Fitting of an external water pump? - thoughts/ advice please

[BartonStag]

Hi all,
I'm sure this is a well worn path, but I have tried doing a search - found one specific item shown - but unfortunately the web page no longer exists. I'm assuming that fitting an external water pump is generally accepted as a wise move? That being the case - which one? I read about a Ford assy (no idea what type - and was the said deleted web page) or are there other options out there? Also exactly what do I have to do with the built in casting space for fitment of the original water pump and also with the drive from the jackshaft?
Any thoughts or advice appreciated as ever.
Cheers
Gord

[barkerwilliams]

Gord,

I bought a Stag with an internal pump and it started to leak. It was rebuilt but continued to leak. From my point of view I didn't mind working on the internal pump as such, but pulling the internal manifold on and off became such a chore I decided to go external. I fitted a the Davis Craig external and immediately the car cooling system behaved better and never had overheating issues. However the engine did run cold for many miles until it came up to temperature and that is not good for an engine. For my case I thought it was because the pump controller had two speeds controlled by the thermostat in the top hose and it may have been better with a variable speed with some additional input from the throttle position. What I mean is that if the engine was warm and the pump just ticking over, if you accelerated hard presumably the engine starts to heat rapidly but there is a delay for the heat to reach the thermostat and the pump to react. I may be incorrect but that is how it seemed to me, so although it worked well it had some areas that I felt could be improved.
So during cylinder head rebuild I switched to a Ford Essex external pump. I felt that this would give me a variable speed pump associated with the throttle position with a quicker response to localised heating. The result is an engine that gets to temperature quicker than with the electric pump and then stays rock solid on the gauge. The quicker rise in temperature results in the cabin heater getting hotter quicker which helps with demisting on damp, steamy days. On the electric pump If I started the engine and left it running on tickover it would not ever get to temperature ever, whereas with the external pump the engine does get to temp at tickover. I never started the car with a frozen windscreen but I don't think it would ever ( I ticked over for 60 minutes) get to defrost the windscreen.
The Davis Craig pump comes with instructions to remove the thermostat and run without, this started me looking at the problem of a cold engine so I refitted the thermostat, Davis Craig then advise drilling a large hole in the thermostat to: 1) prevent the pump dead-heading against the restriction in the flow;. 2) to allow coolant to reach the top-hose thermostat to control the pump speed. There will be times when the thermostat closes but the pump is still running at full speed this needs some consideration when selecting a thermostat temperature and setting the electric pump thermostat temperature.

From my perspective both pump types are good, the electric pump had issues for me on cold damp days and heating/demisting. I also felt, but do not know, that one day both pumps would die, the electric pump would stop and the car would need recovery, the water pump would start to leak and could be limped home with coolant top-ups. The electric pump has a good feature in that it continues to run after ignition off until the coolant is about 10' cooler that the max you set on the thermostat this ensures there is no temperature surge after switch off.

So there are positives and negatives about both types, obviously as otherwise one type would be the market leader. From my experience summer only use, or for use in a warm climate the electric has some nice features, for use all year round or in a cooler climate then an external ,mechanical pump has advantages.

Both external pumps require the alternator to be relocated to NS top front of the engine which is a good thing as its pulls it out of the spray and filth so bear in mind you will need to consider the costs of that as well, (Wards do a very nice alternator conversion kit).

The jackshaft drives the pump and then goes on to drive the distributor and oil pump so it is retained, however removing the load of the water pump from the jackshaft can only be a good thing and assist another area of weakness.

A large brass bung is obtainable which seals both the top of the crankcase and the water jacket when the pump is removed, I have also read of two Welch Plugs being used to seal the removed pump.

https://socforum.com/forum/forum/sta...g-instructions

Alan

[bullstarz]

Most fit the Davis Craig, some with the controller others without and just have pump on. With or without the thermostat and with or without the original pump. Everyone has different views.

Personally i would go with what the manufacture say, remove stock pump and thermostat and fit a controller. I have a Meziere pump but haven't got round to removing the stock pump but the stat has gone. My ECU controls the pump but its off until the temp reaches 83°C then cuts in at 25% and reaches 100% flow at 88°C. It seems to work as when i have looked at the data logger after a 20 mile drive the EWP cuts in and out and temp remains 82-85°C while driving.

Dont get temped by a secondhand/used pump it just not worth it, or even old unused stock. I nearly did but Davis Craig warned me off of it when i asked for the old instruction. They sent them but advised not to use the item as although unused the seals could/would have deteriorated.

[StagJonno]

Alan, I wonder if your Davis Craig controller was either an old version or perhaps faulty. The chart below is what I understand to be the current controller method of controlling the pump and the electric fan (if you install one). This is the type I'm contemplating, mainly for the running-on after switching off, as this is when the engine seems to get hottest. It'll also operate at up to full speed if you get stuck in traffic after a good, fast run.


Chart for Davies Craig EEWP.jpg

[BartonStag]

Both posts extremely helpful folks, certainly helped clarify the issue. Alan (barkerwilliams) special thanks for the link - absolute Gem . Have saved the info and may well go down that route TBH
Incidentally I've NOT had any cooling issues, it's just that with the engine (amongst many major items) removed, i'm just looking to the future to overcome any potential gremlins. When this work is done i'm hoping to use the car and avoid returning to known issues that I could've/should've done something about.
All the best and thanks again
Gord

[DJT]

The external water pump kit was developed by Steve Hill, who frequents this forum. Positive reports from everyone who has fitted it, and the way I would go if ever I had a problem with the OE setup.

[blue 464]

I have used the external pump kit on 2 stags, easy to fit, works ok, Derek

[barkerwilliams]

Stagjonno,

I had the latest David Craig controller, the pump was purchased mid 2018 and used for a couple of thousand miles. I had it controlling a radiator fan. As I wrote my issues were mainly with cool running it certainly limited the coolant to a reasonable maximum temperature.

My unit showed no signs of being faulty it worked as designed it was simply that the low speed pumping was too much flow and consequent cooling unless the engine is been pushed a little from cold. Once in June 2019 I drove the 45 miles to the Noggin & Nag and the temperature gauge never got to the "normal" position. I could have restricted flow but that just puts strain on the electric motor. Perhaps my new radiator is just too efficient. The pump is audible and easy to hear its two speeds in operation in addition to the controller signalling both the temperature and pump speed.

Nothing wrong with the electric pump, much better location than the original. Now if you could get a pump with 1/4, 1/2, 3/4 and full speeds that would be a different animal.

Alan

[BartonStag]

Thanks for the responses folks all very much appreciated. Initial thoughts are that I may well be going down the Stagdad route, seems to be well thought of option.
All the best
Gord

[Mark S]

The original pump pushes water into each head individually, neither the electric or mechanical conversions do that. Does the mechanical conversion recirculate via the bypass to warm the engine evenly? I don't know. The way the electric pump pulses the flow by turning a motor on and off several times a minute though just seems wrong.

[bullstarz]

Stagjonno,

I had the latest David Craig controller, the pump was purchased mid 2018 and used for a couple of thousand miles. I had it controlling a radiator fan. As I wrote my issues were mainly with cool running it certainly limited the coolant to a reasonable maximum temperature.

My unit showed no signs of being faulty it worked as designed it was simply that the low speed pumping was too much flow and consequent cooling unless the engine is been pushed a little from cold. Once in June 2019 I drove the 45 miles to the Noggin & Nag and the temperature gauge never got to the "normal" position. I could have restricted flow but that just puts strain on the electric motor. Perhaps my new radiator is just too efficient. The pump is audible and easy to hear its two speeds in operation in addition to the controller signalling both the temperature and pump speed.

Nothing wrong with the electric pump, much better location than the original. Now if you could get a pump with 1/4, 1/2, 3/4 and full speeds that would be a different animal.

Alan

If you look at Stagjonno's post it shows how the controller regulates the pump. It works at a variable speed from 6 v to 12 v. So if theres too much cooling it will reduce to power to the pump regulating the flow. My Link xtreme ecu does the same but i can set any start voltage and temp it will also do the 10 second on 30 off or 20 on 20 off just the same s all the modern controllers.


500x500-thumbnail-1585011149.8002-WithBracketScreenLitUpFrontOn.jpg
https://daviescraig.com.au/product/e...dule-only-8102

EWP far out perform mechanical pumps as their flow is not regulated by engine speed, when you need max flow ie when you car is in a jam it will. The when you driving in top gear with loads of air flow it can slow right down. An engine driven pump cant do that its designed to be compromise. No engine driven pump can flow well at low speeds but not cause cavitation at high rev's. So it will do both averagely the same as a viscus fan.

My EWP will pump 55 gallons a min (us gallons which is about gazillion ltrs for those that are still in the EU ) regardless of engine speed it could even stopped and it will still achieve this but when the car is moving at speed can slow right down to what ever it requires to maintain the set temp.

[barkerwilliams]

Mark,

Surely the problem was that the original pump pushed water into neither head quite frequently.

Yes to get any "push" from a DC motor it needs to be supplied with quite near its working voltage so a reduced voltage to a pump will not produce much flow, Davis Craig avoid that by pulsing the motor, whereas a mechanical pump if turned slowly can still deliver flow albeit at a reduced rate.

A stepping motor on the pump would be a different proposition and price.

Bullstarz,

"can slow right down to what ever it requires to maintain the set temp"

That is just what the Davis Craig controller cannot do; the pulse shown by Stagjonno is the minimum the pump will do, this has to be so because without circulation warm water would not be reaching the controller thermostat in the top hose to regulate the pump. Not unreasonably there is a minimum circulation, and for my car that was too much cooling. Still you pays your money and you makes your choice.

Alan

[flying farmer]

I have both the Stagdad and the Davis Craig pumps fitted to 2 different Stags.

The Stagdad pump was one of the first batch he made and it has worked brilliantly straight out of the box, the heater works and the temperature stays rock steady.

I actually have 4 cars cooled with the Davies Craig pump. Only one was fitted with the controller, the rest ran continuously with the voltage dropped through a Mk1 Stag ignition ballast resistor so it runs on about 8 Volts continuously. There is the option of switching on full voltage if a boost is needed but this is for very hot weather/ high load combinations like driving up the Alps or hot weather track days.

The one car fitted with the controller was unusable in frosty weather as the screen would ice up internally while driving. So would the driver! This is a function of the pulsed method of control. Refitting the thermostat made a very slight difference, but not enough to defrost a windscreen.

I ended up fitting a ballast resistor to that car as well and it is now usable in frosty weather. I might still have the controller if anyone wants it, but I may have binned it.

It really comes down to how much work you want to do to install the pump. The Davies craig pump can be fitted low down on the nearside of the engine and the alternator left in its original position, its just a matter of fitting a length of pipe from the bottom radiator outlet to cross behind the radiator, but can only be done if an electric fan is also fitted as the viscous fan would be in the way..

Neil

[trunt]

It really comes down to how much work you want to do to install the pump. The Davies craig pump can be fitted low down on the nearside of the engine and the alternator left in its original position, its just a matter of fitting a length of pipe from the bottom radiator outlet to cross behind the radiator, but can only be done if an electric fan is also fitted as the viscous fan would be in the way..

Neil

I’m doing this right now. To leave the option of a/c open I am installing it low left, no mechanical fan makes it pretty simple, I just had to make the lower hose drop down an inch or two and 2-3 hours scouring the local motor factors online provided 3 likely hoses which worked out fine.. it’s a longer run but maybe only 12” more than original in the end.. I have a huge 16” fan that pushes a lot of cfm, and a TR6 Spoiler so we will see how that goes.. I will post it once installed, just awaiting the two captive nuts for the radiator..

Terry

[StagJonno]

Stagjonno,

I had the latest David Craig controller, the pump was purchased mid 2018 and used for a couple of thousand miles. I had it controlling a radiator fan. As I wrote my issues were mainly with cool running it certainly limited the coolant to a reasonable maximum temperature.

My unit showed no signs of being faulty it worked as designed it was simply that the low speed pumping was too much flow and consequent cooling unless the engine is been pushed a little from cold. Once in June 2019 I drove the 45 miles to the Noggin & Nag and the temperature gauge never got to the "normal" position. I could have restricted flow but that just puts strain on the electric motor. Perhaps my new radiator is just too efficient. The pump is audible and easy to hear its two speeds in operation in addition to the controller signalling both the temperature and pump speed.

Nothing wrong with the electric pump, much better location than the original. Now if you could get a pump with 1/4, 1/2, 3/4 and full speeds that would be a different animal.

Alan

Thanks for the extra information, Alan - always happy to learn. Must say I'm surprised as I'd only heard positive reviews, though the sample is small. Intuitively, I'd expect quite a quick warmup with the (initial) long periods where it isn't pumping and only half voltage at that. Gives me some food for thought.

Jonno