Overcooling issue maybe ?

[Paulpen]

Here goes.

RB25DET in a S13 with a Revotec electric fan sender in the top hose and 306 HDi fans.

If I leave the car to idle then it will warm up nicely, the needle will sit in the middle of the gauge and the fans will cut in - happy days your thinking !

When I drive it though the needle goes right down and I do mean right down - below the bottom mark.

Also the top rad hose always seems to be hotter than the bottom one - is this right ?

Its got a brand new Nissan thermostat in and is not loosing coolant from what I can tell. Have tried bleeding the system when hot and cold via the 10mm bolt on top of the inlet but still the same.

Has anyone else had this problem or have any ideas what it could be ?

Im starting to think there is a blockage or that the gauge sender is faulty but how can I test these along with the temp sender to the ecu ?

Pleaseeeeeeeeeeee :

[Carl H]

odd...sounds like either a stuck thermostat or air in the system...did you open the heater to full blast before you bled it?also what temp sensor are you running?you need to use the s13's gauge temp sensor for correct readings.

[Shocker]

also what temp sensor are you running?you need to use the s13's gauge temp sensor for correct readings.

my thoughts exactly, I almost made that mistake back in the day one of the first times out..... turns out I was really basically overheating, then when E-fans were on she went want to proper temp.

[Paulpen]

That might be it then !

I read alot of guides before i did the swap but never saw that I should run the standard temp sender unit !

Its currently got the standard RB25DET one in it.

So ill put the CA18DET one in it and see what happens !

[Paulpen]

Update time then !

Tried covering half the rad with cardboard to see what happens. Same as it was at idle but when driving the needle went about 2mm high on the gauge.

Then took the sensor off my CA18 that just came out and put that in and bingo - all SEEMS to work ok now. Not sure wether to be confused and cautious or just happy and forget about it now !