Electric Water Pump Initial Warm Up

[fussydave]

I re-plumbed mine in the same way as Ian928. I just fitted an 82 degree stat and did not drill any extra holes, just the jiggle pin. After that the engine warmed up in 2-3 miles, the temp gauge coming up to normal and the EWP controller not showing any temp. As the stat started to open the controller temp would rise up, pump ran and the temp gauge would drop as the cool and hot water mixed and then all would settle down at normal. Before this mod my car would go 20 plus miles before normal temp was reached. In the winter it just didn't warm up.

Dave.

[MikeParker]

One thing to watch out for with an EWP is over-heating at the rear of the engine. This manifests itself as boiling after switch-off. After normal driving, that should not happen. The normal water pump circulates water at full pelt at all times via the bypass, so distributing heat around the engine. With an EWP, when the EWP is not running, or when in the thermostatic is fully closed, you are relying on convection to move the water around. Convection needs a temperature difference to move the water, so you will always get a much higher temperatures locally within the engine. The rear of the engine is the most remote, so gets the hottest. So, I would be inclined to have some flow around the engine particularly when getting near to full temperature. If the EWP is in the external rad circuit, then that means having a hole in the thermostat and running the pump at regular intervals. As others have said, I think Wards know a lot about this.

[trunt]

I looked last night and could not find it but they do address the problem of slow warmup in cold winters, same thing… 2x3mm holes on a “normal” install.

I’ll keep looking!

Found it.. right there in the installation instructions under “installation recommendations”. Last page.

https://daviescraig.com.au/media/216...7-SEP-2021.pdf

[flying farmer]

One thing to watch out for with an EWP is over-heating at the rear of the engine. This manifests itself as boiling after switch-off. After normal driving, that should not happen. The normal water pump circulates water at full pelt at all times via the bypass, so distributing heat around the engine. With an EWP, when the EWP is not running, or when in the thermostatic is fully closed, you are relying on convection to move the water around. Convection needs a temperature difference to move the water, so you will always get a much higher temperatures locally within the engine. The rear of the engine is the most remote, so gets the hottest. So, I would be inclined to have some flow around the engine particularly when getting near to full temperature. If the EWP is in the external rad circuit, then that means having a hole in the thermostat and running the pump at regular intervals. As others have said, I think Wards know a lot about this.

I have not heard this one before, but it makes sense. I have always suspected the back of the block ran hotter than the rest, returning the water from under the inlet ports isn't going to allow much circulation at the back of the block.
This is exactly the reason that on my high performance fuel injected engines I take the return flow from the water transfer housings, so I know the back of the heads and block are kept cool.

Neil

[trunt]

One thing to watch out for with an EWP is over-heating at the rear of the engine. This manifests itself as boiling after switch-off. After normal driving, that should not happen. The normal water pump circulates water at full pelt at all times via the bypass, so distributing heat around the engine. With an EWP, when the EWP is not running, or when in the thermostatic is fully closed, you are relying on convection to move the water around. Convection needs a temperature difference to move the water, so you will always get a much higher temperatures locally within the engine. The rear of the engine is the most remote, so gets the hottest. So, I would be inclined to have some flow around the engine particularly when getting near to full temperature. If the EWP is in the external rad circuit, then that means having a hole in the thermostat and running the pump at regular intervals. As others have said, I think Wards know a lot about this.

Not sure of your point here Mike, at least with a Davis Craig controller anyway. As long as there are sufficient holes in the thermostat (was that your point?) there is flow and it doesn’t rely on convection, ok intermittent flow but as it’s on/off in a 10 second cycle it seems to handle things OK.

Once up to temperature it will run on continuous flow for up to 3 mins after switch off I so can’t imagine it boiling after switch off? That was a big plus for me, a mechanical pump can’t do that!

[MikeParker]

Not sure of your point here Mike, at least with a Davis Craig controller anyway. As long as there are sufficient holes in the thermostat (was that your point?) there is flow and it doesn’t rely on convection, ok intermittent flow but as it’s on/off in a 10 second cycle it seems to handle things OK.

Once up to temperature it will run on continuous flow for up to 3 mins after switch off I so can’t imagine it boiling after switch off? That was a big plus for me, a mechanical pump can’t do that!

Terry,
I had real overheating problem on my car at one point. That was because the standard water pump had too greater clearance, impeller to cover (about 4mm). That reduction in flow was enough to allow boiling at the rear of the engine. That was during normal driving The cure was to reduce the clearance on the pump then all was well.

I note that that many talk about removing the standard pump and putting EWP in the rad circuit with the thermostat still in place. That could cause serious engine problems as you suffer from low flow during warm up. Ideally I guess you would have two EWPs. One in the bypass hose circuit which runs when the thermostat is closed, and one in the rad circuit which comes on over 85 degrees.

My point is if you you fit an EWP, make sure that you do have good flow with the thermostat closed and just check the temperature at the back of the block. If you say you need to keep the pump running after switch off, that may mean that the back of your engine is getting over hot.
Mike

[trunt]

Terry,
I had real overheating problem on my car at one point. That was because the standard water pump had too greater clearance, impeller to cover (about 4mm). That reduction in flow was enough to allow boiling at the rear of the engine. That was during normal driving The cure was to reduce the clearance on the pump then all was well.

I note that that many talk about removing the standard pump and putting EWP in the rad circuit with the thermostat still in place. That could cause serious engine problems as you suffer from low flow during warm up. Ideally I guess you would have two EWPs. One in the bypass hose circuit which runs when the thermostat is closed, and one in the rad circuit which comes on over 85 degrees.

My point is if you you fit an EWP, make sure that you do have good flow with the thermostat closed and just check the temperature at the back of the block. If you say you need to keep the pump running after switch off, that may mean that the back of your engine is getting over hot.
Mike

Absolutely, and I am fairly sure the OP had that exact issue, not enough flow...

Ian 928 and Fussy Dave have plumbed the bypass in to the EWP so theirs work as per original but as I have the early manifold I was not comfortable with the constant bypass (no foot) so i stuck with blocking the bypass and the 2x holes. As Neil reported, with 2x 3mm holes and at 1/2 speed the EWP still managed to circulate enough to prevent the coolant reaching the thermostat opening point so he had to reduce it to one hole, however I think that the intermittent mode the controller uses during warmup does need the 2 holes as DC prescribe.

I don’t “need” to keep it running after switch off it’s just a feature of the DC controller, it runs the pump and fan until it drops the coolant 10 degrees, or 3 mins, whichever comes first. Living in the USA where temperatures regularly and consistantly hit high 30's I am fine with that, especially as I do not have a mechanical fan. I have been running with a thermostat for 18 months or so and carefully assessed it on the hottest days and over two winters - it has performed well. The rear of the heads do not overheat, (I checked!) plus my original temperature gauge is still right there and always shows temperatures consistent with those on the controller sensor on the top hose.

[JeffW]

Absolutely, and I am fairly sure the OP had that exact issue, not enough flow...

Ian 928 and Fussy Dave have plumbed the bypass in to the EWP so theirs work as per original but as I have the early manifold I was not comfortable with the constant bypass (no foot) so i stuck with blocking the bypass and the 2x holes. As Neil reported, with 2x 3mm holes and at 1/2 speed the EWP still managed to circulate enough to prevent the coolant reaching the thermostat opening point so he had to reduce it to one hole, however I think that the intermittent mode the controller uses during warmup does need the 2 holes as DC prescribe.

I don’t “need” to keep it running after switch off it’s just a feature of the DC controller, it runs the pump and fan until it drops the coolant 10 degrees, or 3 mins, whichever comes first. Living in the USA where temperatures regularly and consistently hit high 30's I am fine with that, especially as I do not have a mechanical fan. I have been running with a thermostat for 18 months or so and carefully assessed it on the hottest days and over two winters - it has performed well. The rear of the heads do not overheat, (I checked!) plus my original temperature gauge is still right there and always shows temperatures consistent with those on the controller sensor on the top hose.

This is exactly my issue - there is clearly no flow during warm up as it hits the thermostat with only one hole and the temperature on the Stag gauge rises alarmingly towards H. I believe mine is an early manifold as well and it does not appear to like the thermostat being in place with only one hole. I was too nervous to let the temp keep rising to see if the thermostat opened in situ properly, so as stated before I would lower the temperature setting on the controller to get the EWP running and not pulsing.

Without the thermostat, the car warms up quickly and the system behaves almost normally. There is a further issue that that controller alarm starts shrieking when the Stag gauge has reached 'C' after only running for a few minutes, so I don't know what that means - faulty, bad wiring or something else. It stops after about 30 seconds.

fussydave - how far up did your gauge travel before the pump kicked in?


Jeff

[fussydave]

Jeff I had a combined oil/temp gauge, it would rise to just below the middle and then the stat would start to open. As the cold water in the rad mixed with the hot water, temp would drop back (the ewp controller reading having suddenly shot up following it sensing the hot water passing through the top hose) and then temp gauge would rise to normal as per the stat setting. Being a capillary type temp gauge readings were instant rather than the damped response of the Stag temp gauge.

Dave.

[fussydave]

Mine was a MK2 and I reinstated the bypass. I had the Wards pipe work from the pump. I did not drill any more holes in the stat, it only had the jiggle pin hole.

[JeffW]

Jeff I had a combined oil/temp gauge, it would rise to just below the middle and then the stat would start to open. As the cold water in the rad mixed with the hot water, temp would drop back (the ewp controller reading having suddenly shot up following it sensing the hot water passing through the top hose) and then temp gauge would rise to normal as per the stat setting. Being a capillary type temp gauge readings were instant rather than the damped response of the Stag temp gauge.

Dave.

Thanks Dave. Mine was 3/4 up towards H (Mk 1 gauge) and rising when I lowered the temp on the controller. I should have checked the head temps with a temperature gun before removing the thermostat, but I forgot.

[trunt]

Without the thermostat, the car warms up quickly and the system behaves almost normally. There is a further issue that that controller alarm starts shrieking when the Stag gauge has reached 'C' after only running for a few minutes, so I don't know what that means - faulty, bad wiring or something else. It stops after about 30 seconds.

fussydave - how far up did your gauge travel before the pump kicked in?


Jeff

There is an alarm that happens if the temperature does not increase to 40 degrees in in the first five minutes. It may kick it into full flow as well?

[fussydave]

Jeff my head's only reached about 75 at the back. I am guessing that with the MK1 you don't have the bypass thus there is no flow around the block if the stat is closed.

Trunt I never had an alarm during the warm up, maybe this is a feature of later controllers?

[trunt]

Trunt I never had an alarm during the warm up, maybe this is a feature of later controllers?

Seems to be the same on the 8002, 8001 and 8000, Its also there on the early 8020 (which has no digital display) but that has 30 degrees in 3 mins.,

I only really clicked when I was initially filling the system, I was topping up and letting the pump cycle to bleed the system with engine not running and after 5 mins it alarmed.. which alarmed me but I found out that it was a safety feature.

Jeff .... I have been wondering about yours.. It seems strange that the thermostat did not open nor there was any rise in temperature seen by the top hose sensor when you had the stat in, even with one hole there should be enough flow to get hot water to the stat to open it.. but once you kicked in full speed it then started opening.. If you are indeed still seeing that alarm (its "LOW TEMP" on the display) on warmup then perhaps there is some kind of restriction of flow in the system, e.g. maybe the radiator is silted up??

Another wild thought was a large air lock and the sensor is not under water??

Yet another wild thought is whether it has been installed the right way round.. so is flowing backwards.. that would cause issues with the stat.. The pump inlet is in the centre, outlet on the edge.. the outlet should go to the original pump housing edit** just had a good look at the pictures, it looks ok on the flow direction!

[JeffW]

Seems to be the same on the 8002, 8001 and 8000, Its also there on the early 8020 (which has no digital display) but that has 30 degrees in 3 mins.,

I only really clicked when I was initially filling the system, I was topping up and letting the pump cycle to bleed the system with engine not running and after 5 mins it alarmed.. which alarmed me but I found out that it was a safety feature.

Jeff .... I have been wondering about yours.. It seems strange that the thermostat did not open nor there was any rise in temperature seen by the top hose sensor when you had the stat in, even with one hole there should be enough flow to get hot water to the stat to open it.. but once you kicked in full speed it then started opening.. If you are indeed still seeing that alarm (its "LOW TEMP" on the display) on warmup then perhaps there is some kind of restriction of flow in the system, e.g. maybe the radiator is silted up??

Another wild thought was a large air lock and the sensor is not under water??

Yet another wild thought is whether it has been installed the right way round.. so is flowing backwards.. that would cause issues with the stat.. The pump inlet is in the centre, outlet on the edge.. the outlet should go to the original pump housing edit** just had a good look at the pictures, it looks ok on the flow direction!

Thanks Terry - before I saw your edit I went out to the car today and looked at the pump and it does appear to be plumbed correctly.

The radiator is allegedly a new Supergill one and as the engine only has 850 miles on it from Wards, I would hope it doesn't have any casting sand in it. I will check the readout next time it screeches to see if it says Low Temp.

I am still stumped!

Thanks
Jeff