# fit smaller water pump pully to stop overheating



## fiesta62 (Jan 12, 2011)

hi, i have a 67 gto heater only power steer car, but am fitting a classic air ac, i am thinking i might have overheating issues when running the ac, i know factory ac cars have a smaller water pump pully but its a 3 groove so i cant use it, my pully is now 2 groove and the ac fitting is designed for 2 groove pully, but a friend suggested i can use the pullys of a 68 gto as the water pump is same 8 bolt and the pully on the crank is 2 groove, the 68 water pump pully is quite a bit smaller than mine or the factory 67 ac car pullys, so should pump the water around faster to keep car cooler, anyone done this?....sizes below, thanks


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## the65gto (Oct 9, 2008)

Don't know if you read this thread or not, 51 pages, but may shed some light on your overheating problem. Chalk up one more for the cast impeller. - PY Online Forums.


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## geeteeohguy (Feb 2, 2008)

.....There you go. Excellent read. Fiesta, your '68 pulley will work if it is the same depth as the '67 unit. The belts must line up. You also need a good fan (large clutch type..19" or 19.5 is what I would use) an AC-spec radiator core and a good fan shroud. Or else co aftermarket super duper aluminum radiator and electric fans, and you should be ok.


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## Eric Animal (Oct 28, 2007)

Fiesta, If you "MAY" have a problem...I would take the car through the paces before changing parts for what might be no reason.....Eric


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## fiesta62 (Jan 12, 2011)

Eric Animal said:


> Fiesta, If you "MAY" have a problem...I would take the car through the paces before changing parts for what might be no reason.....Eric


hi, yes i get your point, i have not driven car much yet bad weather , but when i have i see temp around 190 give or take, but the other day i did a short drive on a mild day was sitting at lights and it got to 200, i figure when fitting new ac it would have gone higher, and on a real hot day who knows, from what i have read if it stayed at 200 max i am ok, but no hotter, i am thinking with ac and a hot day i will be struggling, but your right maybe i need to see it run first...


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## fiesta62 (Jan 12, 2011)

geeteeohguy said:


> .....There you go. Excellent read. Fiesta, your '68 pulley will work if it is the same depth as the '67 unit. The belts must line up. You also need a good fan (large clutch type..19" or 19.5 is what I would use) an AC-spec radiator core and a good fan shroud. Or else co aftermarket super duper aluminum radiator and electric fans, and you should be ok.


i was thinking to change both the water pump pully and the crank pully to the 68 pullys, the 68 crank pully is bigger than the 67 so will also help to spin the water thru quicker, so both these i assume will bolt straight on and line up correct, but i will check if the 68 pullys are the same depth as the 67 as i still need to line up to the new ac which is designed to run with the 67 2 groove pully.....if anyone out there can tell me the depth of the factory 68 pullys that would be great, might call one of the parts suppliers maybe they might be able to tell me....thanks for the tip..


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## Instg8ter (Sep 28, 2010)

:agree with the guys, fine tune what you have before you start swapping. the impellar clearance, shroud and the clutch fan are the keys. you want the fan about half in the shroud. Also you can install a new 165 thermostat to get it flowing a bit quicker.


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## geeteeohguy (Feb 2, 2008)

Fiesta, please listen to all of us. If you do your homework, you'll find that Pontiacs can and do run at temperatures in excess of 210 degrees for decades and 100's of thousands of miles without issue. 220 is NOT overheating. 240 and puking coolant is. I agree, an AC equipped car in hot climes needs all the help it can get, but I would drive the car a bunch and see what it actually needs. I read your other post that says you want to change out the body bushings....i was under the impression that your car was in excellent shape. Are you one of those guys who just can't leave well enough alone?? If you are, I'm gonna give you He**!!!!!


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## BearGFR (Aug 25, 2008)

I've got a copy of the Pontiac parts manuals here on CD. Guess what? The water pump pulley for 67 and 68 are the same. Both 67 and 68 use part number 9788886 which is a 2 groove, 5 11/16" diameter pulley, regardless of whether or not the car had a/c. On cars with factory a/c, the compressor was driven by a belt from a third groove on the crank pulley directly to the a/c compressor. It didn't "touch" the water pump at all. For model year 69, things got really ugly as far as pulley's because early in the model year the GTO used a water pump with a shorter snout and completely different pulleys. Later in the model year for 69 it "reverted" to the standard longer snout water pump and the short snout pump was discontinued. Whenever a water pump was replaced on one of these cars, you had to also replace the water pump pulley with one that had a deeper offset in order to preserve belt alignment. It was a real mess.

I replaced my factory a/c system with one from Classic Auto Air, so I'm familiar with their set up. Yeah, they want you to run the a/c compressor off either the alternator or the power steering belt and just use a long a** belt to do it. I didn't do that because that's dumb (and also changes how the belts run over the water pump pulley). I set mine up to use just the crank pulley like it did originally, and of course to make it line up right I had to "massage" their compressor mounting bracket to move the compressor back some. If you want details on how I did that, let me know.

If you're having cooling problems, the FIRST thing to do is to remove your water pump and make sure the plate clearance is correct. To do this, remove the pump, the gasket, and the steel plate from behind the water pump. Lay the plate onto the back of the water pump with NO GASKET - and gently "work" the big hole on the back side of the plate with a hammer such that it barely touches the pump impeller all the way around. When you re-install the plate and pump with a new gasket between them, the clearance will be right where it needs to be. Failing to do this and thus having too much plate clearance is the single biggest cause of most Pontiac overheating problems. It makes a huge difference in how well the pump works and circulates coolant. When I got my 69 together and running, I forgot to do this. Sitting still in the garage at an idle, the temp gauge on my 461 would creep up over 200-210 degrees within a few minutes. I pulled the pump and clearanced the plate, changing nothing else, and now it never gets above 160-170, even when I'm driving it hard --- and I'm in Texas so we understand the problems of running a/c equipped cars in stupid hot climates. 

Bear


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## fiesta62 (Jan 12, 2011)

BearGFR said:


> I've got a copy of the Pontiac parts manuals here on CD. Guess what? The water pump pulley for 67 and 68 are the same. Both 67 and 68 use part number 9788886 which is a 2 groove, 5 11/16" diameter pulley, regardless of whether or not the car had a/c. On cars with factory a/c, the compressor was driven by a belt from a third groove on the crank pulley directly to the a/c compressor. It didn't "touch" the water pump at all. For model year 69, things got really ugly as far as pulley's because early in the model year the GTO used a water pump with a shorter snout and completely different pulleys. Later in the model year for 69 it "reverted" to the standard longer snout water pump and the short snout pump was discontinued. Whenever a water pump was replaced on one of these cars, you had to also replace the water pump pulley with one that had a deeper offset in order to preserve belt alignment. It was a real mess.
> 
> I replaced my factory a/c system with one from Classic Auto Air, so I'm familiar with their set up. Yeah, they want you to run the a/c compressor off either the alternator or the power steering belt and just use a long a** belt to do it. I didn't do that because that's dumb (and also changes how the belts run over the water pump pulley). I set mine up to use just the crank pulley like it did originally, and of course to make it line up right I had to "massage" their compressor mounting bracket to move the compressor back some. If you want details on how I did that, let me know.
> 
> ...


hi bear, first just to say forgive any ignorance i might have i'm no mechanic, that info on the water pump plate is great, not sure i would tackle that but i have good friends who could....

on your ac setup i assume you had the 3 groove pully on the crank as you had factory ac, mine is 2 groove as my car is not factory ac, and the classic air system is setup to fit with my 2 groove crank pully, i guess i could go to 3groove crank pully but that would mean messing with the new ac position mounting i guess, would you go this way in my situation and use a 3 groove crank pully ? 

ok on the water pump pully mine is stock for a power steer non ac car as mine is, in the zazarine resto book page 371 its part number 9786819 its 8 inch OD, now the water pump pully for a 67 ac,ps, air injection car is part number 9788886 its 5 11/16" , so about 2 1/4" smaller this will spin the water pump faster and i assume keep car cooler....this part 9788886 is also the same pully the 68 used on the same 8 bolt water pump, bottom line my pully is correct for a 67 non ac car, but it is 8 " OD very large size compared to the 5 11/16" pully, so what would you think, would this help with cooling if i changed ? thanks, tony


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## fiesta62 (Jan 12, 2011)

geeteeohguy said:


> Fiesta, please listen to all of us. If you do your homework, you'll find that Pontiacs can and do run at temperatures in excess of 210 degrees for decades and 100's of thousands of miles without issue. 220 is NOT overheating. 240 and puking coolant is. I agree, an AC equipped car in hot climes needs all the help it can get, but I would drive the car a bunch and see what it actually needs. I read your other post that says you want to change out the body bushings....i was under the impression that your car was in excellent shape. Are you one of those guys who just can't leave well enough alone?? If you are, I'm gonna give you He**!!!!!


hello gt....well i'm a perfectionist and i guess that means i usually want things as good as they can be, i have only ever owned 1 gto so dont have any expierience in how they should drive or handle, i dont feel any issue with mounts now, nothing i know of, i just figure if mounts are original they must be buggered , i thought if they are buggered then a good quality new set might make the car ride better, but as said i cant feel a problem in the ride now , but you know i might change them and say wow the car rides way better, who knows...so yeah i cant leave things alone !....ok give me heaps i can handle it.....

so if car gets to 220 i dont have to worry then, as you say its not overheating... i just thought at 200 it was getting up there, its a matching number HO block i would hate to crack it....a friend dropped by he has a killer 66 455 gto and said it nevers gets over 185 ever, so i was concearned about mine getting to 200 after just a short drive in mild weather...

after some more research i know my water pump pully is 8" OD factory non ac pully.....the factory 67 ac, air injection pully is 5 11/16" would bolt straight on and give 2 1/4 " smaller pully so i would think help with cooling even if i am not overheating now without ac i figure on a hot day with ac i might be struggling, i will wait and see as you guys suggest, its just a long process to get parts here from the usa.....thanks :cheers


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## BearGFR (Aug 25, 2008)

fiesta62 said:


> hi bear, first just to say forgive any ignorance i might have i'm no mechanic, that info on the water pump plate is great, not sure i would tackle that but i have good friends who could....
> 
> on your ac setup i assume you had the 3 groove pully on the crank as you had factory ac, mine is 2 groove as my car is not factory ac, and the classic air system is setup to fit with my 2 groove crank pully, i guess i could go to 3groove crank pully but that would mean messing with the new ac position mounting i guess, would you go this way in my situation and use a 3 groove crank pully ?
> 
> ok on the water pump pully mine is stock for a power steer non ac car as mine is, in the zazarine resto book page 371 its part number 9786819 its 8 inch OD, now the water pump pully for a 67 ac,ps, air injection car is part number 9788886 its 5 11/16" , so about 2 1/4" smaller this will spin the water pump faster and i assume keep car cooler....this part 9788886 is also the same pully the 68 used on the same 8 bolt water pump, bottom line my pully is correct for a 67 non ac car, but it is 8 " OD very large size compared to the 5 11/16" pully, so what would you think, would this help with cooling if i changed ? thanks, tony


Hey Tony,
My parts book doesn't show a 9786819 at all. It lists 9788886 for three applications: 67 All V8 A.C. & A.I.R., 67 P/8 400 G.P. A.C., and 68 All V8 A.C., so chances are that by of this 1979 revision of the parts book 9786819 had been discontinued and superseded by 9788886. The book doesn't say why but perhaps because of the reason you mentioned - it's smaller and spins the pump faster. Pontiac made revisions on service replacement parts from time to time for various reasons, sometimes it was due to problems, sometimes it was to consolidate equivalent parts so they could save parts bin space to make room to start stocking the next model year's parts. 

Don't be afraid to tackle re-clearancing the pump plate yourself. It's not a hard job and there's really not much you can do to mess it up. Drain the coolant from the radiator by opening the drain petcock on the bottom corner of the radiator (save and reuse the coolant if it's relatively fresh), loosen (but don't remove yet) the bolts holding on the fan, loosen/remove the belts, remove the fan, remove the bolts holding on the pump, remove the pump and plate. Scrape all the gasket surfaces clean on the pump, plate, and engine timing cover - I like to use a flat wood chisel to do that. You'll need two new gaskets - one goes between the pump and plate, one goes betweed the plate and timing cover. This is also a good time to inspect the two round rubber seals that go between the back of the pump plate and the two tubes that go through the timing cover and into the cooling jackets in the block and replace them if they're dry and cracked.

Put the water pump in a vise, holding it by the pump body and not the shaft. If you don't have a vise you can support the pump body on the edges near the bolt holes with some short pieces of 2x4 - the idea is to make sure when you're hammering on the plate that you don't put any forces into the pump shaft as it can damage the bearing. Lay the pump plate on the back of the pump with no gasket, then hammer around the big hole until the edges of it just kiss the pump impeller. You want to work it down a little at a time so that you keep the edge of the hole relatively "flat" instead of creating dimples/waves in it. Just take your time - it'll take awhile. It helps to use some small c-clamps to hold the plate in position on the pump and also drop a few bolts through the holes while you're working it. Re-install the plate and pump with fresh gaskets, a little gasket sealer, then reinstall the pulley, fan, belts, etc. and re-fill with coolant. You'll be surprised at the difference it makes.

Bear


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## geeteeohguy (Feb 2, 2008)

Glad you have a sense of humor, Fiesta. 200 is not getting up there, it's actually about the perfect operating temperature of one of these engines, thermal efficiency wise. 185 is about as cold as you'd want to run....cooler than that, you'll start sludging up and wearing out the engine. I've run these cars 100's of thousands of miles over the past 3+ decades through the deserts and backroads of the American West and Southwest woithout ever blowing a head gasket or cracking a block. Have fun.......that's why we're all here!


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## fiesta62 (Jan 12, 2011)

BearGFR said:


> Hey Tony,
> My parts book doesn't show a 9786819 at all. It lists 9788886 for three applications: 67 All V8 A.C. & A.I.R., 67 P/8 400 G.P. A.C., and 68 All V8 A.C., so chances are that by of this 1979 revision of the parts book 9786819 had been discontinued and superseded by 9788886. The book doesn't say why but perhaps because of the reason you mentioned - it's smaller and spins the pump faster. Pontiac made revisions on service replacement parts from time to time for various reasons, sometimes it was due to problems, sometimes it was to consolidate equivalent parts so they could save parts bin space to make room to start stocking the next model year's parts.
> 
> Don't be afraid to tackle re-clearancing the pump plate yourself. It's not a hard job and there's really not much you can do to mess it up. Drain the coolant from the radiator by opening the drain petcock on the bottom corner of the radiator (save and reuse the coolant if it's relatively fresh), loosen (but don't remove yet) the bolts holding on the fan, loosen/remove the belts, remove the fan, remove the bolts holding on the pump, remove the pump and plate. Scrape all the gasket surfaces clean on the pump, plate, and engine timing cover - I like to use a flat wood chisel to do that. You'll need two new gaskets - one goes between the pump and plate, one goes betweed the plate and timing cover. This is also a good time to inspect the two round rubber seals that go between the back of the pump plate and the two tubes that go through the timing cover and into the cooling jackets in the block and replace them if they're dry and cracked.
> ...


bear....wow thanks for the info i will have a go at it when i get a few other things sorted, i am going to run the car first for awhile just to see if it does get over 200 or over say 210 , but sounds like a job worth doing on that plate

also just to mention guys rukee gave me a kick up the backside about multipul threads, and thats cool, i thought if i only put in say general then the tech section may not see my question or visa versa , anyway i will only do 1 thread from now on, thanks


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## geeteeohguy (Feb 2, 2008)

I have to say, Fiesta, I've met a few of your countrymen from down under over the years, and to a man all of them had excellent senses of humor and were grounded, high-functioning individuals....great fun to be around as well. Without the wonders of the internet, think about how much more difficult it would be to get _any_ of this stuff done! Gotta go.....I need to remove all my wheel studs and inspect the splines on them!!! Just in case!


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## Rukee (Feb 8, 2007)

fiesta62 said:


> also just to mention guys rukee gave me a kick up the backside about multipul threads, and thats cool, ...


Really? I even said "Please" and everything....:confused


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## geeteeohguy (Feb 2, 2008)

I think he could use another kick, Ruk!!!! But what's MY opinion worth???


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## pontiac (Mar 6, 2011)

thought the 68 water pump pulley was a one year only since it works on an 11 bolt water pump with the older 67 6 bolt crank. Not sure the depth is the same as the 67 water pump pulley.


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## fiesta62 (Jan 12, 2011)

geeteeohguy said:


> I have to say, Fiesta, I've met a few of your countrymen from down under over the years, and to a man all of them had excellent senses of humor and were grounded, high-functioning individuals....great fun to be around as well. Without the wonders of the internet, think about how much more difficult it would be to get _any_ of this stuff done! Gotta go.....I need to remove all my wheel studs and inspect the splines on them!!! Just in case!


gt..that makes me laugh hope your splines are ok !! by the way my mounts look great so no issue there, not new but look fine....had to check them just in case !


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## fiesta62 (Jan 12, 2011)

Rukee said:


> Really? I even said "Please" and everything....:confused


hey rukee i'm cool...kick away anytime....


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## fiesta62 (Jan 12, 2011)

pontiac said:


> thought the 68 water pump pulley was a one year only since it works on an 11 bolt water pump with the older 67 6 bolt crank. Not sure the depth is the same as the 67 water pump pulley.


hi , the 68 water pump pully number 9788886 is the same part number on the 67 ac, air injection , so i assume same part number then same depth....either way i am looking for that 9788886 pulley....thanks


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