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[Squealey]

Evening All

Just got in from a long day, had an early christmas at my folks in Hemel Hempstead, only time before the big day we could all get together.

All was fine with my TD as it always is. Travelling from Boston, stopped off at the huge Tesco's in Peterborough before travelling down to Hemel. Had to shoot into Comet when I got there for about 5 minutes where I left the engine running with my family in it (the battery is pretty stuffed so I don't like to stop and start it if I don't need to). Then drove the car to my folks, a 5 minute drive, this is when it started playing up.

Stopped at a junction, steam poured out the side of the bonnet where the expansion tank is. I was less than a minute from the folks so limped it back to theirs. Temp guage was trying to go off the scale.

Got there, pulled the bonnet and the expansion tank was bubbling away and the cap was loose. I'd checked the water level and topped it up the previous day so it ran through my mind that maybe i'd forgotten to tighten it properly, so I tightened it down. It stayed down for about 20 seconds then, click, it was loose again.

Is this some feature of these caps? When the pressure gets too much are they designed to click up the thread to release this pressure.

This happened about 3 weeks ago but I put it down to me not tightening it correctly. Looks like I was wrong.

As a matter of course I checked the dipstick and took the oil cap off, theres no water in the oil at all.

I then (very gingerly) drove it back to Boston (After putting over 5 litres of water/antifreeze mixture in it when it had cooled down). It was entirely faultless, hasn't overheated once or even thought of overheating and hasn't used a drop of water. The coolant level warning has been on all the way home but this is not un-normal, its on 90% of the time even though its topped up to level.

So, what are all you experts opinions on this? Likely candiadate for a head gasket? Something simple like a dodgy rad cap or something I haven't even thought of.

This is why I love this site. I was sitting at my folks house thinking of how much up sh1t creek I would be without you brilliant bunch of lads and lasses out there.

Thanks Very Much In Advance

[rustym95]

the threds sound to be lose but should not over heat unless you had an air lock in systerm have seen one fly off before but that was when it had been on a 600mile drive in the hot sun, would just change the tank top or the expansion tank as the threds maybe going on that and see how it gose from there.

[damage consultant]

have you taken or has the viscous fan been removed its the only thing that would force it to boil over unless the h/g, water pump or th-stat were on there way out.
the rad cap is designed to release when the preasure is to great to advoid blowing out the rad so yes it will click up a notch

[Squealey]

The viscous fan was removed by its previous keeper. This had crossed my mind too. But I have done 16,000 miles in it since May without a problem, although it is only recently the weather has been as cold as it is. Think this could have a bearing?

[Elite Pete]

If your car has been left ticking over for 5 mins without a cooling fan then no air will be passing through the rad and it will over heat. If the head isn't knackered as a consequence you have been very lucky

[Elite Pete]

Just to add the boiling temp of the water will be lowered if the cooling system can't pressurize due to a faulty coolant bottle.

[Kevin Wood]

I assume it's got a working electric radiator fan?

If the cap is actually popping loose on the threads I would say it, or the expansion tank neck, is faulty. If it does overpressurise an internal valve will allow it to vent but the cap won't come loose.

If the engine is actually overheating, then make sure the electric radiator fan is working (especially with no viscous fan).

Kevin

[damage consultant]

if its not got air-con it won't have leccy fan or if air-con needs recharged the fan won't come on.
mine didn't until I got it recharged and I leave it on all the time not much diff in mpg.

[Squealey]

It is meant to have climate controlled air con but that hasn't worked since before I got it. (Jaime was completely up front about everthing on this fine car and told me what is wrong with the air con, but its not exactly one of those jobs that I need/can afford to do)

The electric cooling fan is definitly working as I always comment that when it stops (30-60 secs after the engine is turned off) it sounds like a quiet jet engine powering down (yes I know how sad that sounds )

How much would one of you fine breakers charge me for a viscous fan (Inc P+P to Boston)?

[Elite Pete]

I didn't know they had an electric cooling fan as well as a viscous one, you learn something new every day

[Seth]

Try a 'PM' to tigers_gonads ........
He's breaking a TD, and may have an expansion tank and viscous fan.

Best of luck bud!

[Entwood]

New expansion tank and cap needed IMHO

Reason .. while the cap is "holding" in the correct position the system is pressuised and the boiling point raised to about 110C, sitting idling with no fan will get close to this and the internal pressure will start to rise, as soon as the cap "pops" because of this presure the boiling point drops instantly with the loss of pressure to 100C and you will lose a LOT of water.

The internal relief valve does not "pop" the cap, it just opens slightly and relieves excess pressure but does NOT relieve ALL pressure ... so the boiling point does not change.

I could be wrong .. but if it was mine I'd go that direction for the sake of £30 ... cheaper by far than a new engine if you overcook it ..

[platty]

I agree with Entwood - change the header tank comlete with level sensor. This should fix the "coolant level" warning too.

The viscous will make naff all difference IME - I have not run one for 18 months and in the summer the gauge climbs to 95 deg and the fans kick in and it dros to 92.5 - it will do this all day long whether driving or stationary.

Change header and see how it is IMO

 

[Pitchfork]

I didn't know they had an electric cooling fan as well as a viscous one, you learn something new every day

They have 2 electric fans & a Viscous!

[TheBoy]

The caps dont normally jump threads - the cap has an internal release.  Sounds like its knackered the tank and/or cap.

V6 ones are £24 + VAT for tank with sensor and about fiver for cap, not sure on prices of TD ones.


A/C not working will not have a bearing on this.  If leccy fans are working properly, should be fine.


If its massively overpressuring, thats very bad news