Low Operating Temp

[Gohn 68]

mines a TD converted from an Si (so Si radiator and loom/dash)

had a few things going on with my coolant system for a couple of weeks:

the low coolant LEVEL warning light has been showing on the dash

(but its not low and the system has been bled) 

and also, the TEMP needle seems to have dropped from where it used to sit when at operating temperature

 

- replaced the thermostat (83deg)

- repaired both wires from my coolant level sender which had rubbed exposing wires

- and have replaced my coolant level sender now also

 

the low coolant LEVEL dash warning light has now gone

but the needle on my dash is still showing the engine is running at a lower operating TEMP

 

the operating temp has always been very consistent 

 

 

 

 

[welshpug 1,657]

Does it get to 83 and stay there?

[Gohn 68]

until a few weeks ago the needle would steadily increase until it was nudging the 4th mark from left

so just under it, then it would sit there very consistently

in the last few weeks it sits just over the 3rd mark or at halfway 3rd to 4th mark

dont have any digital temp guages to check what the engine or thermostat is at in degrees 

 

 

[DamirGTI 342]

Both thermostat of the same 83C rating ? (there's 80C , 82C , 83C and 88C for TD)  replaced thermostat gaskets also along with the thermostat ? .. filled up with fresh coolant 50-50% mix or old reused ?

 

XUD/XUDT uses dual/bypass type thermostat , need to be cautious so you don't mix it with the ordinary/conventional type thermostat .

 

Any change in the ambient temp. down under recently ?

 

Also , could be cooling fan kicking in-out (because of the some wiring/relay fault) at low speed while driving without you noticing/hearing it .

 

Have an IR thermometer ? if so check/measure on the head around thermostat housing , and top and bottom radiator hoses and compare with the reading on the dash .

 

Coolant temp. gauge goes up in 10C increments , starting from 50C to the 110C :

 

 

[Gohn 68]

yeah D 

the thermostat that was replaced was only 3years old and 83deg

the new thermostat is identical 83deg. both OE peugeot 

thermostat gasket rubber seal ring and thermostat housing gasket both good and re-used

coolant about 40% mix with distilled water, 1yr of a 7yr lifespan, reused

summers coming here so its just getting hotter week by week

changed thermostat just to rule it out as it doesn't seem likely cause

maybe go back in and replace both gaskets tomorrow

 

maybe the temp sensors on the thermostat housing need replacing ?

at least one looks like it was clunked in transit before it got to me

 

why is there a temp sensor (the rear screw in sensor with Red ring) and a temp sender (front with black ring) ?

 

if your guage degrees are accurate to my guage marks then today the operating temp sat mostly about 75deg

and it fluctuates from say 79 down to about 71, in town its lower than highway

the lower temp and the fluctuation are both different to normal

 

 

[petert 586]

Side issue, might be related. The thermostat needs to match the fan switch. ie both 83. The original Si will be more like 95-97. ie the one in the radiator.

Edited November 13, 2023 by petert

[Gohn 68]

great thanks, had no idea 

had noticed a few years ago that the rad fans seemed to kick in much later than expected

 

anyway, went and had a look at the catalog to order the correct part but it confused me (not for the first time )

not sure but doesn't the diesel and Si have a one speed fan, while the GTi has a two speed fan ?

still couldn't decipher when the fan kicks on and off in either the GTi , Si, or diesel 

 

first pic's the petrol fan switch options:

 

 

second's the diesel fan switch options:

 

 

my guess is 126444 although it doesn't have any temp ratings mentioned

(the XUD7T usually came in a car with air conditioning which would suggest the correct part is 126445

but the Si body its now in has A/C removed and the Si only has a one speed fan anyway so #126444 should match up to the 83deg diesel thermostat and be what I need ?

 

 

 

[petert 586]

Si definitely has the two speed fans, identical to Motronic DKZ GTi.

[welshpug 1,657]

fan thermoswitch 1264 44 is 93/97 -88/92,  post 1990 style blue plug with purple ring,    1264 45 is the red ring post 90 sensor, standard on the single fan two speed gti.

[petert 586]

Does your car have one fan or two?

Are there three relays controlling the fan(s)?

 

From my experience, all Aust delivered 205’s had AC. Thus all 205’s had two fans and three relays, to give either slow (fans in series) or fast (fans in parallel). Jetronic models had positive controlled relays, Motronic had negative controlled relays. If your car isn’t as described, it’s been butchered. 
 

The fans have nothing to do with the temp sender or temp gauge. They’re totally independent systems. However, if the thermostat and radiator fan switch don’t match, the engine might never get to operating temp, because the fans are always running.

[petert 586]

Attached is the wiring diagram for Mi16. The Si (and Motronic GTi with A/C) is basically identical, except that the relays are earthed via 58 and 58A via the radiator switch, rather than H114 (the Bitron controller).

[Gohn 68]

thanks peter,

 

think I've got a few things sorted,

what everyone else already knows is sensor is for the dash temp needle reading

sender is to set off the dash coolant temp warning light (at 118deg if I've not read it wrong)

replaced to check both ok

 

mines regular Si by the way, two fans with three relays (A/C was removed for more space/better airflow in the engine bay)

 

21 hours ago, petert said:

The fans have nothing to do with the temp sender or temp gauge. They’re totally independent systems. However, if the thermostat and radiator fan switch don’t match, the engine might never get to operating temp, because the fans are always running.

 

appreciate that, had a look anyway

126444 (violet/purple ring) switch is on the car 

and have a spare 126445 (red ring) which is same but operates fans about 5deg higher range 

 

got a $35 infrafed thermometer gun

basically my dash needle temp is about 10deg short of reality

thermostat's working well, engine operating temp is good

temp just isn't making it thru from sensor to the dash needle, not sure why ?

 

check the sensor wire and earths ? 

 

 

 

 

[Gohn 68]

as above, my temp sender is stamped 118 which sends warning signal to dash at 118deg

 

am considering swapping it for a 110deg sender which will warn me sooner of any overheating, should that ever happen

is that a bad idea ? there any downside to doing that ?