Dalek cap

[what2do]

Noticed today that the reservoir is damp, doesn't appear to be any cracks. Is it time to replace the Dalek cap?

[ghost123uk]

It's usually either a water level sensor sealing issue or a crack at the top of the bottle (in that order).
The water level sensor can benefit from using some PTFE sealing tape.

BTW, If it turns out you need to replace the bottle try and avoid the JK (and iirc the gsf) ones. VW heritage can generally be relied upon, Link to pre 85 one - or - Link to post 85 one

[what2do]

Ill tape the threads on the sensor and inspect the bottle shortly - will report back soon! Thanks again.

[AdrianC]

It's usually either a water level sensor sealing issue or a crack at the top of the bottle (in that order).
The water level sensor can benefit from using some PTFE sealing tape.

Worth taking the rubber washer off and looking at it VERY closely - ours had cracked just behind the washer, between the threads and hex head. Under pressure, it was flexing and leaking, but looked fine externally.

[ghost123uk]

Ill tape the threads on the sensor and inspect the bottle shortly - will report back soon! Thanks again.

Whilst you are doing that, use the opportunity to clean up the probes and test it. When testing, note = It takes a good few seconds of "probes out of the water (or "plug removed from probes") before the light comes on. Then you have to turn the engine off and then start up again to "re-set" the warning system.

By the way, when it dumps a lot of water out, has your low water level warning light come on ?
p.s. = If "Yes" then no need to test as mentioned above

[what2do]

No dumping of water. The expansion bottle may take an egg cup full after 2 or 4 weeks depending on mileage. Good suggestion regarding testing and cleaning of the probes. Ta.

@Adrian. I guess it would be best to remove the bottle from the van, give it a thorough clean and inspection because it sounds as though theses tiny cracks may be too difficult to see in-situ. Is that correct?

[ghost123uk]

No dumping of water.

Sorry, I have also been replying to a different thread and got mixed up

[what2do]

No dumping of water.

Sorry, I have also been replying to a different thread and got mixed up

TART! You made feel like I was the only one!!!!! Thanks anyway.

[AdrianC]

@Adrian. I guess it would be best to remove the bottle from the van, give it a thorough clean and inspection because it sounds as though theses tiny cracks may be too difficult to see in-situ. Is that correct?

The cracking I found was on the sensor itself. The thread comes up to the hex head, with the top few mm hidden under the rubber seal. That was hiding the cracks, which went almost all the way around. Clearly somebody had overtightened it in the past, starting the cracking.

[what2do]

ok, inspection somplete. I don't believe that water is escaping via the sensor due to it sitting a bit of a well which happened to be bone dry. Initially, it lookes as though the moisture was sitting on the join in the moulding of the vessel which would mean than the 2 pieces were coming apart. After thorough drying and 30 seconds running, it was clear that it was coming from the cap itself. Possibly the seal is shot or possibly I've not been tightening it enough. It is now 'MAN' tight, thus we'll see later on if this has made a difference. A new cap has been ordered regardless, but it's nice to establish why things fail.

The reason why the engine was running for only 30 seconds is because I had disconnected the plug from the level sensor, however, it made no difference.

Normal operation - turn key, diode flashes 10 ('ish) times then stops. Start engine - no diode illuminated.

Disconnected sensor - exactly as above.

WHY? Surely, with the sensor disconnected, something different should have occurred with the diode.

[ghost123uk]

A new cap has been ordered regardless, but it's nice to establish why things fail.

Normal operation - turn key, diode flashes 10 ('ish) times then stops. Start engine - no diode illuminated.

Disconnected sensor - exactly as above.

WHY? Surely, with the sensor disconnected, something different should have occurred with the diode.

Yep, this is why I suggested you check it. Mind you, I would have given it up to 2 minutes with the plug off. No harm can result. I suggested on a thread a few months ago that folks should check this. Reason = these WBX engines respond badly to low coolant levels (including air locks).

The causes of malfunction are =
Dirty probes (scrape them clean)
Bad connections between the probes and the fuse board or dash board.
Failure of "relay" 42 (sometimes numbered 43 on later vans) Note = this is NOT a relay but a quite complex electronic circuit.
Only pure water in the system (no anti freeze) reason = pure water is not actually a very good electrical conductor.

Of course our wiki has a very comprehensive write up on all this = HERE

[what2do]

Am I understanding you correctly, should I unplug ut and run the engine for a few minutes to see if the diode illuminates? Ta.

[ghost123uk]

Am I understanding you correctly, should I unplug ut and run the engine for a few minutes to see if the diode illuminates? Ta.

Yes

[DuaneEddy]

Hi - Not trying to hijack the thread!
My Van does not have dalek cap BUT a traditional type of Radiator Cap - As found on conventional motors such as Mini etc (Fitted 1.9DF engine Year 1983)
I still have the LED flashing arrangement and as mentioned 10 flashes etc - Turn On - Stops - Will flash when Temp Sender shorted to suitable earth on engine. I have not tried or to be honest checked the Low Level Sensor - (If Fitted )
Do- Or Should I still retain the flashing led facility for low water level? As per WIKI - If So Where can the 42-43 box of tricks be purchased from?
And Also Is the Conventional Rad Cap A Norm?
Thanks

[R0B]

But you are hijacking the thread.

Hi - Not trying to hijack the thread!