engine temp question

[ferozious]

Just curious, can anyone answer for me why is it when I
am full engine braking, like going down a mountain range in
say third gear at 60 clicks not using brakes, just engine
to keep speed down, why would my engine temp drop to almost
lowest point on the dial?

PS It is a 1994 widetrack Fez, extractors, exhaust, snorkel,
no real engine, cooling, driveline mods to speak of.

Cheers.

[murcod]

They can vary a lot due to the silly design of the cooling system, however that sounds extreme. Do you know what brand of thermostat is fitted? Someone might have fitted an aftermarket one and guaranteed that will be the source of the fluctuations. Factory thermostats maintain the temperature a lot better in my experience (and can help cure overheating in Summer.)

[MightyMouse]

They can vary a lot due to the silly design of the cooling system,

Yep - that's about normal, but its not really a great thing. As murcod says thermostats are an issue but the cooling systems a pita.

I've moved my thermostat to the water outlet and its made SFA difference, currently have a water pump apart and its horrible - bad impeller shape and huge clearances. Will machine up a proper impeller and see if that helps with the overheating. Can't see it helping the low temp operations but its Daihatsu so who knows ?

[ferozious]

Thanks for the heads up guys. Haven't inspected the thermostat
but worth a look. To be honest the cooling system works well, if not
too well at times.

Is there any benefit to the system from an electric pump instead of the mechanical?

[MightyMouse]

IMO you have to spend BIG money to get a good electric water pump - the Davis Craig ones do not use magnetic drive so they have a shaft seal that can leak.

The really good ones are brushless and fully sealed with magnetic drive from the motor to the impeller - making them highly reliable but very expensive.

And you need a controller on top of the pump - if I could get a Bosch one cheap I'd have it but......