenitic ductile iron castings
• ASTM A476 & ASME SA476: ductile iron castings for paper mill dryer rolls
• ASTM A536 & SAE J434: ductile iron castings
• ASTM A571 & ASME SA571: austenitic ductile iron castings forpressure-containing parts suitable for low-temperature service
• ASTM A874: ferritic ductile iron castings suitable for low-temperature service
• ASTM A897: austempered ductile iron castings

 

[Schurkey]

Having different casting numbers may mean something. I only see one pump description that lists a casting number in the two tables provided.

Saying that one item is "cast iron" and the other is "grey iron" does not mean there's a difference. Grey iron is a version of "cast iron". Both items could be grey iron; describing one as "cast iron" isn't lying. They may--or may not--be different grades of iron.

It's like saying one piece is "steel" and another is "1015 steel". 1015 is one of a hundred different grades of steel. "Steel" covers all hundred. 1015 is merely more-specific.

 

[studigggs]

Well Said!

"...Getting you to believe that they injected some quality sauce to make it worth the extra $100 is the magic of branding..."


Speaking as a former production engineer, there ARE actually non-manufacturing and non-material processes that can literally "inject" $100 of quality into two identical parts run off the same production line. There is a whole field of engineering dedicated to it. If you break that production into lots, and test each lot according to very specific statistical methods, you COULD very well have 20 lots come off a production line and only 1 or 2 meet your reliability standards. Those 2 lots get sold for more (OEM) and the 18 get sold for less (Silver). I'm not sure how GM does it, but in the defense industry, demanding 5-nines reliability is one of many reasons stuff aint cheap.

 

[PlayingWithTBI]

demanding 5-nines reliability is one of many reasons stuff aint cheap.

AKA 6 Sigma

Edit: With the alt Codes list here's what it looks like, ha ha
6σ which translates into 3.4 defects per million opportunities or 99.99966% defect free production.

 

[1998_K1500_Sub]

Hmm...

Has anyone used the term "value-based pricing" yet?

 

[clgodwin79]

^^^This is true but there are different levels of Chineseum. I agree with OP with maybe waterpump isn’t 3x better, with 3x the price($50/$150), but I disagree that the only difference is $100 more for CEO’s. Also, since he’s sinking a lot of dough into complete motor rebuild it’s reasonable to not purchase the lower value pump. I was fortunate to find a NOS Made in Canada OEM pump for $45.19

Definitely too much $$! Lol

But if it lasts another 27 years I think it’ll be worth it. Also, like you said, the water pump is too important to me to short cut.

You also have to remember that this Vortec engine is going into a ‘95. Which never came with a Vortec. So I may or may not initially have all of the gauges up and working. So I won’t even know my engine is too hot until it boils over. I can live with a bad sensor, not without 100% peace of mind for cooling.

 

[clgodwin79]

Well Said!

Again, to each their own. I’m making this a very high level, frame off build. Not cheaping out on this area.