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Discussion Starter #1
Some users opt to change out their thermostat to an 82C stant item or similar. Of those users some get along fine, and some say it leaks around the top seal. From there you can either take it out and discard it, or smear some RTV or similar around the top seal in order to get it watertight.


I'm not a fan of using RTV where it shouldn't be as a fix, but i am a fan of perhaps having an 82C stat instead of the marginal 79C one. To that end i had a look around and found that Kotje on here had confirmed using the 82C innard around an OE outer casing with a few mods.

They've confirmed its in and all works nicely although no pics or write ups were available i thought i'd have a go myself. A big shout out to Clayton Usher for providing me with the stats, cheers matey! Also a big thanks to 68FB and Kotje whos converstation excahnge spurred me on to do this.

Now before we start i've already said some users have swapped the stant in just fine. If you have, then well done, but i don't want this thread to turn into some sort of "you need to this, you don't need to that" lark.
If thats your thinking then maybe this thread isn't for you. I've already had confirmed the poor fit of the stant which is why i'm embarking on this little DIY. I want a proper rated 82C stat that fits like OE.


So, first off you'll have your failed or failing OE stat (left) and your stant item (right) side by side,





You can see the difference in the seal mount between OE





and Stant





So first thing is to take apart your OE item. Pop the spring retainers off





Pull out the spring, and the circular pellet seat



Now lift the pellet off its pin and set aside



If you look at the last pic you can see the pin has already been modified. I haven't a pic of the pin before but its just as it is in the pic, but about 10mm longer. I'll explain in a bit.

You can see the OE pellet here, rated at 79C



Now do the same for the Stant item. Notice how in the stant item the pin can be removed from its seat. The Behr units pin cannot be removed





Now remember i said i modified the pin on the Behr unit? Well this is why. The pin in the Behr unit originally is about 10mm longer than the stant unit. This means if we put the stant pellet on the Behr pin it sits too high. We need to cut the Behr pin down so its the same height as the Stant item when installed.



Now you can put the higher rated 82C stant pellet on our modified Behr pin and it will sit at the right height. (I Appreciate the pellet says 180C, it should read 180F from the manufacturer!)



Pop the Behr pellet seat onto the stant pellet and finally refit the spring and we're good to go



All that remains is to fit your OE seal and you can install the new stat with no leaky worries
 

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Neat idea.



PLEASE NOTE THAT I DO NOT OWN AN M5 AND THIS POST IS NOT INTENDED TO BE ARROGANT. PLEASE READ THE IMPORTANT REVISED DISCLAIMER THAT APPLIES TO THIS POST
 

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Discussion Starter #5
The pin is hard and so a hacksaw etc proves difficult. I used a cut off wheel on a dremel and then a stone attachment to clean it up.

Zed, i haven't installed the stat yet, primarily as i only did this tonight here, but also because my thermostat hasn't failed yet, its not that old.
I came upon these stats a little by chance and so thought i'd perform the procedure and document it for others before i have to use it. I won't be installing it for the sake of it, rather i'll wait until this stat starts to fail.
 

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pas wel op dat de pennetje gezaagd wordt. de vorm van de pin moet het zelfde zijn als de originele.
"Be careful when cutting the pin. The shape of the pin must be the same as the original, else it can get damaged internally."

Used Google Translate to help me along the way. Do let us know if something was lost in translation, kotje :)
 

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Discussion Starter #11
I have tried to emulate the pin shape by putting a slightly rounded point on the end of it. Its by no means perfect but nice and smooth and doesn't interfere with putting on or removing the pellet.

Kotje, cheers for the initial information about the possibility of this, the thread wouldn't have happened had it not been for your's and Malcolm's comment exchanges on the "alternative thermostat" thread
 

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Are there any noticeable difference when using a 82 vs 79 degree thermostat? Other benefits?
the benefit of the 79C vs 82C is for those people who live in cold climates (e.g. NY) where highway cruising will force the coolant temp to 79C on a properly working BMW/Behr thermostat

so the benefit is that the 82C thermostat stays closed longer and allows the engine to warm up slightly more especially for those people with short commutes, e.g. i live around NYC and my commute is ~11 miles one-way and I once got my Lubro Moly 0w40 to emulsify because my commutes is so short

now for people living in relatively warm climates (FL, Cali, etc) even their FAILED 79C thermostats won't make a difference, in the spring and summer the thermostat will get past 79C easily, wind chill while cruising at night may drop the coolant temp close to 79C

edit:

forgot to mention, just to add a data point

- my stant unit was ONLY able to hold 78C!... yes I bought the 82C STANT unit

my current Behr 79C for reference
holds 79C-80C from
cold start + <11mile commute + near 0C ambient temp
 

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This is brilliant. Best of both worlds! I have a Stant thermostat which leaks, although it's manageable at the moment, so this is the plan next time. Great idea.
 
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Thanks for the very timely DIY Jamie! I already have the Stant 14538 82C/180F unit and thought it was plug and play after reading that many people are using it in place of the Behr.

Thanks for clarifying this poor assumption. I just need to get the O-rings and then I'll make good use of your write up.

Cheers,

Scott
 
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What's the issue with using the Behr?
 

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What's the issue with using the Behr?
there is no issue with running the Behr

BMW (Behr) = 79C
Behr = 79C
Stant = 82C

the reason people want to run the STANT unit is because they want those couple of extra degrees in the winter

i'm personally not using the STANT, because if the thermostats are consistent in having a 2 year lifespan it will be a simple reminder to change the coolant
 

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there is no issue with running the Behr

BMW (Behr) = 79C
Behr = 79C
Stant = 79C

the reason people want to run the STANT unit is because they want those couple of extra degrees in the winter

i'm personally not using the STANT, because if the thermostats are consistent in having a 2 year lifespan it will be a simple reminder to change the coolant
The trouble is that the Behr units have a habit of failing far too soon. Mine lasted only 7 months before sticking open (which is how most of these units fail). Cooler engine temps mean poor fuel economy, soot in the exhaust and a general feeling that the engine isn't running optimally.
 
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