Thread: Water Temp ? TDI 300

Since you have changed the viscous fan and thermostat, the most likely problem is the radiator.

You said it was flushed, but that is not satisfactory with rover radiators. They need to have tanks removed and the blocked cores rodded out.

When the temp rises to the setting of one of the switches near the thermostat housing, it will switch on the electric fans in front of the a/c condensor. You might like to check if these are working.

My Disco displayed a similar problem when towing our camper last Christmas. At the top of a hill the temp would go up to 3/4 (or more) then drop rapidly by the time we were at the bottom of the hill on the other side - typical symptoms of a blocked radiator. We made an unplanned stop overnight and i removed the radiator and had it cleaned out. The temp was perfect for the rest of the trip.

Just checked electric fans and they are operating (by passed solinoid) but I still need to check Sender switch.
The radiator was only flushed no tanks off, Just disconected the Plugs on the Sender Units to determin which one was to the electric fans and I set up wires and fuse to a switch in cab.
This will allow me to turn on the fans and see if this makes a difference then I will know its the sender.
Well just got back from test and drove down and up range twice pushing hard and the gauge did not move off normal operating temp (go figure) this is not what happened last night.
I wonder if something was amiss with a conection onto the sender units and playing up with them made the difference, although they had come off when thermostate replaced. I did play with a test light.
Who knows, i will just keep and eye on it know as with how I came up it should have got hot and it sat at normal temp as it always has.
Do temp sender units play up much.
Cheers Allan

You should see 1 temp sender for the temp gauge, which has 2 wires, and 2 temp switches, which each have 1 wire.

The 2 switches are set to operate at different temperatures. From memory one de-energises the clutch on the air/con compressor (if it is on) and the other switches on the electric fans.

I have just recently had a similair problem with my tdi 300
It would lose water very slowly then it suddenly became hot and cooled down, as yours did
I topped up the radiator and every thing was fine for a few months and then it happened again.
The problem turned out to be the head gasket allowing gas from the pistons to weep into the cooling system. Which would pressurise it and blow the water out of the expansion tank.
It got to a point that the head gasket let go and blew the water out of the radiator all the time
I have replaced the head gasket and so far every thing is all right.

Run the engine with the cap off the expansion tank and place your hand over the top and release it. If you get a sudden rush of water out of the tank this is prbabl your problem

had a similar situation a few years back where at random the temp guage would reach red even on decents in neutral. eventually the auto sparky found a uneven earthing in my twin bat. set up. once a second eath strap was fixed no more problems with the guage

I imagine the disco gauge would be similar to the factory fender gauge with a designed flat spot. I replaced my fender gauge with a VDO gauge and sender (new sender replaces factory in head).
My 130 gets a bit of a load in when we go north but I was still interested to see what really goes on in coolant temp.

Around town 80 degrees, cruising at 100-110 90ish degrees, up the range out of the McCleod on the way to cooktown the temp will crawl up to 100ish maybe just over, but as soon as you come over the top and come off the power it comes back down to 90 degrees or so.
I think the flat spot then is 80-100 degrees as my old factory gauge would just climb on the same range. (new head gasket, new radiator and hoses)

I dont think the rad is really big enough for the heatload up north... but having said that if it will run at 90-100 degrees all day long on the flat with 700kg in the tray and towing 700 then I spose its not all bad?

I changed over to the VDO to check what was going on... I realise the dead spot is to stop people worrying but.... I like to watch

S

Disco has not been getting as hot as it has in past but sometimes still gets hot comming up the Range only,(not every time) has not lost any real Coolent but today I noticed its had a slight weep around the expansion tank filler lid (about an eye dropper) coolent stain droplet marks on top around lid only.
Have seen this a year ago and thought I overfilled it.
Have been to double Island and ran up the beach at high tide and did not get hot at all in the soft sand fully loaded family and camping gear, but i was waiting for it to.
Could this be the start of the head gasket leeking (slightly) is this a common problem with 300TDI, it has got 265000km but does not use a drop of oil and runs smoothly oils/filters are regularly changed.
Have had Stealers look at it and they have said all is realy good but said to replace Thermo fan (they offered aftermarket or original) I did this myself with fan clutch from British offroad with no change to situation.