Club 80-90 Forums

Can any one help. Coolant light work ok when starting from cold . But when hot even though all temperature and sender's replaced . Light stays on when warmed up . system bleed and gauges working while light flashing. not overheating or using water . any ideas.
Hugo 1988

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David.

If your van is post '86 then go to the fusebox behind the glove compartment and remove what looks like a relay marked 43 or 42 then take the van for a drive. Removing this will isolate the temp gauge from the coolant level warning system

If the LED stops flashing then you have a fault in the coolant level sensor side of the system.

If it continues to flash, and the temp gauge is showing normal, then remove the instrument housing cover and check the three nuts that secure the temp gauge are tight, particularly the smaller centre one.

The Coolant warning LED can be falsley triggered by both supply voltage problems and earth problems. The main culprits being the PCB membrane at the edge connector, regulator voltage below 10V or intermittent supply to the gauge.

Thank you Angeloevs I have now replace both coolant level sender and Temperature sender. Have check voltage stabilizer and earth and wiring . all working . So have put the trouble down to a 30 year old coolant relay switch sticking. As the light goes out when engine is cold and stays on when warmed up . I Will be fitting one shortly and let you know the outcome. Hugo 1988

If the problem persists with a replacement module 43, be aware that poor earths, connections, etc, in the coolant level part of the system will cause coolant led problems. The coolant level module 43 is earthed at the earth crown on the pillar close to the fusebox. The radiator fan generates a lot of heat at the crown due to age related connectivity so the condition of all the earth spade connectors at the crown should be checked.

Hi Angloeves Have now fitted new 43 relay and the problem is still the same ok when starting from cold. but once slightly warn led light flashes . I will check the earth on the pillar next to fuse box. I was thinking of earthing out the gauge itself even though it working . i was wondering if its sending a false reading on restarting once the gauge movies when warm . Hugo1988 ipswich

Stating the obvious, but have you checked that the L/H tank is full to the brim when the motor is warm?
(Take the usual care and precautions when removing the cap from a hot / warm header tank!!!)

I ask because there are certain circumstances that can cause an air gap to appear in the top of that tank when the engine has warmed up.

Your low coolant warning could possibly be just doing it's job!!

ghost123uk wrote:Stating the obvious, but have you checked that the L/H tank is full to the brim when the motor is warm?
<snip>
Your low coolant warning could possibly be just doing it's job!!

Yep, I had that when I first got the WBX. In my case a switch off and restart left the light off again. After the second occasion I read the manual, checked the L/H tank and it needed topping up - took about a litre.

Did you test drive the the van to check wether the fault disappeared with module 43 removed?

If yes, then you can focus on the coolant level part of the system wiring, level sensor, changes in coolant level, etc. Coolant led triggering with the module removed suggests the problem could be elsewhere, dashboard, temp sender wiring, etc, etc.

The triggering after a warm up period does suggest a possible coolant level problem. Have you tried warming the van up whilst parked and then blipping the throttle to around 2500 rpm?

There are a couple of tests you can carry out such as removing the level sender connector and placing a dummy resistor across the level sender socket or placing a spare level sender in a simple dummy tank ( plastic bottle, jar, etc) containing water that will retain the fluid and hold the sender in place during a test drive.

Thank you all for your answer to my coolant problem. Well i ran the van up the road and got it running temperature, rev the engine up and removed coolant cap. collant still up to neck so a bit more revs , now as you said air bubbles appear. keep this up topping up tank all the time . water now overflowing replaced cap RED LIGHT OUT. Let it cool down and run up road to temperature. light stayed out when warm on starting. Used the camper for two days no problemes . Went out to day Red light on again when warm . checked all pipe joints for leakages none showing .check water levels in both tanks both ok. Will Bleed again tomorrow. Can air get into the system and if so how. Sorry to be a pain but i have only owned this camper for 9 months and i still learning my way around these things. Hugo1988 .

2 questions :-

1) Do you have roughly the correct amount of antifreeze in it?
(I ask because, the way the coolant level sensor probes work, they sometimes give false readings if just plain water is in the system).


2) Is it the flat four petrol you have in your van?
(I ask because that engine is prone to leaking exhaust gasses into the cooling system if the head to liner seals have failed or if a head is cracked).

........and in addition to what Ghost added, check your Dalek cap is holding pressure. There are some very poor replacement types out there. See the club WIKI for Dalek info.

Those small 0.6 ltr plastic milk carriers could make a good dummy tank, fill one with water/ anti freeze mix, insert a spare level sensor and secure it with some gaffer tape, connect the sensor and drive the van. If the coolant led stays off when up to temperature then you have a problem with coolant level. An easier way would be to simply fit a dummy resistor across the level sender connector, about 100k iirc.

Have now bleed the system again . Header tank was full but got some more air out. lights once again out on starting warm . I had replaced the Dalek cap from Just Kampers and that still quacks when tested today. The recon engine was replaced in December through Just kampers and is still under warranty .This camper had not be used much over the last few years by the last owner.So when i replaced the engine the cooling system was thoroughly flushed out while old engine was out. I have now noticed that i am getting rust water in my header tank and wondered if its due to the lack of usage caused settlement in the radiator to be released causing a air lock. I cannot see that it might be a failed gasket or cracked head as the van start every time and does not run hot or use water. but will keep a eye on it .Its got plenty of antifreeze as well. I will more than likely flush the system through again and change water at a later date. I will keep you informed and thanks for information . Hugo1988

Hugo1988 wrote:I cannot see that it might be a failed gasket or cracked head as the van start every time and does not run hot or use water. but will keep a eye on it.

Just to say that a WBX engine will start fine, run fine and not get hot with either a blown sealing ring or cracked head. However, it would use water though, to a greater or lesser extent, depending on how the fault is developing.

Fingers crossed for you, but at least the engine has a warrantee, so if if does turn out to have problems you will have cover. Mind you, best get to the bottom of it before the warrantee runs out

I have a similar problem with the flashing coolant light. If the van has been standing for a bit the coolant light does not stop flashing even though the water level and temperature are correct. The problem would appear to be with the connections or earths in the system, or the electronics in the instrument panel. Thankfully after a bit of use my coolant light puts itself right! However, this means I never get round to sorting it! I had the dash panel off to change the heater motor and whilst it was off I cleaned the earths and changed the relay but it has not made any difference.

If you have a really good search on this forum/wiki you will find explanations as to how the system works and possible remedies. There is something on http://www.thesamba.com/vw/forum/viewto...80&swtart=0" onclick="window.open(this.href);return false; (thats what is says on the top of the page I printed off?) Its all to do with capacitors and things and I think one remedy is to put a different capacitor in the instrument panel?

I would guess that your problem is to do with the electronics? Best of luck.