Runs Hot - Out of Ideas

How is the distance between the impeller and the timing cover? Correct?

That water pump impeller looks small and has six vanes. Compare it to this one for a 70 318, bigger and 8 vanes
Hmmmm......

Lose that pump, likely a drag race item, to move water enough for short blasts, but with less drag and less horsepower loss.

I'm with these guys on that pump. Something not right.  Distance impeller rotation size.  Something

Larry Shepard book mentions 6 and 8 blade pumps, pulleys and overheating. Worth trying the 8 blade pump and checking the pulleys to make sure they're correct for the pump.  https://books.google.com/books?id=S7rgkZGzqVUC&pg=PA158&lpg=PA158&dq=mopar+performance+small+block+water+pumps+any+good?&source=bl&ots=UDiCWAZsVd&sig=Nazfh5v5zxfO9yNgIk82pDMMBkk&hl=en&sa=X&ved=0ahUKEwjorpzKkubSAhXH44MKHeoECZ84ChDoAQg6MAU#v=onepage&q=mopar%20performance%20small%20block%20water%20pumps%20any%20good%3F&f=false

Oh god I am in a coolant quagmire. The concept of the eight blade pump is a good idea, except, seems old Larry Shepard wrote the section on pumps following rumors and not Mopar fact. I like the idea, even passed the idea past Bouchillion Performance, the purpose of the six blade was the pulley set up would spin the fan faster providing more cooling and to eliminate cavitation the blade size and number was reduced to six.

Starting in 1970 Mopar supplied two styles of pumps for the small block

Without air--4.38" dia.--8 blade--.95 drive ratio

With air--3.70" dia.--6 blade--1.30 drive ratio (this is the one I have)

I have not been able to find any spec for back spacing of the impeller to the housing.

Picked up a super flow thermostat today, fact or fiction I will give it a try.

Even worse, when driving over to get the gaskets for the van the Dakota decided to do a split on the radiator top seam (plastic to aluminum). I feel like I am coolant ________, rhymes with ducked or plucked.

The one thing that makes sense to me is the 8 blade is what I believe is called for in these vans, and with the correct pulley drive ratio and.that you have the aluminum radiator, moving the water faster is probably what's needed especially with the way these thing cool, or don't cool.....?? Quagmire is dead on!
www.mmshof.org/inductees/larry-shepard I don't think this guy makes statements based on rumors, highly regarded I think.

Calculations of the pulley's I have works out to 1.12 ratio which is closer to the 8 blade so tomorrow after getting the new radiator for the Dakota I will pick up a new 8 blade pump just for the fun of it.

I talked to two different mechanics today about your van    All agree that the coolant level should drop not raise at higher rpm.  Something's not right with the pump situation

Went online to use a real pulley calculator instead of my gray matter, pencil and paper. Seems the ratio is 1:1.07 which is even closer to the 8 blade pump pulley ratio of 0.95.

Here's a GMB hi-perf series, 8 blade w/anti-cavitation plate, [url=https://servimg.com/view/17456329/45][/url] looks and sounds interesting: www.rockauto.com/en/moreinfo.php?pk=3096414&cc=1084621&jnid=483&jpid=6

Have y'all read this? About covers it all!www.flowkoolerwaterpumps.com/how-it-works.html

It covers a lot, not all, it is a good read, some of it goes against the grain of a 100 years of cooling technology which maybe good or bad. When a company needs to sell water pumps that are a one hundred dollar bill or more a simple Rock Auto info ad is not going to make the sale, they are 30% more expensive than Milodon, about 50% more expensive than a GMB and close to 70% more expensive than a new stock pump. FlowKooler maybe the cats meow when it comes to pumps, I will let some other van owner be the test bed this boy is going for a new 8 blade from NAPA with a better flowing 180 thermostat. If there is no improvement then a sixteen blade super duper special anodized flow better than Niagara Falls through your engine in one minute is not going to help much, the issue is somewhere else.

Whatever it takes to fix the problem, it's money under the bridge at this point.

Nope, don't agree, being one of those that does have an "ouch" point, plus that bridge has long since been burned. Also not one to buy into hype, FlowKooler has a lot of flash with some of that good old fashion smoke and mirrors.

Ahem, use what you want, nobody recommended any particular brand or is pushing a companies marketing hype. You're fixated on the marketing hype and cost, I'm merely posting examples of the different versions of pumps after you put a picture of the pump you have for Christ's sake, and some of the theories behind them. I couldn't give a f*ck about marketing mumbo jumbo, hype, cost of the stuff, or of being cynical of it all. I research it all, make my choices based on what I think makes the most sense from reading, and from others experiences. If it were me I'd buy a Gates 8 blade version and make a plate to fix to the impeller for $30+/-. Use whatever. People spend silly money on this old shit with no end in sight and that's money under the bridge. Whatever works is what works, I'm done chiming in. Obviously took a wrong turn somehow😨Good luck

No reason to get testy fellas.  We all want the same thing. We want this thing fixed.  Most of us here are value minded as demoed by these ole rusty vans    That's the draw back of a forum.  You can't hear the intent of emotion being delivered in a typed message

Not really, if somebody were to say they had the same issues I have and that a FlowKooler pump was the absolute cure I would drop the coin in a heart beat. The suggestion about the Gates pump now that is practical, spent the last thirty minutes trying to find one of the "P" versions that comes with the plate already installed here in OKC, so far no luck.

The 6 blade Mopar pump that I have now which may be the root cause of overheating set me back $70, hell of a price to toss in the trash or possibly sell for a small percentage at a swap meet.

So testy, not really, it is not just water under the bridge, it is my wallet and my labor, extensive amounts have already been doled out in mass over the last four years.

I agree, the stock pump should work, if it doesn't there's something else going on. It's not like this is some 500 hp monster. Did you hear back from the radiator guy's or have it flow tested? This is such a bizarro problem from hell, I feel for you busman

I also agree that more flow is always better when dissipating heat, time has nothing more than the circuit length to do with it. It's surface area and flow. I've had a few arguments about cooling wort, time/vs flow. You can't get away from the laws of thermodynamics. It's all about differential temperatures, surface area and flow. The greater the differential the faster the transfer, the more surface area at the sink and the faster flow, the quicker you will cool. 20 years doing refrigeration and heating, geothermal, gas, oil, boilers, steam, wood, chillers etc. You get problems when the coolant does move or is restricted. Coolant is not even the right word, but the transfer medium and it's associate apparatus is what we're talking about.

Seems none of the flaps carry Gates water pumps, resorted to NAPA for a Tru-Flow pump,  no performance pump listed. Got it home when looking at the pump it had the Gates logo and part number on it, NAPA just puts TFW- in front of Gates number. Called the store asked for a "P" model, took an hour but they brought it in from the warehouse, all of $40.

Started putting the steel box back together, did a few sins of investigative repair, changed a bunch of things. The water pump is now 8 blade performance model with the anti cavitation plate, replaced the thermostat with a Stant Superflow 180 which kind of looks like the one that was already there except this one was $4 more expensive. Put a new 16# cap on even thought the other cap was new. Removed the PCV connection to the carb base just in case the valve might be sticking open which would cause super lean even though the wide band AF did not indicate it. Last but not least put the stainless steel shroud back on, made no difference in earlier tests, once the radiator is in there is no way to install the shroud, has to go when everything is out. Pictures later.

Filled the system with water, engine fired right off barely makes one revolution and it comes alive. No leaks!

Now comes the long wait to come up to temp, this is all at idle, finally got to 180, upper hose is hot so there is flow, took some time to climb to 185, then 190, but each time I could increase the rpm for a minute or two and the temp would drop a little, finally let the temps climb to 200, raised the rpm and held at 2500 +/- and the temps dropped to 195. This is like thirty minutes of run time. In prior tests the van engine would of already overheated and been shut down.

The Gates pump may of been the ticket,

Will road test the van tomorrow, have a lot of things to put back together.

The Gates 43026P or NAPA TFW-43026P



Radiator with shroud attached prior to installation


All buttoned up and running, notice the see through fan blade



I do appreciate all the advise, suggestions and support from members, have my fingers crossed that the test run tomorrow turn out to be COOL in many ways.

We'll all keep our fingers crossed for you! With all you've been through, you deserve this to go well for you. Please let us know how it turns out...we gotta know!!!

BTW, thanks for posting the part numbers etc., for future reference if someone else runs into similar situation.

Busman, That sounds real promising, I think you know your on the path to happy vanning now.

Im curious, did you note wether the coolant would raise or lower as the rpms's went up?

Definitely keep us posted on the follow up

Congratulations on the determination to fix that thing....and then there is that recommendation of Bouchillion Performance and your previous pump?

Well dumb ass here, that being me punched the wrong numbers into the pulley calculator, seems I used the crank AC pulley diameter and not the pump crank pulley diameter. Say that three times fast.

Crank pulley 6-9/16"
Pump Pulley 6-7/8"

Those work out to a 0.954:1 ratio, referred to a under-driven which is exactly what ma Mopar provided as stock for the 70-91 non air conditioned vehicles. Course Chrysler listed the ratio at .950 but what the heck that is just 4 rpm difference.

So the pulley's from Bouchillion are dead nuts to the original Chrysler ones, just their pump recommendation sucks. Course their forte is hi-performance so with lots of screaming rpm a six blade pump may be the right selection. I did send them a polite email describing the outcome of the pump selection and the outcome of the test run.

Congratulations Busman. Your intelligent perseverance is commendable and exemplary for all us early van drivers and fans. Now you can enjoy your ride even more.

Been kicking myself in the ass since yesterday, back in my air cooled days there were those that fell for the put a smaller crank pulley on for more umph from you 50hp, hey baby you could feel it in your pants for only $39.95 plus shipping, fun till the cylinders and heads roast down in the engine. No I never bought one of those but did remove quite a few as i tore their engine down to start a rebuild.

Bingo, take a pump that is suppose to spin fast to cool an ac equipped car put it in a engine that is rigged to turn a pump at less than 1 to 1 and you get utter frustration. Seems to be the little obvious things that get you every time.

Excuse me I need to go kick my ass again then climb into the van for a road test.