Replacement Water Pump Pulley # 3770245,Now Being Reproduced

[PAINTJOHN1]

Hey Guys,spent 3 hours yesterday trying to find pulley number # 3770245,a 2 groove top water pump pulley.My pulley total self destructed at the center where the mount holes were.There was no kind of wanring,drove the car for almost 200 miles going to a show on the Eastern shore of Maryland.On the way home this pulley just came apart.Looks as if it was actually cut around the mounting area.Only 2 explainations I could come up with is : that the belt that went around the water pump to the harmonic bouncer was to tight(I do not have an idler pulley),or there may have been a stress crack in the pulley.I also was not running the little stregthening assembly inside of the pulley.(Pulley was NOS,about four months old ,only has about 900 miles on it.I had checked both belts at the show ,everything felt normal.The water pump never locked up,no squealing of the belts,car was running great,infact running about 185 degrees in 90 degree temperature.There was no warning,just a "Ping",and the then temperature sky rocketed.Shut the motor down and drifted to the side of the road.Had to be towed home because the pulley cut my overflow hose from the manifold to waterpump.I wish I could figure out how to show pictures because in 45 years of working ,racing and messing with cars I have never ever seen a pulley come apart like this.Any help on this would be appreciated.
Anyway to the purpose of this note:After calling all over the country to most GM dealers that handle performance parts for pulley number #3770245(with no luck,part discontinued(even though the pulley was listed on all of their web sights),I found out that the Water Pump pulley,double grooved deep pulley is now being remanufactured by the Paragon company,1-800-882-4688..The pulley has just recently became avialiable,exact replica of the GM part,except they have issued their own number.I'm sure they will put their part number(#819) on the part.They sell for about $70.00 and have plenty in stock.They also stock the strenthener (spacer) that goes behind the pulley,sells for $3.00 and change.Strengtheners GM number is #3770616.I also believe they have the double pulley for the harmonic balancer in stock as well(GM part number #3858533).If you order from them be sure to have your GM pulley part numbers in front of you,they will cross over those numbers to their numbers.If you use the non-idler pulley set up ,where you run a belt from harmonic balancer pulley to water pump pulley,and you are using the 2 pulleys I listed,you should use GM belt number #9433722.This belt is designed especially for that application.Belt is avialiable to be ordered from any GM dealerships parts dept.(not a stock item)
I'd like to get some opinions on why this pulley broke,also if anybody can help me to be able to put the pictures of the pulley on this thread ,I'd be happy to E-Mail then to you. Thanks John

[oldskydog]

Hey Guys,spent 3 hours yesterday trying to find pulley number # 3770245,a 2 groove top water pump pulley.My pulley total self destructed at the center where the mount holes were.There was no kind of wanring,drove the car for almost 200 miles going to a show on the Eastern shore of Maryland.On the way home this pulley just came apart.Looks as if it was actually cut around the mounting area.Only 2 explainations I could come up with is : that the belt that went around the water pump to the harmonic bouncer was to tight(I do not have an idler pulley),or there may have been a stress crack in the pulley.I also was not running the little stregthening assembly inside of the pulley.(Pulley was NOS,about four months old ,only has about 900 miles on it.I had checked both belts at the show ,everything felt normal.The water pump never locked up,no squealing of the belts,car was running great,infact running about 185 degrees in 90 degree temperature.There was no warning,just a "Ping",and the then temperature sky rocketed.Shut the motor down and drifted to the side of the road.Had to be towed home because the pulley cut my overflow hose from the manifold to waterpump.I wish I could figure out how to show pictures because in 45 years of working ,racing and messing with cars I have never ever seen a pulley come apart like this.Any help on this would be appreciated.
Anyway to the purpose of this note:After calling all over the country to most GM dealers that handle performance parts for pulley number #3770245(with no luck,part discontinued(even though the pulley was listed on all of their web sights),I found out that the Water Pump pulley,double grooved deep pulley is now being remanufactured by the Paragon company,1-800-882-4688..The pulley has just recently became avialiable,exact replica of the GM part,except they have issued their own number.I'm sure they will put their part number(#819) on the part.They sell for about $70.00 and have plenty in stock.They also stock the strenthener (spacer) that goes behind the pulley,sells for $3.00 and change.Strengtheners GM number is #3770616.I also believe they have the double pulley for the harmonic balancer in stock as well(GM part number #3858533).If you order from them be sure to have your GM pulley part numbers in front of you,they will cross over those numbers to their numbers.If you use the non-idler pulley set up ,where you run a belt from harmonic balancer pulley to water pump pulley,and you are using the 2 pulleys I listed,you should use GM belt number #9433722.This belt is designed especially for that application.Belt is avialiable to be ordered from any GM dealerships parts dept.(not a stock item)
I'd like to get some opinions on why this pulley broke,also if anybody can help me to be able to put the pictures of the pulley on this thread ,I'd be happy to E-Mail then to you. Thanks John

Now you know why GM made the reinforcement.:D

[Dick MacKenzie]

John,
You have a pm. I'll be glad to help with your pictures.
DMac

[Dick MacKenzie]

Here are the pics of John's Pulley

http://i59.photobucket.com/albums/g311/bfnjz52/defectivewaterpumppulley001.jpg

http://i59.photobucket.com/albums/g311/bfnjz52/defectivewaterpumppulley002.jpg

http://i59.photobucket.com/albums/g311/bfnjz52/defectivewaterpumppulley003.jpg

http://i59.photobucket.com/albums/g311/bfnjz52/defectivewaterpumppulley004.jpg

I couldn't resist a couple pictures of his car. This 64 Impala is truly a beauty!:clap

http://i59.photobucket.com/albums/g311/bfnjz52/memorialweekendshows018.jpg

http://i59.photobucket.com/albums/g311/bfnjz52/1964impala409.jpg

[PAINTJOHN1]

Hi Dick,thanks so much for posting the pulley pictures,I really appreciate it. Also if anyone has any ideas why this may have happened I'd like to hear your thoughts on that. I would like to note, that all the bolts were tight,and alignment of the belts were absolutely on the money,no locking up on waterpump. Thanks John

[oldskydog]

Hi Dick,thanks so much for posting the pulley pictures,I really appreciate it. Also if anyone has any ideas why this may have happened I'd like to hear your thoughts on that. I would like to note, that all the bolts were tight,and alignment of the belts were absolutely on the money,no locking up on waterpump. Thanks John

Metal fatique is a sneaky thing. All it takes is a slight wobble and a tight belt causing
fore and aft flexing which could eventually lead to cracking. Gm recognized this in 66 and issued a service bulletin which included the following:

"Some 1966 350 hp 327 cu Corvette engines equipped with two or three groove water pump pulleys may experience pulley failures due to insufficient support of the pully in the hub area (where yours failed). Effective with the start of 1967 production, a pulley reinforcement will be installed on this engine as standard equipment. For service, whenever the above condition is encountered, or work is being performed involving the fan or pulley, add pulley reinforcement number 3720616 between the water pump pulley and the fan."

FWIW
:)

[Ronnie Russell]

John, Sorry, I don't have a clue as to why it broke. Never saw that happen before. But, what a beautiful car. You done gooooood........ :)

[DaveFoster]

I thought that pulley looked familiar, I bought one from the local Chevy dealer in July of 05 to slow down my water pump on a small block. I bought an aluminum set because the 3770245 was of poor balance, it looked slightly out of round and jumped around a little. My cost was $51.25, and the lower, also a double deep groove was $25.48, part number 385833.

[CHEV601234]

Those pulleys just wne out of the books. Ther are toms ogf them on ebay every day if you want a other new one, just get the reinforcement to go ewith it. Search on Camaro too, smae puley. :)

[mpris]

I bought one of those pulleys about two years ago from GM and went through 4 of them before I got one which did not wobble. I can see why the center would have metal fatique.

Poocho

[PAINTJOHN1]

Hey Guys,I recieved my new pulley today from Paragon.To my surprise the pulley does have the GM number stamped into the metal,exact duplicate of the original GM..Only difference I see from the original GM Pulley is that the paint is flat black,almost like a black primer.I will repaint the pulley tonight amnd install it before work in the morning.I also recieved the strengthener plate.Can someone verify to me if that installs inside the pulley or on the outside of the pulley.If I remember correctly from years ago it was installed inside the pulley.Please get back to me on this,any help would be appreciated. John

[oldskydog]

Hey Guys,I recieved my new pulley today from Paragon.To my surprise the pulley does have the GM number stamped into the metal,exact duplicate of the original GM..Only difference I see from the original GM Pulley is that the paint is flat black,almost like a black primer.I will repaint the pulley tonight amnd install it before work in the morning.I also recieved the strengthener plate.Can someone verify to me if that installs inside the pulley or on the outside of the pulley.If I remember correctly from years ago it was installed inside the pulley.Please get back to me on this,any help would be appreciated. John

From my previous post taken from the factory service bulletin:

"........add pulley reinforcement number 3720616 between the water pump pulley and the fan."

I believe the idea is that the reinforcement acts as a clamp preventing the pulley from flexing.

[PAINTJOHN1]

Hey guys,getting back to you all about the reinforcement spacer for the water pump pulley.This spacer should be used on any 2 or 3 belt pulley from 1958-to 1967.This applies to 327ci,348ci,409ci,396ci,427ci engines.According Paragons catalogue and some Ex-GM senior mechanics(who worked in GM dealerships in 1950's-1960's)cars from 1958-1964 the spacer fits directly onto the water pump shaft and goes under and into the water pump pulley.Even though the spacer is only about an 1/16th inch thick it will not hurt the belt alignment. On 1965-1967 Chevrolets Big Bodies including Corvettes,Novas,Chevelles,Chevy Trucks and GMC,the pulleys on 327ci(300hp and more) spacer mounts on the outside of the pulley and between the pulley and the fan.This acts as a clamp as Cecil has suggested in the last post.Also as Cecil has said in the recall notice,all earlier model Chevies back to 1958 were fitted with these spacers when the water pump ,radiator ,belts or fan was serviced at the GM dealerships. 1965-1967 Chevrolet cars and trucks with 396ci or 427 ci,had the spacer installed under the pulley assembly. **NOTE*** This spacer was used on all Chevy big bodies,Chevelles,Corvettes,Chevy II, and some Chevy and GMC trucks with motor sizes listed above. John
Oh Yeah!!! Cecil,thanks so much for the Chevy call back info: It was really helpful in getting me the correct info to make my own application correct again.Even though my car(Impala) has been mine for 43 years,my memory about lot of the things that were on it has been partially forgotten.Sometimes it take a little thought when someone puts an idea forward to you. OH,THE JOYS OF GETTING OLD !!!!!! John

[oldskydog]

OH,THE JOYS OF GETTING OLD !!!!!! John
How well I know. I'm sitting here with a torn disc in my back (It's 112 degrees outside so I can't do anything anyway) and my wife is trying to recover from a torn ligament in her knee. GETTING OLD SUCKS!!!!!!!!

Anyway, glad I could help.

:grumble: :grumble: :coffee: