Over heating?

[Purfleet]

Morning All

sorry for the long message but after a little advice on the Cav

Only had the car since jan and the first job i got done was the timing belt & water pump so i know it was done

I noticed that the coolant was dropping after driving the car for a few days (she never works that hard and only does a few hundred miles a usually at weekends). So i got a local garage/friend to do the head gasket but as he wasn't available for a couple of weeks i poured in some k seal - didnt doing any real mileage with the k seal in and the head gasket was done.

After than all seemed ok, other than 1 or 2 small top ups of water which i assumed were a few burps.

after a 400 miles or so I then flushed the coolant to get out the k seal, again with 1 or 2 top ups.

Drove the car to London one day last week and she was fine with temperate gauge doing up and down as the fan kicked in.

Then this weekend i went out to check fluids and noticed that the expansion tank was empty, filled it up with half a litre or so of water and ran her around for 30 miles, checked later and all good.

This morning i had a 330am airport run all at 60/70mph to luton airport with no alarms. Dropped my son off at the airport and then steam started coming from the bonnet - i put the heater on which was cold to start with the then became burning hot - once back on the motorway with a constant speed the temperature dropped back to the bottom mark.

Managed to get home and left her until now and checked the water and its dropped 1 or 2 cm, so not out of water. The water in the expansion tank is a little milky, but could be k seal? Nothing milky on the oil cap, no steam from the exhaust

Any ideas? head gasket again? what should i try next?

[Robsey]

It could be a weakened reservoir cap.

If you see steam, but the temperature gauge reads normal, then I would suspect the cap.

If the gauge reads very low, or too hot, then you have a problem.

Low temp hints at insufficient coolant to reach the sensor.
Excess temp hints at thermostat not opening or cooling fan not cutting in.

[Purfleet]

Thanks for the reply

The gauge goes up and down depending on traffic, but i assume that is normal. Never noticed it over the last white mark (100?) or below the first white mark (80?) - she sits at the lower white mark when driving.

So you think if hte cap is leaking that would cause it to vent/lower the pressure and steam? I never noticed any steam when drove into work and the expansion tank was empty after that.

Anyway ordered a new cap fom amazon (free next day delivery) so will start with that and report back.

Supposed to be going to Festival of the Unexceptional in her on Saturday.....its only 250 miles round trip

[Robsey]

If the temperature stays low when on the move, especially motorways, then it sounds more like your thermostat is stuck open.
I suspect the car takes quite a while to warm up from cold.

But - this is separate from the steam issue.
If the head gasket had blown, it may have over-pressurised the cooling system.

Do not be surprised if the heater matrix and radiator have been weakened.

Typical running temperatures are between 88°C and 103°C.
My Cav fan kicks in at about 96°C, and goes off just under 90°C.

But the gauge is not super-acurate - it is just a guide.

[Purfleet]

Just went out to put on the new cap and the expansion tank was empty again - this time i have filled with another 0.75 Litres of coolant and put the new cap on.

Where could the coolant be going other than out of the head gasket?

[ilovedmymantas]

I've been poring over this for hours because it sounds similar to a problem I had with my last cav.

The first thing I would do is change the thermostat. If there's steam it's overheating, that points me to either thermostat stuck closed or temperature sender, as Robsey says, the gauge is just a guide.


After a couple of frustrating months trying to find out why i was losing water the culprit turned out to be my top hose to radiator. The plastic pipe on the radiator had degraded and was broken, probably due to previous owners over tightening the clamp, that cost me a new radiator

Also, fitting a new water pump has probably increased flow/pressure.
Check where the hoses connect. If it's not down to the different rates that metal/plastic/rubber cools it may be furring on connecting metal parts.

[Robsey]

A bit hard at the moment, but a quick visual check is to look for wet patches on the floor.

At the front indicates the radiator or one of it's hoses.
I use red / pink coolant as it is very easy to see any leakage residue on dried components.

Near the off-side (left) front wishbone - indicates water pump, thermostat, or associated hoses.

Rear of the engine - indicates a problem with the rigid plastic hose across the back of the block.

The one to worry about is wet carpets, as that would indicate a leaking heater matrix behind the dash.
That would be a pain to sort.