OK, my son has a D2 that he was given and completely rebuilt the engine on it (all the way down to top hat sleeves).

The reason for the rebuild -- and why it was given to him -- was a slipped sleeve, so I am very tuned in to overheating issues.

As part of the rebuild, we replaced the 192 thermostat with a an aftermarket 180 version from British Atlantic. (black casing)

After about 2 months of working quite well -- temp never got above 190 in Texas in August (measured via ECU using a bluetooth ODB2 adapter and Torque app on an android phone) -- the ECU starting throwing a "not reaching operating temp" code, and the temperature never got above 175-180.

Frankly, I would have kept that thermostat in except for the code it threw.

B-A was kind enough to honor the warranty and sent a new 180 degree thermostat, however, this time the casing was that opaquish yellow instead of black.

We put it in -- along with two new temp sensors for good measure -- but never checked it to confirm it was operating at 180.

My son just came back from college this week and we made a 300 mile round-trip yesterday, so I decided to track the temp on the OBD2. It ranged between 204 and 209 according to the Torque app. We probably averaged 65 mph, little/no stop-and-go and the air temp was as high as 70 and as low as 50 during the trip (coolant temp tracked to ambient air temp -- when air was 50 degrees, coolant was 205 and when air was 70, coolant was 209). I think that operating in that range probably wasn't bad for the motor (right?), but I would still like to get it to run lower before Texas summer sneaks up on us in March (no time for Spring here).

So my first question is you think whether B-A sent me a 192 thermostat by mistake or did they send me a 180 that just prematurely failed the other way -- instead of sticking open like the first one, this one is sticking at least partly closed?

My second question is if they did send me the wrong version or if it failed quickly again, where I should order my next one (if in fact B-A made a mistake, should I give them another shot) and what brand I should get: generic, motorrad, genuine Land Rover other something else.

Given how much time and effort my son put into rebuilding this motor, I really want to get this right -- and as simple as it is, don't want to have to be changing thermostats every couple of months until I find the "correct" one.

If anyone can shed some wisdom/light on this Quixotic search for THE thermostat, it would be greatly appreciated.

 

Sounds like you've got a motorad stat now. I've got one also, they're pretty hit or miss. Mine runs 195 on the road and 201 at idle, but I'll be switching it out when I can. I recommend doing the inline 180 thermostat mod. Click the link in my description and there will be a link to it near the bottom under useful mods by others. Probably cost you around $100, but most everyone seems to agree it's the best route to go.

 

I am currently using that Black thermostat from A.B.,,,
Mine is stamped 78*c =(172.5*f) on the thermostat itself, & it is a soft spring, meaning the bypass spring is softer than regular & needs less coolant pressure from bypass inlet of thermostat housing (top hole) to let coolant in, (so state is introduced to hot coolant sooner),,, mine runs between 184-192* depending on driving conditions & ambient temp,,,
Highest it has ever reached was 197*at ambient 100* & truck ideling for 25min standing still with AC on,,,,
( before this I had the regular stat which would make truck run min. 5-6* higher, & I never let it idle for 20 min to see where it will go,,)
I think your Black state (if same as mine) is should work fine, check to see if bypass plate on state (the one sitting on soft spring) moves up & down easily without sticking to housing
when pushed down by finger manually,

 

I've read several accounts of the Motorad thermos failing prematurely. I'd avoid them.

AB may well have sent the wrong thermostat. I'd call them about it. If they did send the wrong one, see if you can send more money for an upgrade to the OEM 180 deg diesel stat.

A lot of folks are happy with the diesel thermo, so I think that's an acceptable solution. I did the inline mod before folks had heard about the diesel thermo, or else I'd have gone that route.

That said, my inline works great with one caveat. I don't think the stock cooling system can maintain 180 deg F in traffic at >90 deg F ambient temps. Several of us have seen temps crawl up to the low 200s. My next mod is a high volume electric fan, which I hope will help stabilize my temps during next summer.

 

sound like AB sent you a motorad as a replacement for the original that you purchased

 

I just went out to the garage and verified that:

1. the thermo that came with the "free" D2 and that presumably contributed to the slipped the sleeve was the yellow opaque type (my son was given it in April 2014)

2. first 180 thermo I bought was a black casing (bought it in Jan 2015 from A-B, installed it in April-May); It has a number stamped on the thermo inside it but I can't make it out; this is the one that I think stuck open and when I shake it something metal is loose inside.

3. the warranty replacement thermo sent by A-B and currently in the vehicle has a yellow opaque casing and came in a box labeled BritPart PEL500110G.

Searching google on that last part number, I get mixed results: some say it should be a black casing, others the yellow. Some say the G version is warm weather while others say it is the one without the G at the end.

On the A-B site, it shows the "G" as the regular and the non-G as the warm weather, so maybe they did ship me the wrong replacement after all?

Land Rover Parts, Accessories and Information

Needless to say, I am confused.

 

so iirc they sent you a stock dii thermostat not the td5 180 degree.

G = genuine as in LR

 

slight correction. The A-B site has thermos starting with PEL and and with PEM.

Interestingly, the one they actually sent me -- PEL500110G -- is not even listed on the website, so maybe they did send me the right one and the website is just a typo.

It sure would be easier if they stamped the temperature onto the side of the casing.

 

PEL500110 is the 180 degree
The PEM500990 or whatever is 190 degree

 

Motorad from Britpart used to be Opaque/yellowish. Lately they have been coming black. All-Makes does not offer the PEL500110 in anything but Genuine.

When getting parts from the UK, if a part has a G behind it and it is coming from All-Makes, it only means it is the PR2 or OEM upgrade, not Genuine. If coming from Britpart, the G is also an OEM upgrade, but not Genuine. They actually put GEN behind it to designate.

Atlantic British has their own part numbering system as does Rovers North as does Lucky 8.

See picture from my All-Makes ordering screen, hope it clears up confusion.

The true Genuine 180* is darkish Grey, and Atlantic British does not sell them, so you will continue to get the cheap knock-offs.

I sell the Genuine to forum members for $72/shipped