Coolant boiling over but temp gauge normal and no fans kick in?

[Johnc172]

Hey All,

Took the car out for a spin and was fine whilst driving but when I left it on my drive to idle, the coolant started boiling over and the fans didn't kick in.
The temp gauge in the car remained in the middle too, which I can't get my head around!!
Checked under the car and no leaks (as i thought maybe water pump) and also checked heater in car and had hot air pumping out.

Any suggestions? I replaced the temp sensor a few months back and now seems to work fine (no skipping about and rises gradually to the middle)

Could it be thermostat? But then why wouldn't the fans kick in, as the water temp would surely be high!

Baffled!

 

[Chrisgti6]

Hey All,

Took the car out for a spin and was fine whilst driving but when I left it on my drive to idle, the coolant started boiling over and the fans didn't kick in.
The temp gauge in the car remained in the middle too, which I can't get my head around!!
Checked under the car and no leaks (as i thought maybe water pump) and also checked heater in car and had hot air pumping out.

Any suggestions? I replaced the temp sensor a few months back and now seems to work fine (no skipping about and rises gradually to the middle)

Could it be thermostat? But then why wouldn't the fans kick in, as the water temp would surely be high!

Baffled!

Does the rad get hot? How long was it left idling for?

 

[bashracing]

Undo the bleed screw on the stat housing, if that's ok change stat,

 

[Johnc172]

Does the rad get hot? How long was it left idling for?

I didnt actually check if the rad or top rad pipe to see if it was hot actually!

Thing i dont understand is why the gauge didnt go up? Is it because it reads after the thermostat and if its stuck shut it reads as normal?

 

[Johnc172]

Undo the bleed screw on the stat housing, if that's ok change stat,

I'll run it up again and see bleed it all - see what happens

 

[marinemackay2003]

I reckon you have a dead stat or a big air lock

 

[STEVE.M]

Just a little puddle of clear water from the aircon?Must admit I`ve had a Oh No moment with this till I worked it out.

 

[Johnc172]

Air lock may be the one, as when I took the bottom rad hose out to drain the coolant only a bit came out, took the coolant sensor out and s**t loads of air came out followed by coolant all over my garage floor!!

Stat deffo works as took that out and dumped it in boiling water to make sure it opened

Got an car electrician mate coming round at midday to check the override switch he wired in, hopefully get to the bottom of it today

 

[Johnc172]

Fixed!!! Thought I'd update this in case anyone else has the same symptoms.
It was the lilac relay (rad fan relay - 50amp jobby). All the contacts had got corroded and water was inside the relay itself at some point by the looks of it! Put everything back together fired up and the fans came on after 20 mins of idling.

Still don't understand why the temp gauge didn't rise past the middle - it obviously works as the fans came one...can anyone answer that one?

 

[Chrisgti6]

Was that 20 minutes from cold start?

Something still not 100% IMO. It should take longer than 20 minutes for it to get hot enough for the fans to kick in at idle.

 

[Johnc172]

Was that 20 minutes from cold start?

Something still not 100% IMO. It should take longer than 20 minutes for it to get hot enough for the fans to kick in at idle.

It's a boost bus so heats up a lot quicker as the turbo is water cooled