V8 coolant experts question

[Trevsked]

My 99 V8 indicates a little warmer than I'd like before the fans cut in. I've checked the reading on the temp gauge against the reading on an OBD reader and that's the same so think the gauge is correct. Anyone know where the sender for the fans is located as I think this may be faulty?

 

Trevor.

[sailorbob]

The OBD-II coolant temperature reading comes from the ecu coolant temperature sensor and the ecu controls the radiator fans. There isn't a separate coolant temperature sensor for the radiator fans.

[Trevsked]

Ok thanks for the reply. Any ideas why it appears to be triggering late? I suppose change the temperature sensor first then.

 

Trevor.

[Bibs]

I think there are 2 sensors of the V8, one is a water temp sensor and the other is called the Engine Coolant Temp (ECT) sensor. I'd guess one is for the ECU and one is for the gauge.

[Trevsked]

Well that was my belief so currently no further ahead. A call to GST as he'll probably know.

 

Trevor.

[mike_sekinger]

Bibs is right.  Both sensors are located to the left of the thermostat housing, but unfortunately access is poor due to the plenum.

[Yellow and Green]

What do you consider a little warmer than you'd like?  The ECU should tell the fans to come on at 100 degrees C.

 

Jake

98 V8 #5651

[Trevsked]

Ahh, is that right, in which case it's performing correctly. It does exactly tat but I thought that seemed a little high?

 

Trevor.

[Yellow and Green]

Nah, that's not high at all.  100C equals only 212F, and most manufacturers these days aren't turning on cooling fans (aside from with the A/C) until 220F or more.  The Lotus manual even says not to worry about high temperatures unless you get to the warning light level - but I would never let mine go that far.  

Keep in mind that the gauge is not linear; that is, it has the widest "swing" in the normal operating temperature range (82C - 100C).  If it appraches 120C, then it's time to start worrying a bit.  An engine is most efficient at warmer temperatures, so don't be tempted to remove the thermostat or install a cooler one.  I've seen some on these forums who believe it will help prevent liner leaking issues, but that logic is completely counter intuitive.  Once the thermostat opens at the stock 82C, there is no difference whatsoever.  The only thing a cooler thermostat accomplishes is making your car less efficient, more of the time. (** all assuming the car hasn't been modified from stock requiring changes to the cooling system design **)

Enjoy that car.  It's working perfectly!

 

Jake

[Trevsked]

Thanks for the advice, time to get out for a drive soon, it's been parked far too long.

 

Trevor.