Ignition/Stop oil & water lights comes on after warming

johnpaul2847 · Post by **johnpaul2847** » Thu Oct 28, 2010 11:58 am

I had a issue with a internal air leak getting into water system. I have changed the cylinder head gasket and had the head skimmed and pressure tested. The air in the system has gone and runs good.

After a certain time the oil and water stop lights come on. Can someone please help me with this problem?

johnpaul2847 · Post by **johnpaul2847** » Thu Oct 28, 2010 1:31 pm

I have bridged the fan switch and has had no affect is it possible that a sensor is faulty?
The car does not seems to be over heating the orange temperature light is not coming on and there's no water loss? and oil levels are correct.

electrokid · Post by **electrokid** » Thu Oct 28, 2010 7:07 pm

Welcome to BX club

When you bridge the fan switch at the bottom of the rad then the fan should definitely run.

Trace the wires back from the fan itself to find a 2 pole connector somewhere in the area behind / below the NS headlamp - if that isn't underneath some of the grille plastic-work then it gets drenched with water and corrodes very quickly so that's a good thing to check anyway.

Way2go · Post by **Way2go** » Thu Oct 28, 2010 9:10 pm

electrokid wrote:
When you bridge the fan switch at the bottom of the rad then the fan should definitely run.

From memory, bridging the two pins on top of the switch won't switch it on as they are the half speed and full speed terminals. Either of these need to be connected to chassis to gain the respective operation for testing.

electrokid · Post by **electrokid** » Fri Oct 29, 2010 12:57 am

Hi,

I'm still a bit puzzled - obviously getting the cooling fan to work is a good idea but at this time of year it's very unlikely to be needed anyway. As Way2go said - if you have a 3 pin switch at the bottom of the rad you need to short one at a time to the common pin of the three to get fans to work.

The fan circuit is normally (I say normally because there are many variations on the circuit diagrams) independent of any dash warning lights so although the fan circuit needs to be fixed it's not going to bring any warning lights on.

There's normally 2 temp switches just in front of the fuel preheat just to the right of the dipstick - these operate at quite a high temp - 105°C for the orange light and 110 or 112°C for the red light - you can check the operation of these by shorting across each in turn while someone looks at the dash to see the lights come on.

Probably a good idea to find out where the 'signal' is coming from which is causing your oil and water stop lights to come on.

If you have the rad where the header tank is built in on the left hand side of the rad as you are looking under the bonnet - the sensor is about 3/4 the way down and is a 2 pin plug that can be removed.

If you run the engine until the fault appears (how long does that take by the way ?) then switch off briefly so you don't catch your hand on any belts in the area - remove the coolant level sensor plug and run the engine again. The coolant level sensor should no longer have any effect and if the lights are now out then it was the coolant level sensor causing the problem.

Obviously check that there's still enough coolant in the header tank - the question is whether the level sensor is telling the truth or telling a lie.

The same sort of check for the oil pressure switch which is behind the engine on the same end as the clutch / gearbox.

Basically - find the sensor that is causing the lights to come on by disconnecting each in turn while the fault is there - then investigate why that sensor is showing a 'fail' condition.

Where do you live - there might be someone nearby to give you a hand.

johnpaul2847 · Post by **johnpaul2847** » Mon Nov 01, 2010 8:18 pm

Hello and thanks for your reply sorry for delay in getting back to you...

The problem still exists on this BX there is no water loss from the engine since changing the head gasket and skimming the head and the internal air leak is fixed.. but since doing this its is putting all the stop lights on the dash.... I have located the place/censor that I think may be causing this I have read in the manual that the oil pressure censor is at the back as you are saying however there is one on the front of the block with a single connector and have not seen one on the back, if I disconnect this terminal the lights do go off...The car runs for around 20 mins b4 the lights come on there is heat to the heater & top rad hose is hot, but the rad cap does not get hot at all as I would suspect ?? there is NO pressure now. so is a complete reverse of the original problem I am suspicious something is still wrong.... I have bleed the water system from both bleed valves and can really not think of anything else?
A friend suggests its a water pump. Have tested the thermostat and have had the car running with out this....

Thanks

johnpaul2847 · Post by **johnpaul2847** » Mon Nov 01, 2010 8:28 pm

As far as the switch for the fans I have bridged this and they do come on, but not for very long, there are 3 wires two large and one small wire I have bridged the two large wires, thinking that the other wire operates the fan after engine is turned off as with some other French cars.
This is not my car, its my dads beloved BX hes had for years, it seems to be getting all the common problems that I have seen in these forums, He loves the car and in recent months I have been trying my hardest to keep it on the road for at least another year my time comes free, but he has bought many parts recently and just want to get the BX running for him..

johnpaul2847 · Post by **johnpaul2847** » Mon Nov 01, 2010 8:32 pm

I live in Hemel Hempstead, Herts... We have asked around but money is tight for me dad so a garage is not really a option, as with most things its easier to get another car

electrokid · Post by **electrokid** » Tue Nov 02, 2010 12:48 am

I have located the place/censor that I think may be causing this I have read in the manual that the oil pressure censor is at the back as you are saying however there is one on the front of the block with a single connector and have not seen one on the back,

That's another place it can be - just above the oil filter.

Good idea to find out whether the sensor is telling lies or if the oil pressure is actually low - 2 possible routes - if you have an oil pressure gauge and you can fit it where the sensor is then you can check the actual pressure to make sure it's ok - or just replace the sensor.

Does anyone else know if the oil pressure switch is prone to failure - or if there's a common reason for low oil pressure after HG change ?

Post by **mat_fenwick** » Tue Nov 02, 2010 12:54 am

If the top hose gets hot within a reasonable time it suggests the pump is OK. Are the radiator and bottom hose getting warm? Did you find and eliminate the cause for the HG to fail in the first place?

Never come across an oil pressure sensor on the back; however the oil level sensor is at the back, pointing vertically downwards at the flywheel end.

electrokid · Post by **electrokid** » Tue Nov 02, 2010 11:19 am

Never come across an oil pressure sensor on the back; however the oil level sensor is at the back,

whose brain is this

Yeah - level sensor at the back and pressure switch at the front.

Is the pressure switch prone to failure though... or is low oil pressure more likely ?

johnpaul2847 · Post by **johnpaul2847** » Tue Nov 02, 2010 11:48 am

Yer the head gasket did have a breach still had the factory clips on the pipes so suspect it has been on the car from new... I replaced the gasket b4 it was skimmed and pressure tested due to a lack of funds. I know this is very stupid and should have been done as a matter of course...
As the problem was still the same with huge bubbles coming from rad cap a pressure test was a must and the head had a slight skim.
There is no air in the system now... yes the top and bottom hose are getting hot but the cap is not.. I have not seen the sensor at the back yet....

The oil is on the max line as I did suspect this... it was btwn the min and max however I think the oil has lost its viscosity it is due a change but don't wana do this until the problem is resolved....

Thanks for all your help so far

johnpaul2847 · Post by **johnpaul2847** » Tue Nov 02, 2010 11:52 am

The sensor in question that does turn the lights off is the one at the front of the engine close to the oil filter, is it worth buying a new one of these as I think it will only be cheap...but b4 the HG was replaced this problem did not exist

Post by **mat_fenwick** » Tue Nov 02, 2010 12:03 pm

That'll be the oil pressure switch and yes, replacements are cheap. Just a wild theory, but did the oil mix with the coolant at all? (Could the pressure switch be blocked/contaminated?) Or was it just bubbles in the coolant as seems more usual?

johnpaul2847 · Post by **johnpaul2847** » Tue Nov 02, 2010 12:20 pm

Yer it was just bubbles in the cooling system. the water did not mix with the oil or oil in the water, the BX has had a history of electrical faults also of late and since these stop lights have been coming on the heat/glow plug light is not coming on and also along with the oil/water stop lights coming on there is another light, to me it looks like a brake light (O) something like this.

Other than all this the car runs well. although the stop lights come on after 20 mins or so it is not using any water and the temp warning light is not coming on suggesting it is not to hot... Its annoying there is no gauge!

My dad has since gone out and bought a water pump for the car.. but I am not convinced that this is the problem just because a neighbour said I would rather go with the advise from a enthusiast of the BX as you have no doubt seen these problems before.

Thanks again for your continued help with this matter