Has anyone modded a thermostat?

As per the title. I've been contemplating the running temp of the 200tdi since installation in December. The engine came without a fan or cowl.
I fitted a Durite gauge recently, which shows the engine temp climbing well into the 90s, then dropping to the low/mid 90's as the thermostat opens. It then stays there, even when climbing a 2km long steep motorway hill at 50mph. I'd like to see the thermostat opening a bit earlier/quicker. Maybe I'm just being daft - feel free to say so!
I have tried two other thermostats, including a waxstat, with no difference. I'm now thinking about thermostats, and how I can tweek them to open a bit earlier. I've buggered about with the spring, made no difference, and now I'm thinking of gently reducing the size of the wax chamber to change the operation of it.
Any thoughts or ideas?

Get a lower temp stat, but it will slightly reduce the efficiency of the engine. Don't play with the one you have it may end in tears. And yes you are being daft.

Thanks Wammers, I think I was just surprised to see the reading go so close to 100 degrees before the stat opened. It looks like 88degrees is the only stat option for the 200tdi - unless anyone knows different. I can see the tropical ones for the V8 and other 4cyl engines, but not the tdis. I thought someone must have fitted them to the 300tdi vehicles going to sandy places?
I'll have a tinker with one of my spare stats to see if I can alter its behaviour slightly when testing in a pan of water.

As you know I have a very similar setup to you...however I've never seen mine climb above 80 degrees, and it's usually lower. I'd be very tempted to double check that your gauge is working correctly...have you tried a laser thermometer thingy to get a second opinion on the actual running temp?

I have used a laser thermometer when testing with a pan of hot water, haven't tested the gauge. If yours doesn't get above 80, is the stat stuck open? 88 is the normal running temp.

Capilliary gauge on my two and they climb from mid to low 90s then stat opens and then they stay pretty much mid to high 80s, but if you run down a long hill with no load in the winter the temp can drop to high 70s and that gives a really crap heater output.
Waxtstat in both Ive tried different stats and they all give the exact same results.
I would leave yours alone.

Thanks Lynall, you have the exact readings I would like to achieve. I wonder if my electric gauge is a bit out. When not loaded - pootering around or downhill, the temp drops like yours.
Do you have an engine fan and shroud? I wonder if that might explain the small difference.

Zeaphod I had a new Britpart and then a new Waxstat. Both 88 degrees, however although I'm around the high 70s it does run marginally warmer since I fitted the Waxstat.

Thinking about it, I do vaguely remember Steve Parkers saying that with that multiple thread adaptor setup the temp sender is slighty less "immersed" and will potentially give a different reading so that could be the (non) issue?

Like Lynall's my 200's gauge reaches the low 90's then you can see when the stat opens and temp drops back to high 80's where it stays most of the time [no fan or cowling] Electric fan only ever comes on if working hard towing a heavy load. If you need to know then fit a capillary type gauge.

Thanks tottot, looks like running temp around 90 is normal. I think my Durite electrical gauge is reading correctly - or within a degree or two of it. I still might have a play with one of my spare stats - for a laugh as much as anything.

i had all this issue to and i experimented a bit, here are my findings

Well I have been having some weird over-cooling ( i have a mechanical gauge) - it would never get hotter than about 70c. I thought stat stuck open type issues so replaced it with a genuine waxstat one from a random online supplier. Engine now warmed up quicker but sat at 95c all the time which was a bit hot for me and gave no leeway for working hard imo. So i boiled my new (genuine) and old bearmach stats and got some surprising results

Bearmach old 88c stat - fully open at 83 in 8 minutes - dash temp gauge sits at 70c
Waxstat old 88c - fully open at 91c in 10mins - dash temp gauge sits at 92-95c

That surprised me, they are both way off. thought they perhaps were old stock or something so i brought a bearmach and a genuine again. This time i went for genuine direct from land rover (stratstones) and bearmach from paddocks. some more surprising results, this time i looked at which closed the quickest aswell.

Bearmach new 88c - stat full open at 87c in 10mins. Dash temp gauge 80c. Closed medium speed
Waxstat new 88c full open at 90c in 12mins. (not fitted to vehicle). closed very fast.

So i hedged my bets and fitted the new bearmach one. warms up nicely, temp gauge sits at 80c idling and 85c when driving so that makes me feel more comfortable.

very e interesting results

zeaphod said:

Thanks Lynall, you have the exact readings I would like to achieve. I wonder if my electric gauge is a bit out. When not loaded - pootering around or downhill, the temp drops like yours.
Do you have an engine fan and shroud? I wonder if that might explain the small difference.

Click to expand...

No mines naked and has been for the entire time Ive owned the car must be 5 odd years now maybe more?
Its also got a 16 inch elec fan on the back of the rad and I only switch it on to see if it still works! only really needed once when off road in the winter as she got hot hot real quick but I was being cruel to the motor.
Its std gearbox std 1.4 tfer box slightly taller tyres and er thats it.

I ran the same route to and from work for 8.5 years so knew almost to the yard where each car would be up to temperature and the stat opens etc and all the diesels were at full temp after 4.5 miles even my current D3, the only advantage the modern cars have is they heat the cabin faster than the 200 ever could,

Great replys guys - thank you, saves my sanity if nothing else! I might buy a few more stats from various sources and see if I can get one that runs a few degrees cooler. The Bearmach test results from flats testing sounds ideal.

Quick update, I bought another stat from Eurocarparts. Tested in the pan, opened at 88 - hoorey! BUT it's longer/taller overall (42mm, exactly the depth to the bypass entry hole in the stat housing) than the other stats and as standard, the bypass would be closed all the time - boo. I modded it with a bent stainless washer at the bottom end to reduce the height by 5mm and gave it a good test on a 5km hill. The temp gauge sat at 85-87 no matter how hard I pushed, it looks like I've got the readings I was looking for. Mind you, I've a stat coming from Bearmach on Monday...

isnt to much drama swapping a stat, as long as you dont strip a thread like i did.

i made a note what temps the stats run at - i have the 'normal' one fitted at the moment but i have a spare one that opens early in case the uk turns into the sahara and one that opens later for arctic winters lol.
Bloody annoying trying to work it all out though

Well I think you may have the thermostat market cornered .

Just to finish this one off. With the stat from Eurocarparts fitted, the temperature gauge reading varies from 88-91 over a varied 300 mile weekend drive, including several long/steep hills.
I might fit an electric fan for the summer, but given our summer temperatures barely reach 18 degrees, I think it won't ever be needed. The lesson is, keep trying different stats, they are all different!