mk1 v4 temp gauge up and down.

[walt1984]

I've started having problems with the temp of a 2ltr v4. Last year it was flushed, new hoses, new summer stat and temp gauge read 1/4.
About a month ago started fluctuating sometimes off the scale, sometimes 3/4 sometimes 1/4. But heater is aired to warm. So now flushed again, sripped heater cleaned and flushed, new water pump, thermostat has little bleed hole and is running + 75 anti freeze .
Its never lost any coolant, never seen any steam.
If I took out the drain bung on passenger side of the block and screwed in a capillary tube gauge would it read engine temp or just the temp in the left bank.

[baconsdozen]

The standard gauges just aren't that accurate.
Start it from old and hold the top hose,it should get warm suddenly not gradually. If it warms slowly the thermostat is stuck and if its only part open could cause overheating. Bleeding the heater might help,loosen the top hose on the heater to let the air out.
If you run it with the cap off you should see the water moving if the pump and thermostat is OK.

[walt1984]

Hi, thanks never thought about bleeding heater and I'm a rumoured to be a plumber !!
I forgot to put I checked stat opens and closes.

[DougT]

As BD says, it may be the guage/ sender not the engine. An intermittent short would send the temp high.

If it isn't steaming then are you sure it is actually overheating ? Do you have a diff means of measuring temp for measuring the temp of the water in the rad.

Doug

[walt1984]

Thanks Doug. Yeah I can measure temp in rad when I get back tonite. What sort of temp am I looking for ? 80 - 100c ?
Been thinking could I tap into the thermostat housing for a secondry temp gauge if orginals are iffy

[DougT]

Yes about that. 90 is a good middle temp. Over 100 is normally getting on the hot side, 120 is into the red. Depends how you are measuring the temp, but if you have a spare sender (the bit on the engine with a wire coming from it) which will fit, could you just change it while everything is cold. Should't lose too much water if it is just a quick swap. Otherwise have you got a kitchen thermometer that will measure 100 deg C and that you could put in contact with the water outlet on top of the engine.

My guess would be that it is the sender rather than the guage itself. The "sometimes 1/4 hot , sometimes 3/4", sounds like a dodgy connection or faulty sender unit. If the wire was broken but connecting on and off you will get a lower reading than normal. But a high reading says it is shorting out somehow.

Have you tried touching or clipping the wire from the sender unit directly to the block ? Basically the guage works along the lines of "no connection = cold, direct connection = maximum hot" so connecting the wire directly to the block should give you "maximum hot". Disconnect the wire and it should show cold again. Do this a few times just to check but if that works as it should and doesn't get stuck. If that all works fine, then I would suspect the sender unit and change it.

Hope this helps

Doug

[bambi mk 1]

Walt check the earth from the battery to the body is clean as this will cause the gauge to play funny buggers.

[baconsdozen]

Engine running temperature should be at maximum, just below boiling,from memory the gauge is fed by a voltage stabiliser,if thats gone kaput the gauge will read all over the place.

[FredTransit]

My money's on the voltage regulator. The same thing happens with the Mk2, but the petrol usually goes up too. Either way, I would say the reading's electrical rather than actual temperature....

[walt1984]

Hi guy thanks for info. I didn't get back till late last nite so hoping to check temp tonite.
I've got a nos temp sender coming too, it says its for corsair, capri, transit.
It dosent do the same thing every time, I traveled around 70miles with the needel up around 3/4 then did the return trip on a warmer day and it stayed down at 1/4

[walt1984]

ok. been out tonight with a thermometer wire probe on my multi meter in through overflow on rad and into coolent then put the cap back on.
went out for a drive making it work driving up hills and temp never got above 80'c and gauge was 1/2 way.
came home parked up left it ticking over, 86'c. put the heater on gauge moved, got me thinking so i put lights on head beam moved some more, put fridge on gauge moved into what would be red and charge warning was glowing well.
turned everything off gauge went back to 1/2 and started twitching.
the voltage at the battery at tick over all off 14.1 volts.
every thing on 12.2 volts
could alternator failing be causing this ?
this ties in with the last trip, going there side lights on fridge on. coming home sunny day fridge empty and switched off.
i dont seem to have the same problems as every one else i have to be bloody different.

[DougT]

Not quite sure if I get the "put fridge on gauge moved into what would be red and charge warning was glowing well".

Presume that the temp appeared to go up when you put fridge on ?? And it takes big current then !

But it all seems to be electrical rather than the engine actually overheating so that is good. 14.1Volts would seem to be OK and it will drop to 12 if you are pulling a lot of current from the battery and the alternator can't keep up.

Seems like Fred is most likely to get the prize with the regulator being the culprit based on this info.

Cheers

Doug

[bambi mk 1]

Walt did you check the earth lead to the body as I suggested earlier.If the more things you switch on causes the gauge to rise further points to an earthing problem as your main earth is on the engine and one of the only ways back to earth is through the temp gauge as it is connected to the engine.Had this on transits mk1 mk2 escorts cortinas and a lot of other makes over the years.

[walt1984]

hi doug, sorry ment to say when i switch the fridge onto 12volt ( draws around 8 amp) with the heater blowing and head beam on the needle moves to the top of the gauge but this area is not red just a square. when all these are switched on the charge warning light comes on.

bambi, i forgot to check the earth i have a look and clean them and check again. thanks

[walt1984]

Bambi, went to clean earth wires like you said and found earth to bulkhead was broken. Going for a drive now to see if it stays cool.