In case your New Year resolution is to lower coolant operating temperature...GroupBuy

[BMW540san]

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Update 1/6/17

All units sold. I've started another Group Buy at even better price here:

http://www.bimmerforums.com/forum/sh...ee-US-shipping

This topic been covered zillion times but general consensus is that 108 C operating temp in M62TU is great for the fuel economy and emissions but not so great for plastic cooling components.

For those who remember the High school Physics classes, more heat = more pressure so it's 2 enemies against the cooling system.

I've sold about dozen of these, mainly on ebay and on this forum and then my supplier in Europe run out. They're back in stock and I have batch of 5 coming in about 7 days.

1 is sold, 4 are still available: $92 including free shipping. I can get more if these 4 sell.

Direct fit to any E53 X5, E38 740i and E39 540i with M62TU engine. This is mechanical thermostat that opens at 88 C and you'll see average running temp of around 88 C - 92 C vs. 108 C.

In order to avoid CEL you simply connect 10 OHM resistor to disconnected OEM thermostat DME wiring connector.

This thermostat came originaly on E38 740D and here are some specs:

https://catalog.mahle-aftermarket.co...lterId=1164537

It is genuine Mahle / Behr brand made in Germany and it comes with o ring included.

PM if interested.

Thanks.

[Da Beemers]

+1^, Great mod, really like the lower temps. Getting another for the other car and wish I had done it sooner.

Thanks BMW540san!

[BMW540san]

No problem. Thanks for getting another one.

+1^, Great mod, really like the lower temps. Getting another for the other car and wish I had done it sooner.

Thanks BMW540san!

[BMW540san]

3 sold, 2 left.

[CTJoe]

I'll probably get one too. It always seemed like my engine pushed faster before full operating temp.

[DD540i]

Im about to do my VCG and VPG this sounds like a good idea too... where can u buy a 10ohm resistor though

[Mach540]

http://www.mouser.com/Search/m_Produ...lyfophLA%3d%3d

[geargrinder]

Well done Mach - indeed 12ohm is a closer match for the "11.2 ohm" that I seem to recal the thermostat is.

Theoretically if the resistor was powered up all the time it would need to be 12W or better (hence the 25w in that link) but IMO that's overkill as the DME only powers it briefly and intermittently, it would almost never be powered up for more than a handful of seconds. Also you can extend the intermittent power handling of a resistor a bit by heat-sinking it, therefore my setup is a 10W resistor tightly screwed to a small slice of aluminum channel with heat sink grease, and I think this will be 100% fine. (has been so far - approaching probably 1k miles on the new setup).

In fact one theory is the resistor may never get powered, because the DME sees the engine temp at 88C and doesn't feel it needs to drop the temp at WOT / high loads after all. Nobody I know has ever tested this theory, would be fun to check it though with a voltage or amperage probe run back to the cockpit (or on a dyno if you have such a luxury). This theory would propose that the resistor only needs to be there to pass 'self check' pulses that are looking for proper resistance but not actually carry current. A less direct / scientific way to test that would be toss, say, a .5A fuse in line w/ the connection and then thrash the car and see if it ever blows.

- - - Updated - - -

BTW now that I'm in cold weather season, I DO find the car takes longer to heat up with the new T-stat. The OEM T-stat makes this motor when stock, one of the fastest heating engines I've owned, but now it takes notably longer for coolant temp to come up and for the heat to work etc.

[philly98540]

Interesting stuff on the resistor GG. May never even be asked to perform with the colder stats.

I've found my car seems to warm up at the same pace with my 85 deg stat. I drive to work the same path most days, and the heat comes on at the same spot. Traffic light just outside my hood. These 540's are amazing at how soon heat starts to hit my feet.

Maybe yours is not seating fully shut when cold? My stat is a different model, but all the stats should be closed when cold and only pass through the little vent gizmo.

[geargrinder]

Yeah C, I thought of that but then I'd have trouble w temp regulation if it was stuck. Like driving highway speeds in 20F weather like I have, if it was stuck I should see temp drop if it can't close all the way.. And it stays rock solid once its warmed up.

On another car I had trouble with a fussy T-stat design that could trap a bubble behind the T-stat (what that little vent is for) and indeed then the car would run cold... maybe I have something like that going on? This is new T-stat from Brian's buy and looked perfect but you never know I guess. Like I said it appears rock solid once it warms up but maybe I'll futz around w/ Testo again and track actual temps...

[Mach540]

I totally agree that the resistor probably will NEVER get used. Just not needed for the engine since it never gets any where near the 100+C temps of previously normal operations. The small fuse check would be interesting.

I started mine yesterday to charge the battery. For various reasons I haven't properly put it into hibernation yet. Anyways, I let it run for 15 minutes, (I set my alarm so I wouldn't forget it, cuz I'm sure I would have fallen asleep and let it run for hours,) and the temp gauge had not yet reached straight up. I didn't check KTEMP, but I assume it was only up to ~145 F. 32F ambient.

- - - Updated - - -

Re: the wattage. Yep, 25W way overkill, but for 3 bucks.................

[geargrinder]

Yeah. That mirrors my experience, where as w/ the prior t-stat the car would be piping hot in no time..

[philly98540]

Engine should get up to the stat opening temp at the same rate as the stock stat. After that point the stock stat will continue to be closed until the point it cracks open. Essentially the water supplying the heater core will be hotter once fully warmed up on the stock stat, but the time to get heat should be the same.

[peter540]

I may be interested in one of these, although I'd need it by the weekend. Radiator hose just blew. My Zionsville SPAL fan hasn't been working because I need to relocate the fuse. Any chance of receiving the tstat by this weekend? If not, I may still be interested, although less so if I have to drain the coolant AGAIN.

Also, what's the final consensus about whether the resistor is needed? My car's an '03 540i/6.

Related topic, what brand of radiator hoses do a of you prefer? My upper hose failed at one of the one-use band clamps. For now, I suppose I could replace the band clamp with a traditional hose clamp and keep using this hose, but pushing my luck with the old hoses doesn't seem worth it. BTW, the failed hose is BMW, about six years old with about 50k miles on it.

Thanks, as always!

--Peter

[geargrinder]

Peter no resistor will lodge a code but shouldn't throw a light or interfere with emissions monitor stuff.

I go for continental hoses and belts on my cars... 50k seems a little short lived, I'd normally not proactively replace until 60-80k.. In your shoes I might inspect the rubber and then make the call. If the clamp failed because the rubber was deteriorating under it vs if the clamp truly just had a flaw...

[Da Beemers]

No light or code on my '03 without resistor.

If you ask him now you may be able to get it by the weekend.

[peter540]

Peter no resistor will lodge a code but shouldn't throw a light or interfere with emissions monitor stuff.

I go for continental hoses and belts on my cars... 50k seems a little short lived, I'd normally not proactively replace until 60-80k.. In your shoes I might inspect the rubber and then make the call. If the clamp failed because the rubber was deteriorating under it vs if the clamp truly just had a flaw...

Thanks, GG. Actually, I now remember that my hoses are older than I thought. I had a second radiator replaced when the car was still under warranty with 44k miles on it. I'm now at 117k. So they're due, anyway. Going to replace them all (but not the heater core hoses, which seem fine and have no plastic parts).

No light or code on my '03 without resistor.

If you ask him now you may be able to get it by the weekend.

Good to know, and thanks. Yes, Z and I have been in touch; I should have it by the weekend.

[peter540]

Update: I have the thermostat in hand. Z just happened to be passing through Atlanta today, and he brought the part with him. THANK YOU, Z!

I should have the other parts (all radiator hoses and BMW coolant) from the stealer tomorrow, weather permitting (snow expected here tomorrow and Saturday). Perhaps the car will be done by Sunday or Monday (still have to relocate the Zionsville positive wiring harness and fuse, and I have to find a a resistor for the thermostat).

--P

[peter540]

And the evidence that I'm the proud owner of an 88° thermostat -- pictures!

Thanks again, Z!

--Peter

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[BMW540san]

Peter,

It was a pleasure to meet fellow BMW enthusiast and be able to help out by the sheer coincidence of me leaving for Atlanta trip and finding your message about needing thermostat.
BMW gods have smiled upon you. Good luck with everything!

P.S.

Just recently had original (11y/108k) upper radiator hose blew on my X5. It's the one that has tenticals like an octopus. There was nothing wrong with the rubber it self but the plastic connector with steel ring decided to separate which dumped just about all coolant.
I was able to find Reinz / Gates hose locally. It was made in Turkey and looked decent quality but once you install it, the rubber would twist and it was smaller diameter. I decided not use it and went with BMW OEM and I'm not regretting it.

[AngelEye5]

I can vouch for the 88c stat I installed mine 7/16/2016.
The car doesn't feel like its heat soaked anymore it just runs cooler and performs well at all times.
Open the coolant reservoir and hear the amount of air escaping and its not much unlike before were it would want to erupt.
No CEL my wire connector is hanging exposed under the Throttle Body area.
Temp gauge stays in the middle.
Note im running a Spal EFC using the signal off the Aux fan switch over the lower rad hose its the High Temp Blk/White wire, Temp=88C or 190.4F

Before specs Stk stat
93C or 199.4F Low when its just being idle it will drop due to the electrical 12V feed into the heating element inside the thermostat.
105C or 221F Low
108-110C or 226.4-230F High

After specs 88c stat
93C or 200F Low
101C or 214F High


Also my MAF IATs Intake Air Temperature Max idle
Stock MAF 140F
Alloy MAF 175F
Gold MAF 135F
All drop under 100F right away when accelerating

[peter540]

Peter,

It was a pleasure to meet fellow BMW enthusiast and be able to help out by the sheer coincidence of me leaving for Atlanta trip and finding your message about needing thermostat.
BMW gods have smiled upon you. Good luck with everything!

P.S.

Just recently had original (11y/108k) upper radiator hose blew on my X5. It's the one that has tenticals like an octopus. There was nothing wrong with the rubber it self but the plastic connector with steel ring decided to separate which dumped just about all coolant.
I was able to find Reinz / Gates hose locally. It was made in Turkey and looked decent quality but once you install it, the rubber would twist and it was smaller diameter. I decided not use it and went with BMW OEM and I'm not regretting it.

Yes, Z, great to meet you, indeed - not only for me, but also for my two little girls.

I'm with you about the BMW gods having smiled me. What are the odds?

I also hear you about going with BMW hoses. Might get them tomorrow, weather permitting.

--P

[mxchris727]

What is the normal operating temperature that everyone is seeing with these? I'm on the fence; I never get anything but OEM/correct parts for my cars. Would the lower engine temperature increase engine wear?

[geargrinder]

What is the normal operating temperature that everyone is seeing with these? I'm on the fence; I never get anything but OEM/correct parts for my cars. Would the lower engine temperature increase engine wear?

Haha prepare for a can of worms there. A lotta enthusiasts will jump up and exclaim "NO THE HIGH TEMPERATURES MAKE MORE ENGINE WEAR! IT'S ONLY FOR EMISSIONS!!!!! IT SUCKS!!!" but this is scientifically / engineering wise incorrect.

Pros to higher temps:

• High temps actually make for less wear on internal parts, and make for higher efficiency (which the skeptics will scream "GAS MILEAGES AND EMISSIONS!" but efficiency also equals more power!) There's um like, science and shit all proving that very clearly. F1 engines run up way up above 100C. High temps (at least within reason...) are actually 'good' for the motor under ideal operating conditions. Hillbilly shadtree "Cars run better and wear less when the oil is nice and colderrer!" claims are just plain wrong.
• 

Cons to higher temps:

• Coolant pressure goes way up, and BMW cooling systems blow dead donkeys all day long, so that's a terrible combination. This is why most of us do this mod. Guys who have taken the pressure down or out of the M6x engines using thermostats or Evans no-pressure coolant have dramatically less (oops wife english teacher would insist I say "fewer") issues w/ cooling systems than those on the 'normal' program.
• Although efficiency is all well and good, you're naturally approaching closer to the limit of temperature induced failures so if something goes wrong, like catastrophic cooling system failure, you have a lot less time before really bad things happen. This is the other solid reason to do this mod.
• While the chart above is fine for the big metal on metal parts in the motor, plastic parts inside and on the engine have a dramatically decreased lifecycle at higher temps, which includes the notorious timing chain guides and proven out by the S62's similar setup yet notable lower incidence of issues due to lower temps.

You can see why BMW loves this MAP thermostat thing where they can run it at higher temps for efficiency most of the time but then under high loads where maybe you are anticipating a heat spike and want more safety buffer, you can activate the thermostat and bring it down to a lower point... Trying to get the best of both worlds. But in reality your running the whole system at a higher pressure all the time and that doesnt seem to be good for the parts that they spec. If the expansion tanks and radiators and valley pans and everything else were a bit more bulletproof, the MAP setup might be fine, but as a guy whose had to limp from Georgia to the Everglades with a failing expansion tank during a tornado watch... I'll take the lower cooling system pressures and slightly less efficiency every day of the week now.

[philly98540]

Don't forget the increased wear on the timing guide plastics and the VC gaskets, etc. IMO lower temps helps there too. No solid evidence though, but correlates good with the common engineering theory on such parts and is somewhat re-enforced by the S62. I say somewhat since it has a double row set up, but lifespan is curiously better and that engine runs much colder.

Increased efficiency at higher temps is true, and that can give more power out of every drop of gas at normal cruise speeds (partial loads). At WOT, the propensity to pre-detonate, with higher temps, can reduce allowed timing. Also the packing factor is reduced with higher temps. Both of these can lead to lower power at WOT.

The whole MAP stat sounds good on paper, but its not really helpful for a street car to give more power. By the time you get any affect of its design to lower the cylinder and head temps, the full throttle event is long gone.