Have a Felicia 1.3 that has symtoms: dash board temperature gauge at minimum, heater element only blows luke warm air.

Tested gauge by earthing black wire - deflects nicely, removed coolant temperature sensor and noticed coolant level low. Add about pint of water to expansion tank until overflows out of sensor housing, refit and heater and gauge work fine, rad works fine etc

By morning same problem - have tried radseal, can't see any obvious leaks.

Am wondering whether air is entering round sensor seal but guessing really

Any ideas?

Thanks

David

Is it possible that you have an airlock in the system? When the symptoms occur, do the hoses feel hot ? The bottom one will be very warm rather than hot as this is the cooled water.

All hoses to radiator get hot / warm as does rad. I've removed sensor 3 times now and refilled till overflowing so assume not an air lock?

what height is the coolant in the expansion bottle?

to bleed they system we usually leave the sensor out and fill from empty untill it comes out from the sensor hole then warm up and check level in bottle..

it may be wort removing the small bleed pipe from the housing to the expansion bottle and checking that water is able to pass thru both plastic ends and the pipe

I filled up to top mark in expansion bottle and have seen water flowing through small pipe to expansion bottle.

This problem started suddenly -I didn't drain anything down / plenty of water in expansion bottle

Run at fast idle with the front end of the car higher and coolant cap off. Keep the fans on and wait till it burns your hand. Are you sure the thermostat is functioning correctly. If the Felicia plastic one is as useless as the Fabia one, it's a fair bet that you need a new thermostat and the housing bit (a revised less likely to break bit is available from Jorily). If you can move the thermostat with the temp sender removed then the clips have broken.

Edited 6 March, 201016 yr by anewman

Tried that and ok till next day.

Warmed up engine, gauge didn't move. Left for 5 minutes, released pressure in expansion tank then removed sensor from housing - small gush of water, replaced sensor. I then restarted car and warmed up again - sensor works ( gauge moves)

is it worth trying

change sensor gromit? (air being sucked in when engine cools?)

Since no visible leaks could it be water pump internal leak?

Any more ideas? Thanks

If there are no visible leaks and you're losing water, then it has to be the head gasket. That is if there are definitely no visible leaks - I've known a couple of people say their cars weren't leaking and that it must be the head gasket. when actually the cars were leaking when they were hot, just a bit, and it was steaming off. But most of the time in cases like this, there's a head gasket problem. Sometimes worth taking a look at the spark plugs, you can sometimes get a really clean one as the steam cleans it off (and indeed the entire cylinder), hence the chav decoke technique of spraying a bit of water into the intake on a running engine.....

Actually there is another possibility; the radiator cap; if the cap rubber is slightly perished it can vent when hot,and messing up your engine cooling (lower pressure means it never gets hot enough to work effectively); had this on my car last year, and my Grandfather's old Rapid had the wrong cap fitted and it completely buggered things up, the car would overheat above 40mph, yet the heater never gave hot air.

It only really happened when the engine was fully warmed up, at lower speeds and when cold, the cap remained sealed and everything looked normal.

That's a leak!

Check for Mayo in the oil filler cap - thats a sure sign of a head gasket failure.

Not a sure sign, but an indication. Some engines, particularly if used on short journeys, will have mayo in the cap.

No Mayo on dip stick or in filler cap

I'll clean up all the hose ends, and watch when the engines reving - I'll also check in a couple of days for any deposits on ends of hoses. Good news that probably not head gasket!

Have you checked for leaks in the matrix or matrix pipes. If it is only blowing warm air but you think the pipes are hot as you have said,, maybe the water is not getting through it. My gauge would not move, unless the engine got really hot, but the heater always gave out plenty of hot air though. I put in a new improved stat and the guage is fine, heaters are just as hot as they were.

Check that coolant is going around the system, do you see it trickling into the expansion tank once it has warmed up.

Edited 16 March, 201016 yr by myjalopy

Some external leaks (not HG) can be difficult to detect.

i had all the symptons you've mentioned and i got a new thermostat from jorily which took about 10 mins to swap over on sunday morning and all symptons have now gone!