Low Engine Temperature

[angus99]

Noticed on a drive at the weekend that engine temperautre was dropping dramatically at speed.

In traffic the temperature was reading 75-80C but dropped almost of the gauge at speed.

I've always thought that the guage read low, and it was a fairly cold day, but this is the first time I have seen it drop right of the scale like this.

A couple of Questions:

1. what is the minimum safe running temperature, and what are the likely consequences of low running temperatures? Excessive engine wear would be my concern.

2. Is there a second switch/themostat that controls the cooling sytstem and if so is this likely to be the culprit?

3. Anyone had the same problem and found a fix?

[PRTVR]

They all do that ! I think the problem is the location of the sensor its in a dead end extended bit of pipe on the front of the engine as you move along it gets cooled down but when you stop it heats up,
it has been discussed a lot over the years on here, just check out the search function at the top and use advanced select chim and griff and enter temperature in the search field, it should should keep you entertained for an hours or so.

Phil
edit to add
I also think that the dead end pipe may not be full of coolant,maybe after a coolant change if it gets air locked it would make thing worse it really is a bit of bad design.

Edited by PRTVR on Thursday 28th April 09:21

[scotty_d]

Take the thermostat out and put it in a pan of water, place a thermometer in with it too then put it on the hob and bring to the boil. See what temperature it starts to open at. When my old one was failing it was opening very early at around 60 degrees whan it should have been 80 degrees ish.

Changed it out for a new one and it was all fine again.

They do drop temperature a bit when getting lots of air flow on the move but yours sounds very low.

[rigga]

Thermostats are designed to fail in the open position, id take yours out and have a look as that would cause the same thing.

[angus99]

Did a test last night,
The water outlet from the radiator was cool intil it reached ~50c on the guage, at which point the outlet pipe heated up very quickly. So looks like the thermostat is not stuck open. By 55C the outlet pipe was virtually too hot to touch.

Left it running and it warmed up to 65C at which point the fans came on. Not sure what temperature the fans are supposed to kick in at but would expect it to be well above 80C, so this seems to indicate that the guage is giving a low reading. I assume the fans are switched on from a separate sender?

Drove to work this morning and the temperaqture was about 50C all the way in until I hit traffic and it heated up to about 70C. Even at 50C there was plenty of heat coming from the heater vents.

Think this all points do a faulty temperature sender. Anyone have the part no. for a replacement. I assume its a standard Rover part?

[haircutmike]

Recently changed to the sender above on the manifold, (what the R/Rovers use I believe) seems to be more accurate.

I had to put a 100 ohm resister in the circuit to get an accurate reading.

Alexdaredevilz will give you more details.

[Alexdaredevilz]

120 ohm resister

Let me know if you want one,

I found the Tvr sender was in deadwater and fills up with crap, in other words-useless

Where as the RR sender is in the flowing water part of the manifold

[J400GED]

Could somebody tell me where the standard water temp sender is (picture with arrow would be good) and also where the alternative position that you mention is ( again a picture with an arrow would be good)? Also, if someone could give me details of the 120 ohm resistor, that would also be very much appreciated.

Cheers,


Ged