Faulty Temp sensor!

[Griff71]

1997 2.5 Legacy Quad Cam into 1989 T3 with RJES products.

Ok following on from my previous thread 'more cooling issues'. I now reckon i have a faulty temperature gauge or sensor. The reason i know somethings faulty is because it indicates overheating even with the ignition on and no engine running when cold. When the van is idling needle sits in the middle with no flashing light. Round town it will creep up and flash and then come back down. Or intermittently flas on and off. Engine is definitely not overheating see previous post but i definitely have a fault somewhere.

Question is where. The subaru loom is all connected as it was so is it a case of going through everything and testing replacing. Or has someone experienced this who can help pin point the exact cause.

I apologise i'm on here far too much with problems lately.

Thanks

Griff

[ElusiveStranger]

Is your fan ECU controlled, does it come on?
If so you're prolly ok

Failing that

First things first:
1/ What temp sensor are you using? I have lag on mine, VDO sensor along with a VDO gauge. They're pretty bobbins TBF - not quality any more
2/ My 12v (yeah right) is driven from the lighting cct. During daylight hours it reads approx 6-8° below "proper" temp. Seriously I have to bare that in mind when driving in the dark.
I think Gerrelt's also said about this on here


Is your motor ODB-I, along with the port socket? I'll lend you my TTL (ECU) to RS-232 cable (PC) an you can diagnose after d/l ing software. You can see everything the ECU sees.

To anyone else reading, if you're worried about your engine overheating; chuck water on it. If it boils, you're too hot.
_________________
The advice you receive on here is worth the paper it's written on.
Your experiences are worth shed loads to others, including the f'ups - live and learn.
Wouldn't YOU rather learn by someone else's mistakes? So would they.

'78 Bay, 2 litre 091 box, EJ20 NA & the ashtray's on the 'right' side.
I don't lean forward for hills any more
Bugger, missed out on "Live fast, die young"

[B4Tfink]

iirc fan should be ecu controlled if RJES, temp guage is via the manifold sensor with a resistor fitted i beleive..
when i had issues on start up i was advised to change the coolant manifold sensor, i did it made no difference to my issues at the time (it was an air lock) so have a spare one to lend if you pm me your addy..

Apart from yours being a pickup we have the same .. for comparson my needle at temp is near just to left/middle of the bulb, fan comes on just to the right side of the bulb (needle just clears it) however only when statioary for 5mins+ then it cuts in for about 20 secs then off again.

The flashing light bit is that still T25 wiring linked to the coolant level bottle? has that water level sender been goosed with your previous issues by any chance?
Maybee air working its way round/out the system ending up in the bottle giving brief coolant level warning??, i take it you must have hoofed it by now and most if not all will be out..

any help ? its in the sand!! (cant for the life remember what advert that was sorry ive an abstract mind)

itl be OBD1 btw . also my extra guages are affected by lights and the like however the original dash dosent seem to be and remains steady..

Griff keep the questions coming i learn so much when Elusive answers them
_________________
1988 T25 EJ25 n/a.. it just makes more sense that way..

[Griff71]

As you say b4tfink fan is activated via the sensor on the coolant manifold. Yes the light is directly linked to the top of the stock header tank. Yes i have give it the boot and i am pretty confident i have got all the air locks as the engine has stopped taking on more coolant. Strange thing is have driven since Sunday but this fault didn't arise until Thursday, so possibly not related to previous problems.

Fan works when i connect the green connectors and as i am positive it is not overheating i reckon the fan has not needed to come on.

As above within 2 mins of driving the light was flashing and the needle was off the scale. I could touch the engine so i am positive it is a fault with the sensor or gauge. On thursday i switched on the ignition and the light did not go out and the needle went off the gauge. Hadn't been driven for 8hrs.

I will have to get my electrician friend to go through wiring again. Just wondered if anyone had had similar problems.

Thanks

Griff

[ElusiveStranger]

[B4Tfink]

[Griff71]

Ok have been out and about today and it is apparent that the sensor indicates engine is overheating on leavel ground and when giong down hill. However not on hard acceleration or up hill. So definitely a short but where. Have checked Scooby sensors. and VW binacle wiring and all seems ok. Fuses are all in tact. Baffled.

B4tfink i only just twigged, are you the guy who bought my mates panel van the other week think you also know my other mate Ed. I was going to pop over and have a look at your conversion however i was up to my elbows in engine parts. If you are one of the same keep me posted on the panel van i was interested in it but lack of funds due to a new arrival of a different kind stopped that.

Hopefully i will get to the bottom of this fault soon!

Thanks
Griff

[B4Tfink]

Hello Griff
Yes it is I . our paths have nearly crossed a few times now.

I bought the van as i couldnt resist a bargain and needed a change from my tax hungry, fuel guzzler of a car, better the devil you know i say . since then been on a auto jumble treasure hunt an got most of the bits i need mainly the gearbox but a few other nice bits too.
The idea was a rough n ready daily, but looks now its gonna turn into another scoobyvan, i just cant get away from the idea

hope you sort yours soon fella
_________________
1988 T25 EJ25 n/a.. it just makes more sense that way..

[ElusiveStranger]

Griff, run another wire. Just do a quick botch job, out of engine bay, along floor to gauge. If that cures it run it properly

B4Tfink.. I love slow roasted lamb shanks & "Taylor's Dark Side of the Moon" is another coffee
_________________
The advice you receive on here is worth the paper it's written on.
Your experiences are worth shed loads to others, including the f'ups - live and learn.
Wouldn't YOU rather learn by someone else's mistakes? So would they.

'78 Bay, 2 litre 091 box, EJ20 NA & the ashtray's on the 'right' side.
I don't lean forward for hills any more
Bugger, missed out on "Live fast, die young"

[Griff71]

I don't believe this:

Just got home following a drive of 15 miles with the sensor going off and on. To find expansion tank erupting like niagra falls again see my previous cooling problems post. Temp guage was bang in the middle with no flashing light as i live on a slight incline. I give up how can it be fine for a whole week with all kinds of driving speeds and this problem reoccur?! I really am a my wits end.

Reckon i will be posting in for sales shortly, really had enough now as i am back to square one.

Griff

[ElusiveStranger]

You haven't done anything silly like shut down your heater matrix have you?
Or maybe snagged it on your jacket when you were working under the dash etc
_________________
The advice you receive on here is worth the paper it's written on.
Your experiences are worth shed loads to others, including the f'ups - live and learn.
Wouldn't YOU rather learn by someone else's mistakes? So would they.

'78 Bay, 2 litre 091 box, EJ20 NA & the ashtray's on the 'right' side.
I don't lean forward for hills any more
Bugger, missed out on "Live fast, die young"

[Griff71]

Positive i haven't snagged anything as majority of pipe work was left in situ i pulled rubber hoses of both ends of plastic pipes to make sure i got any gunk out and there were no blockages. (Completely drained system). These are angled so no possibility of confusing which is which.

How would i shut down my heater matrix?

Heaters work fine and gets hot pretty quickly.

Now i have replaced pump, stat, head gaskets and numerous header tank caps (i am back to the original VW one now), have followed filling procedure rjes method, could do this with my eyes closed now, have repeated this until i can get no more coolant in.

Could this be a blockage somewhere? Possibly in smaller pipes in the radiator core?

Just been out for a drive after topping up system and to start with no overheating or false sensor reading (did get one flash i think) up until needle gets to centre anyway. Checked pipes to and from radiator and one is hot and the return is luke warm as they should be. So stat is opening and the rad is apparently doing it's job and the pump is circulating the coolant.

However the light will come on from here and the needle will very rapidly go to max. Water on the heads steams (boils) so there is not sufficient cooling (note however the needle and light will be on/off and giving all kinds of readings, never going cold but fluctuating between working temp and too hot).

After sitting for nearly 45mins and just switching on ignition needle instantly goes to max with light flashing. Only time it goes out it at full acceleration and it will sit dead centre with no light until i brake and slow down. Obviously the temperature rises again.

Surely this indicates i still have water pump issues?

I trained 8 months as mechanic and have worked on my own cars for 13 years and always managed to solve any issues with what i consider common sense but i seemed to have covered every avenue with this and now i have no idea what to do next.

I am thinking surely this can only be a blockage.

Tried to explain as in depth as i can so any ideas what to try next?

Thanks

Griff