Water temp sensor in header tank faulty?

[Gasman GT3]

Last week I had the water level/high temp light come on, which also activates the engine check light. The engine was not overheating so I checked the level which also seemed ok. On a run the same happened today with the engine running at a constant 80 degs. After a while the warning light goes off.

I vaguly remember someone else had the same problem a while back and it was a faulty level sensor in the header tank. I have the combined engine coolant/chargecooler header. I have looked for the thread but cannot find it.

Is the sensor repairable and what should I look for as a fault? All help gratefully received.

[fflyingdog]

Take the sensor out of the header tank(cold),it should rattle when you shake it (ala coffee shaker),the float gets stuck ,just squirt some adhesion removing stuff ........ok WD40 and keep shaking you will find the float will loosen up its only crud in the float chamber(probaly)

Nick S4s

[Gasman GT3]

Thanks Nick,

I'll give that a try

[Paul C]

With the check light on the car will not give you full boost,

easy to see on the S4 and SE, but not so on the late dash

with no boost gauge.

Low coolant on the SE brings on the check light and the boost

will only go half way. Probably just the sender, and one of those

things that prove a check light is not always

[rogerch]

When did you last flush and replace the coolant? including the header which tends to collect sludge, I took mine off to flush it properly. May not be the issue but a job well done to eliminate it.

Roger

[Gasman GT3]

Paul,

Thanks for the tip. That explains why I got poor boost yesterday.

Roger,

No not flushed the system recently, but I am going to service the car in Jan and as part of that I am fitting a poly chargecooler impellor so will need to drain down then, so thats a good opportunity to give the system a good flush through.

[Splodge s4]

Hi Ade, hope you had a great christmas & all the best for the new year, it was my thread about the coolant sender. Mine ws gunked up & following Nicks advice I removed it & washed it through with hot water & gave it a good shake. lots of gunk came out & its been fine since.

See you sometime in the new year mate. Oh heres the link to the original 3 page thread.

http://www.lotusespritforum.com/forums/ind...mp;#entry173940

Edited December 31, 2008 by Splodge s4

[Gasman GT3]

Hi Gary,

Had a great Christmas thanks.

I took the unit out today and yes it was full of crap. I have refitted it but still get the warning light. Perhaps you could help me out by letting me know what the water level should be as I think that also my be a tad low. I have no owners manual so am not sure where it should come up to. Inside the neck of the header is a red liner with a slot cut in it, does the water level come to the top of the slot?

Thanks for posting the link by the way.

Happy new year to you and Mary

[Paul C]

You need someone with more knowledge than me, but...

Have you pulled the battery or reset the ECU using freescan?

I'm not sure the check light goes out automatically once the item

is fixed.

Also, and this might be from the pixie land in my head, i thought that

the check light could come on for a certain amount of starts after a

problem had been sorted, unless it the ecu was reset.

?

[Jonathan]

It should self level, the expansion bottle in the passenger rear wheel arch is sued to take any excess - I always fill mine to the brim and let the car do the rest (assuming your pressure cap is working OK)

You need to meter the switch out and make sure the contacts are working - As Paul says, reseting the ECU is probably a good idea too as some of the codes flash up regardless of there being a fault to prompt you to 'clear' them (not sure if water sensor is one of them but it doesn't hurt to try) - as always if you have freescan the fault code # is always the best help.

[Gasman GT3]

Thanks Jon,

I'll try that, and disconnect the battery to reset the ECU, then I will have no alternative but to go out on a nice long drive to get it all set up again. Shame

Just one more thing, My pressure cap is looking a bit grubby and so I want a nice shinny new one, What pressure setting do I need?

[Jonathan]

Heres where I got mine :

http://shop1.actinicexpress.co.uk/shops/Ra...t=Radiator_Caps

15psi version should be fine (which is the one I have), the good book says 110KPa which is 16psi. Not had any issues with mine appart from the bottle in the arch filling up more which is expected.

Lowering the system pressure lowers the lowers the boiling point somewhat which isn't ideal but I've never experienced anything un-toward. I guess it could be a problem if you caned the living daylights out of the car like you were at Le Mans or something - perhaps someone on here knows more ?

[Gasman GT3]

All sorted,

nice clean sensor, system topped up, ecu reset and all lights are out.

Thanks for all the help and advice, and Jon thanks for the link, I have just ordered a nice shinny new rad cap for added bling.

Cheers

Ade

[Jonathan]

They are very nice - shows the rest of my engine bay up though !

Glad you got it fixed up.

[rene1993earlys4turbo]

Try replacing heather tank preassure caps it work for me