Water Pump - BAD and Depressing Discovery. Please help

[Peter B.]

Guys(71 small block)OK, I am in Contact with Bill Mock to re-build my water pump. I took the water pump off last night and this morning after wiping away all the grime, I noticed that it is NOT an original water pump. No "3991339" numbers. See pictures. Soooooo, I will get a proper water pump. But here is the question. I think I have an unrestored original engine. Never been pulled out of the car. See pic. I have a serial number on the block that says 3970010. When I bought the car in 1998 it had 38K miles but a broken speedo cable. I honestly don't feel this car has more than 70K miles on it based on the way it drives and looked on the outside. Is this my original engine? This water pump looks bad so how can an original water pump fail unless it actually did have a ton of miles on it. I am questioning the originality of my engine now being that I am going to replace a replaced water pump. Anything I can do to check that all out and see what I really have?Thanks Guys

[Robert E.]

Re: Water Pump - BAD and Depressing Discovery. Please help

Pictures??

[Patrick H.]

Re: Water Pump - BAD and Depressing Discovery. Please help

My 61000 mile 1972 5 Star Bowtie has had its original pump replaced at least prior to 1986 and prior to at least 52000 miles. The 1971 83000 mile car I recently worked on has had its water pump replaced loooong ago, but thankfully the owner saved it and we had it rebuilt and reinstalled it. Water pumps rust from sitting, seals dry up, stuff happens. Live with it, it's a normal part that gets replaced on a regular basis. Oh - my 1971 still had its original water pump when I rebuilt the engine in 1996 at about 120000 miles, but I was very surprised at that.

[Peter B.]

Re: Water Pump - BAD and Depressing Discovery. Please help

Sorry guys - here are the pictures.

[Michael W.]

Re: Water Pump - BAD and Depressing Discovery. Please help

G I have a serial number on the block that says 3970010.

That's the casting number, not the serial number. 3970010 blocks (cases) were used on just about every GM product of the era. Look at the stamp pad just in front of the passenger side cylinder head to see if it might be the original engine.

[Peter B.]

Re: Water Pump - BAD and Depressing Discovery. Please help

Sorry - just posted the pictures

thanks

[Peter B.]

Re: Water Pump - BAD and Depressing Discovery. Please help

Thanks Patrick - makes me feel better. See pics and let me know what you think of this replacement pump.

[Peter B.]

Re: Water Pump - BAD and Depressing Discovery. Please help

Hi Michael - OK, on the head or block?

[Jimmy B.]

Re: Water Pump - BAD and Depressing Discovery. Please help

Peter,

Not a big deal, some w/p's appear to leak just from sitting. I had a 56 once, prior to engine rebuild w/p fine, when I reinstall a totally rebuilt engine w/p goes out - I was not a happy camper, especially since you have to jack the engine up to get those front mount bolts loose.

I do have a tip for you that I believe John or Joe posted here on the FORUM a long time ago and it works for me. 1) go buy thread stock or longer bolts than what mounts the w/p hub to your clutch fan assy - cut out 4 nice long pieces of threaded stock (or like I did grind the heads off the bolts), screw these into your w/p hub, now when after you get your w/p mounted to the engine and all sealed up you can place your pulley hub over these 4 pieces of thread stock and it is centered correctly, now place your fan clutch mounting hub over the 4 threaded studs, gently remove 1 stud and screw in your original mounting bolt with lock washer, continue process and finish mounting up the assy. . This works for me and I keep 4 pieces of cut off bolts in the top of my tool box for use when necessary. Have fun.

[Patrick H.]

Re: Water Pump - BAD and Depressing Discovery. Please help

Thanks Patrick - makes me feel better. See pics and let me know what you think of this replacement pump.

It's a replacement pump, worth about $0.58 in recycle value at the nearest metal recycling center. Find a 3991399 of the correct date, install, be happy.

[Alan S.]

Re: Water Pump - BAD and Depressing Discovery. Please help

Hi Peter,
Look for the pad that's part of the engine block, and just in front of the right side head. (You were very close when you were working on the water pump!)
You'll likely see 2 groups of stamped characters…..the engine assembly date and suffix code, and also the serial number derivative of the car the engine was installed in at St.Louis.
Regards,
Alan

This pad is from a 71 car.
It a base engine for a 4-speed car assembled on January 7th.
The derivative indicates it was installed in a 71 coupe with a vin sequence number of 6589.

[Bob H.]

Re: Water Pump - BAD and Depressing Discovery. Please help

Peter:

DON'T go using something harsh on the stamp pad to clean it. Gently clean it off to read the numbers and post a picture.

[Peter B.]

Re: Water Pump - BAD and Depressing Discovery. Please help

Hi Patrick - GREAT news, I was checking and my engine is matching. Whew! I have found 3991399 pumps and Bill Mock has some but you state "of the correct date", what does that mean? Is there some other stamping on the water pump that has a date on it that I need to look out for or is it just a 3991399 stamped pump?Thanks

[Patrick H.]

Re: Water Pump - BAD and Depressing Discovery. Please help

Hi Patrick - GREAT news, I was checking and my engine is matching. Whew! I have found 3991399 pumps and Bill Mock has some but you state "of the correct date", what does that mean? Is there some other stamping on the water pump that has a date on it that I need to look out for or is it just a 3991399 stamped pump?Thanks

Everything has a date on it. Well, at least for cast parts and all major components. So, for your car you need to find a water pump that was cast before your engine was assembled. If you're going to use Bill Mock he will know what you need if you give him your engine assembly date located on the pad at the front of the engine we've all been talking about and Alan has pictured for you.