Thermostat housing/temp Sender unit + ??

[DumDum]

Hi All,

T25 1986 1.9 petrol Carb type newbie - Temp Gauge not working!

Without looking i bought a temp sender from GSF Yesterday, Brass with one terminal.

Looking at the setup today i have two sensors on the stat housing. So, from reading looks like GSF have given me a 1.9 Diesel temp sender?

Anyway, removed the two others (in prep for coolant flush) to test and one reads 1.14 ohms (meter set to 20k Ohms) and goes down to 0.09 when the face is placed in Hot to boiling point water (presume this is my temp gauge sender?)

The other sensor reads nothing and looks worse for wear so i'm back to GSF in 5 to replace one or both. Can anyone tell me which is which and what the other one does? - One faces the front of the van (red and white wire) the other is at 90 degress to it and faces the nearside of the van?

Any help advice much appreciated as i've looked and searched here but only found one similar question and one answer (Manifold inlet heater?)

[Rich Tea]

Hello Dumdum,

Welcome.

Only a partial answer I'm afraid.

One of the sensors is for the guage, the other is for the manifold heater (on a 1.9) sorry can't remember which is which. If you have a 2.1 you don't have a manifold heater and the second sensor does something else (not sure what).

One should be blue and the other black both, I believe, have two contacts (not sure why you only have one).

I wanted to replace both and bought sensors from GSF one of them wrong, I think it was a 2.1 one they sold me. They didn't have the one I needed on their system, so you could be flogging a dead horse by trying to get the right one from them. Try Brickwerks.

If i remember correctly, one of the sensors has smaller terminals and connects via a multiplug, the other has two spade connectors on it.

Regarding the gauge not working, check and clean the terminals, also clean the earth crowns on the A-pillar next to the fuse box. if that doesn't work carefully clean the dash multi plug per the wiki.

Sorry it's not a full answer.

Rich

[DumDum]

Thans Rich. GSF only had the same as the working one i tested, so i swapped the brass single spade for the other and have put both back in tonight and at least have a working Gauge!..Have ordered the 'Thermoswitch' (blue) from Euro Parts to arrive Monday...

My question regarding Manifold heater is which sensor is which? i.e Is the front one Temp Gauge or side? i.e when i get the correct 'other' sensor which should i swap out?

Also what doed the manifold heater do and why does it work off the Water temp? does it open a valve/flap somewhere in the bodywork? i.e. ....Is that what the big knuckle (rotten) should be on the the number 1/3 (nearside) manifold outlet? with two pipes going up to the vent..some form of heat exchanger/heat venting system?

I'm learning fast but the Hanynes Manual/Wiki's on here all come up blank on this subject!

[Rich Tea]

Can't be sure which goes in which position, If pushed i'd say the blue one goes on the side but I'm guessing. I'm not sure how much it would matter, there so close to each other and both in the coolant so I assume they'd both have the same temperature exposure. Perhaps someone else will confirm.

The manifold heater sits in the inlet manifold. If you removed the manifold off the engine and looked underneath, you see the cover panel for it. As far as I know it's there to help fuel vapourisation, the inlet manifold is long so one it take a while to heat up. It's my asumption that the heater comes on when you start the engine (to aid starting) and turns off when the engine is warm.

....Is that what the big knuckle (rotten) should be on the the number 1/3 (nearside) manifold outlet? with two pipes going up to the vent..some form of heat exchanger/heat venting system?

I think you mean the system for preheating the air off the exhaust, this is controled by vacuum tubes from the carb, takes air from around the exhaust when it's cold and takes it from the vent when the engine is warm. This is another system for warming the engine up quickly but I don't believe it's directly connected to the manifold heater. On my van the shroud had been cut from the exhaust (they tend to rust well before the exhaust pipe itself) and the pipework up to the vent was missing. I think most people don't think it's absolutely necessary in the UK, at worst the van warms up more slowly.

Don't forget when you refil the cooling system to follow the wiki, it's very difficult to bleed the system properly if you don't follow one of the stated proceedures. Remember the tank with the pressure cap on must be full to the brim when you've finished and at anytime post that.

Hope this helps

Rich

[kevtherev]

Temp gauge sensor (blue) for plastic thermostat housing is at the rear of the housing and the manifold and carb de-icing switch is on the side.
(the single pin sensor is for metal housings..i.e syncros early water systems and diesels)
the black sensor (normally on) switches off at 87 deg C.
it switches a relay(relay No.1) in your junction box.
the relay allows a big current to the manifold heater (de-ice) directly under the carb.
it also allows current to the choke heater and carb de-icer.

The exhaust has a cold start hot air take off on No.1 cylinder header pipe.
The hot air would be channeled into the airbox
This is not essential for our climate, and can be disregarded or removed.

[DumDum]

Thanks for the useful replies guys...waiting on the blue stat (tomorrow) and have used both black since. Temp gauge now works but sits mid-way between red light and top of gauge...can only assume that blue works off a lower volt range across the temp range giving mid gauge read for normal.

120mile round trip with 2 more bleed sessions and temp was high, but steady and now put this down to the wrong switch (black) as per 1st post.

Only one new issue, no starter, so review of solenoid and wiring next weekend!