Hey Jason, how are you doing ?? Hope your not PO'd cuz I talked you into tackling this one. Follow Joel's instruction on getting the four clutch/pulley bolts loose and remove the fan. One thing I forgot to mention is that the pulley assembly is actually two pieces, the original two groove WP pulley and a second single groove add on pulley for the smog pump. Hopefully with the fan and pulleys out of the way you can get back to my original instructions. The A/C bracket can be a bit tricky but you can do it. When you get the pump off you have the option to install the new rebuild or purchase a rebuild to get the new components out of it to rebuild yours like Joel mentioned. You can also save it and send it to a professional rebuilder if your not comfortable rebuilding it yourself. So let's take a look at your to see if it's original, if not, then the decision is easy, just put the new rebuild on and turn the old one in for a core. On the front face of the pump on either side of the shaft there should be two sets of numbers. The first is pretty big and easy to read, that would be the casting number. The correct casting number for your car is 330818. If that number matches look for the casting date on the other side of the front face. That number is substantially smaller and a little harder to read. The casting date starts with a letter denoting the month A=Jan., B=Feb. and so on. If I remember right your car was a March or April build so hopefully the date code starts with a B, C, or D. The second character will be one ore two digits indicating the day of the month and the last character is one number indicating the year, hopefully your is a "3". So if our casting number matches and the date code is prior to the built date of your engine, you have the original water pump !! 99% of the time the old pump is just turned in for the core charge and a bit of the car's originality is lost. It also another small part of that "numbers match" statement you hear about most Corvettes. Let us know where your at and what you find out about your pump.

Another great morning!  Got the water pump out!  Vman73 your instructions were perfect!  Again, thank you very much! 

A few things I hate: the AC bracket and the smog pump in general :/  Smog pump was very difficult to remove and that AC swivel bracket is impossible to swivel out of the way while the water pump in still attached.  Matter of fact, when I removed the lower left AC bracket bolt (lower left if looking at the car from the front) that attached the AC bracket to the water pump, a fairly large chunk of the AC bracket itself came off with the bolt.  I do not think it is a big deal, but still.  I am assuming I have to keep the chunk on the bolt when reassembling to allow the proper distance that bolt is supposed to go into the bracket/water pump.  I hope that made sense.  I think I would like to bypass both the AC and smog pump at some point.

Other than that...Adam's, brilliant idea using a screw driver as a lever to stop the pulley from spinning while removing the fan clutch.  Worked like a charm!

I scraped the old water pump gasket material off of the block.  Both sides.  Seems nice and smooth.

Any suggestions to clean things up in there?  I'm guessing I have to be very careful if spraying with Simple Green...wouldn't want to get a cleaning agent in water pump block holes, correct?

A few things I found: on the front of the fan clutch is a large "CA".  Does this stand for California package?  Does this further verify the car was an original California production?  We talked about that a few threads ago when we were deciphering engine numbers.

On the water pump itself I found the following numbers: 330813  C53GM1.  To my untrained eye, I tried looking for a leak area on the water pump and I couldn't find a ting.  I hope the leak WAS the water pump LOL 

Here are a few pics of today's progress!!

Thanks again!  You guys rock!

VMan - You must have been writing me as I was updating you guys on today's progress! 

It seems the casting numbers are a bit off.  Mine are 330813 (instead of 330818) and C53GM1 (instead of GM3).  So close!

Jason, looks great and it looks like we both posted at about the same time. First of all your right, you don't want to get a bunch of cleaning solution or grease into the WP holes. I suggest using some paper towel to soak up the anti freeze that's immediately in front of the holes until it 1/4" or so below the level of the hole, then clean the surface with some lacquer thinner or other solvent. You may also have to use a razor blade or sharp putty knife to scrap off any of the remaining gasket. Once the bare metal surfaces are clean and dry, use some duct tape to tape off the holes before you start cleaning. Don't get too aggressive around the taped areas and blow the tape off. So the second part of your note is also great information, your casting number is correct and the casting date of C53 which is March 5th of '73 looks good for your car (if I'm remembering your engine build date correctly). Now you have a decision to make on if your going to rebuild the original or just install the rebuild. Installing the rebuild is probably the easiest, just save the original to rebuild at a later date. If you install the rebuild unit, you'll notice there might be a few things that need to be transferred over. The four studs that hold the fan on and the pipe fitting that connects the larger heater hose. The pipe fitting is pretty straight forward, just be careful not to damage it or the WP casting. Clean the pipe threads with a wire brush and use a small amount of liquid pipe dope to seal the thread when you reinstall. The studs can be taken out in a number of ways depending how how tight they are. The easiest is to run two of the nuts together on the same stud and turn the bottom nut out to get the stud moving. The second option is to buy a stud removal socket at your local auto parts store, I believe those studs are 1/4". The last an most tempting option is to use a small vise grips on the non threaded section of the stud. This is my least favorite option, but I have done it, just be very careful so you don't muck up the threaded section of the stud. Hopefully the first option will work. Regarding the CA on the clutch, I don't think it has anything to do with California but I could be wrong. There is however another date code on the clutch if you're interested. I'll post some additional information and a picture of mine so you can see what your looking for. You're doing great !!

Wow, we cross posted again. Take another look at the last casting digit, I'll bet its an 8 not a three. Disregard the GM1 below the casting date, the 3 you are looking for is in the C53 above the GM1 portion. I could be wrong but I believe you've got the original pump, take a closer look.

We're vibing today!

Here are some better pics of the casting numbers.  See what you think.
I also found a set of numbers on back of one of the fan blades.  Not sure if they mean anything...

Jason - Looks like your on a part number roll !! 3991427 is the correct part number for a 1973 seven bladed cooling fan and they are date coded with a single letter for the month and two digits for the year, so B73 is Feb., 1973, perfect for your car. Back to the water pump, the C53 above the GM1 stands for March 5th, 1973, again perfect for your car. There is a slim chance that it could also mean '63 or '83 but I'm going with '73. Regarding the last digit of the casting number it certainly looks like a three but could also be an eight with a void cast into the center. It looks like there is a small hole there in the center which may indicate a potential void. If you also look very closely at the center of the other two 3's you'll see that the center section returns a bit farther than the one in question. So even if it's a three there is still a void cast into that number. I don't have any particular reference to see if 330813 is even a legit casting number, but with that date code to support it, I'll say that 3 is indeed an 8. Perhaps someone else has a different opinion or a way to validate if 330813 is even a legit number (Joel or Kyster??). Keep going, your doing good. Your probably in clean-up and paint mode, have fun.

I'm really excited about all these numbers matching!  I'm starting to think the previous owner did not know what he really had!  I am keeping detailed notes on each thing we uncover.  It's like unraveling a mystery!

Question - what does a "voided" casting number mean?

At this point I have to stop for a few days.  Have to get to the office :(

I am going to clean things up as best I can.  Do some painting (brackets, pulleys, water neck).  That will give me time to decide what to do with the water pump - have it professionally rebuilt or buy a rebuilt and store the original.  I think I am leaning towards having the original rebuilt.

Until next time...

Jason

The "CA" on the fan clutch is the production/option code. It told the assy line workers which clutch to install on an engine, depending on if it had A/C or not.

Take a look at the bottom of your water pump....the leak is coming from the weep hole.




It's either leaking from there, or possibly the rear sheet metal cover. Either way, it needed to be replaced. Yer doing a great job...keep at it!

Jason, the void in the casting that I'm referring to is when the material that is being cast does not fill the mold properly. It could be something that got stuck in the mold from a previous part or a defect in the mold itself. When the hot metal is not allowed to fill into the mold properly it can cause a void or a hole in the part. Something in that last 8 of the casting number prevented the metal from getting into the mold at that point preventing that portion of the number from being properly formed. No casting expert here, just my opinion.