Variable speed control for Electric Water Pump

with the thermostat in place you should'nt need to slow it down any...it will only pump as much as it can.....

centrifugal pumps are non-overloading

I think you have the wrong truck for your requirements.

4.5ton?

said it before theres squillions of others without the $100k cooling system yours has that are touring the country happily - infact group of 6 just set off from our club on weekend on their 2nd large trip of the season - none have the issues you do.

Is shifting the water through the radiator faster recommended by the experts . When I put a Chev 350 into my Jaguar the radiator specialist recommended triple core with a reversing cross flow . That is , the top half of the radiator flowed left to right , and the bottom half flowed right to left .The objective seemed to be to have the water exposed to the radiator longer . The modification was relatively simple being a baffle half way down the left hand [ entry ] side and the exit hose shifted to the left . Ran very cool , but then so did every other car in Ballarat .

Bill I wonder if maybe you need to refocus on your comment above as to weather 100 to 110 degrees (Or 90 or 150 for that matter) is the correct temperature, rather than continue spending $ on a problem that may not be there in the first place.

I don't know if it is or isn't high but surely that info must be available out there, Nissan itself won't give you the right info?
What about trying to speak to a couple of automotive engineers about operating temps?
Considering the variables that must apply to all of our various vehicles, I would think that the typical automotive engine must be capable of a wide temperature tolerance?
What that tolerance is I don't know, but someone must?

I know you love to stick more gadgets on the old girl and finding the answer to this question may just deny you that pleasure, but I'm sure you will find something else to tinker with. LOL.

By the way fitted the Poron last week, Really impressed with it, cleaned up the blind spot to the rear brilliantly.

Cheers

Hmmmmm.... in my distant youth I recall noting that pressurised radiator caps were there to allow the water to rise above 100 degs C without boiling. The pressure suppresses the ability to boil it seems (physics 101) - so maybe quite a few degrees above boiling is not an issue - its only the temperature at which pure water boils at sea level -no ? Maybe engines made of certain metals and full of oil are happy to be many degrees above ? Anyway, those Nissan techs would know exactly how far it can go, but would they share that with us ? Not bloody likely !

110, is to hot I my book’s for long operation It should only be going up there when the car is working I.E Up hills. If you water temp is 110 how hot do you think the engine oil is getting.

With a 40% mix Coolant+ Distilled water gives me anti boil protection to 125c the water should never even get close to that 102c water temp is upper limit for continual operation in my book.

2 years ago I was towing a descent sized trailer loaded up in my dad’s Fairmont and on a 41c day with the Climate control set on 19c sitting on 110K/ph it was sitting on 106c coolant temp (On the diagnostic dash readout), The regular temp gage was close to the red. After 600k’s at that water temp the engine was not happy I.E Idling ruff and unresponsive.

I told ford at what temp it was running at, There answer was even in those conditions it should not be going that high.

I think the electric water pump is a good idea even if it fails to fix it, at least then you can completely rule out coolant flow and the radiator as the problem and look at other possibilities.

Good luck

It's a heat engine, so in terms of efficiency , the hotter the better . Three limits I can think of are ;
1 exhaust valves , the first part of the engine to be damaged ,
2 water boiling , can damage hoses or cause gas blockage ,
3 oil temperature , limited to 105 - 115 [ depending where measured ].
If you look after 2 and 3 I would expect No 1 to be OK . If so , how about a temp senser on your oil cooler ?

Hmmmmm ..............just goes to show that when you over-engineer a 4by you end up with a monster. Flog the thing and go back to a GQ...hahahahahaha

No I say ....... tinkering is good therapy - Bill should follow this one through ! There must be someone who knows what the safe limit is - how about the oil companies ?
They would be very particular about their product performance re working limits in temperaturesetc - no ?

roachie,

Just making sure i understand what your doing here ok....
You want to add an electric water pump onto your bottom radiator hose right?
My question is this, Are you removing the factory pump or running both ?

If you are running both, then wont you have a conflict between flow rates between them? My point is, If the genuine pump can only flow so much at one time, then wouldnt that defeat the purpose of having the electric one added. After all from what i understadn of this issue, it dont matter how much more water the electric one can push along because the original pump becomes a bottle neck with my way of thinking will cause you more problems than what you already have.
Sorry mate, not trying to add negatives but its like trying to push a watermelon through a 3 inch hole.

Just my opinion bro.
Ange

In answer to the potentiometer (variable resistor) question, use a proper system of mofets which is a very good electric motor speed control, not a variable resistor. These have many advantages including more range, longer operation, reliability, efficiency etc.. you can get a kit from jaycar or from www.evehicle.com.au (i dont work at either of these places). Just call em up and tell them what you want to do. I have built the jaycar kit before, it was easy and worked well but i think the other place has ready to go ones with twist throttles which are plug and play.

G'day Roachie
Not really answering your question... but I considered one of those pumps a few years ago, and was going to use an old "manual" electric brake controller to vary the voltage for the pump as required.
However I did a few "mods" to my cooling system and now have NO overheating issues at all- even towing my 2.5+ tonne van up to Toowoomba on a stinking hot day, aircon running flat chat, etc. (Doesn't even LOOK like getting warm!)
1. Now runs on about 85% water , only 10% glycol and Redline "water wetter". (An engine will ALWAYS run cooler on straight water than a glycol mix as water needs more calories/BTU's/joules to raise a degree then glycol) Downside is not a lot of antifreeze protection.
2. Fitted a "Hi Flow" thermostat.
3.Fitted a Commodore heater valve in the heater line and now have an old heater core in series with my heater ie:There is now always water flowing thru the heater hose thru the heater core I got from the wreckers (It is mounted behind the 'roo bar)
4. Fixed my Viscous fan, both by bending the bi-metallic spring and adding more silicone fluid.
It's a TD 42, DTS Turbo with "power up" running 12 psi boost and mandrel bent exhaust. Outstanding power, outstanding fuel economy (way better than original) and absolutely not a hint of running too hot! Love it!
Cheers

Roachie.
Maybe you have an oil problem. Don't know much about the Nissan 4by more the Tojo's. Marine engineering is my game. Any temp that is slow but relentless to both rise and fall points to over heating oil giving up heat to the underside of the engine block. Does the Nissan have a sump guard?? these are bad at stopping air flow over the sump, even the factory ones. With the all up load you have I would think that an oil cooler behind the grill would be a good investment. Though don't be tempted to put a temp gauge in the sump as you will never get a good nights sleep again.
Clive.

PS. 100c for water temp is ok on continuous running for petrol or diesel marine engines, 110 is to high.

Ditch the 4.2Td for a tidy sum while it's still in good nick and whack in a Chev 6.5 V8 diesel.

Better in every respect for what you're doing IMHO. 4.5T is a HUGE load for a small Jap motor to pull all day at speed I'd say. You're simply asking too much of it.

The golden rule is that you simply can't beat cubic inches - especially when towing (BTW Brunswick Diesels alone have done over 7,000 V8 conversions apparently)

On another note, the F250 is an amazing tow unit. I regularly drive in one that tows a 32' 3.5T offshore speed boat with twin big blocks in it and the F truck barely knows it's there. No fuss and comparitively cheap to run too.

I think V8Diesel is right go the 6.5Chev.

At 4.5t all up can't betoo much of a strain on that 4.2, the Disco happerly tows our 1.3t camper, all up we're about 3.8t with a 2.5l diesel.

Gotta be something wrong mate the 4.2 is a great motor and that sorta weight shouldn't effect it really.

Baz.

hita roachie, just a simple question mate.
what is the pressurerating on your radiator cap.?
i ask this because if it is too low, things will heat up, too high ahd things tend to pressurise to much, either way not good.
go back to a standard cap (new), then go up and down each way from there.
our truck,,the real one ran a 10 pound cap when i bought it, at the first service, the mechanic changed it to a 7 pounder and things got real hot, real quick.
now back at the 10 pounder and no more problems.

rick.

For my 2 cents, if your standard pump is in good nick, why change it? slowing down the water flow while under heavy load would be disasterous as the coolant will be heating up more as it flows thru the block, causing part of the engine to get much hotter before the coolant exits to the radiator. Its the job of the thermstat to regulate flow, not the pump.

Umpteen thousand Nissans doing the same work as yours , funny that never hear of the same problems that yours has , whats that old saying ? something about if it aint broke it dont need fixing ? or is the vehicle/owner a mechanical hypocondriac ? LOL.

Hi there Roachie, probably a stupid question but do you have an extra temp guage besides the factory one. If not maybe your guage on the dash is out of calibration, also have you had the viscious (hope spelt write) coupling checked out. I had problems with this on myn, would be ok at idle in hot weather sitting in traffic which you would think make the temp climb but it was fine but get out on the highway at 110klm and it would head for the red zone, took me a while to work out the problem as I would sit there idling the car waiting for the fan to lock in and it would at idle speed but as soon as you revved the motor the fan would slowly cut out again pain in the ar@e but that was the problem. My mate had the exact same problem with his navara cool at idle heat up when doing 100klm you would think at that speed you would be getting enough air without having the fan cut in but you don't so put a new coupling on his now doesn't go over half 40 c day with air on at 1ooklm. You probably have already checked this out but it might hopefully give you some help. Take Care Vitara/ Steve m

Hello Roachie,
Can't offer any more advice than what you've been given, just a question.
I gather that looking at the Davies Craig pump means the "Waterpumpman" made some pretty vague references and then couldn't pump anymore so he evaporated.

Pity he didn't come through with the goods,

Geoff.

wouldn't a greater water flow restrict the amount of time that you have for air cooling?
I'm no expert but this strikes me as what would happen and is why the bypass system is such a success mostly since the water runs through the tank twice

Roachie --- I seem to recall that you had a problem with your radiator cowl not fitting properly after fitting the new radiator? -- you had a gap betweeen the cowl and the radiator ? If this is still the case this may have a bearing on your overheating. Just a thought, that`s all. Regards G.T.

Roachie,

I haven't spoke with you for a while but I follow your dispear with interest as I went through the same thoughts before the turbo mods I had done.

Nissan told me in writing ( I think it is in with heaps of paperwork from them ) that the temps I was running were within their safe operting temp guidelines, direct from engineers in Japan. Now when the vehicle was running constantly at 110c and going to as high as 118c ( before I would pull over ) I, and dozens of radiator blokes thought this was too hot, but not Nissan. As you may recall I have now got 226 000 km, and rising by the day, on my speedo with no other problems to mention regarding engine or component failure so maybe there is some truth in what Nissan say. I personally believe 110c (constant driving temp) is too hot, but that is not from any technical background knowledge on this matter only research due to this matter. My running temps since the turbo mods are still down around 85 - 90c and rising to 95 - 100c max. This still means the Nissan temp gauge rarely moves a needle thickness.
I went down the airflow and cooling capacity track before I settled on the turbo mods. What swayed me was some ambo's up here use the 4.2 turbo GU as an emergency vehicle, the mob I talked to at Oakey were having all sorts of probs with their trucks, (overheating bad) but fixed the overheating problems with the same modifications as I had done.
Maybe some ambulance stations near you are running the same vehicles, if they are talk with them and see their opinions, and solutions if any. I also spoke with fleet maintainance at QLD Railway as they always seem to load up their rigs as well but Q/Rail didn't get these overheating probs, as you said b4 you don't get o/heat when slow trail work (similar to rail blokes).

Dubbo Nissan had the Jap engineers out there trying to solve this problem as they have quite a few spray contractors that can't use their vehicles for what they bought them for. Last report from Western Plains Automotive (Dubbo Nissan) is no fix apart from standard replacement items like t/stat, a/c cutout sensor, rad cap ect ect.

Other than that I can't help, but the offer still stands if we ever catch up, you can use my vehicle to see the difference in running temps fully loaded as mine is constantly at or above your GCM anyway so 4.5T loaded shouldn't hurt it.

Kind Regards and hope you find a happy medium soon.
Trevor.

Roachie, I know you've tried just about everything but perhaps give "all head services" @ 10 Tarnard Drive, Braeside Victoria 3195 AUSTRALIA
Telephone (+613) 9587 3066 Fax (+613) 9587 3887 ...
a ring. I know that on the petrol Patrol heads they recondition they also supply a modified water pump with what looks like a stainless cage impeller which supposedly reduces cavitation in the pump. I don't know if they do one for a diesel though.
Check out their website and the page they have on "cooling system.
All Head Services
cooling system
Regards Andrew.

One other thing to try is folding the rubber flaps on the inner guards up or better still, packing the trailing edge of the bonnet up an inch or two with longer bolts and some flat washers. No good having air going in if it can't flow out at the same rate.

Have you got your engine bay full of stuff that might be preventing air through flow?

Just a thought.

I don't know if this has been mentioned but have you had the intercooler checked as this is part of the cooling system might be worth investigating.

Hope you get things sorted as this seems to be turning into a war & peace type saga.

Baz.

Roachie

I know I'm late on this post but maybe I can answer some questions and ask some more
1/ check the temp rating on the thermostat,this should tell you what Nissan wanted the engine to run at?
2/ most late euro spec engines are designed to run hot e.g. 105 oC or hotter with GOOD coolant to help with combustion.
3/ the "Davies Craig Electric Water Pump" if fitted do you remove the old Nissan water pump? (if not how will more water pass through the old pump than the speed (RPM) or clearance allow)?
4/ the temp gauge is this reading input or output to the radiator?
5/ I have see and heared of times when too high a flow rate can cause more problems than slow e.g. liquid travels to fast throw the radiator not have time to transfer it heat to the fins, you need to do a Delta temp test a cross inlet and outlet of the radiator to see the temp drop.

Please take this as you want but I would be looking for the problem first rather then trying to cure it

Regards

Richard

Ps the ansewer to the second Q a rheostat will do the job just have to size it

Roachie
When i said euro spec engines i didn't mean late models, 10 years ago I worked as a plant fitter (earthmoving) when the 1000 series Perkins engine came out. we had overheating problems????? how hot is hot???? we spent hours, weeks, months, with test probes every were inlet, outlet, exhaust, having the operator record all values, never did we see any signs of over heating or any failures.
We changed rads. flushed blocks etc. to only be told from JCB/Perkins they the engines were designed to run at 105oC to meet Euro spec (I only use Euro as I can not spell europion)LOL.(this does not mean that they should run there, 76oC as the thermostat is were the engine should start its cooling)
To fix the problem we fitted Resistors in line to the temp gauges so the they would read a lower value (this worked)

In my day we would be looking for a 5 (good)-10 (great) oC temp drop across the rad.(to test this place cardbord in front of rad till engine temp gauge reaches RED remove and test temp drop)

I now work as a service manager in Hydraulics and would want the same temp drop, in Hyd we design a systems cooling to be able to cool 25% of the input power as this is the max amount of loss we want, any more the system needs repairs......

The other problem we have in Hyd. is that oil is to slippery (when it flows through a cooler it can travel inside it's self and not pass any heat to the coolers fins, the same as have the wrong mix of coolant (to strong will cause the coolant to become to slippery and cause the same problem) coolant mix needs to be tested, you can buy testers from good spares outlets

And yes i understand the worm coolant goes in the top of the rad that was a trick Q

This new rad is it painted black?

Another problem we had with an old 4-236 Perkins is a long over heating problem (this time for real water out the overflow) it came down to the wrong thermostat being fitted the bypass valve had less travel than it should have and would not close the bypass port, leaving a 3mm gap allowing coolant to always bypass as a liquid will always travel the least line of resistance it would travel across the bypass around and around the block.

I could go on for ever but it,s 11.23pm wa time and i'm sure you (and all the restmay get bored)

Regards

Richard

It is standard practice to put two pumps in series to increase the pressure and therefore the flow through the Radiator and Block.

A centrifugal pump is quite open and won't restrict the flow when stopped.

You don't really need to vary the speed of the Electric Pump continuously - just Off, slow and Full speed would be enough.

To do this automatically get tw thermoswitches say 80 degrees and 90 degrees.

The 80 switch feeds power to the Electric Pump. In series with the Electric Pump you connect a light bulb (same power as the pump - 50 watts if its a 5 Amp pump) and across the light bulb you connect the 90 degree Thermoswitch. Under 90 the pump and the bulb get 6 volts each. Above 90 the Thermoswitch shorts out teh bulb applying full 12 volts to the Pump.