Fan running time!

[Mr Tank]

Hi

Ever since I did my rebuild the car has run hot! It even did this with the previous owners.

I have tried everything, changed most things. Rad is new, water pump is new! Hoses are new!
Yesterday I put in a yet another new themostat, this time a 74deg one! and yet another otter switch.

The problem still the same!

The temp goes up to nearly 100 on the gauge then the fans cut in, but they only switch on for 30- 45 seconds at a time, hence the reason for changing the otter switch.
As the only cut in for a short time the temp still rises to 110 in traffic!

Any ideas!

Andy

[Waynester]

Air locks?

How many miles has the engine done since re-build? Could be quite tight, and run a bit hotter.

Sounds like you have done all the obvious checks...

Not ideal or be the real cure but could you wire up an override..to keep fans on longer?

[Brap_Brap]

Why not just run it full time? It's not as if it's the fan's job to turn on/off and control engine temp, your thermostat does that.

[redweapon]

Yes, my wedge did similar in traffic, fan cuts in around 115 and then off at 105. So it just sits in the red needle going up and down. I fitted a new fan otter switch on the bottom of the top swan neck. Got a switch that is rated to cut in at 92 & off at 87. Now in traffic the needle never gets above 90. All that is required is to drill a hole and weld a M22 nut in place, then you can use a standard fan switch from any old car. See pic.

Hope this helps.

[Brap_Brap]

Pretty ingenious.

[chedder]

Their is a possibility that your temp gauge may not be telling the truth and over-reading.
It sounds like the fans are cycling correctly, try popping down to your local garage and see if they have one of those hand held infra red temp gauges that they use to find hot spots on engines, they could point it at the temp sensor and see if the reading matches the one on your dash guage, it may just be a dodgy gauge or more likely the sensor.

Chedder

[RussWood]

Have you fitted the thermostat correctly?

There is a hole in the thermostat with a little jiggler to break up bubbles. This should be fitted at the top, otherwise there is a chance that air might stop the water heading the thermostat bulb.

Russ

[mac123yre]

My gage is the same but all seems well I think just a dodgy gage

[adam quantrill]

Andy - I bet you didn't fit the "calibration" resistor in-line with the sender for the temp guage.

This might be 5 to 10 ohms, you need to use a decent thermometer to measure the water temp and set up the gauge to read the same by adding resistance. Otherwise you run the risk of over-cooling the engine which is just as bad as running it too hot! Aim for 85-90 degrees running temp.