1964 water pump pulley cracked/reinforcement spacer

[Tim D.]

My 1964 327/365 Special Hi Performance (no A/C) water pump pulley cracked. It is pretty bad and I am not comfortable having it welded. I am looking to purchase a new one (they are getting hard to find). In reading archives, I understand a reinforcement spacer is now recommended on all applications even though mine did not have one from the factory. I found the spacer in my parts catalogs. My questions are;

1. Does the spacer go in front or behind the pulley..I think it goes behind which would seem to make it more solid?

2. If I install the spacer behind the pulley, I have read the water pump flange would need to be "pressed on" a little farther (the same thickness of the spacer) to accommodate the added spacer and still maintain pulley alignments. HOW do I press it on farther? Can I do this at home? Do I need a press or can I use a large socket and tap it with a hammer? Do I have to remove water pump to do this? Or do I have to take the car and or the pump to a shop with a press?

3. Does anyone know where I can buy the water pump pulley GM #3770245, 7 1/8" O.D. deep 2 groove?

4. What is a fair price?

Thanks in advance!!!

Tim

[Dan B.]

Re: 1964 water pump pulley cracked/reinforcement spacer

Tim, I've been dealing with these pulleys a lot lately and if you are going to use the WP pulley spacer it would deffinately go behind the pulley against the WP shaft to spread the load as a reinforcment. I have seen a few of those 3770245 pulleys on E-bay. One just sold for $130 or you can pay a little more and get a new one from any of the vendors.

I don't know if you would find the difference in pulley alignment objectionable enough just from the reinforcement to have to press the hub further, but if you do, you must remove the pump from the car and remove the back cover of the pump to properly support it and press it down. If you try to hit it unsupported, you will likely break the pump casting. Dan

PS

Are you by chance running P/S on your car?? See my pulley thread question posted.

[Tim D.]

Re: 1964 water pump pulley cracked/reinforcement spacer

Dan, thank you VERY much for your knowledgeable reply. I am not running Power steering on my car. As far as my issue, I would love to hear others chime in that have run across my problem. Tim

[Dan B.]

Re: 1964 water pump pulley cracked/reinforcement spacer

I will add, that I have come accross a few pulleys over the years that were out of round. In other words, if you rotate it with a straight edge against the lip, you could easily see the high spots. Some as much as 1/8" off. That would create an imbalance which could eventually cause a failure from the vibration.

[Cecil L.]

Re: 1964 water pump pulley cracked/reinforcement spacer

The reinforcement 3720616 goes in front of the pulley. That was a common problem from at least 64 through 66 on trucks as well as Corvettes and cars.

[Tim D.]

Re: 1964 water pump pulley cracked/reinforcement spacer

Cecil, Wow!!! Thanks for the extremely helpful reply. The tech letters, dates, drawings are a HUGE help. I guess this verifies several things: GM has been experiencing double groove water pump pulley failure for years, they not only came up with a fix but also made it retroactive. I am so glad to know the reinforcement spacer installs between the front of the pulley and the fan flange. That makes this job so much easier than having to press the water pump flange etc. I had considered installing it that way thinking everything would fit just fine, no pulley alingment issues but the fan would be 1/8" closer into the shroud which would be fine on my car. It just didn't seem like it would provide as much support. Also, most of what I have read previously said yes, go ahead and install the reinforcement spacer in 63 - 64s even though they didn't come from the factory that way but to install it behind the pulley. Since the service bulletins prove that wrong the job just became very simple. Some sources say to install the reinforcement spacer on big block cars in between the front of the pulley and the fan flange. Perhaps that is where the confusion is? Your letters are proof for me as to how I am going to install the reinforcement.

Thanks,

Tim

[Dan B.]

Re: 1964 water pump pulley cracked/reinforcement spacer

Very interesting, that reinforcement part number 3720616 has been around for quite some time previously and was used on the C-1's. I thought I read on the early cars it went behind the pulley So what would be considered the existing reinforcement referred to on the last page of the document?

Shows you when you get involved in trying to help with a question, you can learn something new even after 35 years. Cheers!

[Timothy B.]

Re: 1964 water pump pulley cracked/reinforcement spacer

What's interesting to me is that if you look in the 1967 AIM the picture cut out shows the reinforcement between the water pump flange and pulley, (inside the pulley).

MY 300hp reinforcement was outside the pulley but I assumed someone put it back that way because the W/P had been changed. I installed one inside and everything went together OK so now I am confused.

[Tim D.]

Re: 1964 water pump pulley cracked/reinforcement spacer

Update...I have my new 245 pulley and reinforcement spacer. I test fitted the reinforcement spacer behind the pulley and it fits perfectly flush within the shape of the back of the pulley. Also, it does not throw the belt/pulley alignment off because it is so thin. Conversely, if I test fit it in front of the pulley (between the pulley and the fan flange) the reinforcement does not sit flush with the pulley where the 4 bolt holes are. I would need to insert a flat washer behind each bolt hole in between the reinforcement and the front of the pulley to keep from crushing the reinforcement when I tighten the 4 bolts.

Also, the pulley I just bought is an NOS 245 pulley (used) and I can clearly see where a reinforcement spacer was once installed behind the pulley. Therefore, I am pretty sure I am going to go ahead and install the spacer behind the pulley as many have suggested. I will not need to press the water pump flange on farther to maintain belt alignment.

Like Dan, I wonder what they mean by "existing reinforcement" in the last tech bulletin drawing. Could they possibly be saying that a reinforcement was installed originally behind the pulley and in order to prevent future pulley failure to install a second reinforcement spacer in front of pulley as well?????

I will report back when I have it all installed and test driven.

Thanks,
Tim

[Dan B.]

Re: 1964 water pump pulley cracked/reinforcement spacer

Tim, thanks to your post and Cecil's TSB posting, I did install the spacer on my 64 in FRONT of the 0245 W/P pulley (same as yours) as pictured above. Car drove perfect and no balance problems. However, on my 59 it is installed on the INSIDE of the pulley (per the cutout in the AIM). Both ways seem to fit, but my pulleys aligned a little better. Either way, it's a good move as it reinforces the front pulley area and spreads the stress load out. Dan


P.S. : With reference to the TSB above, I believe I have found part of the answer. The W/P pulley referred to 3827846 (and pictured below) is a HP pulley with a stepped snout. Clearly, the reinforcement could not fit inside of this hub.
Maybe they wanted to avoid confusion with the other pulleys and kept it all the same.

[Tim D.]

Re: 1964 water pump pulley cracked/reinforcement spacer

Ok, so after all of that, I decided to install the reinforcement spacer inside of the pulley...in other words in between the water pump flange and the backside of the pulley. It fits perfectly with no alignment issues what so ever. In fact, I think it lines up even better than it used to. The ticking noise coming from my engine is gone...problem solved. I used medium lock tite on the 4 bolts. I have to wonder if my other pulley failed from any or all of the following...I had it powder coated (did the heat cause it to weaken), did I over tighten the 4 bolts, was it slightly out of balance or alignment causing a small wobble that over time caused it to fail do to stress????

A huge thanks to all that responded...your help was beyond measurable! I truly appreciate everyone's help.

Tim

[Timothy B.]

Re: 1964 water pump pulley cracked/reinforcement spacer

Tim,

Make sure the fan clutch has a 5/8" pilot hole to match with the 5/8" shaft from the water pump. Later years used 3/4" and it will bolt up but cause a out of balance condition and failure.

[Cecil L.]

Re: 1964 water pump pulley cracked/reinforcement spacer

Sounds like you have the problem resolved.
It seems to me that when the reinforcement/spacer is used behind the pulley, it is serving more as a spacer than reinforcement although it does stiffen the pulley bell and prevent flexing at the hub edge.
When used on the front of the pulley, it is truly a reinforcement spreading the clamping load over the mounting surface preventing stress cracks around the bolt holes.
There were other part number reinforcements for other pulleys referenced in other TSB's , but the 616 is the most common.
Of note for those looking for the 3827846 pulley so familiar to us from the early SHP engines is that it was also used on some truck applications.
I always wondered why it seemed to be so common at swap meets when it supposedly had such limited application..

[Tim D.]

Re: 1964 water pump pulley cracked/reinforcement spacer

Tim and Cecil, thanks. I will double check 5/8" vs 3/4" just to make sure but I think it fit pretty snugly. Cecil, I tend to agree with you that the reinforcement seems like it would provide more support when mounted on the outside of the pulley. Also, thanks for the interesting info on trucks. I will keep my fingers crossed on the pulley holding up this time. I plan on driving the car this Sunday.