Dreaded temperature.....

As some of you are probably aware, I have struggled with the temperature or at least the gauge over the last year.

Until last Summer the gauge hardly ever went past half way. When it did the electric fan would kick in and the gauge would return to its usual position. Last Summer it started going up to the end of the white part. On inspection the header tank had developed a split on the seam - replaced and job sorted. Shortly afterwards the gauge started creeping again. On inspection one of the heater hoses had split - replaced and job sorted. Three months ago the gauge started creeping again. The bottom radiator hose had a small split. I've replaced all of the hoses and the thermostat now but the gauge sits almost at the end of the white part.

I've flushed everything through and replaced with new fluid. The top hose is hot but not that you can't hold it. The top of the radiator is less warm and the bottom only look warm. The bottom hose is only mildly warm as is the header tank.

The radiator fins have definitely seen better days.

Any thoughts?

Radiator
Water pump
Temp sensor

Defender 200tdi

Water pump test: start the engine and slowly unscrew the bleed point on the top of the thermostat housing, water gushes out = pump ok.

Temp sensor: remove wire and short to engine block, if gauge shows full scale (hot) gauge and wiring ok, if sender is suspect - replace it with a new one.

Radiator: Take the car for a spin until the thermostat opens, stop engine and feel radiator - top should be hot and bottom should be slightly cooler - if not possible radiator blockage/fault - replace it with a new one.

Daz

Thanks - done those three tests and all seems in order.

I think the problem is more technical than previously thought. Is there a difference between the temperature gauges on a 88 TD and 91 200TDI - are they individually calibrated? If not then I might not have the correct sender installed?

I think the sender should be PRC8593? the current one has ES111-1 marked on it.

Presumably anyone that's but a disco engine in their pre-tdi defender will have a similar problem.

I just ordered sensor prc6663 for my tdi conversion I think it's the right one but I have not got it to try yet

If it was ok before how could that be the problem?

Gave up with the standard temp gauge after doing my 200tdi conversion from 25n/a, put in a vdo gauge cost about £20 on ebay and now I know exactly what the temp is do away with the original gauge and get a vdo is my advise

If it was ok before how could that be the problem?

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Not sure that it has ever been ok - I've been replacing everything for the last two years, and the heater has only just started working properly. Also, until recently I've had to constantly top the coolant up. I'm convinced that the cooling / heating is working as it should except for the gauge.

I just ordered sensor prc6663 for my tdi conversion I think it's the right one but I have not got it to try yet

Click to expand...

Let me know how this goes.

The ES111 marking suggests that it is a military one but they didn't have 200TDIs.

I've recently had problems with my 2.5na running hot. It would sit a tad above halfway on a normal run and edge up to the red after a clogged rad and going up hills on the way home.

I noticed some play on the fan so thought I'd replace the water pump as bearing was going. Also did a holts 2 part rad flush while I was at it and also replaced the thermastat too.

Now it sits at 1/4 on temp gauge on a normal run and between 1/4 & 1/2 after a days laning on the way home.

In the past I had naively used different coloured antifreezes which may have clogged up the waterways a bit. I think a combination of this and a warm water pump together with a stat that didn't open fully made it run hot.

May be worth trying these steps.

bluehaze said:

Not sure that it has ever been ok - I've been replacing everything for the last two years, and the heater has only just started working properly. Also, until recently I've had to constantly top the coolant up. I'm convinced that the cooling / heating is working as it should except for the gauge.



Let me know how this goes.

The ES111 marking suggests that it is a military one but they didn't have 200TDIs.

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the other one it could be is PRC2236 but this has a course thread the other has a fine thread, i hope this is correct it is how i understand it to be anyway

bluehaze said:

Not sure that it has ever been ok - I've been replacing everything for the last two years, and the heater has only just started working properly. Also, until recently I've had to constantly top the coolant up. I'm convinced that the cooling / heating is working as it should except for the gauge.



Let me know how this goes.

The ES111 marking suggests that it is a military one but they didn't have 200TDIs.

Click to expand...

Not sure this is the correct sensor, got it warm tonight and the temp got just below the red and the thermostat was not open yet. i will get a temperature gun to check the actual temp at the stat to make sure its not to hot(it is new), if not might just buy a new gauge with matching sender and just forget about it

wangie46 said:

Gave up with the standard temp gauge after doing my 200tdi conversion from 25n/a, put in a vdo gauge cost about £20 on ebay and now I know exactly what the temp is do away with the original gauge and get a vdo is my advise

Click to expand...

This is what I done, I got a durites gauge and now I know exactly what the temp is!

i might give it one last try to keep the original gauge, if not its gone!

mark-d said:

Not sure this is the correct sensor, got it warm tonight and the temp got just below the red and the thermostat was not open yet. i will get a temperature gun to check the actual temp at the stat to make sure its not to hot(it is new), if not might just buy a new gauge with matching sender and just forget about it

Click to expand...

well i got a temperature gun on it today i got it as hot as possible and the thermostat opens fine and the hottest temp i could get was 74c and that is quickly jumping out and testing, it soon drops down.

The gauge sits right at the top of the white part just before the red this is on a 1985 90 using a prc6663, so this is not the right sender for my gauge but i can live with that for now knowing its ok

I've swapped the sensor for the correct, thermostat and now the water pump; the problem seems to have got worse. Within 5 mins of setting off the temperature is almost in the red. When I checked the pipes the top radiator one is absolutely redders to touch but the bottom one is cold. The new radiator is getting fitted on Friday...

Sounds like it should sort hopefully

Fingers crossed.

Fitted the new radiator today and went for a blast. For the first two miles the temperature needle was just on the white then it shot up to 3/4 then within another mile was at the end of the white area - gutted. Another mile and I was home. Having looked under the bonnet the lower oil pipe was spitting oil everywhere. I tightened the pipe up and restarted the engine. The needle rose instantly to 1/2 way but then stopped and didn't move any more.

I need to take it for another blast but I'm cold, p!$$£d off and hungry. If it's not cured then I'm all out of ideas and money!!!

Had days like that before Have a cuppa, wash those filthy hands and have a bottle of wine

Can you use a different method of checking the water temp? Temp gun, etc? Are you sure the stat is working and fitted properly? I'd be tempted to take the stat out and see what happens. Check the engine to chassis earth strap isn't knackered. Also, I'd flush out the entire cooling system a few times.

Like I said mine sits at the top of the White and I know it's ok it's only the sender/gauge combo

I kept driving and stopping to check when the stat opened and once it has it should not go any higher while I done this I kept checking with a temp gun just to be sure, if you can get hold of one it is a great help

Is your heater matrix getting warm ??

Is your heater matrix getting warm ??

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Yes, toasty.