Cooling system nightmare 740 e38

[oatmealwithwate]

I am incredibly interested in purchasing a lower running temperature thermostat for my 2001 740il, can someone point out the difference between these two thermostat that were linked earlier in the thread? Is one a plug and play and another is a direct fit that doesn't use a connector?

http://m.ebay.com/itm/252674439812?_...49&_mwBanner=1


https://www.ecstuning.com/BMW-E38-74...8c_Thermostat/

[740iSport303]

The first one has been recalibrated and still includes the MAP sensor connection and is a direct replacement. The second is also a "direct replacement" but does not have the MAP sensor connection.

[oatmealwithwate]

The first one has been recalibrated and still includes the MAP sensor connection and is a direct replacement. The second is also a "direct replacement" but does not have the MAP sensor connection.

okay thank you for clearing that up for me. I ordered the first one re calibrated with the MAP sensor.

[Ruskii]

What are the possible issues of installing the one off ECS (88 degree) which does not have MAP connection?

I recall changing a coolant temperature sensor for the radiator when I switched to a lower temperature thermostat on my e30 318is (m42).

[740iSport303]

What are the possible issues of installing the one off ECS (88 degree) which does not have MAP connection?

I recall changing a coolant temperature sensor for the radiator when I switched to a lower temperature thermostat on my e30 318is (m42).

I've read and heard a lot of different statements/opinions regarding not having the MAP sensor plugged in. Some have said it made no difference to the DME or performance, but when I had mine unplugged to test the theory, I ended up with an error code that after about two weeks set the SES light. Others have mentioned that they had zero issue.

[luka117]

I have 88C thermostat and only thing is the error in DME. No SES light for me. No difference on performance. Now I install resistor to the MAP connector and don't have a error in DME any more.

[Ruskii]

I have 88C thermostat and only thing is the error in DME. No SES light for me. No difference on performance. Now I install resistor to the MAP connector and don't have a error in DME any more.

please share more details!

[psjr]

What are the possible issues of installing the one off ECS (88 degree) which does not have MAP connection?

I recall changing a coolant temperature sensor for the radiator when I switched to a lower temperature thermostat on my e30 318is (m42).

BTW I have 88C thermostats for $100 each shipped, and they are Behr (OEM with BMW roundel ground off) not the Vemo aftermarket that ECS has.

[PiotrC70]

I have the 88C stat as well, MAP sensor cable unplugged (obviously) with no resistor and no adverse affects except the internal DME error. I've been running this for a few months now.

[Ruskii]

Nevermind the resistor question... found this thread: https://www.bimmerforums.com/forum/s...ermostat/page8

(good thing I found this thread before racer2086 got a flashback! )

[racer2086]

Oh god that thread. I ran across that the other day when reading about these lower thermostats. I'll be keeping things simple and getting the recalibrated stat for a few bucks more.

[MrChrysler]

Oh god that thread. I ran across that the other day when reading about these lower thermostats. I'll be keeping things simple and getting the recalibrated stat for a few bucks more.

Re calibrated in software or mechanically?

[XAlt]

Re calibrated in software or mechanically?

Software, AKA no risk of tripping a CEL.

The diesel stat looks interesting, try it out. Maybe even go waterless coolant if it's running nice and cool.

[bass528]

Overfilling is catastrophic and overlooked, Just a tip for those doing coolant work, the expansion tank is designed to allow for fluid expansion when the coolant gets hot, like wise this tank should never be overfilled or filled to the top, which I have seen many mechanics and DIY do, then claiming poor BMW engineering. Filling it to the top leaves no room for expansion and creates extreme hydraulic pressure that's above the systems design, this pressure will be released in the weakest link of your system, which can be the expansion tank, hose, valley pan, gaskets or radiator. If you check the level when cold, the dip stick should be flush, mine is even slightly lower but not low enough to set off a low coolant light on the IKE/cluster. You can easily compress air and is the reason for that air pocket in the expansion tank thus dropping the system pressure to specs.

[racer2086]

Re calibrated in software or mechanically?

This guy actually recalibrates the thermostat. I imagine he does something with the spring to get it to open sooner and stay open more to drop the coolant temperature. I'm sending 2 to him to do and I will report back.

[oldroller]

Been running the ECS unit for a few thousand now, absolutely no adverse effects. No lights, etc. Haven't scanned the DME yet, but probably a code for the wide open throttle activation of the thermo.
No worries.
Pros? Much less heat, less swelling of the hoses at temp, less pressure on the entire system while keeping the mill at 93/94C in all conditions.

And Bass528 is right on, the expansion tank is just that, for captured expansion. Air is much easier to pressurize than water. Keep the dipstick at level, no problems.

[chrisn7]

Overfilling is catastrophic and overlooked, Just a tip for those doing coolant work, the expansion tank is designed to allow for fluid expansion when the coolant gets hot, like wise this tank should never be overfilled or filled to the top, which I have seen many mechanics and DIY do, then claiming poor BMW engineering. Filling it to the top leaves no room for expansion and creates extreme hydraulic pressure that's above the systems design, this pressure will be released in the weakest link of your system, which can be the expansion tank, hose, valley pan, gaskets or radiator. If you check the level when cold, the dip stick should be flush, mine is even slightly lower but not low enough to set off a low coolant light on the IKE/cluster. You can easily compress air and is the reason for that air pocket in the expansion tank thus dropping the system pressure to specs.

This scenario implies that the system is totally sealed - which it isn't. The header tank cap is rated to 2 bar, and this is stamped on the inside of the cap. This allows pressure above this to blow off, avoiding pressures 'above system design'.

As regards MAP cooling, under everyday driving conditions its true that you won't notice any performance issues if the connector is corroded or unplugged. This is because its only when the system gains extra heat from say hard driving, that the DME activates electrical heating of the thermostat, to open that further and increase coolant flow rate to the radiator.

[bass528]

You shouldnt be relying on caps to regulate your pressure, thats a last resort and a safety net, the expansion tank is there for the reasons above. Ultimately your cap is rated at 30 PSI, your 20 year old hoses/gaskets might not withstand that type of pressure. you should not be replying on a cap to regulate your system pressure. The dipstick is easy enough to follow and the expansion tank is there for a reason, just dont overfill, thats what BMW is "implying" and run at 14 PSI instead of 30.

[Ruskii]

This guy actually recalibrates the thermostat. I imagine he does something with the spring to get it to open sooner and stay open more to drop the coolant temperature.

My thoughts are the same. I ordered one last night, very curious to see it in person.

[Aitch]

I've been wondering if I have a lower temp thermostat. Since I've unlocked my cluster I've never seen ktemp over 95c in the past 3 weeks.

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