Water pump flow at idle?

[Scottmillhouse]

I bought an unfinished MK3 from an estate and finished it. With that in mind I'm not sure of some components. It was being built originally as a track car so I don't know if it has a special race style water pump. Issue is that it does not appear to flow at idle. Stop at a light and idle and you can watch the temperature climb with electric fan obviously cooling coolant but it not flowing to engine. Rev engine quickly to 1400 and the temperature will instantly drop 20 degrees or more. Go back to idle and it will climb back in less than a minute. New long block, vintage 1993 Ford Mustang Cobra 302 with GT-40 heads with Holley carb and MSD ignition. As it is now it will quickly overheat if idling.

[NAZ]

Of course you should review your system and check for design, installation, and other problems first. But this is a common symptom when an owner installs pulleys to slow down the water pump (and or the alternator). Mechanical water pumps vary in flow rates and efficiency and most designed for passenger cars are very inefficient at higher RPMs. Many won't stand up to the high RPMs a race engine is designed to run at. So either in the interest of durability or reducing some parasitic HP loss on the track, the simple and cheap solution is to slow down the pump speed. And that can create cooling problems at slow speed.

Once you've checked for and resolved any other issues with your cooling system, the simple fix might just be a pulley swap if you find the pump drive ratio has been changed. Of course, there are lot's of mechanical and electrical driven pump options available as well. The good thing about electric pumps is they maintain a constant flow independent of the engine speed. Coolant flow rate through the engine is of paramount importance. It's difficult to have too much flow using the typical off the shelf pumps available so usually more is better.

[Scottmillhouse]

NAZ-You probably nailed it. Crankshaft pulley is about 4.5" diameter, pump 6" and alternator 2". I believe that may be the reverse from stock with pump at only about .75 crank speed rather than 1.25 or greater as stock.

[rich grsc]

Another possibility is the belt pull system was changed and the pump is turning in the wrong direction. At higher rpm's the pump can move enough to cool the engine but efficiency at lower speeds is poor. What is the belt setup?

[Scottmillhouse]

Belt system is old style simple crank, pump, alternator so impossible to have wrong direction. See photo.

[rich grsc]

Not impossible. You said the engine was a 93 mustang, that would have had a reverse rotation pump, not a standard rotation pump that v-belt would turn.

[davekp]

Good info here. I've always thought an underdrive pulley to be less than optimum on a street driven car. Most of the time I'm cruising at 2,000 rpm or less. If you need greater flow, high volume pumps are readily available.

[NAZ]

NAZ-You probably nailed it. Crankshaft pulley is about 4.5" diameter, pump 6" and alternator 2". I believe that may be the reverse from stock with pump at only about .75 crank speed rather than 1.25 or greater as stock.

For a street car, I like to see the water pump driven at the same speed as the crank at a minimum. To maximize the cooling system performance you need lot's of flow -- both air across the fins and water through the system. If you can find a smaller water pump pulley or larger crank pulley that has the correct offset and provides a 1.0:1 or even a slight overdrive of the pump that may solve your overheating problem at idle (assuming you don't have other issues). The photo looks like what you would expect from an aftermarket under drive combination.

Most performance street cars don't rev high enough to require slowing down the mechanical water pump. But if you find yourself in that situation and want to stay with mechanical, look at Stewart Components as they make racing pumps for drag racers and NASCAR that put out 180 GPM at 8000 RPM and do so with minimum HP loss. They also have some good technical info on cooling systems in general that will help educate any gearhead looking to know more about the subject.

Good luck.

[Scottmillhouse]

Not impossible. You said the engine was a 93 mustang, that would have had a reverse rotation pump, not a standard rotation pump that v-belt would turn.

Enlighten me. This is a new one on me having clockwise or counter-clockwise water pumps for the same engine family. Since engine rotation does not change I don't see the application. How do you tell rotation short of disassembly and examine the impeller? This was a long block with no cam chain cover so that and pump, pulley are all after market aluminum probably from Summit as can be seen in the previously posted picture. The builder had lots of errors and wrong parts that I had to work through so if there was a choice he could have gotten the wrong one.

[NAZ]

https://www.youtube.com/watch?v=zBUxuhTVUbs

Leave it to Ford to make things confusing.

[Norm B]

Normally a V belt pulley will not fit on a reverse rotation (serpentine) pump because the bolt spacing is different but, your pulley bolts have some oversized washers on them that has me wondering if the holes in the pulley were enlarged to make it fit. The other thing I noticed is you don’t have a bypass line connected to the pump. I am not familiar with race engine set ups as far as thermostats and stuff go so this could be normal for that application. A street car normally has the bypass line connected to allow the engine to heat uniformly before it reaches operating temp and the thermostat opens

Norm

[rich grsc]

Normally a V belt pulley will not fit on a reverse rotation (serpentine) pump because the bolt spacing is different but, your pulley bolts have some oversized washers on them that has me wondering if the holes in the pulley were enlarged to make it fit. The other thing I noticed is you don’t have a bypass line connected to the pump. I am not familiar with race engine set ups as far as thermostats and stuff go so this could be normal for that application. A street car normally has the bypass line connected to allow the engine to heat uniformly before it reaches operating temp and the thermostat opens

Norm

Good catch, I didn't see that, important on a street car. It could be just how the picture was taken, but the pump looks different, like the impeller housing is small??
I have seen pumps with both sets of holes.

[totem]

Thermostat may be installed upside down.

[Scottmillhouse]

Thermostat may be installed upside down.

That I know is correct since I installed the thermostat. Pump was already on engine when purchased. Looks like I have some disassemble to do to find out what I have and see if pulley was modified. Bypass was already plugged so I assumed it was not needed but then again this was being built as a track car. For me it is for street and maybe some gentlemen autocross when sorted and normal activities resume. Will have to investigate which plug and where it would go. The original builder had countless wrong parts that were challenging to sort out so I would not be surprised if it was the wrong pump too. Examples include wrong starter, carburetor, ignition, belt, fuel pump, clutch hydraulics, pedals, oil pan seals etc.....

[johnnybgoode]

If you are checking your pump here's what one of my CC rotation (serpentine) pump impellers looked like. Scott

132033

I also just installed a new Flow Kooler pump which so far is handling the hot summer traffic on my 414W without issue.

132034

[Scottmillhouse]

Verified that the holes are not enlarged and spacing is 1.75" so by NAZ youtube this is a clockwise rotation as needed. After research bypass will help engine warm consistently until thermostat opens up but does not matter once warmed. Was told to look for an air pocket at rear of intake manifold that may be a contributor. I'm thinking this is probably caused by the large pulley reducing the water pump speed especially since raising the rpm directly cools the engine.

[CraigS]

Ford actually did it really well. The OE pumps and pulleys had one bolt pattern for normal rotation and one for reverse so a tech couldn't mess them up. But years go by and people run 302s like crazy so the aftermarket starts cranking out parts for odd combinations including pulleys w/ 2 sets of holes, and under drive diameters. That is where the problems started happening. I do wish Ford had molded a directional arrow into the pump housings though.

[Scottmillhouse]

Ford actually did it really well. The OE pumps and pulleys had one bolt pattern for normal rotation and one for reverse so a tech couldn't mess them up. But years go by and people run 302s like crazy so the aftermarket starts cranking out parts for odd combinations including pulleys w/ 2 sets of holes, and under drive diameters. That is where the problems started happening. I do wish Ford had molded a directional arrow into the pump housings though.

So are you saying that a 1.75" diameter hole spacing could still possibly be a counter clockwise rotation pump?

[AC Bill]

Belt system is old style simple crank, pump, alternator so impossible to have wrong direction. See photo.

That pump looks just like my w/pump, which runs CC. It runs fine with the underdrive pulley. (I've since replaced that ugly donor alternator pulley.)

[mike223]

So are you saying that a 1.75" diameter hole spacing could still possibly be a counter clockwise rotation pump?

Not likely - but you'll always wonder until you've had it off.

Here's what I'm running on my 393w (with no problems, runnig 1:1 speed, 6k rev limit):

https://www.summitracing.com/parts/gmb-125-1700p/make/ford


P.S. - I would never take a water pump off without putting a new one on...

[rich grsc]

I wouldn't worry about rotation till you sort out if you have the correct size pulley first. You can remove the pulley and look at the pump hub. If it only has one set of holes, and they are 1.75" spacing its a good chance it's standard rotation. Remove the under drive pulleys if you have them and see if that corrects the problem

[Scottmillhouse]

Update. I broke down and drained the cooling system and removed the pump. Turns out it is the correct standard rotation but it appears very inefficient compared to what I see posted. Sheet metal impeller with only 6 blades rather than 8 and also not the cast type impeller that appears to be used on high flow models. Also chamber appears oversized. Unlike most parts this pump is apparently used as shown by internal deposits and corrosion. Also measured pulley diameter at belt contact and the pump is 5.5" (appears to be stock size) and the Crank is 5" so pump speed is 91% of crank. I'm going to replace it with a high flow model and try keeping the same pulleys.

132747

[NAZ]

Sounds like a good plan. If you haven't selected a pump yet, take a look at Stewart: https://www.stewartcomponents.com/index.php?route=product/category&path=60

May give you some ideas about what's out there beyond NAPA.

Good luck.

[rich grsc]

Great pumps, at a price that won't break the bank.
https://flowkoolerwaterpumps.com

[Scottmillhouse]

Great pumps, at a price that won't break the bank.
https://flowkoolerwaterpumps.com

Ordered one last night

[Norm B]

Your original pump looks like a lowbux produx aftermarket pump from China. A new pump will go along way towards solving your over heating at idle but I would double check the ignition timing and be sure to use a good aluminum compatible coolant mixture just to be safe.

Good Luck

Norm

[johnnybgoode]

Ordered one last night

I just installed a Flow Kooler on my 414W. Here's a link to the install thread if you are interested.

https://www.ffcars.com/threads/cooling-system-upgrades.641415/

The main thing I do is to glue/seal the backing plate to the pump first with some old 2" bolts and let that dry overnight and then mount the pump/gasket/backing plate/gasket to the timing gear cover. This way I'm only worrying about one gasket. I also just use sealant with the timing cover to pump gasket around the actual water ports vs coating the whole gasket. Scott

[Scottmillhouse]

Comparison of old and new FlowKooler. Should solve problem. Looks like a very well engineered and machined unit. Only problem is casting bolt location heights are different so new bolts and some machining needed to match alternator tension bracket for mounting.
133011

[Norm B]

That is quite a difference. Hope your timing cover has the right mounting bolt pattern for the new pump.

[rich grsc]

Not sure what pump you ordered, but that does not look like the correct pump for 1993 5.0/302.

[Norm B]

133072This pump more closely matches your original bolt pattern. I have a pump similar to the one you bought and it fits my older timing cover.

[johnnybgoode]

I used this one. FYI. Scott
https://www.summitracing.com/parts/bra-1660

[rich grsc]

Yes, the 1660 would be the correct pump, the one in his post(#28), doesn't look anything like that.:confused:

Correction--the 1660 is counter-clockwise... not correct for a v-belt setup

[Norm B]

Rich he is running a V belt system so he needs a clockwise pump. The 1660 is the wrong rotation.

[Big Blocker]

There seems to be some confusion about rotation of the pump . . . Just to clear things up a bit, a factory '93 FORD 302 (5.0) spins counter-clockwise and uses a serpentine belt system that would spin the pump clockwise (reverse rotation pump designation).

IF the drive system has been changed to a "V" belt configuration and the [original] pump was retained, it's spinning in the wrong direction and will lose [approx.] 1/3 its flow capabilities (read: overheating at lower engine rpm).

He needs a pump from an EARLY 302 (not 5.0) or 289.

Here is the blade configuration for both pumps:

https://i.postimg.cc/8k0SJRPK/Water-Pump-Rotation.jpg (https://postimages.org/)

Doc

[rich grsc]

Rich he is running a V belt system so he needs a clockwise pump. The 1660 is the wrong rotation.
Yes, but the bolt pattern is what I'm looking at, that and the shape of the housing. If you look at the picture you posted, the housing has the same shape as his old one, but the new pump has a different housing shape. The one in your picture is correct, and yes I forgot, the 1660 is the wrong rotation

[davekp]

[QUOTE=Big Blocker;422656]There seems to be some confusion about rotation of the pump . . . Just to clear things up a bit, a factory '93 FORD 302 (5.0) spins counter-clockwise and uses a serpentine belt system that would spin the pump clockwise (reverse rotation pump designation).

Doesn't the serpentine system turn the water pump counterclockwise?

[Scottmillhouse]

Yes this is very confusing and it has been for me too learning and trying to sort this out. 93 engine but pulley setup for early 302 with clockwise rotation and v belt. After investigation the new pump needed different length bolts to attach due to casting heights. It had two holes not on original pump but timing cover had bolt locations. So we ended up with 3 bolts around each coolant ports instead of two (better) and I had to remove .5" from one cast web and bolt location and make a .3" shim for another to put the alternator bracket at the correct geometry. Sealed pump to back plate first with bolts with back nuts snug in all holes, once set then added sealant and gasket to timing cover and bolted up with all aligned fine. Added the bypass from pump to thermostat housing but had to change out thermostat housing, needed angled outlet with bypass port because of the over sized MSD distributor so sourced from a 70s something Ford truck with 302. Switched to a high flow 160 degree thermostat too just because it should keep things cooler.

So to make a long story longer, it now works fine. Seems to take forever to reach 190 when stopped and the fan kicks in and drops to below 180 and will cycle continuously so it could now idle for hours without any expected overheating. The FlowKooler appears to be a good high flow pump.

[NAZ]

Good news!

I sometimes forget how difficult it was working with Ford engines. So much easier on the old school Chevy.

[Big Blocker]

"Old School" anything works for me . . . worked on all of them. Todays engines are way to complicated for my single celled brain.

Doc

davekp,
Quote: "Doesn't the serpentine system turn the water pump counterclockwise?" NO, the serpentine belt system spins the pump clock-wise. Go back and check ACBill's post #19 and you'll see an example of what can be done to retain that feature when customizing the belt system - I run the same configuration but my alternator is on the DS.

scottmillhouse, quote:"Switched to a high flow 160 degree thermostat too just because it should keep things cooler.

Seems to take forever to reach 190" . . . . Hmmmmmm, wonder why? 160° might just be a bit tooo cold for today's engines running the fuel we have available to us - most like 180° or a bit higher. FORD efi engines are factory set to 192°. Just my 2¢

[NorCalRobert]

Have you removed the water pump to see if someone used to much silicone sealer which oozed into the water port restricting water flow? I see too many people do this on SBF since they silicone both sides on the plate.

[rich grsc]

Guess you didn't read the post. :confused: