After a few issues
with the standard mechanical pump including a leaking seal I
decided to change
the unit for an electric water pump. There was a lot of debate
on the yahoo group about which was better but decided that I
wanted to find out rather than just talk about it.
I had a look around at pumps that where easily available
and seemed to be up to the task. The WC engineering unit has a unrestricted
flow of 4gallons per minute and I took that as a base line.
MAW Solutions of Stamford
is a distributor of the Davies Craig Electric Booster Pump that seemed
to fit the bill.
The unit is automotive quality and seems able to handle
the water oil and general muck of car engine bays. Relatively
small to allow easy placement. Has an unrestricted flow of 13 litres
a minute. Has a 2000 hour continuous running warranty and estimated
motor life of 15000 hrs.
A couple of images of the standard mechanical
The installation of the new pump was relatively
First was the removal of the old pump. This was possibly the
most awkward part of the procedure as it's a tight and mucky
squeeze to get hands and tools down between engine and inlet
plenum. It is vital and simple to remove the air box that gives
the best access. Some people also remove the oil filter and give
the car an oil change at the same time. This had been done recently
anyway so didn't see it as required. I'm always up for a challenge
A valuable piece of kit is a flexible shaft screwdriver that
can take 1/4" sockets to remove the jubilee clips.
Finally unit was out and it looked in reasonable
condition, but I had previously replaced the rubber impellor
the first year I had the car. The car can't be left with a whole
where the pump is as it would just leak oil of course. I did
try just putting the housing back after blocking the holes but
found that I was getting low oil pressure on occasion. I think
the housing needs to fill up with oil at before the oil pump
starts working peoperly.
End decision was to fit back the shaft but to remove the locating
key so that it would not spin. The water inlet and outlet are
plugged up and impellor left out. This seems to work effectively.
Also means I can go to a mechanical pump in future if there is
Fitting the electric unit, which was nice and
compact, was accomplished using some new hose from Halfords so
that I could have better choice of where it would go. Origional
return to the front of the car was not touched. Feed to pump
was I tried to keep the pump as low as possible in it's location
to give the pump a good head of water. Also I made the decision
it would be best to push cold water into the charge cooler rather
than pull the hot out. This was done to reduce chance of any
air pockets reducing pump efficency. First location was attaching
unit to side of plenum.
This was fine but vibration from the engine was
an issue possibly plus it could be lower. I then moved the unit
under the air box and bolted it to the plate that feeds the HT
leads. This is out of the way visually, low enough to provide
a good head of water, away from hot parts and any engine vibration.
The wiring for the motor was done by using the
wiring used for the vaccum pump. I don't have this pump since
I've had the car so it seemed an ideal position. I may look into
using the Lotus recomended rlay and link into the ECU loom. I'm
always a little reluctant to start splicing into anything going
to the ECU.
After a few test runs it seems to be working fine but haven't
done enough to fully test it. Using freescan before and after
the pump was fitted I did notice that the temprature reduces
quicker after an extended run. I think the pump holds a high
flow rate even when car is just ticking over. On initial and
sustained boost I didn't see any appreciable difference. Temprature
still climbs very quickly and got to similar tempratures before
holding. Any difference could have been due to difference in
the outside temprature. Also it did take a few runs and top ups
before the system cleared all the little air pockets in the
Overall I'm happy with the installation and think
it is one less possible point of failure in the future.