[george kujanski]

Glad to hear another success story Richard! Welcome to the boards. You owe me a buck.. just kidding.....

George

[PMDRACER]

Hey George - I get a cut!

Woo-Hoo! 10,000 views.

[car guy]

Are the factory pumps cast of steel impellers? The reason I want to know is that my car has a part # 488296 on the water pump and I hate to take it off just to find out. I belive it is original as the rest of the car is and would hate to replace it with aftermarket if I don't have to. A search of that number on the PY part# page gives no result. Anyway the car has never had a heating problem until this year so I will look at other things as well but am currious about the impeller question.

[george kujanski]

If indeed it is original, I would leave the pump alone, altho it may be a good idea to open it up to check for corrosion, deteriorated sleeve seals, etc.

PMD: you certainly deserve a finder's fee. I'll give you 30% of what I get. Now if I get a buck for each view.....I might have to give CCass a cut.. then there's OLD GOAT67, then there's...

George

[pontiacjeff]

Well, now I might have hit on it. I have been saving stock pumps for a while, but realized I might have screwed the pooch on my 455. I just thought 200-225 temps (highway only, 4.11's) were just a fact of life with that much gear (70mph=3800). It will idle or creep in traffic at Tstat temp or less (180) even on extremely hot days (90's-up), but on the hiway, even in the winter when air temp is cold, it runs 200+. I will be checking the pump on Monday, first thing. THANKS! And to the guys a CP. for posting the link.

[Old Goat 67]

George, Thanks but I already have my payoff... 165 degrees and the pleasure of watching these others find this post 10133 times and fixing their "old goats" so easily.
Thanks dude, Charles

[grandville455]

Ok guys you want to hear some funked up stuff I got my other pump in yesterday and I used the bigger cast impellar one of the 3 I bought lol....now here's the great part my old one was a stamped ONE with about 1/4 inch clearance on the plate!Never had one bit of overheating probs with old one,but had to replace cause bearing was bad....anyway no over heating with this new one either also went to 180 super stat...
just something more to think about The pot thickens more?

[ped.2]

Wow, what a difference. I was previously running too hot to feel comfortable taking my GTO past 75MPH for more than a few minutes. Since I reduced the gap to .06 to .1 from .25, I’ve seen a tremendous drop in temp. I can now cruise for as long as I wish on any day at any sane speed without any worry about temp. Thanks so much for the tip. An hour’s labor and the cost of a gasket solved all my temp concerns. It’s quite amazing that an inexpensive easy fix made such a tremendous difference.

Thanks
ped.2

[unclescratch]

This is excellant work, guys!! We should not be too surprised if we recall comments made by Stewart Components (a manufacturer of water pumps for NASCAR racers). Among their suggestions: a 160 t-stat, 22psi radiator cap, smooth radiused hoses ( not those fitzall accordion type) and precise ((close??)) tolerances between the housing and impeller, and others.

[george kujanski]

Grandville: go figure.

ped.2: welcome. glad it worked for you.

with the amount of new members to this thread, maybe Ccass should give us a cut......

George

[GR8ONE68]

Well, I installed the new/rebuilt pump and plates. I am not sure of the actual clearance, but it is less than the thickness of the gasket. Let me start by saying that I believe everything in this post and it is breaking new ground in the Pontiac cooling problems.

When I remove the old pump and plates, I measured the clearance at .200". I thought, "this is it, I will stay at the thermostat temperature." I put in the new pump and plates and took it out on the highway for a test at 80 mph and 4,000 rpm. I was disappointed to run at the same temperatures as I had run before. I did get piece of mind out of it, I would think that my clearance is less than most. The impeller hit the plates with the new set up without the gasket in place. When I put the gasket in place, it cleared. It moved freely when it was installed in the car.

I believe the next step is to put a new factory fan set up in as 71Formula recommended. I have a new heavy duty Hayden fan clutch. I believe that the issue with to old one is that someone put in a fan spacer to "push the fan closer to the radiator." From what I read, the fan blades should be half way out of the shroud and they were flush with the edge of the shroud. I believe that this spacer caused two problems, 1) it put the fan too close to the radiator not allowing enough air to be move through the radiator. 2) the spacer put too much weight on the water pump bearing and was causing them to fail prematurely (believe me I am an expert in premature things ). I have to find a new/used fan to replace the one that tried to go all the way through my radiator, it only made it about 1/4 of the way through.

I will post back with my results.

[george kujanski]

Too bad that the pump/clearance was not THE problem, but as you say, it is working at max efficiency, at least.

High speed cooling mostly depends on getting airflow thru the radiator, assuming coolant flow is correct and the engine is not developing too much waste heat.

Perhaps the incorrect fan setup was somehow preventing max airflow thru the radiator? In any case, let's see what the new fan clutch and fan will do. Do you think the gauge is correct? Obviously you don't see a change, but is the actual temp indicated pretty close?

George

[car guy]

For some reason my 71 Lemans with a 400 has started to run hot enough to cause slow cranking when starting, temp.200-210. Never had a problem until I got it out of storage this spring. Anyway I plan to pull the pump and check things out and adjust the divider plate clearence either Monday or Tuesday and will let everyone know what happens. By the way My car dosent have a temp gage so I got one of those hand held tempeture gages that has an infrared pointer. You point it at the object and it gives you the reading.It seams to be pretty accurate. I get the reading by pointing it at the thermostat housing. Anyone else use on of these? Do You think they are any good?

[convbird]

My buddy sent me the link to this web site and I thought this would be the answer. I bought a new backer plate and cast impeller water pump for my 68 firebird 400, but temp still keeps rising at idle. I have a new clutch and fan(6 blade from hayden. Timing and mixture is good. I just can't seem to get this thing to run cool at idle. Temp also increases dramatically when I shut the car off. If I down shift while driving and raise up the rpms the temp will drop quickly(This is why I think it is a flow problem). This engine is almost stock(.030 over, .42 lift cam., Holley 750) Any ideas guys? This has been going on for 3 years and I have run out of ideas.

[convbird]

One more thing. I am running a brand new 4 core radiator.

[GR8ONE68]

George,

Yes, I have a new set of gauges. It will sit right on 160° at idle, which is the temperature rating of the thermostat that I have in there now. The other thing that I was thinking about is the mixture. I do have a lean condition. I know this because after a run at the track, I pulled a plug and it was as white as the day I bought it. At 4,000 rpm, it may be running too lean. I have an Edelbrock 750 on it now. I also have a '68 Q-Jet sitting on my other motor. I will pull it off and try it and see what happens.

Kevin

[wheelspin]

I would like to add something to this xlnt cooling thread, once you have reduced the coolant temp. in the the radiator, the hot air generated must be able to exit the engine bay. I have found it very benefical to remove the the a-arm "skirts" on my non-concourse Pontiacs in order to remove trapped hot underhood air.

Les

[azbirds]

One thing I've noticed on this thread. When some of you are talking about a new overheat problem and you haven't changed you waterpump the fix with the backing plate will probably not be an issue, unless someone has slipped into your garage at night and changed the pump. I know some people have to put their cars up for the winter and it could be an issue of the silicates falling out of suspension in the antifreeze. I bought a 70 Formula from a friend that had no heating problem, until I headed for Phoenix with it.Long story short: It was the 70% clogged radiator. Letting a car sit for long periods is not good for it.

[george kujanski]

Good point, azbirds. If a car starts overheating with no other changes, something else is going on that pump and divider plate tweaks may not change. A clogging radiator would be most likely if overheating after storage, for example. As mentioned B4, that fits one of the causes of overheating, i.e. flow restriction.

Perhaps running a test such as OLDGOAT67 did early on in this thread to check flow thru the radiator would be a thing to do.

George

[car guy]

Where do you get these water pumps at? I have been to NAPA, Auto Zone, And Advance Auto and all they have are the steel. That is typical where I live you can never get anything done without making several trips and special ordering. My car is a 71 I would think the pumps are the same for most 400 Pontiac engines.Is this cast impeller limited to certian years?