This bullshit cracks me up in my 37 years as a professional mechanic i have had about 3 cars overheat because the impeller had mostly rusted away and not pumping enough water ....then old mate comes along with this load of shit 🙄

I have built and driven and raced hundreds of small block Chevy's over the last 40 years. By far, timing is the biggest thing that affects overheating on these engines.

Strang them engineers at Chevy made so many of them engines that ran cool for so many years. Don’t get me wrong, I love hot rods and Chevys more than anything but my family. I am 80 and worked on junk all my life. I found a clean radiator , a new thermostat, and a bottom hose that don’t collapse , I had no trouble even with my 60 over 13 to 1 327 in my 1936 Ford I drove to work for several years in over 100 degree temps. Must have been that old Ford radiator.

Having a cooling system that works correctly is the answer. I have 468 30 over 3 core aluminum radiator clutch fan 190 thermostat is the south that never gets hot .

Tryed it out on my truck. It’s running alot cooler. After changing temp gauge staying at 170. Wating too hit the trail. Thanks

I had this conversation with an engineer at work because of a problem with overheating his triumph tr6. He said it's impossible for that to help. Speeding the fluid up always helps to transfer heat.

That will be in perfect balance, probably makes the bearings last longer too🙄

The issue is not the flow through the block but the radiator. The Coolant is not staying in the radiator long enough to shed heat. The best solution is a higher capacity radiator to slow the flow of the coolant and allow it to shed more heat so it can absorb more heat from the block.

I usually tap water out of the back of the heads and plumb it to the water neck above the thermostat. The difference in pressure and flow forces the water to flow through the full length of the heads. Haven't had much of a problem, even running 36 degrees ignition timing.

I think O’Malley might be right but for the wrong reason he’s talking about splinting that pump beyond 7000 RPM which I’m sure is just frothing up of large amount of cavitation and if that fluid is pumping through the head it’s not gonna do a good job of extracting heat. Halving the number of blades for that given rpm, the likelihood of cavitating is much less. Although I would also smooth out all of the jagged edges off where he cut the blades off. For sure if the engine is running with more timing, it’s working harder and going to produce more heat, so yes, you can affect the engine temperature by varying ignition timing. And if your cooling system has border line problems, then advancing, the timing could cause it to overheat. I think it’s common practice at times for people to leave the radiator cap off or loose when they have an overheating problem. But if the overheating problem is due to loss of coolant via a leak, yeah that loosening the cap is a good idea. But if the system is not leaking, it’s better to have a pressurize cap., This because boiling water has less heat, transfer ability than completely liquid water and a pressurized system has a higher boiling point. I think one other point is that in at high-performance engine that has thinner cylinder walls it’s possible that the engine could be cavitating directly on the cylinder walls much like some of the early power stroke diesel engines. And once the cavitation starts, there would be less heat transfer which would lead to more cavitation ad infinitum. If someone has an overheat problem , I’d try the power stroke coolant to see what happens. Thanks for the video, the smoking is a real turn off.

The only heating problems I've had are insufficient radiator size or no fan shroud. Never got into HV or electric water pumps. Most people are not driving their engines 5,000rpm and up on a circle track. You need to resize pulleys to slow down rotation speed not foul up the pump. Same with the alternator. These are sized for daily driver not tach warp speed racing.

I have a 440ci big block Chevy making right around 600hp with 11:1 compression. It runs on 94 pump gas. I run a proper sized aluminum radiator for maximum fin to tube surface area, a stock 7 blade steel fan, and a 160 degree thermostat, with an aftermarket (flowkooler) stock replacement style waterpump. On a 90 degree day, turning 3500rpm on the highway itnruns at about 170 degrees, and in traffic will get up between 180-190. You just need a proper tune and the correct parts, not gimmicks.

This is similar to how to help a Ford flathead engine cooler. The water passages in the head gasket were shrunken down over the evolution of the development of the engine. Washers placed in the thermostat housings restricted the flow too. I found that a good aluminum radiator in tandem with a high flow electric cooling fan does all you need it to on my flathead engine.

For the street where I'm under 3000rpm 99% of the time, I run a smaller pulley on the water pump (long water pump), with the biggest factory lower pulley (8 inch?) and run it without a thermostat. In traffic for long periods of time it will hit 180, but while I'm moving it comes down to 170. That truck never overheated even though I had 3 different small blocks in it (the 283 .030 over ran the hottest at 185). I guess it depends on the climate of your area (60- 92 degrees over the course of the year, sometimes the humidity hits the 90's).

While this may solve an overheating problem, probably because the impeller is a crap design, the idea of why it works is completely wrong. Slowing down the water flow does not increase the amount of heat transfer in a cooling system. Ask yourself this; if you double the flow rate, does the amount of time the water spends in the engine block increase or decrease? The answer is neither; the amount of time is exactly the same because the water is always in the cooling system. It's not a single pass. If higher flow rates caused less heat transfer, then the water pump wouldn't be set up to be proportional to engine speed. Heat transfer is proportional to the temperature difference. When the water first enters the block, that is when the temperature difference is highest. The longer the water is in the block, the less heat transfer from the block to the water is taking place because the water is heating up. So to maximize heat transfer, you want to repeat the initial introduction of cooler water as often as possible. So high flow rates. Water can't move too fast for heat transfer to take place unless it moves at infinite speed which is impossible.

Great job, alot of good information here. Thanks!

I to have been a mechanic and a small block fan for years and have never see this before , I wish I had the time to try it out !

This is very counter intuitive. I'm not saying your wrong, but it isn't the 1st solution that would pop into my head.

For racing multiple companies sell hign flow or high volume pumps that flow faster. Are you saying those companies that make parts actually used in racing are wrong?

Much easier to install a restrictor cone in the upper hose.

Had a 91 chevy I bought in 95, always ran at halfway mark on gauge. Radiator developed leak so I replaced, ran on 1/4 mark after that.

I don't guess it matters about the balance of the impeller?

Just replaced the water pump on my work truck 94 c2500 it doesn't run hot as it is so I'm not going to tear it back apart but that might have helped with pulling up in the mountains and stuff.

I purposely install distributor onto cam shaft 180 degrees off. Then i reverse chassis polarity by hooking the positive cable to the frame and the negative cable to the starter. Then the starter runs backwards when you start engine, so the engine runs backwards too including everything else like the water pump n alternator. It's runs A LOT cooler this way.

Interesting. I'll definitely try this.

Wouldn't it be easier to just install a bigger water pump pulley?

Why cant you put a restrictive orifice in place of the thermostat to slow the flow.

for a overheating problem u need more water flow,, get a water pump with a cast iron impeller,, that stamped steel wont do it..

Hi this would help when the radiator core is smaller than it should be and cannot cope with the high volume of hot water . But eventually a bigger radiator will be needed as hp increases . On some very high hp a high perf pump CNC impellor that runs slower is also needed .

I’ve owned a few 350s and I’ve never had a problem with overheating.

Man I wish I knew this trick when I was racing circle track , and I was always having over heat issues, this is a great hack, I will do this,

I’m sure being out of balance also improves its longevity.

Not saying this will not work and I do remember the round track guys using a fixed opening insert for a thermostat to slow the water down but with the thousands spent on R&D you would thing the water pump manufactures would have figured this out. I think it is all about the individual build but you do need to slow the water down I would do it at the thermostat that way you can change it back easily. Just my 2 cents

I´ve always used copper-brass 3 core radiators in all my GM cars , and the only time it overheated, it was when my car was stopped in slopped road, in a traffic jam, combined with an engine cooling electric fan that failed.

Put back the thermostat it’s restricting enough

in the last 20 years or so us Pontiac guys have had overheating problems because the water moves too slow, and starts to boil... seems most of the rebuilt water pumps use that stupid stamped steel impeller, which doesnt move water like a old style cast iron impeller does...we looked in parts catalog till we find a Pontiac water pump with cast iron impeller,say off a 1975 firebird w 455 and AC,it has the cast iron impeller and will move plenty of water,try that if u are overheating, did u install a stamped impeller water pump??

For oval racing I used a gutted thermostat ring that kept the engine coolant under 180*f .

We use to use a large washer instead of a thermostat. We kept drilling it out until the temp stabilized at max RPM.

Sounds like a trick to gain hp not aid cooling

This is slowing down the water leaving it longer in the radiator to cool which means a bigger radiator would do the same thing without cutting make sure to clean all that metal out 160tstat big radiator and problem solved because when you make it work hard you will need that water moved

Will this work the same with 6 blade water pump

Dad gad a 1950 Ford coupe. After a boring , and rebuild the flathead V8 ran hot. An old man told him to do this to the twin waterpums. Flat head V8s had 2. Anyway it fixed the problem.

That's ok I guess as long as you are not doing that to a vehicle with an ECM or PCM. Will never go into closed loop .

Nice trick good to know thank you Mike FLA

Wow in the past if i had a heat issue the thought of i hi flow water pump i would think ya that might cool it off weird things thx for the know.

Or, run a smaller pulley on the water pump. :/

I don't know that I would agree with "The lower the temperature on a small block Chevy, the better she runs." I mean I get what you're but there's definitely an optimal range, and I've often found them to be quite comfy in the 180-210 range. Just my experience.

IIR, the same trick was used on flat head Ford track cars for the same reason.

Couldn't you just change the pully size to slow down the impeller?

Only time I ever had a small block run hot was when the valve on the exhaust manifold wouldn't open because someone that had the truck before I did hacked the vacuum lines for the emissions stuff together and made it so the valve was always getting vacuum.

Bullshitto. Go to Stewart water pump web sight and read up on water speed. Slowing water down does nothing.

You’d mentioned altering the thermostat too?

You can do that to your $30,000 engine not mine , I've never hurd or seen someone cut the cooling propellers of a water pump !!

Use a electric water pump with a momentary switch to cycle the pump. Creating a heat exchange effect. And run a 160 thermostat. Works great keeps it at 145degrees all day and night. Even at idle.

I have also found if you build a radiator shroud or grill If there is any gap on the edges of radiator or shroud Will over heat Air finds least path resitence and will go threw cracks rather than radieator Also a grill using to much rods orto close will also give you high temp

During the '60s the 327 had 2 different water pumps available. If you put the 350 hp version on an A/C equipped 250-300 version you had an overheating problem.

Moroso makes a piece of aluminum that you rivet to the blades it makes a high volume water pump out of your stock water pump and it works really well

Could only imagine how much vibration this causes and how quickly the seal will fail. Drag racing car or circle track minimal use great trick. Not for street use.

Other ways to slow water flow without cutting. Cutting blades might show positive horse power gains though. Physics "nonsense" to slow down coolant flow to decrease temps. Laws of thermodynamics apply. Entertaining for a moment tho.

I simply use a 160 degree thermostat in my small block. Everything else for the cooling system is stock OEM parts. 330k miles and never overheats. Even when it's over 100 degrees outside my truck never gets above 180 degrees.

Dont smoke when you explain

i dont understand how this can help , only thing i can think of is the pump cavitates at high rpm and removing half the blades prevents that????? i dont know the laws of thermodynamics but it would seem to me if the water moved "too fast" it would just bring the heat to the radiator faster??? But what do i know

I have a 355 flat top block with aluminum heads, 4 row aluminum radiator, 4-12"elct fans-2-pushers an-2-pullers,160⁰ thermostat ... and I still over heat. Need a good water pump.

And you can't put the cigarette down for 7 min

Why does everyone think slowing down coolant is the answer. And speeding up airflow through the radiator is the answer.Does one medium have a reverse effect over the other?

Why do you think there is a pressure cap on a cooling system? For every lb of pressure it takes 4 more degrees for water to boil so 212° boiling point with 1psi takes the boiling point to 216° 2 psi is 220° and so on, the psi between the water and the metal parts also increase the absorption of the heat from the parts to the water and then from the water to the radiator.. A hotter engine with in reason is more efficient than a Cold engine why ? Because more of the hot fuel is burning IN the engine, and not EXPELLED into the exhaust with that engine cycle ..

Nice...so all those metal shavings are in the seal. 😦😖

Is fresh rebuilt 350 new 2 core radiator 2 electric fans still is still overheating when at idle could this fix the problem

So you didn't tell us what to do to the thermostat you mentioned some kind of mod

Yeah, tried it on my 350 sbc on my 04 Jeep Wrangler TJ conversion, did not reduce overheating at all. I have a 3 core aluminum radiator with an electric fan. Any other suggestions?

Demolition derby guys do tricks like this

My 65 and 66 GTO's were fine temp wise until you got above 55. Guess the 390 rears did that. I believe a 5 speed would have solved that.

Quality/simple idea for track - soak time matters in both the engine and the radiator, and not everybody has calibrated why their [stockish] pump impeller might be wrong at 8000+ rpm. Pulley ratios help, but mainly as rpm goes high a street design impeller is simply outside its design curve. Had you tried removing say... 0.150" off the tip of all blades instead of the method shown? Or, is it possible that rather than soak time, it is simply cavitation wrecking flow efficiency with that stock impeller [by poor suction]? Only a flowmeter would prove which is happening. I worked on some marine stuff before with shell & tube exchangers and raw water flow always had to be pinched down [on the exit side] or we suffered high temps. So yes... flow rate does matter, because temperature differential correlates directly to thermal efficiency [as in btu/hr exchanged] no matter what the naysayers tell you..

this stuff kinda contradicts science and common sense, although i could definitely be wrong for some reason. But uh the water extracts the heat based on the temperature difference or delta. The greater the delta, the more heat transfer occurs. The more water is pumped through the pipes, the more heat transfer can occur with the same delta. I suppose this would just increase the water exit temperature, having higher delta in the radiator, however this doesnt help us because we never had issues with the radiator. But it decreases the delta in the block, because the hot water in the hot block, will absorb less and less heat the hotter it gets. Yeah idk anyway i look at it seems like making the water pump slower will just increase the overheating problem. The only feasible benefit is maybe if the engine is mostly under low load with random spikes of max load, this slower moving water would create a thermal capacitance, where it could probably damper heat spikes, but would overheat from prolonged high load.

You know I’ve often wondered about cutting all of em off and cut 1/4 of the vertical part off and weld em back on if you have a big radiator like I do and maybe increase the speed a bit by way of smaller pulley.ahh I’m probably reaching here

Correct size radiator

88 GMC C2500 350 abc 700r4 trans with 373 gears. New 3 row radiator aluminum new 190 thermostat and a 50/50 mix antifreeze. Question : at an idle with stock fan with new centrifugal clutch the temp goes up to 280 in 100 plus outside temps. Driving down the road temps are fine around 215. Could your water pump fix help in this situation? Thanks

Just get a Adams water pump. Its the best belt driven water pump EVER made

Brother 😎 I'm gonna be your Friend today, I excuse the safety glasses always neglected that one myself... But as a Friend quit that smoking...😎 Scotty in Alabama.. Cool trick,,,,no punn intended... AIN'T IT JUST AIN'T IT 😜 lols

I have a 434 csb. I ja e a electric water pump, two electric fans. They run right from the start. My engine gets up too 240° on a hot day. The engine wants to stall . On a cool day never a problem. Any ideals ?

Thanks for this great video . Would this help on the stock 1990 Corvette L98 engine, with the original OEM radiator , electric fans and shroud set up . Any information is greatly appreciated.

so what your saying is chevy cant even design a waterpump correctly? lmao

Does this on small block ford engines aswell??? Or do they not have the same issue?

I have high performance sbc 283 I have temp issues would you recommend this trick?

I have a easier method leave the thermostat in it I found that out in a mud truck and get hotter in a two peckerd tomcat in the middle of the hole with no thermostat and as soon as I put one in it stopped over heating

Interesting 🤔

Hello! I could use a solution to my freshly rebuilt small block chevy getting hot upwards between 220 to 230 in temp. The shop its at is saying its too tight internally and to take it back to the engine builder. More info I live in AZ and the temps can be 115. The sbc has a aluminum 2 core radiator with dual fans putting out 3,000 cfm. FYI it only gets hot at high speeds like 65 and higher. Thanks

Wait, so you’re saying that slowing down the coolant flow will dissipate heat better…then why do they make high flow water pumps? I’m no expert but it makes sense to me that a faster flowing liquid will dissipate heat better. Have you ever tried a high flow pump?

NOTE: adding a straight fan and changing the thermostat out are needed. He makes this comment. I wonder if a thermostat alone will do it? Wonder what the temp range on the replacement? You get half of the info needed in this video. LMAO

When the pipe is dry

If that molecule of water was going so fast it didn’t pick up enough heat I bet there was another one right behind it that would On the radiator side if it was not in radiator long enough to remove its heat there was more water right behind that water that would This cutting off blades may fix your problem but not for the reasons you think

If you're running a thermostat and it's working properly this shouldn't be necessary.

Wow 😳 don't do this. I have been working on motor for over 50yrs that's a good waste of a water pump

Hope ya didn't get TOO many metal filings down in there.....🙄 The water is a "solid" constant...slowing it down isn't going to pull more heat off. Ever shoot a static water-cooled machine gun? Get a better radiator with better flow and hi-perf electric fan.

You know nothing about physics, the faster a fluid or a gas moves the quicker it removes heat. example: you will cool off quicker with the fan on high then if it were on low.

Get a bigger than stock radiator, use a shroud and toss the flex fan. Problem solved.

Can't see for the smoke.

get the impeller from Moroso or slow down the pump with the pulley ratios

Bigger radiator is the fix.

All i can say is your right but its wrong in so many ways