The '71 with the new motor always ran hot. And by hot, I mean 200-210 degrees while driving 80MPH when the temp outside was in the 40's. The last time I drove it during the day, it rose to 220 degrees and it was only 80 degrees outside. Not good.

Pulled the water pump and sure enough, it had a stamped steel impeller. Went to Auto Zone and got one with a cast impeller. Even though the stamped impeller was 4" in diameter versus the cast impeller being only 3", I drove it home tonight with a 55 degree outside temp, and the guage never went over 180, whether on the freeway or the street. http://forums.performanceyears.com/g...on_biggrin.gif

very interesting......
Glad it helped...!

I've got a few words on that subject: I don't have a stamped impeller, but I do know that pump efficiency is directly related to the clearance between the divider plate and the vanes. If your clearance, (regardless of cast or stamped) is more than say, .060", YOU ARE THROWING AWAY COOLING EFFICIENCY. I tweaked mine from about .250" down to about .100" and it made a drastic change in my engine temps with no other changes.

You can spend money on big radiators, electric fans, magic cooling fluid, yadda,yadda, but if you are running a large clearance all the other stuff is a band aid. Do the clearnace thing first, then go from there. Cost is a few bucks for a gasket.

Not only that, hot start problems went away too...a possible side benefit.

George

George,
After reading your post above, it tweaked my interest enought to cause me to go out to the shop and pull the water pump to check this out. Sure nuf, about a quarter of an inch between the pump vane and the rear internal housing that allows water into the pump vane. Looks like you have hit the nail on the head! If it can't pump efficiently, all else is just for fun. I assume you just tweaked it with ball peen hammer to fit closer to the pump vane, right? I'd love to just do that and put it back together, but I'm thinking a new pump and fan clutch wouldn't hurt before I put it back together. Sure hate it when you know you should change something, then don't and it fails two weeks later! I know there is nothing wrong with the pump or fan clutch now, but if I change them I'll wonder which did the trick. Your suggestion sure does make sense AND it can't hurt. I will try it.
Thanks George, I do appreciate it.
Charles

[I tweaked mine from about .250" down to about .100" and it made a drastic change in my engine temps with no other changes.]

I agree that this sounds like a pretty good idea. How did you measure the clearance though?

I took the pump & put it upside down on the bench (obviously you have to take the pump off) put the gasket on it then the divider plate. Measure the clearance between the pump side surface of the plate and the edge of the vanes. This should be made as close as possible. I used a hammer to carefully bend the circumference of the hole of the divider plate towards the vanes.

The suction of the pump is thru the center hole, and the pressure side is around the tips of the vanes. Too much of a gap between the plate and the vanes and the pump tends to draw coolant from the pressure side instead of from the center hole (which is plumbed to the radiator and the hot side of the block).

That's why minimizing this leakage path improves flow thru the engine and thru the radiator (when the thermostat is open).

George

George,

Thanks for the additional info. I just added that to my "To Do" list once everything warms up around here. It would be great if that dropped temps enough that I don't have to spend the $$$ on an aluminum radiator.

Here is a picture I borrowed off ebay. So you are saying to bend the center section towards the impellar so there is about a .100 gap? Is it pretty easy without distorting the whole plate?

Yep, that's exactly it. Tap lightly and evenly at the perimeter of the hole. It doesn't take much. Remember to size it up with a gasket in place to give the proper installed spacing.

Measure it first; if more than .1" (approx), you should adjust it. Mine was about .25". I stopped at about .1" to make sure the vanes wouldn't contact the plate when the gasket was compressed.

George

George,
Have you had any problems with the plate contacting the vanes once it gets hot? Or is the plate strong enough not to flex with the heat?

I don't have any problems with contact. I also doubt if the plate would deflect enuf under normal temps to cause contact. I tried to be reasonable about closing up the clearance to avoid just that scenario.

A mechanical engineer can chime in here... but I'll bet that pump efficiency is VERY sensitive to small changes in gap; max efficiency at very small gaps and efficiency probably decreasing very quickly with small changes, i.e. the pump will probably be useless at a gap greater than .3" or so.

Since the vane tips have higher pressure, and the center hole has lower pressure, it doesn't take much of a gap for the fluid to take the short path around the vanes instead of flowing out to the block. Would be nice to have some hard data......

I'm looking forward to reports from yourselves to confirm or deny my results.

George

A while back i also received correspondence from Geoff in Australia regarding this subject. I'll paste it in here:

George,
I saw your comment about closing the gap between the impeller & the divider plate. I went even further than you did. Using some scraps of stainless steel
exh pipe, I cut strips about 1/4'' wide & the same length as the impeller blade & brazed them onto the back of the blades. I did one blade at a time, & carefully
ground the extension a little bit at a time until the impeller would rotate without touching the plate. I then did the next blade until all 8 were done. Clearance between
blades & plate was 0.030'' at most. What a difference! This pump cools better than the Flow Kooler.

Geoff,
Australia

Pretty innovative, I'd say.

George

Does anyone know if this works on the earlier water pumps or just the later ones? Also, George can you whip up some kind of diagram to show where and how you took the measurement. I'm still not completely clear on where and what you bend but then again, I haven't had the water pump off my pontiac too look at it. Thanks

Here is the pic with a markup showing the edge to adjust. The pic shows the convex side up. When installed, the pump vanes are under this plate. Bend this edge down until the gap between this edge and the edges of the vanes are minimum.

George

Well, I got a rebuilt pump yesterday from Cardone, because I was impressed by the larger pump vanes from my old one.

http://www.partsamerica.com/PartDeta...ype=54&PTSet=A

Tried the fit before bending the divider plate, and was surprised to see that the Cardone pump had vanes that were 3/16 " taller than the old one. The divider plate would only require minor tweaking. Will attach two photos showing the difference. Old pump first, new one next post, cause I can't figure how to attach two pics in one post.
George, I love the way you think simple. Is it plugged in? Is the ground loose? Think before you spend all day going around in circles and starting over at the beginning.
I know I said I wouldn't make any changes except the tweaking of the plate, but I just could not resist the pump with the larger vanes. Will have it running on Saturday and give you a full report then. Same everything else for now, because we can change the others easily if needed.
Charles

New pump, check the clearance. No difference in plate tweaking.

Dean, he's advocating bending the internal housing on attached photo from 67 manual.

Gang, sorry if I caused some confusion. The pic from the '67 manual is not exactly what I have since my engine is a '74 455. conceptually, tho, the plate that needs adjustment is the one that comes closest to the face of the vanes as in Charles' pix, above. In the pic from the '67 manual, the plate in question is what the book calls the internal housing.

I was unaware there was such a difference over the model years.

Interesting that there exists such a difference in width of pump vanes! Perhaps this is a good example of the idea that "the cast impellers are better"?

George

Gang,
Couldn't wait to get in here to tell the story! The only change being the new water pump with bigger vanes ($24.00) and tweaking the divider plate and I can report fantastic success with George's suggestion!
Before I did this the after market gauge was reading as high as 230 degrees, and had been for years! After I did this, the highest it read was 190 degrees. It's 81 or 82 degrees here today. Running a high flow Stant thermostat tested at its rated 160-degree opening. I decided to test the temp of the water in the filler of the radiator with two of Mama's cooking thermometers (she's NOT here!), after I returned home, with the engine still running. By the way, the flow of water from the pump is so high that if you rev the engine a little, the water hits the cooking thermometers and jumps out the top of the radiator! One cooking thermometer showed 163 and the other showed 165!!!! Therefore, we calibrated the Temp gauge to read properly by adding a 10-ohm resistor in series with the sense lead. Now it is as dead on as those things can be!
I am so tickled; I'm like a kid at Christmas when he gets his first BB Gun! When I think back on all this, I guess I never thought to check the clearance of the divider plate to the pump vanes years ago when I replaced the original water pump!! Just ASSUMED it was the same configuration! There's that word again! Dad was right.Think, Son, Think!
To George I owe a great THANK YOU, you caused me to start using my head.
To the other guys that make money on radiators, I am sorry, but I won't be buying a $500 radiator.
Have a marvelous day guys, it is now SPRING!

That's great to hear yet another success story! Your configuration is better yet, since the vane area with your new pump is even greater.

George

george, are you running a fan shroud?
clutch fan?
thanks,david

hey 67 where did you buy that pump?

nevermind i reread the post .lol...plus i think yours is older I have a 74 455 but the same concept applies thats why i never run a thermostat cause they run hot I will definately have to check mine now and then run a 160*
thanks George!

No, I don't have a shroud. That was in my plans earlier, along with a larger radiator, but now I'll wait for the warmer weather B4 I make any further changes. First I have to finish the windshield repair, paint the dash, get the windshield back in........etc.

I do have a clutch fan, tho.

I was heating at idle, temp was going up to 220 just at idle, fan was working, everthing seemed to be in order, yet the system couldn't get the heat out of the engine. One thing led to another...... the simple fix worked; cost was that of a gasket.

So far so good!

George

old goat, how about you?
running a shroud and clutch fan?
thanks,david

Yes, David, everything stock except the 160 thermostat. Oops, I have a staggered 5 core radiator in there for about a dozen years. Forgot about that, it's been in there so long! The core was put in the original top & bottom tanks. Brother in law had a radiator shop! Bumper sticker read "Lafayette Radiator - Best place in town to take a leak!"
Charles

went to parts store today to check on water pump oldgoat suggested.
part no. is good, they have to order in part. will be here monday.
but...my clutch fan seems to spin quite easily.hardly any drag at all. does this mean it is bad?
looked into replacement clutch.
question...what is diff between thermal and non-thermal clutch. which should i get?
thanks,david

David,
When you get the new pump in, check the position of the impellor on the shaft. Reference to my picture on preceding page, the impellor was not pressed on the shaft far enough, it was flush with the end of the shaft. The impellor was not sitting in the recess of the pump housing properly. It was too far out on the shaft for the divider plate to fit. Your unit may or may not have to be adjusted. Someone may just have done mine on Friday afternoon. Feel free to holler when you need to.
I am not familiar with the Thermal or Non-Thermal designation. Could they mean Thermal or Friction clutch? Below is the clutch info from the 67 Pontiac manual, so you can understand the operation of the fan clutch.

THERMOSTATICALLY CONTROLLED ENGINE
FAN FLUID CLUTCH
A thermostatically controlled engine fan fluid clutch is used on Air conditioned equipped cars and operates only when additional air flow is required to reduce radiator coolant temperatures.
This clutch is of simple functional design and is made of lightweight metal filled with silicone oil which is hermetically sealed. The finned (rear) housing contains a hub assembly (secured to the housing bearing) which attaches to the engine water pump. Four bosses with tapped holes (in the rear face) provide for attachment of the engine fan. The front surface of the housing has six deep circular grooves which index with six matching bosses on the rear face of a floating clutch. A separator plate and front cover (with thermostatic coil control) complete the clutch assembly.
FUNCTION
During periods of operation when radiator discharge air temperature is low (below approximately 150°F.), the fan clutch limits the fan speed to 800-1400 rpm. In this position, the clutch is disengaged since a small oil pump driven by the separator plate forces the silicone oil into the reservoir between the separator plate and the front cover assembly. In this position also, the passage from this cavity to the clutch area is closed by the coil spring leaf valve.
As operating conditions produce a high radiator discharge air temperature (above approximately
150°F.), the temperature sensitive bi-metal coil tightens to move the leaf valve (attached to the coil)which opens a port in the separator plate, allowing flow of silicone oil into the clutch chamber to engage clutch, providing a maximum fan speed of approximately 2200 rpm.
The clutch coil is calibrated so that a road load with an ambient temperature of approximately 90°F.,the clutch is just at a point of shift between high and low fan speed.
No attempt should be made to disturb the calibration of the engine fan clutch assembly as each assembly is individually calibrated at the time of manufacture.
Under certain temperature conditions there is an apparent lateral movement at the fan tip which should not be considered as a hub or bearing failure. This condition is a design feature of the clutch assembly which allows up to approximately 1/4" lateral movement measured at the fan tip.
NOTE: Testing a fan clutch by holding the small hub with one hand and rotating the aluminum hous
ing in a clockwise/counterclockwise motion will cause the clutch to freewheel, which is a normal
condition when operated in this manner. This should not be considered a test by which replace
ment is determined.

Hope this helps you to decide. Why not change just your pump first to see what good you did there, and then change the clutch if you still need it? Do you feel good air flow from the fan now or not?
Good Luck
Charles

Facintating !

Border line brilliant
My opinion only, Where's my ruler and hammer.
the larger vane pump, the cardone, were did you get it?
I noticed that the diagram did not show the plastic tubes.

Duh, I see it now.

I would like to offer a suggestion / test.
Try running it with no T - stat.
My car runs 20 degrees coler with no T - stat.
However she will climb in temp at idle.
Once the stat is open, it's open, try drilling some holes in the stat you have that didn't work well. I am pushing the idea of trying no stat vs. modified stat.
Really the distance of the plate seems such an easy solution when you think of it,( I didn't ) It will just grab more water to push thru the system, the larger the gap, the more it spins in the same area of water, slowing down the flow. I was wondering what the temp difference will be between the two, Glad to see your problem fixed, just wondering how much the flow will relate to temp changes.
Facinating.........

Seems so easy......Nothing more than a few taps of a hammer.
Could this be the cure for us?

I think it may be presumptious to say it will cure all temp related evils, but in near-stock applications I think it very well may.

More data from board members would be nice to see just how good a solution this is; i.e. a more scientific test.

So far 3 members yes, 0 no.

I became curious when reading all the posts related to high engine temps and kept asking the question "Why now? That wasn't the case when the engines were new 40 years ago. What's the diff?"

Since mine was essentially stock, and seeing the same thing, I pulled my pump to see if it had the stamped impeller. To my dismay, it was cast. A closer look and I saw the clearance issue and figured "what the hell, maybe in all the years, the rebuilders got sloppy and didn't press the impellers on the shaft to the proper clearance spec.

ANyway, my idle temps stabilized and it doesn't puke coolant after shutdown. This summer, I'll do some more testing & see.

Some more data from board members would be nice to see just how good a solution this is.

George

The termostat is there for a good reason, to get the engine up to operating temp quickly & evenly. It's function is to regulate the engine temp to allow proper expansion of all parts. Running without one is not a good idea in my opinion. In a properly funtioning system the thermostat will regulate the temp by opening and closing on design. Too much flow, it closes and brings the temp back up. I have always believed this and after trying George's suggestion, proved it again. Now I'm worried about it running too cool! That's a hell of a change! As I said, I am running a HIGH FLOW Stant, same design as the Stewart components thermostats talked about on this forum. Folks, be sure not to use the one's you get at the local auto parts "deaf and dumb village" places we all have now. Most of what you can buy there would not be sufficient for a four wheeler engine.
Rugratman, if you are running 20 degrees cooler without it, your machine is trying to tell you something. You are marginal in the cooling department. Fix it before you are telling a tale of woe about overheating for a long time, LIKE ME!
George made me go back to thinking and I cannot thank him enough!
I bought this GTO brand new, and should have been able to sense that something was not right after replacing that water pump 12 to 15 years ago. It wasn't that bad at first, because the rest of the system was at peak. Instead of getting down to ANALYZING it, I tried to fix it with everything else I could think of.
Of course, I can use the excuse that it wasn't the main transportation tool anymore, but that's a weak excuse. She has never let me down, why did I let her down?
Anyway, all I'm trying to say is "learn from my mistakes".
Have fun and keep Wide Tracking,
Charles

Aonther thing: to me it looks like the idea that you have to slow the coolant flow to pick up heat from the engine and exchange it thru the radiator doesn't hold "water" (sorry for the pun). The more efficient pump will be moving a greater volume of coolant in a given time and that seems to cool better, IMO.

George

You Da Man george!

All members with a cooling improvement please send $1.00 to: Georges' Retirement and GTO fund,
Grand Cayman ISland, BWI LOL!

I'm game! Damn straight!

If I am to understand you correctly, the divider needs to be pushed in or pulled away from the internal housing? When I put in my rebuilt water pump in the fall, along with hoses, thermostat and radiator cap, there was some kind of sealer between the two that I peeled off,cleaned up, so I did the same again. I think I put a sealer on the dividers to keep em from moving around and in place next to the internal housing. When I parked it in the fall, on the way to storage it ran sluggish and the temp was going up. http://forums.performanceyears.com/g...n_confused.gif

This IS very interesting, I haven't visited this forum yet, I'm glad I did!

Two things:

1) I've done lots of waterpumps and I have definitely seen lots of impellers pressed on to the wrong depth. Too far, or not enough.

2) While this careful attention to impeller depth is good, is there a penalty in how much more HP the "new and improved" waterpump is consuming? Can there be too much pumping resistance? I think I've heard that some waterpumps can suck up 10-15 HP? Probably not a big deal to most, but the semi serious racer guys may care...

Rudy, on that '67 diagram of the pump assy, the flat surface of the internal housing shoould be adjusted towards the surface of the pump vanes.

There certainly will be more power used by an optimized pump. However, I believe the goal here is to get the assembly back to the OEM design specs; as such there obviously is a limit as to how "good" or lossy the pump will be.

I guess for race purposes, the pump clearance can be relaxed, (less power wasting) at the expense of heating. An interesting trick...

One way to estimate how much power is used by the pump is to check the specs of an electric pump and get the HP figures from that. They should be fairly close.

George

With a mechanically driven pump, the power usage increases with RPM. An electric pump such as a Meziere uses about 98 W, less than 1/4 HP, according to their specs. Of course, it's constant speed and delivers 35GPM.

Just a thought for the serious racer.

George

George do you accept Canadian at par ? I didn`t think so .

OK, I read the post, and immediately tore into the engine last weekend. Pulled the water pump, and divider pump. I measured the clearance between the vanes, and the center hole in the internal housing (mine looks like the pic that old goat posted) and it was about at .4"!!! So I knocked it with the hammer until it was about .09” reinstalled, and much better, but not completely fixed. It used to run about 220, especially in traffic, now it’s down to 200 plus or minus. It really helped, but still looking for a little more. Any suggestions from you guys? I put in a 160 stat. With that, and that water pump housing modifications, it takes a lot longer to get hot, but still will eventually. This was a great tip though, thanks for the help.

[This message was edited by eric17621 on March 23, 2004 at 01:12 PM.]

Interesting observation. Since you say your configuration is similar to Old Goat, could it be possible that the original had the deeper vanes? I find it hard to believe that the factory would design it with that large of a gap. (.4",WAY too large). With this new data I would suggest that engines using the internal housing style of pump should have a pump style such as Old Goat installed currently.

Looking at the problem from the other direction, Old Goat stated he replaced the original pump (he bought the car new) some 10 years ago or such, and his heating problems started then, but not really noticed since the car was driven less.

This leads me to believe the first replacement pump had the wrong vanes.

Eric: I'd say If you could get a pump with the deeper vanes, you would be better yet.

Kate's GTO: the banks in Grand Cayman will be happy to accept your currency!

George

Those who still believe the old wives tale of water flowing 'too fast' should view the stewart components website, where this & many other 'myths' are de-bunked.

www.stewartcomponents.com & then click on Tech Tips

Guys and/or Gals,
I tried the best I could to tell the major difference between the two pumps. YES, the old pump I took out DID NOT have the depth of vanes that the replacement has. Therefore, it can be concluded without much speculation two things. 1) A greater amount of surface area of impellor blades WILL move more water. 2) Absence of space between the vanes and the rear and front of the impellor WILL NOT allow as much cavitation. That is why I used George's suggestion to the maximum.
I first made sure the pump was pressed on the shaft to put the impellor as far into the front casting as it was supposed to be, and secondarily "tweaked" the divider to conform to the back side of the impellor configuration as possible. Any impellor on any water pump must operate in a specific area to be efficient, without any external or internal forces acting against its performance. Case in point from my boating days; any propeller on a boat motor that has a blade out of sync with the rest of them or air allowed to enter the slip stream of the water pump (that’s what a prop is) will create turbulence (inefficiency) in the water flow. Turbulence is defined as A: “wild, unruly, disorderly commotion” and B: “disorderly or tumultuous conduct” and C: “departure in a fluid from a smooth or streamline flow with accompanying sinuosity and eddies”.
It ain’t rocket science, it’s just so simple it works! That’s what’s called the KISS principle. “Keep it simple, stupid!”
What’s really mind-boggling is that I missed it 12 years ago! My only defense is that after changing countless water pumps before and never having such a problem is that most other pumps do not have a rear pump plate that affects the operation of it as ours does. Most go into a predetermined back spacing area that is not going to affect the pump operation, as is present in this design. In 37 years, this is the most aggravating thing I have found about the design of this engine, and it wasn’t Pontiac’s fault. It was the fault of the supplier of the replacement pump I happened to use AND mine! My GTO engine is RIGHT now and I hope only to help you folks have the same. Knowing that I can go down the road and get back to listening and feeling for the symphony between man and machine while not having to worry about that DAMN temperature gauge is priceless. My only worry in that department now is “am I running TOO COOL”.
There are at least 4000 other parts on that thing, let’s give them their fare share of time and attention. She has always taken care of me; I should do the same for her. In 124,800 miles, this girl has NEVER let me down. Sunday driving or “buddy, gonna shut you down” type.

Would I contribute to George’s retirement fund, Damn Straight!

Please, everyone have a good day!
Charles

This is a great thread!!! I'd bet many of our cars have this problem to some degree. I can't wait to tear mine open and check. Thanks George.

Old Goat - Unless theres something I don't understand about the cooling system, I'd say that running too cool is an easily controlable problem (vs. running hot). Can't you just install the appropriate temp thermostsat to rectify it?

Thought I would add some more.... I'm going for 1000 posts...

A good analogy for water flow is air, fans and heat sinks used in the electronics industry. Anyone who has looked inside a computer knows that there is a massive heat sink and fan on the processor. The obvious purpose of the fan is to increase airflow thru the heat sink to keep the CPU as cool as possible. The greater the airflow, the cooler the CPU.

In fact, the thermal specs on heat sinks show heat sink temperature vs. air flow. The sink temp is ALWAYS lower with greater airflow. Air is a fluid, same as water, just less dense.

An excellent analogy. Why didn't I think of it before?

Keep those dollars coming..... 1000 posts are in sight!

George

Fantastic results and a great explanation! http://forums.performanceyears.com/g...icon_smile.gifI think this is as close as we've come the "holy grail" for cooler-running Pontiacs. I can't wait to try it.

Nice work George.

Regards,
Bob Trimpe

My local checker auto parts store has that water pump in stock. I will be trying this also, as soon as I get the chance.

Hey Bob, can I get your pledge for a buck? (a shameless attempt to increase the number of posts)

George