A few months ago my heater started to only function intermitantly and with a little help from forum members I realised my coolant was low. I have kept and eye on it has been fine since.

On Saturday morning I want for a 150 odd mile razz. All seemed fine, the temperature was normal and the heater worked fine all of the way (thank god because it was COLD).

This morning on the way in to work the water temp went up to four bars which I have never seen before so I stopped and sure enough coolant was being bubbled out of the overflow tank and the radiator was about 2 liters short of coolant!

I assume I have a leak somwhere but it would seem it only manifests itself when I thrash the car.

Does enyone have any ideas as to how I can find it?

I seem to remember a horror story of someone haveing a catastrophic radiator faliure where the fluid ALL drained out meaning that the temperature readout stopped functioning and he totalled his engine!! Needless to say I am a bit worried!!

Any help would be greatly appreciated.

 

Could be something as simple as a stuck thermostat or a failed rad fan or rad fan switch.

Where you in slow moving traffic or stop start traffic when you noticed the temperature going up?

 

I once had a small leak on one of the hoses on the side of my intake manifold.

This was only dectectable when the engine was very hot.

Very easy to fix.

Run your car on your driveway for 10min and then search for drips. If it is boiling out of the top of overflow tank it could be the fan or the fan switch.

 

OK, Thanks...

When I stopped the car to top up the radiator I had 4 bars on the dash but the fans on the radiator were not running I presume that is not normal?!

If I go to helfrauds and buy more colant should I be looking for anything in particular?

Cheers,

Alex

 

the fan should have been on. Did you check the coolant levels when you did your 150mile run. Had they dropped at all?

I ask again, were you in slow moving traffic or stop start driving when the overheating happened?

 

Sorry,

I did not check the coolant before or after I went on my run, the first I knew of the problem was this morning on the way to work when the heater wouldn't worjk and then the temperature went up to 4 bars.

I was in slow moving stop start traffic at the time the temperature started to climb.

 

Ok, that sounds like either the fan switch or the fan itself that has failed. Top up the coolant, start the car and let it idle on the drive. If the coolant temperature goes past 3 bars without the fan coming on its the fan or the fan switch that has failed.

You can test the fan by following the instructions below



if the fan runs then its the temperature sensor that has failed.

 

Thanks for that

I will test the car out in the car park this lunch time.

 

OK, the fan comes on and off as it should when idle and it stays at three bars which is good but I still don't understand why I am losing coolant.

The pic below shows the front face of the engine:



Image doesn't seem to work so here is a link: http://www.leonpaulnews.com/uploads/coolant3.jpg

Is the tube along the face of the engine part of the coolant system and is the black stuff on the front likley to be coolant?

 

Ok if the fan is working when the cooling system is full of coolant then it's not the fan or the fan switch.

most likely what is happening is:

you slowly lose coolant.
fan switch is not covered by coolant due to leak so fan does not come on (same reason heater does not heat car (not enough water and air gets into cooling system.)
in slow moving traffic with no fan remaining coolant will boil.

so it looks like you have a slow coolant leak somewhere.

Check all joints between all coolant hoses and their connectors. check engine both hot an cold and look after long runs in case you get a bit of boiling while your back is turned.

Until you find the leak top up every day.

BTW I don't like the look of the leak down the front of your block. If you can't find a coolant leak externally then you must assume you are losing it internally. Keep looking though. I once took 3 months to find a leak. Just kept topping up then one day I spotted it. It only leaked when the engine was semi warm. Fine when cold and fine when fully warmed up. I still lost about a pint a week though)

Keep a very careful eye on oil levels (if it appears to go up stop driving as you have a serious problem of either a cracked block or a head gsket gone.)

You should also consider if your problem is due to scale build up. It might be creating a hot spot and causing local boiling. You could try flushing the system but in my experience this tends to knacker the water pump anyway.

Good luck.

Oh yes - use only a Honda approved anti freeze mixture.