External water pump for K-series

[rj]

This thread because I can't keep spamming the "RADIATOR FAN NOT COMING ON PROBLEM (R500K)" thread.

A few of you will know that I've fitted an external water pump because I had overheating issues when I had had a spirited track session. This had been a problem for a while, and it would take three cooling down laps to avoid it. My final conclusion was that the internal water pump was inadequate when the engine was idling. On the circuit the temperature has always been rock steady, and it took me a while to realise what was wrong.

Then I fitted a Davies Craig external water pump and a remote thermostat. As it turned out I could turn out two flanges, one that fits in the hole for the old thermostat housing and one that can be bolted on the water pump. Between those flanges there's welded a tube and the pump is bolted on the block Very simple exercise in deed.

As there's no need to waste energy on running a pump that's not needed I used an Audi  thermo-switch, that was originally used for a warning lamp in the very old days indicating that the engine was cold. This was supposed to switch on at 85 degrees, but in reality it switches at 68 degrees.

Therefore I'm going to make a small electronic relay where the sensor is going to be a water temperature sensor off a VW Golf MK1 as these are readily available. The output is similar to the Stack dash water temp sensor, so even there it could be replaced. I have of course brazed in an extra boss in the water rail. A boss with an M10x1 thread cut in.

The circuit I'm going to make is not dissimilar to this

Which is nicked from Craig's Thermostat Circuits. Resistors will have to be changed to fixed and the NTC is not a 10k so R1 will change too.

The output from the voltage divider formed by the NTC and R1 will be fed into two op-amps as I will also let this control (in parallel with the old fashioned mechanical thermostat) the fan. Both circuits will be active with ignition off but master switch on.

Any questions?

 

[anthonym]

you read my mind, I have been wondering about one of these, I have over-heating trouble when hill climbing with high revs and low speeds (if that isn't a contradiction in terms), have had for years. Very interested to hear this is a solution. Below 40mph there just isn't the airflow. 

Questions 

(1) can I continue to use the existing temp sensor? Presumably yes.   edit: I am confusing sensor with thermostat.

(2) how can I remove the existing pump (reclaim some horses?) edit: I now realise this replaces the existing pump, I think.. edit2 or not...

(3) where/how can it be fitted? - see edit to (2)

http://daviescraig.com.au/electric-water-pumps

ant

[Nigel Fox]

Are you thinking of starting and stopping the water pump?

If so, how would you be able to get a representative water temperature measurement with no water flow?

[rj]

I'm keeping the old pump. There's almost no restriction in the new one.

 

Anthony,

 

I guess if you fed the signal from your Stack sensor into rhe opamp via a resistor, then you could use this signal. The input impedance has ro be high not to foul the Stack reading..

 

The ols pump has to stay, but if you run the electric all the time, you can temove the impeller. In my setup there's redundancy. The electric pump will kixk in even without water floe as the sensor is just above the primaries. (In the water rail)

 

When you fit a remote thermostat you remove the bypass hose from the thermostat housing, dunno what people with heaters do though.

 

Edit: This was written on my mobile - no cr's displayed.

[anthonym]

I wondered about that, but in my unpleasant experience a non running waterpump overheats an engine from stone cold in a little under ten minutes, and a hot engine in much less, so I figure constant running for me.

edit: and I suppose I don't really need more horse power.. and redundancy sounds like a good idea

[rj]

In that case, as you already have a fan relay, which is controlled by a sensor in the water rail, and a mechanic water pump I'd wire the pump in parallel with the fan.

You need to have made a couple of flanges like these:

 

 

I made the mistake that I made the "necks" to short, which made it more difficult to match up things than needed. You have to beware the hoses from the dry sump system and the steering column - mine clears the latter by just a few mm. Next generation will be slightly different. I want to make alloy tubes for the dry sump system etc. Should you need a DXF of the flanges for someone to make them up it can be downloaded from here: http://www.regins.dk/Caterham/waterpumpflanges_V3.dxf In this file I have corrected the length of the necs.

The pump I used was the EWP80, you don't need the controller that sold for it. Someone forgot to keep things simple and made a lot of bling only adding unnecessary weight and complexity. There's a company in Wales, whom I will not recommend due to personal experience *) that sell the pump for just under £150 eff eBay.

*) They kept spamming me whilst I was traveling in a time where you paid some 5£ a megabyte - Though I had never subscribed, they sent marketing emails of 8-10mb and as the limit at the time was 10mb I had to download the crap from my mobile. Even though they in the mail said "we hate spam as much as you do, so please let us know if you don't want this email" I couldn't unsubscribe and I had to take them to court to stop them. Before that I did of course try both to write and to call them, they kept saying we're sorry and they kept spamming me.

[rj]

[CageyH]

Unfortunately, I think I have a steering column going through this area.

[rj]

Nope, it just clears.

It has been there anthe only miss was that the flange entering the water pump housing on the block could have been 5mm longer

[CageyH]

I am wondering if one of these would be sufficient, as it is probably easier to install.

https://www.merlinmotorsport.co.uk/p/davies-craig-ebp40-electric-booster-pump-9040

[rj]

It depends on how you install it. The reason I chose the EWP80 was that dimension-wise it's close to the original hoses and tubes. The impact on flow when off then is less significant. Installing it with hoses shouldn't form a problem; it's first when there goes blin in it, it gets complicated.

[CageyH]

I was thinking in between the water rail and where ever the other end goes - the bypass loop.

Thinking about it, that won’t give enough cooling through the radiator. Back to plan A.

[rj]

I agree. It wouldn't flow enough through the radiator. If anything you'd want a one way valve and two tees. These are available for pre-heaters, but the hose dimension is something like 19mm (3/4"). Maybe you can find something for a lorry.

[CageyH]

Any chance of a picture of your set up in the car? Was the mounting to the block supplied with the kit?

I have ordered my new drive belts, cam belt, INA manual tensioner, water pump. Done my oil change, and now need some coolant, then the 7 is good to go, but I want to fit the electric pump when I change the mechanical water pump. I figured that the pump can be switched in when sat in traffic with a car getting hot, rather than having to lift the idle speed to get good coolant flow.

I won't be doing the same thing with the pipe/flange as you have. I will use a length of silicone hose.

[rj]

I think there were two "ears" to bolt the pump onto something. I don't think they also came with the second pump I got. (No 1 was a NOS I got from a friend, No 2 was purchased in the automn.)

I don't have a picture with the engine in the car. It's currently on the workbench and a small modification need to be done. I will also add a second mount, and then I'll probably just leave it hanging in the tube.

I can point you to a suitable thermo-switch; it has M14x1.5 but I managed to turn it down and cut a M10x1 on it.
 

[CageyH]

The EWP115 seems to be the same price, so I may go for that. I am looking at a kit so that the controller can take care of things when needed.

The question is, alloy or Nylon 66 for the pump housing?

 

The EWP115 is not as flexible as the EWP80 as far as mounting options go.

[CageyH]

After investigation, I only have two options.

Option 1 - Top radiator hose between the cambelt cover and the inboard shock tower as shown below:

 

Option 2 - buried under the air box and throttle bodies:

 

Option 1 looks better for ease of access etc. but I would like to relocate my header tank back to near the original position so I may not have enough space. Option 2 looks possible, but fiddly.

I am going to try and avoid hard mounting the pump if I can.

I had forgotten just how complex the plumbing on my car was in this area, avoiding the dry sump pump and the inboard suspension.

[CageyH]

Further reading done tonight. The digital fan controller kit is also not what I need, so there is no need for the kit. I just need to work out how to control the water pump, and the most obvious solution is to piggy back off the radiator temperature switch, on to a new relay to power the water pump.

This will kick the pump in when the fan comes on, which normally happens when I am either moving slowly or am stationary. If I could find a timer that worked for about three minutes after I switch off the ignition, it would be awesome.

[rj]

I've got mine under the TBs.

With regards to controlling it, then it depends on how you control your fan. If it's controlled by the ecu and the temp sender is in the water rail, then using the fan control signal is fine; if it's the switch in the radiator, then don't do it. I've seen mine boil without the fan starting. Afterall it's better to start it a little on the cold side than a little after the water has come off!.

Search eBay for delay off timer 12V, then you might find something useful. I tried to copy in a link, but it went crazy with formating...

(This forum is crap. When will MT realise that it's defunct? )

[elie boone]

Isn't there a risk that the flow will stall when both pumps are working ? as they would be pumping at different rate ?

[rj]

I haven't seen any problems at all since fitting the second pump. I reckon it just boosts the flow.

That said, after fitting the thermoswitch the electric pump only runs when the car is at ilde in the pit.
 

[Jonathan Kay]

If I could find a timer that worked for about three minutes after I switch off the ignition, it would be awesome.

...

Search eBay for delay off timer 12V, then you might find something useful.

Exactly.

I'd restrict that search with "car" or something similar to avoid hits on controllers for domestic plumbing. Let us know if you can't find one.

Jonathan

[CageyH]

I was thinking of using the fan switch in the radiator. I want the pump to come on when the fan starts, if that makes sense.

I guess I could change the setup to be controlled by the ECU, but I have never looked at that as an option.

 

[CageyH]

Another question RJ, what did you do with the thermostat take off for the bypass loop? Mine is still in place, and is another hose that potentially gets in the way.

[rj]

Problem is that the fan does not come on when water is boiling - there'll be an air lock in the radiator. Been there.

I've removed the bypass hose as I run PRRT. I was told to blank it, which I did at the water rail end. There's no take off at the flange I made myself.