2000 TD5 defender temp gauge afraid of hills

[mickymack42]

My 2000 Defender TD5 is having an unusual problem with the temperature gauge typically going up hills on the highway in 5th gear – I feel a bit of a blip or miss with the engine probably last less than a second and the temp needle jumps to red, drop the gear down to 4th and it goes back to normality. But at the first sign of another hill, it jumps back into the red and as soon as we crest the hill back to normal.

There doesn’t seem to be a build-up of pressure in the header tank and it doesn’t appear to be overheating signs, I can get stuck in peak hour traffic and have no problems with a hot engine.

Things done to the engine in the last 3 months:
I had the head gasket replaced because I was building up pressure in the header tank, head tested out ok and all that was found during the head works is that it had walked a little on the old plastic pins now replaced with metal ones.
Prior to this, I took it to a Wally who said it wasn’t the head gasket causing the pressure build-up in the header tank and he replaced the radiator, water pump, hoses and viscous fan. (yep I should have known better)
I replaced the temp sensor out of good measure as well but still had the same problem. All help/suggestions are greatly appreciated.

Cheers Mike

[shack]

My 2000 Defender TD5 is having an unusual problem with the temperature gauge typically going up hills on the highway in 5th gear – I feel a bit of a blip or miss with the engine probably last less than a second and the temp needle jumps to red, drop the gear down to 4th and it goes back to normality. But at the first sign of another hill, it jumps back into the red and as soon as we crest the hill back to normal.

There doesn’t seem to be a build-up of pressure in the header tank and it doesn’t appear to be overheating signs, I can get stuck in peak hour traffic and have no problems with a hot engine.

Things done to the engine in the last 3 months:
I had the head gasket replaced because I was building up pressure in the header tank, head tested out ok and all that was found during the head works is that it had walked a little on the old plastic pins now replaced with metal ones.
Prior to this, I took it to a Wally who said it wasn’t the head gasket causing the pressure build-up in the header tank and he replaced the radiator, water pump, hoses and viscous fan. (yep I should have known better)
I replaced the temp sensor out of good measure as well but still had the same problem. All help/suggestions are greatly appreciated.

Cheers MikeHave you got access to any diagnostic equipment?

It's pretty hard to do much without it.

[Graeme]

Possibly a sticky thermostat, assuming that it's fitted correctly.

[V8Ian]

Someone, possibly rick 130 or Slunnie, recently changed water pumps and discovered the pump was ok, but was was not working properly, due to the worn drive.

[Slunnie]

Someone, possibly rick 130 or Slunnie, recently changed water pumps and discovered the pump was ok, but was was not working properly, due to the worn drive.

That was me, it was really strange. The drive was worn out on both the PAS pump and the water pump, so even replacing the water pump wouldn't have changed a thing. This is at about 290,000km. It may be worth popping the PAS pump off (this is easy, basic tools, no need to seperate an lines) and just check the dog gear on the back of it which drives the water pump.

My other immediate thought was the same as Graemes with the thermostat. I replaced that on mine at the same time as the pump and now the motor always runs cold. :huh:

[DazzaTD5]

as others had suggested check/replace thermostat and the other items listed, but also...

check to see if the thermostat has been installed correctly, as in the side with the 2 outlets arent arse about, while I thought that really wasnt possible to do, it has been done and caused odd temp issues.

Although from where I am sitting the odd, blip in the engine and then suddenly a temp increase to me sounds like an electrical issue.

EDIT: just on that electrical issue i suggested, unplug the temp sensor and see what the temp gauge does? if it flies upto the red then its a electrical fault (i simply cant remember what a td5 does)

[DazzaTD5]

Possibly a sticky thermostat, assuming that it's fitted correctly.

what he said