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Gavin Waddell

Cooling temp gauge

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Gavin Waddell

After finding why my car was running on  three I have a new problem. The cooling temp needle  reads of the gauge after about 5 mins of driving.and it’s was a nice damp cool afternoon over her.  I checked the lower rad hose and it’s cold so the thermostat hasn’t opened yet so the gauge should not been reading so high. 

 

Kind of stumped, I did ground the connector and the needle went of the clock and when I grounded the other connector nothing? Normally the light should come on. These out the two on the back of the block

 

i did a coolant change the other day  because I fitted a new radiator and when I was warming up the engine it took about 20-25 min before the fan kicked in. And toda

 

dodgy sender ? 

 

gavin 

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DamirGTI
Posted (edited)

Not properly bled i'd say .. air/steam pockets within the system , can be nasty thing if it forms around cylinder liners or exhaust valve seats on a hot summer days can lead to metal cracking , best to fix that asap . 

 

With the engine warmed up , do you have heat in the cabin from the heater/ventilation ?

 

When initially filling up with coolant , need to open at least one bleed nipple , and mostly that'll be the one on the hose going to the heater matrix (it's at the highest point anyways so best to use that one) .. next one is on the thermostat housing , but myself i always tend to skip that one (as it tends to break and leak) .

When filling is till the almost end the coolant will start exiting from the bleed nipple , when it does cap it off and keep filling the expansion bottle till the top of the ex. bottle neck , leave the expansion bottle cap off/removed , turn the cabin heater on fully hot (just the knob not the fan) , start the engine , and leave it running/idling 10/15-ish min. on little bit faster idle , or normal idle but rev it up from time to time ... and that'll do , they're kinda easy to bled .

 

If you've filled it up but skipped the expansion bottle cap bit , redo as above ... remove the cap , turn the cabin heater on fully hot , start the engine and leave it running/idling with the expansion bottle open , give it some revs from time to time as you do .

 

When done .. put the cap back on the ex. bottle , engine switch off , and leave it settle for a while so it cools down .. and recheck the coolant level in the ex. bottle afterwards , top up as/if needed .

 

D

Edited by DamirGTI

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PhilNW
Posted (edited)

Slow warmup can be a sign of thermostat stuck open, is the top hose the same temp as bottom hose when warming up? 

 

Re the light, might be a blown bulb, with ignition on take terminal off the switch sensor and see if you have any voltage on the wire side, if zero likely bulb has gone. 

 

Re the gauge, did it slowly go up to top of scale or a sudden jump?

Edited by PhilNW

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Gavin Waddell

Damir: A

An air pocket was my initial thought as well.

ok so when i changed the rad i opened the bleed screw on the heater matrix hose and left it open until coolant started to come out, i also pulled the small hose that goes to the thermostat housing, like you said that bleed screw breaks quite easily. i then let the car run up to temp which took about 25 min till the fan kicked in, i did have the cap back on the ex bottle though. i then left the car when i came back to it i found it had a few leaks wher i hadn't done a jubilee clip properly, one was the heater matrix pipe, could some air of got back inside?

 

i will go back and do the expansion cap bit tonight to make sure.

 

Phil: it only warmed up slowly when i was doing the bleed, it was also  a cool day and the car wasn't moving, i did check the bottom and top hose regularly and when the fan kicked i they where both hot.

yesterday i took it for a spin and after about two miles the gauge was reading high nearly in the red so took it home and i could feel the rad was hot, top hose was hot but not the lower hose was stone cold so the thermostat had not opened yet so like Damir said probably an air pocket in the system.

 

The needle moved regularly up the scale, it didn't jump, it just went up fast .

 

i will re-bleed the system tonight and see what that changes

 

Thanks gavin

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PhilNW
Posted (edited)

probably an air lock but check the thermostat is opening fully , it may be restricting flow to the radiator.

 

Might be worth leaving it out during a test run to eliminate it as a problem or just replace as they are cheap enough.

 

Does the gauge needle go into the red?

Edited by PhilNW

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Gavin Waddell

Needle doesn’t go into the red and the thermostat was brand new, and when I checked the the hoses the first time I bleed the system they where both hot so the thermostat is opening .

 

likeyou and Damir sais its probably an air lock in the system will rebleed  it tonight and see what happens.

 

 

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Gavin Waddell

Another thing if i had a few smal leaks it’s not possible that air got into the system through a leak? 

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PhilNW
4 hours ago, Gavin Waddell said:

Another thing if i had a few smal leaks it’s not possible that air got into the system through a leak? 

It is a pressure system so a low risk of it happening, the volume in the expansion tank should compensate 

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DamirGTI
Posted (edited)

Right , system is under pressure thus unlikely to "suck in" air ... external leaks turn up often on older cars during the coolant replacement , old hoses , gaskets , seals etc. fresh antifreeze "eats trough them" the stronger the mix % of the antifreeze poured in .. heater matrix often spring a leak after coolant replacement , which on more complex cars is pain in the rear end to replace .

 

Cap off the ex. bottle and re-bleed , it's a must procedure ... it can't be done just by opening up the bleed nipples and fill up , unless you have vacuum refill kit .

 

 

D

Edited by DamirGTI

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Gavin Waddell

Ok so I rebleed the system with the cap off and it took about 20 min to get up to temp. Kept an eye on the ex bottle I gave a few squeeze of the hoses and I had bubbles coming out, one up to temp I checked the top and bottom hoses and they where both nice and warm so hopefully it’s cured.

 

going to let it cool off and then take it out for a run to see how quickly it heats up. I’ll let you know how I get on.

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Gavin Waddell

So just went out for a run and it’s still doing it what’s weird is that the gauge is showing nearly at the red but the fan isn’t kicking in like the gauge is reading high.

 

could à dodgy ex bottle cap play havoc on the system or not. I ask because before I had a plastic one and I found my old metal one and put it back on ?

 

clutcking at straws now.

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Gavin Waddell

Ok something just happened. I pulled the car into the garage and turned the lights off and the gauge went to zero, when I turned the lights back on the gauge went to the 4h notch ? So I can make the gauge go up and down using the lights? I’m guessing that it must be a bad earth that’s causing the gauge to read weirdly? 

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PhilNW

Just to clarify with ignition on or off?

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Gavin Waddell

Ignition off

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PhilNW

Side lights or side lights and headlights?

 

Any other lights on or switches in on position?

 

EDIT - did you test the high temp warning light? thinking it might be something to do with instrument panel

 

EDIT2 - Do the side and headlight warning lights come on the instrument panel?

Edited by PhilNW

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Gavin Waddell

All positions, another thing if I ground the temp light it not work. Meaning it has no ground throughit.

 

soni started going throuHaynes wiring diagram and the temp gauge is just a grounded sensor. The wire runs to cluster via the brown multi plug ( which I have removed and wired straight to under dash, which then runs to the fuse box plug W. Which runs through fuse 2 and all the relays...... any way I’m guessing there is a short some where along the line. Our the lights grounded to come on which then grounds the temp gauge wire ?

 

???????

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PhilNW

Temp light earths through the switch/engine block, either bulb gone or no voltage supply through the instrument panel 

 

The temp gauge went to max when grounded so supply is probably OK to  that instrument

 

Any other instruments or warning light not working properly?

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Gavin Waddell

The oil pressure fluctuates with the revs a bit.

 

justwent to have look  if i turn  ignition on gauges work I pull due number 2 and

they all stp working I then put the fuse back and they wok I they turn off the ignition and leave the lights in it holds them when I turn the light off they drop down?

 

another thing I removed the bleed scars from the heaters matrix and nothing came out do I un did the cap of the ex bottle and water same out. Might of been a possible air bubble?

 

whatvi don’t get us when doing the bleed by running up to temp the gauge seems to run normally as soon as I go for a drive it goes straight up?

 

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PhilNW
1 hour ago, PhilNW said:

 

EDIT - did you test the high temp warning light? thinking it might be something to do with instrument panel

 

EDIT2 - Do the side and headlight warning lights come on the instrument panel?

 Did you check these?

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Gavin Waddell

Tested high temp warning light ang if I ground the wire nothing happens. No light.

 

didnt know the lights had a warning light will check tonight. 

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Gavin Waddell

Ok so I went and had a play again tonight. 

 

Still cant get the temp lightg to turn on.

 

i decided to clean up the head light earth points. I

 

i then checked what happened:

ignition on all gauges flutter up to the first bar on the gauge.

 

then turned lights on one the temp gauge didn’t move but the oil pressure gauge needle moves up to next bar.

 

how to I test the headlight earn light ?

 

going to take it for a run tomorrow and see if any thing has changed now the temp gauge doesn’t move any more with lights on.

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PhilNW
8 minutes ago, Gavin Waddell said:

Still cant get the temp lightg to turn on.

What did you do/change? 

9 minutes ago, Gavin Waddell said:

i decided to clean up the head light earth points

What makes you think this is part of the problem?

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Gavin Waddell

Haven’t done anything else try to reground it to no avail. Need to check it along its path to see if there is not a break in the wire. I redid the entire ending loom this winter so might of made a mistake. 

 

The oil gauge needle moving when lights out turned on is a bit weird also.

 

I’ll take her out tomorrow and see what what.

 

Like I said yesterday, I took the heater matrix bleed screw out and no water came out so I opened the ex bottle and water came rushing out. Don’t know if it’s normal or an air bubble in the system 

 

Just thought as the temp gauge light is grouded to work and the headlight where making it do weird things maybe there was a bad ground. Also for the fact that when I changed the rad I disconnected the ground point off near the headlight too look at the wiring as it was a bit of a mess and then left it alone and connected it all up.so went back and had a look to just check, they had some surface corrosion do sanded it off. That’s all really.  

 

 

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PhilNW
10 hours ago, Gavin Waddell said:

Haven’t done anything else try to reground it to no avail. Need to check it along its path to see if there is not a break in the wire. I redid the entire ending loom this winter so might of made a mistake. 

See my previous post re how to check this. probably broken bulb

 

10 hours ago, Gavin Waddell said:

Like I said yesterday, I took the heater matrix bleed screw out and no water came out so I opened the ex bottle and water came rushing out. Don’t know if it’s normal or an air bubble in the system 

This is normal , with a well sealed system the water will stay in the system by vacuum/suction effect until you release it by undoing the cap to let air in.

 

Suggest you take out the instrument panel (a bit fiddly) to check for broken bulbs/connections, you have not said whether the warning lights for side and headlights are working. 

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