gse1986

Active Member
Hello,

I've just rebuilt my landy, and carried on using my 200tdi that was in the vehicle originally. I plan to rebuild it at some point, though there's not really anything wrong with it. It's a solid engine and I've never had any issues with it, it's maintained regularly.

On the way back from the MOT on Friday, I noticed the temperature sensor was quite high. I haven't paid much attention to it, as it never really moved much....once it got upto temp it used to sit around mid way through.

I was a little worried, so looked a little more on Friday night, and when you start the engine the gauge does climb quite quickly. The thing is, as it climbs, touching any part of the engine doesn't really feel hot.

Today I've taken the water pump off as I thought I'd determined that it must be broke - the water pump is about 5 years old. I got it off and it turns fine. The fins seem fine, and are metal so I doubt they could have been damaged.

Whilst I had the pump off I took the thermostat housing off too, and tested the thermostat. It seems fine as well, though I do have a spare on order. I could touch the temperature sender whilst the housing was off, and it was barely warm, though the gauge was showing about 1/3rd - this seems quite high to me, but I'm not sure?

The other thing I've noticed just now with it all back together, is the pipes don't seem to really get hard - when should this happen? Is it once it's been running for a while or pretty much straight away?

Have I filled it with coolant correctly? As i'd just had it apart, I put the water pump back on and tightened up pipes, then took the bleed valve on top of radiator off. I then filled it up through the thermostat housing as I thought then I'd not get any air in the head. Once that was full i put thermostat housing on and put coolant into the expansion tank until it came out the radiator, put cap on and then started engine. I left it for a few minutes and saw it steadily climbing. I then took off radiator cap again (as the pipe wasn't hard) and it wasn't up to the top now - so I put a bit more in.

I tried turning heater on but got cold air out (fits with my experience, heater takes AGES before you get hot air). I touched the pipes going to heater and they were quite warm, but again perfectly fine to touch.

This has been a bit of a brain dump, sorry. I'm a little anxious as I don't want to have damaged the engine, but I also want to have it back working reliably (even though it seems fine, but the temp gauge is confusing me!).

For reference, during rebuild it's had a new radiator, so I've assuming that that isn't at fault. The rest of the involved bits were on the engine before I rebuilt, and were working fine. The engine itself seems absolutely fine - I don't know how it would be if it was overheating though?

My thoughts on what could be up:

Temp gauge/sender is broke - possible, and I may order a new sender just so I have one, though surely if it was broken I'd get either 0 or full, not a steady increase? (we're talking into red within 5 mins or so).

Thermostat - I've tested it in a cup of water and it seemed to open. But again, engine usually takes so long to heat up that surely it shouldn't be needing to open that quickly?

Water pump - it seemed to work, but I obviously can't have it running at the speed it is on the engine. Any way of confirming it's working correctly?

Something else?

What temperature range should the gauge show?
 
Unsurprisingly land temperature gauges are about as accurate as a 30 day weather forecast. Are the rad pipes getting to hot to hold your hand on? Your heater matrix is possibly clogged up with leaves and other detritus as this is also very common as I rebuilt mine a while back and now it's toasty warm. I'm looking at putting a durite capillary gauge on mine for a true reading
 
Nope - none of the pipes are too hot to hold.

I've ordered a electric gauge as recommended in ashleywood.ash 's thread, so will see what happens. I've also ordered another waterpump just to put my mind at ease.

I figure if I replace the water pump and thermostat, plus put a better sensor & gauge on, then there's not much else that could be up.

All the evidence is telling me it's something with the sender, but I still don't understand why it would go up quicker when broken - surely it should either be completely dead (no continuity to earth) or be at full straight away (dead short).
 
A while back my temperature gauge was reading hot.it was the sender unit. I bought a replacement from BritPart I went through three within a year before getting a Bearmarch one which I have now had in there for about three years.
 
I fitted the mechanical gauge I ordered and had it running for about 15 minutes. it got upto 60 degrees which matched my laser thermometer pointing at various bits around the head.
I'm yet to take it for a drive, will do that tomorrow hopefully however it seems that the issue was indeed the temperature sender :D

Edit: it definitely isn't overheating. Took it on a short drive and was fine, around 60 degrees ish....then took it down motorway and it got upto 80 something, then dropped again probably due to thermostat opening.

What a relief
 
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