isbjorn Posted November 4, 2013 Share Posted November 4, 2013 Hi. Can anyone confirm my theory. My 200tdi never gets warm (stays on maximum first mark) unless I am towing a trailer up a mountain pass, then it gets close to red. So my theory is that the thermostat is open in some kind of half open state. Sending to much water to the cooler for normal use, but not enough for heavy work. Is that possible? Thanks Quote Link to comment Share on other sites More sharing options...
Team Idris Posted November 4, 2013 Share Posted November 4, 2013 Unlikely. It is more likely that it is circulating too much water when cold and rad is stuffed as well. But I can't rule out a thermostat that is stuck half open, because there is always some interesting new fault around the corner ! It's just that normally many things are wrong all at once Quote Link to comment Share on other sites More sharing options...
weasel_110 Posted November 4, 2013 Share Posted November 4, 2013 My 200 Tdi wouldn't get warm....I took the thermostat out and there was a tiny piece of rust holding it open....Just buy a new one! Quote Link to comment Share on other sites More sharing options...
Maverik Posted November 4, 2013 Share Posted November 4, 2013 Hi is this a genuine 200tdi or a discovery 200 engine?... the reason I ask is I get exactly the same symptoms as you with my Disco 200tdi conversion. I've got a brand new radiator, I've lets say extensivly tested the thermostate in parallel with a brand new one, while monitoring with a K-type thermocouple and it reacts as it should with no apparant anomolys opening/closing... My next course of action was to replace the temp sender, then I was going to swap the temp dial... it just doesn't make sense... I have a theory and its to do with exhaust temp, which I'll be able to monitir soon once I've got my other thermocouple in place. Mav Quote Link to comment Share on other sites More sharing options...
Team Idris Posted November 4, 2013 Share Posted November 4, 2013 So the thermostat could be held open a little by rust and the wax not opening it fully? I hope this is the case Quote Link to comment Share on other sites More sharing options...
isbjorn Posted November 4, 2013 Author Share Posted November 4, 2013 Well. I swap it then. And yes its a converted one with a disco 200tdi.. I just figure if the thermostat is open it explains why the engine is not warming up. But not why its overheating when driving heavy. But a new rad is probably a good ide, the old one is missing a lot of fins (or whatever they are called. Thanks for the ideas. Quote Link to comment Share on other sites More sharing options...
weasel_110 Posted November 4, 2013 Share Posted November 4, 2013 Maybe the cool(er) water circulating past the wax prevented it from melting, thus stopping it opening and doing its job? Quote Link to comment Share on other sites More sharing options...
isbjorn Posted November 4, 2013 Author Share Posted November 4, 2013 How does the thermostat actually work? Quote Link to comment Share on other sites More sharing options...
landroversforever Posted November 4, 2013 Share Posted November 4, 2013 Are you using the sender for the discovery or the previous engine? You need the one for the previous engine for the gauge to work correctly. Quote Link to comment Share on other sites More sharing options...
Maverik Posted November 4, 2013 Share Posted November 4, 2013 Hmmm I just googled it and found some interesting youtube explanations, but ultimatly its down to some special wax that has a high thermal expension coefficient, meanign when it gets aroun 88 degrees it swells up causing a piston and the valve to open... quite simple but rather claver... Quote Link to comment Share on other sites More sharing options...
Maverik Posted November 4, 2013 Share Posted November 4, 2013 Are you using the sender for the discovery or the previous engine? You need the one for the previous engine for the gauge to work correctly. Yeah, i was lead to belive that mine was... BUT something definetly isn't tallying up so I'll be doing some swapping me thinks... Quote Link to comment Share on other sites More sharing options...
isbjorn Posted November 4, 2013 Author Share Posted November 4, 2013 If you have the wrong sensor. All that happens is that it shows the wrong temperature, but it should be a stable temperature. I tried it once and it stayed on red the whole time. But putting back the old sensor solved that. Quote Link to comment Share on other sites More sharing options...
isbjorn Posted November 4, 2013 Author Share Posted November 4, 2013 Hmmm I just googled it and found some interesting youtube explanations, but ultimatly its down to some special wax that has a high thermal expension coefficient, meanign when it gets aroun 88 degrees it swells up causing a piston and the valve to open... quite simple but rather claver.. Good to know.. Quote Link to comment Share on other sites More sharing options...
Landowner Posted November 4, 2013 Share Posted November 4, 2013 My 200 disco used to get hot on long climbs, the radiator eventually burst while towing my mate home after a breakdown, we had to pinch his radiator on the side of the motorway and blag some water from a stables alongside the motorway Quote Link to comment Share on other sites More sharing options...
Maverik Posted November 4, 2013 Share Posted November 4, 2013 Are you using the sender for the discovery or the previous engine? You need the one for the previous engine for the gauge to work correctly. Ross you may be onto something and rather annoyingly I don't know how I've missed this before... Quote Link to comment Share on other sites More sharing options...
weasel_110 Posted November 4, 2013 Share Posted November 4, 2013 Am I right in assuming once the stat has gone over design limit (ie overheated) its useless? Quote Link to comment Share on other sites More sharing options...
Landowner Posted November 4, 2013 Share Posted November 4, 2013 Am I right in assuming once the stat has gone over design limit (ie overheated) its useless? Its only wax inside it, gets liquid at temp so as long as the wax doesn't escape it'll cool back to its solid state. Quote Link to comment Share on other sites More sharing options...
weasel_110 Posted November 4, 2013 Share Posted November 4, 2013 Landowner, thats good news then...Mine overheated recently as I had removed viscous fan and had a second hand Saab electric fan fitted...This went to heaven mid traffic jam on the Runcorn bridge, and engine temp went way up!But I'm sure Iv'e read on this forum to change them once a year just to be sure? Quote Link to comment Share on other sites More sharing options...
DavidW Posted November 5, 2013 Share Posted November 5, 2013 I'm using a disco 200tdi with the original 2.5 petrol sender and gauge. Mine gradually gets 'warm' after about 6 miles when the gauge sits in the middle of the dial where it never really moves from until I start again. David Quote Link to comment Share on other sites More sharing options...
isbjorn Posted November 5, 2013 Author Share Posted November 5, 2013 I'm using a disco 200tdi with the original 2.5 petrol sender and gauge. Mine gradually gets 'warm' after about 6 miles when the gauge sits in the middle of the dial where it never really moves from until I start again. Thats how mine used to be... Quote Link to comment Share on other sites More sharing options...
Maverik Posted November 5, 2013 Share Posted November 5, 2013 Thats how mine used to be... Hmm so something has changed... Quote Link to comment Share on other sites More sharing options...
isbjorn Posted November 5, 2013 Author Share Posted November 5, 2013 Hmm so something has changed... Yes. Replaced the head a while ago and the new one is running fine. Its just the temp thats acting up. I don't have my old thermostat to test with, but it would make sense that the one i got from the new head is faulty.. But I can't think of anything else that would cause this, so a new thermostat and a new radiator it is... Quote Link to comment Share on other sites More sharing options...
Maverik Posted November 5, 2013 Share Posted November 5, 2013 Yes. Replaced the head a while ago and the new one is running fine. Its just the temp thats acting up. I don't have my old thermostat to test with, but it would make sense that the one i got from the new head is faulty.. But I can't think of anything else that would cause this, so a new thermostat and a new radiator it is... Having done both on my truck, the only thing its done is bring the minimum Temp down (on the dial) even lower and it takes longer for the needle to creep up the scale, but it just seems to keep going rather than settle out. I tested the thermostat and the original (old) one I found was actually working better than a new one I'd purchased. I've got refurbished injectors and a nice Alisports intercooler, but not running any extra in boost fuelling. The only things I can now put it down to are a possible issue with the head (she's always been a bit of a smoker on start-up) - or exhaust... My exhaust is a bit cobbled together from various vehicles and I think the bore could be a little bigger. Oh and I've got a timing pin kit too... so I was going to check once and for all the timing, as I've read that the fuelling adjustment on the pump can have effects on the engine temp... Quote Link to comment Share on other sites More sharing options...
Team Idris Posted November 5, 2013 Share Posted November 5, 2013 I think the rad will make a big difference. My transit rad didn't look that bad, and wasn't leaking or had missing/damaged fins, but a new one bought the temperatures down when towing I'm running odd stuff I suppose, but the challenge truck and the 88" S1 both run fergy tractor style 'capillary tube' gauges, with green and red bands instead of numbers. I was looking for good repeatability from a gauge, that works independent of everything else. Being white make them easier to read! So maybe not what folks would want for the 'look', but if 'operation' is your need, they are good Quote Link to comment Share on other sites More sharing options...
Maverik Posted November 5, 2013 Share Posted November 5, 2013 Also something I forgot to mention... the continuity of your coolant circuit... if you have a bit of a leak at a hose, this will allow the system to not hold pressure, the coolant system is designed to be able to hold pressure of about 1bar, this is quite important as the increased pressure brings down the boiling point of the water. if for some reason your coolant system is leaking a bit it will allow the water to start to boil off... i.e. for a non faulty engine there is no limiting point (pressure). You see this effect much more pronounced on petrol cars due to the excessive heat they give off, its a bit more subtle on diesels as they inherently don't produce as much heat... so something to check is all your hose units and gasket connections etc... Quote Link to comment Share on other sites More sharing options...
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