Cooling system problems

[soberphil]

Hi all,

Anyone any ideas about this:

Recently my fan has been kicking in a lot more than normal, radiator is looking a bit worse for wear - quite a few broken fins so I planned on replacing it soon (temp gauge still never gets above half way).

Today my fan kicked in after literally 4 minutes of driving (starting from totally cold, vehicle moving the whole time not stuck in traffic) and stayed on for the rest of my journey (about 20 mins). Guage still not shifting from half way. When I stopped I felt the top hose - this was pretty hot as you would expect, but the bottom hose was stone cold.

On my way home, the fan didn't come on at all and when I stoped I felt both top and bottom hoses - top hose was very hot, and bottom hose was warm, exactly as I would have expected.

Any ideas what's going on here - it's as though the rad was blocked on the first journey?

I still plan on replacing the rad (sooner rather than later), but not sure if this is the only problem - could there be some other issues?

Cheers,
Phil.

[soberphil]

Air lock?

[mafcaw]

Thermostat sticking?

[mafcaw]

Thermostat sticking

[slhhughes]

I had the same problem with mine when I first bought it, the temperature was perfect but I was also losing water. I had it diagnosed as HG failure by one mechanic but a friend of mine found the problem.

The coolant loss was due to the rubber in the reservoir cap being split and the fan issue was a sticking thermostat. The thermostat caused the water to come out of the cap under pressure.

Hope this helps

Steve

[BenH]

I have a cooling issue also, it has started doing it recently. Under normal motorway / main road runs the coolant level stays the same, no loss at all.

However, if a journey involves prolonged waiting in traffic, the coolant level drops a cm or so. The temp
gauge reading remains normal, and I can't hear the fan coming on - don't know if it does though.

I recently replaced the reservoir cap with a genuine one.

The coolant and oil is perfect clean, no mayo or sludge whatsoever anywhere and the compressions very healthy indeed. 38,000 miles on the clock.

Any advice greatly appreciated!

Cheers,
Ben

[soberphil]

Thanks for all your help guys.

Update: had the car in the workshop today and when stationary it seems that the fan kicks in when the top hose gets to about 90 degrees and it then quickly cools to about 85 before stopping (measured with infra red thermometer). Bottom hose getting warm as you would expect.

Drove home (15 mile motorway, no traffic), when I pulled up the fan was going, when I felt the bottom hose (no thermometer available at home), it felt cold.

Temperature gauge staying normal throughout all tests, no apparent coolant loss.

I wondering if anyone has technical data for the temperature the fan should come in at?

Cheers,
Phil.