Lotus Elan

Leaky water pump options

PostPost by: holywood3645 » Sat Jun 15, 2019 5:25 pm

Which electric water pump did you use?
Is there a way to stop/block the present water pump leak (in place) as it would no longer be utilized.
I think the electric pump is my best option as I have lots of stop and go traffic in a hot climate.
As I sad the engine is running excellent and I can address replacement on next rebuild.
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PostPost by: bulfin » Sat Jun 15, 2019 8:18 pm

I used a Davis-Craig EWP80. My installation is different because the radiator (installed by the PO) is not stock and has input and output on the wrong sides.
When I had my engine rebuilt I told them no water pump and they made a plate to blank it off, so can't answer you question about how to handle the existing pump/leak.

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PostPost by: mbell » Sun Jun 16, 2019 1:41 am

Looking at the three options:

1) replace original pump
Work: remove front cover, press pump out, press new pump in, fit front cover
Parts: new pump kit ($)
Advantage: original setup, least work, probably lowest cost
Con: potential future repeat failure

2) electric pump
Work: remove front cover, press pump out, seal up pump holes, fit front cover, fit electric pump
Parts: electric pump ($$)
Advantage: water flow not tired to engine speed, external pump so easy to replace failed pump
Con: pump likely in lower hose so no circulation with thermostat closed, none original setup, electric issue could cause pump to not run, maybe to more current draw for your alternator

3) cartridge kit
Work: remove front cover, remove back plate, fit new back plate, for new front cover
Parts: new front cover and backing plate ($$$)
Advantage: easy future pump replacement, looks original
Con: cost, might not be bolt in place, possibly more work to remove back plate.

For me if I have to do the water pump I'd probably end up going for option 3). The electric pump has some advantage but personally I am concerned about a lack of flow around the engine when the thermostat is closed as the thermostat being closed effectively prevents water flow into the pump inlet if it's in the lower hose. This may not be a real issue, as no flow may let the engine warm up quicker and the thermostat is at the high point in the engine so convention should move the hottest water there and cause it to open once the engine is is warm. (Or maybe I am missing that the thermostat is removed with an electric pump so it's a none issue, none sure that I am that keen on that setup either thou.)
'73 +2 130/5 RHD, now on the road and very slowly rolling though a "restoration"
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PostPost by: Gray » Sun Jun 16, 2019 5:36 am

I would have thought there is little point in retaining the thermostat with an electric pump, with the pump controlled on water temperature. Also, pumping against a closed thermostat could potentially overheat and damage an electric pump.
On the pump instructions I looked at on one pump it pulses on/off at low temperature to maintain a minimum flow. I would suggest a minimum pump speed, or pulsing control, is essential to provide adequate/even heat dissipation even when warming up.
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PostPost by: mbell » Mon Jun 17, 2019 12:50 am

That would make sense, would need to buy/install a suitable controller to go with the pump but probably still cheaper than the cartridge kit.
'73 +2 130/5 RHD, now on the road and very slowly rolling though a "restoration"
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