300tdiTemp Gauge Issue

[heuer27]

After a bit of an oil pump disaster I have had to change the engine in my 300tdi defender . I have been told by the breakers that the new one is a Discovery engine.Which fits because the turbo manifold was in the wrong place

The temp guage is now playing up. When the engine is off its reading well above the cold on the gauge. When running its right in the red but the thermostat is closed , replaced that bad boy as well, checked it and its sorted . I initially thought it was the sender and replaced i,t first with a cheap pattern one and then with a genuine landrover one still no difference . The sender that in the old engine was a green topped one as was the old one in the new engine .I even opened up the dash and disconnected the gauge ,still reading so probably the gauge then. Have I missed something . I have got my hands on a TD5 temp gauge and was going to fit this to see it it made a difference , Will it fit . Basically is there any difference between a defender and discovery 300tdi sender unit and are they interchangeable with a TD5 gauge.

Please help cause this is getting right on my man boobs.

[western]

with ign on, unplug the sender wire & earth it to the block, the gauge should go to full deflection, if not the gauge is duff.

is all the wiring free, not trapped anywhere

green top senders are AMR1425 so they will be the same, there is a black top version, the Td5 gauge will work with Green sender as I've got that set up in my 110.

[PS_Bond]

I've had a similar problem with temperature senders on the 300tdi - there are 2 resistance ranges, from memory. First one I got hold of meant the needle was at full deflection after 3 minutes of running despite the coolant temperature being at normal levels; swapped it for the "other" model and all was well.

Interested in your comments about the turbo manifold - although my "Disco" engine (that I was told would simply drop in once the fuel pump was changed over) turned out to be from a RR - and an auto as well.

[heuer27]

Thanks guys. I've got myself one of those infra red temp sensor guns and when the temp gauge is reading normal ie straight up the gun is reading 45 deg right across the engine( cool gadget).

I changed the gauge to a td5 one and although not reading when ignition is off it's giving me mad readings about 45 deg out. I'm thinking I might need the black sender unit. Does anyone know where I can get that part no.

With regards the turbo manifold on the disco it sits lower down in the engine bay it's really obvious when you see the engines side by side. Well I'm asumming it's a disco engine because that's what I was told when I bought it. Could be a lot of tosh though don't know enough about the different configurations to be 100% on that

[western]

The black sender is AMR3321

I couldn't get the Td5 defender temp gauge to read correctly with that sender, used the green AMR1425 instead, now reads fine.

[heuer27]

Thanks for that. Did a little research and like you said it doesn't work. The black one makes it read low and the green one high. You can add in a variable resistor into the wiring to get it to read properly. This all seems like too much hard work to be honest and after nearly 6 weeks of messing about changing nearly every cooling component and almost taking the head off. I've decided to buy the vdo vision kit and be done with it.

Thanks for all the advice. No doubt when some other head scratchers raise thier heads I can beg some help again.

[Retroanaconda]

If it's a Td5 gauge it won't work correctly wired straight into the sender, the signal has to be altered first. Either by an in-line resistor or by passing it through the Td5 speedo head which has the resistance circuitry inside.

[Landy'd Gentry]

After doing a 200tdi conversion to my truck,I had a similar problem, i.e. after a wee bit of running, temp guage almost in the red.

My buddy who also did a 200 tdi conversion lives with the problem. I went a different route.

I bought off a well known internet auction site, a 52mm gauge aftermarket guage with sender. (Yes it was a bling digital model!)

Now the guage reads between 70-76 degress whilst driving, with my blood pressure not going too high due to a 'potential overheat problem'