205 Rallye Coolant Level Light Keeps Flashing On.

[fliprio 9]

im having an issue with the coolant level light flashing on all the time on the Rallye.

 

I have replaced the sensor and it still does it, I can lift the expansion tank up above the line of the bonnet and open the bleed points at the thermostat and top of the heater hose and water comes out so im assuming its not the water level dropping low, although it does do it more often breaking or going around left hand corners where the water would be moving away from the coolant level sensor in the right hand side of the rad.

 

It seems to also correlate with the thermostat opening, from cold its fine, it only starts doing it when the stat opens and you get water flow around the radiator.

 

A simple check from cold with the sensor out the car turns the light on and off accordingly.

 

The expansion bottle doesn't seem to be much higher that the top of the rad and the hose to it dips up and down, but there must be affair fluid drop of an inch or so to get the light to come on.

 

Any ideas?

[jackherer 543]

I don't know if the same problem affects Rallyes but sometimes with GTIs the HT leads interfere with the coolant level light wiring and make it flicker, the fix is normally just clipping the HT leads in the holder properly.

[fliprio 9]

I think the wiring is on the other side, the level sensor wiring looks like it goes down the left hand inner wing while the HT leads are on the right. Good thought though.

[jackherer 543]

Sorry, I didn't see where you said the sensor was in the rad. Is there anything significant and electrical nearby such as the alternator?

[fliprio 9]

yeah, it goes down near the alternator but doesn't touch it

[jackherer 543]

It doesn't need to be touching the source of interference, it can radiate a surprising distance. It might be worth checking the electrical connections on the alternator, the battery terminals and the engine earth to make sure the alternator circuit is good.

[DamirGTI 329]

Had just the same issue on my mates 1.1 years ago , was doing head gasket , bled the cooling system afterwards at least 3 times but the light keep on flashing intermittently .. so i took the coolant sender out , cleaned it , and did the coolant system bleeding two more times and afterwards it was finally good .

 

Coolant system on a TU's are really b*** to bled completely free from air bubbles/pockets ... but also if theres junk inside the sensor (oil deposits particularly from previously blown head gasket) it'll partially or completely block the sender float and thus it'll lit the warning light .

 

D

[fliprio 9]

Had just the same issue on my mates 1.1 years ago , was doing head gasket , bled the cooling system afterwards at least 3 times but the light keep on flashing intermittently .. so i took the coolant sender out , cleaned it , and did the coolant system bleeding two more times and afterwards it was finally good .

 

Coolant system on a TU's are really b*** to bled completely free from air bubbles/pockets ... but also if theres junk inside the sensor (oil deposits particularly from previously blown head gasket) it'll partially or completely block the sender float and thus it'll lit the warning light .

 

D

I redid the coolant after it started getting a bit hot, I think I had a big airlock at some point when the waterpump went. Since then though I have bleed it about 5 times, hanging the expansion bottle in the air, i always get a bit of air out the thermostat bleed point and thats it. Strange it only does it hot, unless the top of the rad is a air-trap or something. Its something its always done (friend who perviously had it said its done it for the past couple of years).

 

I have put in a brand new sensor and it still does it

[DamirGTI 329]

Then there's still air inside the system (i suspect in the heater matrix) , juts a small amount of air inside is enough for it to lit the warning light via sender as the sender is on top of the radiator on the level just after the expansion tank .

 

I’d suggest trying to re-bled it again ..

 

Undo the strap and raise the expansion tank as up as high you can (as high as the connecting hose allows you) an hook/tie it up on the bonnet . Open the bleed nipple on the hose which goes into the cabin heater matrix , bleed nipple on the thermostat housing and filling cap on the radiator and turn the heater on fully hot (not the fan just the knob on fully hot) .

Drain few liters of coolant out , and start addining again but fill the system via radiator (not the expansion tank !) until the coolant first starts to leak on the thermostat housing bleeding nipple , when it does close it , then the heater matrix hose nipple again close it and overfill the radiator all the way up top to the neck and put the cap back on (make sure it seals , as there are pretty crap design .. there's an rubber seal underneath the cap which wears) , and lastly fill the expansion tank all the way up to the top as well whilst it’s tied up to the top of the bonnet .

 

Crack open/close all the bleeding nipples again , starting from the - radiator cap , thermostat housing , heater matrix . Add more coolant into the expansion tank (make it full) and lower it down in position and secure with the strap but do not put the cap back leave it open .

Start the engine and hold/vary the revs from 1500 to 2000 rmp , while running grab the top hose with your hand and squash/pinch it a few times in order to “add loosening the air bubbles” , try the bottom hose if you can reach it also .. after about 10min. , turn the engine off , wait a bit till it cools down (not completely , still needs to be warm but not hot !) , lift the expansion tank up again and crack open/close the bleed nipple on the thermostat housing then on the heater matrix hose . If it’s fine (no air) , check the coolant level in the expansion bottle , add some more coolant if needed lower it down in position and put the cap back .

 

With the cabin heater still set on hot , go for a spin .. drive for a while until the engine fully warms up and every 15min. stop , shut down the engine lift the bonnet wait a minute or so and crack open/close the expansion cap (use an rag or gloves to open/close the cap) and let the build up air/steam out from the expansion tank , till it stops hissing close the cap and continue driving .. repeat this procedure say 5 times i think it’ll be enough - stop , crack open the cap to let the pressure/steam out , go back driving and repeat - need to note the cabin heater must be set on fully hot all the time while doing this ! otherwise air lock can easily create inside heater matrix .

 

This should free it from all the remaining air inside the system , at least myself i always had successes with this method .

 

 

Hope this works for you !

 

D

Edited August 30, 2014 by DamirGTI

[fliprio 9]

Then there's still air inside the system (i suspect in the heater matrix) , juts a small amount of air inside is enough for it to lit the warning light via sender as the sender is on top of the radiator on the level just after the expansion tank .

 

 

I’d suggest trying to re-bled it again ..

 

Undo the strap and raise the expansion tank as up as high you can (as high as the connecting hose allows you) an hook/tie it up on the bonnet . Open the bleed nipple on the hose which goes into the cabin heater matrix , bleed nipple on the thermostat housing and filling cap on the radiator and turn the heater on fully hot (not the fan just the knob on fully hot) .

Drain few liters of coolant out , and start addining again but fill the system via radiator (not the expansion tank !) until the coolant first starts to leak on the thermostat housing bleeding nipple , when it does close it , then the heater matrix hose nipple again close it and overfill the radiator all the way up top to the neck and put the cap back on (make sure it seals , as there are pretty crap design .. there's an rubber seal underneath the cap which wears) , and lastly fill the expansion tank all the way up to the top as well whilst it’s tied up to the top of the bonnet .

 

Crack open/close all the bleeding nipples again , starting from the - radiator cap , thermostat housing , heater matrix . Add more coolant into the expansion tank (make it full) and lower it down in position and secure with the strap but do not put the cap back leave it open .

Start the engine and hold/vary the revs from 1500 to 2000 rmp , while running grab the top hose with your hand and squash/pinch it a few times in order to “add loosening the air bubbles” , try the bottom hose if you can reach it also .. after about 10min. , turn the engine off , wait a bit till it cools down (not completely , still needs to be warm but not hot !) , lift the expansion tank up again and crack open/close the bleed nipple on the thermostat housing then on the heater matrix hose . If it’s fine (no air) , check the coolant level in the expansion bottle , add some more coolant if needed lower it down in position and put the cap back .

 

With the cabin heater still set on hot , go for a spin .. drive for a while until the engine fully warms up and every 15min. stop , shut down the engine lift the bonnet wait a minute or so and crack open/close the expansion cap (use an rag or gloves to open/close the cap) and let the build up air/steam out from the expansion tank , till it stops hissing close the cap and continue driving .. repeat this procedure say 5 times i think it’ll be enough - stop , crack open the cap to let the pressure/steam out , go back driving and repeat - need to note the cabin heater must be set on fully hot all the time while doing this ! otherwise air lock can easily create inside heater matrix .

 

This should free it from all the remaining air inside the system , at least myself i always had successes with this method .

 

 

Hope this works for you !

 

D

 

Thanks, that's how I did it, the only thing I notice is once it's all cooled back down and I take the radiator cap off the level is just at the bottom of the filler neck, it's not all the way to the top of the neck

[DamirGTI 329]

Not sure on that one to be honest , dunno if the level would "grow" up to the top of the filler neck once the coolant reaches operating temp or does it need to stay full even when cold .. suppose it doesn't matter as long as the coolant level is maintained at the top of the radiator level (filler neck just protrudes a little bit higher from the top of the radiator)

 

Have you tried to remove the sender from the radiator , plug in the connector and flip it up side down - does it turn off the light on the dash instruments while doing so ? i know you've said it's new , but maybe it's something within the wiring if you're 100% sure that the system is bled free from air .

 

D

[fliprio 9]

Not sure on that one to be honest , dunno if the level would "grow" up to the top of the filler neck once the coolant reaches operating temp or does it need to stay full even when cold .. suppose it doesn't matter as long as the coolant level is maintained at the top of the radiator level (filler neck just protrudes a little bit higher from the top of the radiator)

 

Have you tried to remove the sender from the radiator , plug in the connector and flip it up side down - does it turn off the light on the dash instruments while doing so ? i know you've said it's new , but maybe it's something within the wiring if you're 100% sure that the system is bled free from air .

 

D

 

Well I was fairly certain it was bled, but today I have been having a play with it and it seems to be trapping air in the top of the rad, if I now bleed it by running for 10 mins, de-pressurise and take the cap off the radiator the level has gone down and the filler neck section is empty, it takes 50-100ml of water when you open up the thermostat bleed point. Its better but the light still comes on going around roundabouts so I just need to keep going with it, ive done it 3 times and its still taking a bit of water each time so maybe its just taking its sweet time to bled properly!

 

I tested the sensor when i installed the new one, light goes on and off etc

 

Maybe from cold its got enough pressure into the rad to keep the level up and when the stat opens and you get flow through the rad it doesn't have as much pressure in the rad and the level drops, or all the air ends up getting trapped at the top rather than the bleed points

[DamirGTI 329]

So you still have air when you open up the bleeding nipple on the thermostat housing ?

 

Could try to bleed it on the radiator filler neck as well , whilst is warm (cooled down a bit but warm) just quickly crack open/close the radiator cap and see what happens .. the cap is a little bit dicky to open/close quickly so be careful .

Maybe this air pocket which forms in the radiator filler neck travels from one to another side of the radiator when driving around roundabouts and thus as it reaches the sender makes it trigger the warning light ?!

 

D

[fliprio 9]

yep, if i open the radiator up, fill up to the top of the neck and crack open the thermostat bleed point, the water level drops but its slowly getting better.

 

Radiator cap is a pain, I have marked on it exactly where to tighten it to so it seals and doesn't jump off the thread.

 

Unless its a bad head-gasket and while im trying to get air out its letting more in! although the top hose doesn't get instantly pressurised when you fire it up so the internal pressure doesn't seem too bad.

[DamirGTI 329]

Just remembered one more thing i used to do when bleeding these TU's , and some other cars as well with odd coolant bleeding system (when i fed up by unsuccessful result with the usual bleeding ! or if i'm in a hurry to bled it quickly) :

 

Find yourself an spare coolant hose (or any kind of hose) which fits snug into the expansion tank neck (radiator top hose works if i remember) , fill up the expansion tank up to the top making sure that the level doesn't droop below min. mark (keep on topping it up with coolant as you do this) , then stuff the hose into the expansion tank filler neck grab the hose around the neck with your hand/fist to make it more air tight , have a mate to help you out by opening and closing bleeding nipples while you breath deeply and blow the air trough the hose into the expansion tank thus you'll force bleed the system by blowing air into the expansion tank .. start from the lowest bleeding point and work your way to the highest as usual ..

 

If theres still air in the system no matter what you do in order to bleed it , if you suspect head gasket , do a block test (chemical combustion blow by gas test) .. it's very quick and accurate method for diagnosing internal head gasket leaks .

 

D

[fliprio 9]

Just remembered one more thing i used to do when bleeding these TU's , and some other cars as well with odd coolant bleeding system (when i fed up by unsuccessful result with the usual bleeding ! or if i'm in a hurry to bled it quickly) :

 

Find yourself an spare coolant hose (or any kind of hose) which fits snug into the expansion tank neck (radiator top hose works if i remember) , fill up the expansion tank up to the top making sure that the level doesn't droop below min. mark (keep on topping it up with coolant as you do this) , then stuff the hose into the expansion tank filler neck grab the hose around the neck with your hand/fist to make it more air tight , have a mate to help you out by opening and closing bleeding nipples while you breath deeply and blow the air trough the hose into the expansion tank thus you'll force bleed the system by blowing air into the expansion tank .. start from the lowest bleeding point and work your way to the highest as usual ..

 

If theres still air in the system no matter what you do in order to bleed it , if you suspect head gasket , do a block test (chemical combustion blow by gas test) .. it's very quick and accurate method for diagnosing internal head gasket leaks .

 

D

 

well today it shoved all the coolant into the expansion tank and the level light comes on permanently, also the coolant temp warning flashed on for 10 seconds and then went out and stayed out, wondering if it locally boiled a pocket of air to expand everything and shove the excess fluid into the header. Usually the coolant level stays the same give or take a cm or so.

 

might have to test the coolant for exhaust gas

[dobboy 231 2 Cars]

Just a thought if I you prob is definitely bleeding related. Could try using a ramp or ramps to get the car up on one side or the back or front up?

 

The warning lights (and full scale deflection) all work by earthing the wire. Perhaps you have a bit of loom bare hitting earth?

[fliprio 9]

Just remembered one more thing i used to do when bleeding these TU's , and some other cars as well with odd coolant bleeding system (when i fed up by unsuccessful result with the usual bleeding ! or if i'm in a hurry to bled it quickly) :

 

Find yourself an spare coolant hose (or any kind of hose) which fits snug into the expansion tank neck (radiator top hose works if i remember) , fill up the expansion tank up to the top making sure that the level doesn't droop below min. mark (keep on topping it up with coolant as you do this) , then stuff the hose into the expansion tank filler neck grab the hose around the neck with your hand/fist to make it more air tight , have a mate to help you out by opening and closing bleeding nipples while you breath deeply and blow the air trough the hose into the expansion tank thus you'll force bleed the system by blowing air into the expansion tank .. start from the lowest bleeding point and work your way to the highest as usual ..

 

If theres still air in the system no matter what you do in order to bleed it , if you suspect head gasket , do a block test (chemical combustion blow by gas test) .. it's very quick and accurate method for diagnosing internal head gasket leaks .

 

D

 

I found a good way of doing this, using a brake easy bleed kit, 10psi in a spare tyre and it works a treat. Bleeds up ok and runs ok, next day its full of air again and you can hear the heater gurgle when you first start the car and rev it.

 

Chances are its the head gasket, so thats coming off tomorrow

 

My main problem is that both Peugeot and Eurocar parts list the engine as an alloy block and only list a alloy block head gasket....im 99% sure the rallye is a iron block - anyone got any ideas what head gasket to use?

[fliprio 9]

 

I found a good way of doing this, using a brake easy bleed kit, 10psi in a spare tyre and it works a treat. Bleeds up ok and runs ok, next day its full of air again and you can hear the heater gurgle when you first start the car and rev it.

 

Chances are its the head gasket, so thats coming off tomorrow

 

My main problem is that both Peugeot and Eurocar parts list the engine as an alloy block and only list a alloy block head gasket....im 99% sure the rallye is a iron block - anyone got any ideas what head gasket to use?

 

the head is off, gasket looks fine, all the cambelt was off to do the crankshaft oil seal so not too much hassle and rules it out.

 

Why else would I be getting air trapped? the heater gurgles when the engine is stone cold and you give it a few revs to start it, it runs nice and hot thought quite quickly but the air would essentially be moving from the heater to the top of the rad and then moving back again when cold which doesn't sound right. The expansion tank didnt empty itself when I drained the rad, the connecting tube takes a bit of a tour around the engine bay and dips down from the hight of the rad so part of the tube isn't above the hight of the rad.

 

Any help or things to check is much appreciated