QUESTION
I just installed a 74 degree Centigrade thermostat but the engine wouldn’t run at the correct temp and instead went high.
The thermo fan came on but was not able to drop the temperature unfortunately, it just stayed on with the temp around 95.
I’m thinking there must be something else going on, water pump issue?
The car came without a thermostat so perhaps this is the best they found it to run without looking into the real cause.
Would you recommend pulling the water pump out of my Lotus twin cam engine?
J.S. - Melbourne, Australia
ANSWER
Removing the water pump on a Lotus twin cam engine is not a trivial task
In the Lotus manual, the recommended procedure is to first remove the cylinder head
However it is possible to remove the front timing chest/water pump by first removing the sump pan
If this is carried out whilst the engine is still in the vehicle then it is going to cause problems when re-installing the sump so it is completely oil tight
This may sound strange but the best way of overhauling the water pump is to remove the engine
This gives unprecedented access to installing the sump cork seals whilst the engine is ideally mounted up-side-down on an engine stand
It is also an opportunity to change the rear crankshaft main seal, change the gearbox input shaft spigot bearing and inspect the clutch
The message is - you only ever want to do this job once and have a water tight and oil tight engine
Having discussed the merits of removing the Lotus twin cam water pump, then this problem needs to be fully diagnosed before moving forward
It is highly recommended that simple tests be carried to determine if the water pump is possibly cavitating and not operating efficiently
Details how to carry out these tests can be found here
https://lotusmarques.com/info/technical/29-general/105-water-pump-efficiency-test
In these circumstances it is wise to correctly diagnose the apparent over heating problem before embarking on removing the water pump
Copyright © 2020 Lotus Marques
I just installed a 74 degree Centigrade thermostat but the engine wouldn’t run at the correct temp and instead went high.
The thermo fan came on but was not able to drop the temperature unfortunately, it just stayed on with the temp around 95.
I’m thinking there must be something else going on, water pump issue?
The car came without a thermostat so perhaps this is the best they found it to run without looking into the real cause.
Would you recommend pulling the water pump out of my Lotus twin cam engine?
J.S. - Melbourne, Australia
ANSWER
Removing the water pump on a Lotus twin cam engine is not a trivial task
In the Lotus manual, the recommended procedure is to first remove the cylinder head
However it is possible to remove the front timing chest/water pump by first removing the sump pan
If this is carried out whilst the engine is still in the vehicle then it is going to cause problems when re-installing the sump so it is completely oil tight
This may sound strange but the best way of overhauling the water pump is to remove the engine
This gives unprecedented access to installing the sump cork seals whilst the engine is ideally mounted up-side-down on an engine stand
It is also an opportunity to change the rear crankshaft main seal, change the gearbox input shaft spigot bearing and inspect the clutch
The message is - you only ever want to do this job once and have a water tight and oil tight engine
Having discussed the merits of removing the Lotus twin cam water pump, then this problem needs to be fully diagnosed before moving forward
It is highly recommended that simple tests be carried to determine if the water pump is possibly cavitating and not operating efficiently
Details how to carry out these tests can be found here
https://lotusmarques.com/info/technical/29-general/105-water-pump-efficiency-test
In these circumstances it is wise to correctly diagnose the apparent over heating problem before embarking on removing the water pump
Copyright © 2020 Lotus Marques
