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

[GeeTR]

Top hose sends post engine, hot water to the rad, so yah, its normal.

I would think the controller is running the fans too often, or before the motor's reached its normal op temp.

Had a quick look at these Revotec setups, look pretty impressive!

Can you tweak the fan activating temperature?

EDIT: Keep in mind the cluster gauge is a three step unit. It wont show finite variants; used to stop your average commuter from freaking out cus the needle is always moving.

Your after market ECU will have a decent water temp reading fed to it from the 2 wire sender.

PFC, Autronic (assuming your from the US - AEM? will have the output there somewhere.

Find a known accurate temp reading, if your indeed too cold (u mention uv replaced the thermostat) then one would think your lecky fan setup is cooling it down too much, how ever strange it sounds.

Interesting, let us know how you go!

Edited February 23, 2008 by GeeTR

[Paulpen]

Top hose sends post engine, hot water to the rad, so yah, its normal.

I would think the controller is running the fans too often, or before the motor's reached its normal op temp.

Had a quick look at these Revotec setups, look pretty impressive!

Can you tweak the fan activating temperature?

EDIT: Keep in mind the cluster gauge is a three step unit. It wont show finite variants; used to stop your average commuter from freaking out cus the needle is always moving.

Your after market ECU will have a decent water temp reading fed to it from the 2 wire sender.

PFC, Autronic (assuming your from the US - AEM? will have the output there somewhere.

Find a known accurate temp reading, if your indeed too cold (u mention uv replaced the thermostat) then one would think your lecky fan setup is cooling it down too much, how ever strange it sounds.

Interesting, let us know how you go!

The fans are adjustable from about 70 - 120 degrees centigrade - its currently set in roughly the middle.

The engine is still standard and running a standard series 1 ECU. England btw

As for the ECU temp sensor - is there any reading / test I can do to know the temps at hot and cold so I have something to go by to get the correct operating temperature ?

[R34GTFOUR]

the only thing that regulates temperature is the thermostat, even if you were running massive thermos constantly they shouldnt affect your operating temperature since thats is purely controlled by the thermostat. The only thing the thermos will do is give it greater cooling power to prevent overheating, not operating temperature.

My bros r33 reads 88 degrees celcuis from an electric apexi gague whether its the middle of winter and summer, so get a thermo gun (most mechanical workshops will have one) and just get them to give you a quick reading of what the coolant temp is at. If its around the 80-90 degree mark your car is fine and its most likely just a gauge or a sender. Is the thermostat just a standard nissan item? its not a nismo variant that has a cooler opening temperature?

[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 !

Will get the leccy thermostat at work out tomorrow - wheres the best place to check it ?

the only thing that regulates temperature is the thermostat, even if you were running massive thermos constantly they shouldnt affect your operating temperature since thats is purely controlled by the thermostat. The only thing the thermos will do is give it greater cooling power to prevent overheating, not operating temperature.

My bros r33 reads 88 degrees celcuis from an electric apexi gague whether its the middle of winter and summer, so get a thermo gun (most mechanical workshops will have one) and just get them to give you a quick reading of what the coolant temp is at. If its around the 80-90 degree mark your car is fine and its most likely just a gauge or a sender. Is the thermostat just a standard nissan item? its not a nismo variant that has a cooler opening temperature?

[GeeTR]

The fans are adjustable from about 70 - 120 degrees centigrade - its currently set in roughly the middle.

The engine is still standard and running a standard series 1 ECU. England btw

As for the ECU temp sensor - is there any reading / test I can do to know the temps at hot and cold so I have something to go by to get the correct operating temperature ?

A aftermarket gauge would be best, but you don't wanna hear that. If you know the C⁰ values, could use a multimeter on the temp sender terminal. If you don't, get ghetto on the stove top with thermometer and multimeter to find out.

R34GTFOUR is correct, its still most likely the thermostat, or the housing it sits in... even though you mention you replaced it with a NEW one.

Edited February 24, 2008 by GeeTR

[GeeTR]

Sweet, good times - bung sender