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Hello,

I am looking for a little help/advice.  I have a 1985 GT5.  My water pump went out recently.  Two questions;

1) Any advice or instructions that you would recommend or follow for the easiest way to replace the water pump?

2) Any recommendations on what water pump I should buy to replace the old one?

Thanks.

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Since no one has answered I'll take a shot.

Most of your work will have to be done thru the hole in the firewall.  You will have to wedge yourself in the car maybe even remove the seats if they are in the way.  The actual removal and replacement is fairly easy and just like any other ford V8.

Please keep in mind I have not had to replace one in my pantera yet but have done many on my mustangs.

Burping air out of the pantera cooling system will be a challenge.  I understand there is a great tool for this someone posted about a few weeks back.

Take out the safety belt bolts (2) from the firewall be aware of the distance bushes , and the passenger seat, slide the driver seat to the front . Than on the bottem of the panel there are 2 screws each side , slide the panal upwardts and you can take out the panel .

Than you have acces to the center section of the firewall wat has 10 small bolts . take out this and you have acces to the waterpump.

check also the alternator if the bearings are ok.

1971 Mustang repair manual was always helpfull for work on the 351Cl engine.

Simon

What I experienced with the Edelbrock water pump was that if I started turning my engine over 6000 rpm, there was a cavitation problem. This lead to a temporary increase in water temperature. From what I can tell, the Edelbrock water pump has an open impellor design, which can make it prone to cavitation. Other than that issue, it is certainly a quality water pump and might be fine for someone else's application. It just didn't do that well with my engine set up and will be replaced with a FlowKool pump. I also installed the SACC smaller aluminum pump pulley which does move more water than the stock pulley.

@panteradoug posted:

Whatever pump that you use, make sure that the bypass hole is drilled.

The Wieand is not. Don't panic though. It only needs a 1/4" hole.

You want the bypass open on a Pantera. On a Mustang, maybe not.

Hi Doug,

Just curious why you want the bypass open on a Pantera water pump?  I've had the Weiand on my Pantera for 10 years without issue.  Warmup might have the temp needle climb and fall a couple of times, but engine gets to temp pretty quickly and then runs cool, regardless of the outside temps.

Like Garth I ran a Cleveland for 50,000 miles with a Weiand  water pump that was not drilled for bypass. In addition to that, previous engine builder had completely blocked off the brass restrictor plate except for a small air bleed hole. I know this is not “correct” per common wisdom but it worked fine. 🤷‍♂️🤷‍♂️

My new 404 Cleveland stroker uses the Edelbrock pump, a proper brass bypass plate and the proper thermostat from Tim Meyers.

there are multiple solutions, I should probably say approaches, regarding the Pantera cooling system…….

for me, the bottom line is having a Pantera that can be parked without coolant boil over, gurgling or expansion tank discharge after becoming totally heat-soaked in heavy traffic with a true and correct coolant temperature of 230°F.

this does of course require an accurate coolant temperature gauge, but if your system works this well I wouldn’t put tinkering with it near the top of your upgrade list.

YMMV

Larry

@garth66 posted:

Hi Doug,

Just curious why you want the bypass open on a Pantera water pump?  I've had the Weiand on my Pantera for 10 years without issue.  Warmup might have the temp needle climb and fall a couple of times, but engine gets to temp pretty quickly and then runs cool, regardless of the outside temps.

There are several threads on this subject on this forum. They are pretty old by now. Probably from around 2000.

As supplied new with the blocked bi-pass, the engine temp was erratic. Not something that I wanted in a Pantera.

In all honesty, I didn't know what was wrong initially until I read a thread here on this forum about the subject.

Upon opening the bypass in the pump, all returned to normal and relieved the additional tension associated with the running hot syndrome.



Interesting enough, I had a Boss 351 in my 68 Shelby GT350 for a few years. I had the pump installed as it came from Wieand.

In that application it showed none of the nasty tendencies it did in my Pantera.



It's a simple recommendation from me particularly to Pantera newbies. Use the bi-pass...you will probably live longer as a result.

The Wieand pump comes with it undrilled. I am not aware of the combinations of all of the others but I do believe that the Edelbrock has it drilled.



Here's one here. https://pantera.infopop.cc/top...er-pump-modifacation

There are others.

Last edited by panteradoug

Jffr, I don’t believe your experience with the Edelbrock waterpump necessarily means it doesn’t flow as much coolant as the Flow Cooler. Cavitation is a complex issue. It could be the Elelbrock flows more coolant than the Flow Cooler, right up to the point where it cavitates. It may be that the Edelbrock simply reaches a point where it simply isn’t possible to pull more coolant through the Pantera’s cooling system. The Flow Cooler might not reach that maximum CFM point until a much higher RPM.

Years ago, I spoke with an engineer at Stewart about the Pantera’s cooling system. He mentioned the exact situation I just described. He said a great waterpump might be worse than a poor one due the the flow restriction caused by the physical length of the Pantera’s system. His advice was to remove as much restriction from the cooling system as possible. He said this is one car that should never use a multi-pass radiator! He also described the Pantera’s waterpump as a cavitation machine!

As far as the Pantera’s coolant bypass is concerned, it’s there for a reason and most modern cars use similar systems. It gives a more even, gradual warmup. It helps to eliminate hot spots in the heads and the heat shock that’s so harmful to aluminum radiators, when the thermostat finally opens and lets boiling hot coolant to flow into the rad. Some owners may have zero trouble without a bypass but as a rule, any 351C should have a correct and functioning coolant bypass system.

When I was still using a Cleveland block with aluminum CHI cylinder heads, I bypassed the coolant fill tank and eliminated a lot of the cooling system restrictions. In my opinion, the original coolant flow design in a Pantera appears to be about as restrictive as it could get. I used a FlowKooler pump at that time and didn't seem to have a cavitation problem at high rpm. When I removed the Cleveland engine and went with an aluminum Fontana block with aluminum CHI heads, then engine is now considered a Clevor. The coolant lines come out of the front of the cylinder heads into a remote thermostat housing. The engine builder used an Edlebrock water pump for the new engine, which under normal or high performance street driving has done an excellent job of cooling my engine. My issue with what I have determined to be a cavitation problem showed up on the race track where my rpm is up at the 6000 range and tends to stays there. I don't track this car very often, but from my research on the Edlebrock pump it shows that they are not using an enclosed impellor design. The FlowKooler pump has 16 vanes and has an enclosed impellor, which helps to eliminate cavitation. I have worked on and been involved with pumps and cooling systems at the industrial level for over 40 years and have seen issues with cavitation, so I do have a working knowledge of pump design. I have owned my Pantera for 44 years and have tried a lot of different things to keep the engine cool, which living in southeastern Arizona isn't exactly easy when you are trying to drive the car in the warmer months.

The water pump cavitation brings up the traditional Pantera question of what is it? Is it a street car or a race car?

This is compounded by the fact that the stock 351cj has much more potential then the version Ford decided fit the character and intended use of the Pantera best.

As such, the engine is basically a 5,500rpm operating range unit. That's likely the high end operating rpm of the average new buyer.

Everything in that package is aimed at that. If you want to go higher, you start to show the limits of the package and need to alter some of the initial "settings".

The original engine has a by-pass in the water pump. That's how it is designed to operate.

Want to re-invent the wheel? Go ahead but why change things for the sake of change?

@davidnunn posted:...

Years ago, I spoke with an engineer at Stewart about the Pantera’s cooling system. He mentioned the exact situation I just described. He said a great waterpump might be worse than a poor one due the the flow restriction caused by the physical length of the Pantera’s system. His advice was to remove as much restriction from the cooling system as possible. He said this is one car that should never use a multi-pass radiator! He also described the Pantera’s waterpump as a cavitation machine!...

did the Stewart guy say any thing about the Pantera's location of the pressure cap  (at pump discharge versus at pump suction)?

When I purchased my Pantera in 1977, the previous owner had converted the radiator to a single pass set up. With the worn stock engine and low compression that the 1973 models came with, this radiator design actually worked. When the engine was rebuilt and the horsepower was increased, the single pass radiator became useless. It couldn't cool the engine at all at temperatures above 80 degrees ambient. When I switched the radiator back to a stock dual pass system the cooling improved greatly. It wasn't perfect, but I was at least able to live with the set up. The basics of cooling a Pantera come down to where the cooling problem is. If it is running hot only at low speed, then it is an air flow problem. If it is running hot only at highway speeds, then it is a cooling flow problem. If the engine seems to be running hot all the time, then you might have a leaking head gasket of several other issues.

@jfb05177 posted:

did the Stewart guy say any thing about the Pantera's location of the pressure cap  (at pump discharge versus at pump suction)?

I did not discuss this with him specifically but I did discuss George Pence’s cooling tank (self bleeding) modifications and he thought it made perfect sense. His biggest overall concern was how difficult it was to pump coolant through the Pantera’s “miles” of plumbing. He said “flow is everything” when it comes to cooling systems and to avoid cavitation at all costs.

ND, there are two different basic pumps available, assuming  you have a 351-Cleveland in your car. Some later GT-5's had a factory installed 351-W, which takes a different pump and does not have a bypass system like the Cleveland. Not seeing a photo of your engine compartment, we can't tell.

Once that question is answered, there are both iron pumps (stock) and aluminum (aftermarket & a couple of Ford performance models for both 351-C & 351-W). Aluminum pumps are generally about 7- 8 lbs while iron pumps are maybe 14 lbs so the aluminum pumps are easier to work with. Both pump water nicely for street cars and should not leak. Stay with brand names- chinese copies abound, with questionable reliability.

Your old add-ons (small spigots for heater hoses, and the pulley) will not be included but will interchange onto the new pump, so don't give them away with your core. If you choose an aluminum pump, use a few turns of teflon plumbers tape on the small spigot threads and do NOT tighten them super-tight, as the cast aluminum can split if pipe threads are over-tightened. Internal pressures are far less than in your home plumbing. Try-fit the pump gasket to the pump at the store to verify they included the right gasket in the box; sometimes, there are two for various models, or none at all.

Bleeding all the air out of the convoluted Pantera cooling system is slow, repetitive and may take a day or so. Drive it around the block, bleed, add more water and go around again. There's a description in your red Owners Manual that may help. 

I absolutely agree with the pressure tester vacuum kit for filling the coolant system in a Pantera. It gets all of the air out of the system and there is no more jacking the back of the car up and everything else that goes with it. Simple to use and the kit has every type of fitting and adapter to work on any car made! It makes it easy to check for leaks in the also.

jffr,

I think you and Doug are talking about different devices. Doug's talking about a cooling system pressure tester, that pressurizes the system. You're talking about a vacuum coolant system filling device, that pulls a vacuum in the system, then uses that vacuum to draw coolant into the system.

You're correct in that the vacuum filler completely eliminates any chance of air in the system, as long as there are no leaks. The first time I used mine, I left the system under vacuum overnight before filling it, so I then knew without a doubt, there were no leaks.

It works either way. Pressurizing it is more efficient.

If you have large voids or air pockets, negative pressure does not have the same effect as pressure which pushes eveything through the system and catches the air in the expansion tank.

In addition, vacuum is not going to test all of the joints and hoses. Pressure will.

You can probably rent a Stant kit at auto stores that rent tools. Try one. You will like it.

To me it is worth the $120 or so to buy one. You no longer will have to hang the car from the rear bumper from a tree to get the air out...most of the air out.

Wait til you hear the car belching. It's like a volcanic irruption.

Last edited by panteradoug

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