Rising Temp at Idle and strange fan behaviour

**discorevy** · 16th March 2020, 06:54 PM

Originally Posted by Discodicky

The basic principle behind the o/flow bottle is that as the coolant depletes (or leaks) the vacuum created causes the water to be sucked from the bottle to replenish. Similarly, as the coolant heats it expands and goes into the bottle, and as it cools it contracts which causes said vacuum, so it gets sucked from bottle back into radiator. All very well and ok, however if the coolant leak is fairly rapid or even not noticed over a long period and is significant it doesn't create a vacuum therefore no water gets sucked from the o/flow bottle. Therefore, by looking at the bottle and seeing/thinking the level is ok however the radiator could be seriously low of water.
Might pay to check the rad level but when cold of course. Pressure test system for potential leak.

these aren't an overflow bottle , they use an expansion tank as an integral part of the cooling system .
there could be an air lock which , if it was big enough would stop flow through the bleeder in the expansion tank
As a stop gap until you get it to a workshop top up the coolant and bleed the system

**Oohsam** · 16th March 2020, 08:20 PM

Thanks for the replies everyone!

Yes Im going to have to invest in a GAP tool. I have a very expensive scan tool that I am yet to try on the LR, normally reads everything and all monitors, I'll check that first.

I did some diagnosing on the clutch fan, and it is working as normal.
This new found information about the expansion tank has got me thinking.

I didn't realize that the coolant was sucked in when the car was running - I need to go back and do some more checks on the coolant levels as it definatley needs to be topped up. its quite low.

I will top up and bleed and re-pressure test it. Im glad I got that pressure testing kit those years ago, has come in handy a few times now.

**DiscoJeffster** · 16th March 2020, 08:33 PM

Yes the tank is part of the system, is pressurised and is vital to the system. It being low is an indicator of your problem and as other have said, add coolant and use the bleed screws to draw coolant through and remove air. Crack on!

josh.huber · 17th March 2020, 10:32 AM

Don't forget aircon condenser will command engine fan aswell.
I would turn off AC while diagnosing. Have you done a good clean of the cooling pack externally

**eddy** · 17th March 2020, 12:45 PM

If there is coolant loss,another area to check is the plastic coolant outlet[LR073372] can slowly leak and evaporate away,leaving pink staining on top of the motor.

**Oohsam** · 17th March 2020, 12:53 PM

I haven't done a clean of the cooling system - I will though.

I'll double check that plastic thermo housing for leaks...Tonight is the night I will start diagnosing.

Wish me luck!

**DiscoJeffster** · 17th March 2020, 12:56 PM

As you probably know coolant leaves behind a white residue when it dries so do a thorough inspection around the back of the engine, top and front (under the plastic cover etc). Good luck.

**shanegtr** · 17th March 2020, 01:13 PM

Originally Posted by Oohsam

I did some diagnosing on the clutch fan, and it is working as normal.

From your first post it sounded like the fan was responding to the ECU seeing high temps - fan clutch locked up hard so you where getting full drive to the fan

**Oohsam** · 17th March 2020, 02:50 PM

Originally Posted by shanegtr

From your first post it sounded like the fan was responding to the ECU seeing high temps - fan clutch locked up hard so you where getting full drive to the fan

Yes, you are correct - I checked it further and it was respnoding well - AC on, engine on idle, cold start etc.

I have ruled out the fan for now.

Blue Rover · 19th March 2020, 09:06 AM

Make sure electric condenser fan/fans are operating correctly.

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