Water level light comes on at speed

[surjit25]

I too had this problem at high revs but my water level was low,
due to a leaky water reservoir,cleaning the sensor probe, bleeding, after changing it so far the problem has not
reoccured.

[petwar]

hi there, os means 'off side' which is the right hand side. if your heator is cold after this happened im guessing an airlock is likely to be at or in the heator matrix behind the dash. when you said you had bled the cooling system did you use all the bleeding points? there are 3 different points on these cars if i remember correctly see here ...



also i dont think bouncing off the rpm limit a couple times would do any harm, i have often got trapped air out a system by revving the engine, i guess the higher rpm will create higher water pressure with the pump going faster?

rossco

I did opened all three bleeder points and also opened the heater fully.

The problem has actually gotten worse now, when I was driving to work this morning, the light went on during moderate acceleration. Also, it was delayed a bit, just when I let go of the gas pedal for a gear change, the lights when on and then off again a second later ???

I'm going to stay after work today and have a colleague check the level in the water bottle while I'm revving the car enough to get the lights to go on. To bad the water bottle isn't transparent, but I'm guessing a powerful flashlight could be enough to see the level if you shine it through the bottle. I'm hoping you guys are right, that the level won't change, at least than I know I can starting revving again If it's simply an electrical problem I'll just probably leave it...

[petwar]

I went ahead and started looking at the car during my lunch hour. A colleague checked the coolant level while I was revving and what do you know, the lights lit up but the level in the reservoir didn't move an inch! Using the flashlight was no use, so we ended up checking the level by simply taking the lid of the reservoir.

Seems all my effort to breathe the system was for nothing...

Anyway, I located a black plastic box (looks like a big relay) left of the right side head light and pried it apart and cleaned it. No difference. I cleaned all the contacts going to the box, and still the problem remained... I'm leaving this for now, maybe someone else will come up with a solution.

By the way, the black box is no.84 in the wiring diagram, named "Coolant level indicator unit". It is mounted on a plate between the radiator and the headlight.

[Toddman]

Hi Petwar
As I said in my previous post have a look at the actual sensor in the bottom of the water bottle.

It is a simple job to remove it and woul dbe my first point of call.

Cheers
Luke

[petwar]

Hi Petwar
As I said in my previous post have a look at the actual sensor in the bottom of the water bottle.

It is a simple job to remove it and woul dbe my first point of call.

Cheers
Luke

It was replaced when I renovated and decked (is that the proper word?) the cylinder head about two years ago... And I've checked the sensor again after that. The previous sensor gave out, causing me to miss a radiator leek and the engine to overheat on the hottest day of the year (of course). I had to spend a few days of my vacation removing and refitting the cylinder head (NOT something I want to do again!)

But you're right, I should check it again, in case this one has given out to, one never knows.... I should be quite simple to check if the sensor is broken by bridging the cables going to the reservoir. If the light still comes on while revving, the fault lies elsewhere.

[Toddman]

Over here we class "decking" as just taking enough material off the cylinder head to ensure it is straight or true, i.e. removing any distortion.
We "skim" the head by however much depth or thickness we take off after "decking"

Well that is how we call it in Lincolnshire

Cheers
Luke

[petwar]

Over here we class "decking" as just taking enough material off the cylinder head to ensure it is straight or true, i.e. removing any distortion.
We "skim" the head by however much depth or thickness we take off after "decking"

Well that is how we call it in Lincolnshire

Cheers
Luke

Good to know!

[Toddman]

Over here we class "decking" as just taking enough material off the cylinder head to ensure it is straight or true, i.e. removing any distortion.
We "skim" the head by however much depth or thickness we take off after "decking"

Well that is how we call it in Lincolnshire

Cheers
Luke

Good to know!

Does this mean you have "skimmed" the head a little to raise the compression ratio ?

Cheers
Luke

[Frenchracingblue]

From a machine shop point of view, blocks are decked (to reface and/or achieve a compression ratio), heads are skimmed!
The old fashioned term for excessively skimming a head to achieve a higher compression ratio was planing (minis etc)!

[petwar]

Toddman:The head had .5 mm shaved of I believe, so maybe you would call it decking?

Frenchracingblue: The Swedish word for decking a block is "decka" and the word for the same procedure but with the cylinder head is "plana"... quite similar to what you're saying...

It's hard to get the terminoligy right in a forreign language, posts at english technical forums such as this take a whole lot longer to write than ones in swedish forums

[Toddman]

From a machine shop point of view, blocks are decked (to reface and/or achieve a compression ratio), heads are skimmed!
The old fashioned term for excessively skimming a head to achieve a higher compression ratio was planing (minis etc)!

That is why I added the Lincs comment.
If I myself talked about "decking" with regards to a block that would include me bringing the piston tops into line as well - again harking back to minis

Your terminology is fine Petwar

Cheers
Luke

[prm]

MoRtYMer, Petwar

You seem to be experiencing the exact same problem as I had. Bl- -dy frustrating, especially after changing and checking all the components.

I think, possibly??, this fault is due to a charge build-up in the cooling system or reduced conductivity of the water, interfering with the header tank sensor, due to the accumulation of scale insulation lining inside the ageing engine water ways. If the pump is also cavitating, this will increase any static.

As I seem to have cured the problem on my present 16v @120k, and unable to induce the same fault, could I ask you to do me a favour?
It’s OK, the wheels haven’t fallen off my trolley!!!!!!!!!!!!!! Not yet anyway.

By using a length of braided copper cable, similar to TV ariel outer cable, placed in the coolant on the upper section of the header tank, away from the sensor, and bonded down to the a good earthing point on the engine, to dissipate any charge present.
You should be able to run the flat cable, and still be able to replace the cap to avoid any possible spillage. Try increasing the revs quite slowly to above 5-6000rpm.

With a test meter, check to see if there is any coolant DC or AC voltage readings, with negative test lead to negative battery, and positive test lead, just touching only the coolant in the header tank.

Any voltage, if present, might be quite low, from about 0.5v and upwards.
If static is the cause, the light may extinguish once the engine has reached normal temp. If not –I’m back to the drawing board!!

Maybe they just require the use of a good flushing/cleaning agent??

Try draining the header tank only, by removing the hose, and refill with fresh tap water might increase the conductivity between the level probes.
I hope, it’s not just a question of hard and soft water areas.

What percentage of antifreeze are you using – 40-50%??

Best of luck and many thanks.

Regards Pete

[petwar]

I tried bridging the connectors to the sensor, and the lights didn't go on any more. So at least I've located the problem in my case.

prm: You may be right, but my money is on the sensor being faulty. At least in my case. If the problem persists even with a new sensor, I'm going to give your experiment a try

I flushed the system and replaced the coolant about two years ago. 50-50 mix of antifreeze and tap water.

The waterpump was replaced seven or eight years ago but has only done about 10-15.000 miles since then.

[MoRtYMer]

I've haven't had much time to check this out, but I've removed the plug to the sensor and it was a little green, so I've put a some WD-40 in it, and the light didn't come on, on that day.

Today it has light up, but I didn't correctly cleaned the plug so I'll try to clean it tomorow and check if it was only that.