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Old 02-13-2020, 05:32 AM
The German The German is offline
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Lower temp thermostat for an N55 engine?

It seems to be pretty easy to find lower temperature (90c) thermostats for the N62 engine, but does anyone know where I can get a lower temperature thermostat for an N55 engine?

Thanks
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Old 02-13-2020, 07:24 AM
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To what avail? Electric water pump controlled by the DME.
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Old 02-13-2020, 07:41 AM
The German The German is offline
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To lower the engine operating temperature and reduce coolant pressure. Pretty common mod for the N62 to make the engine more reliable. I just don't see any lower temp thermostats available for the N55 except one made by Mishimoto that I've heard doesn't actually fit.
Any other vendors that anyone has tried?
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Old 02-13-2020, 07:52 AM
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N62 belt driven pump always turning (pumping) when engine running. N55 ELECTRIC pump. Turns on when the DME tells it to turn on and off again. Otherwise it just sits there looking cool.
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Old 02-13-2020, 08:09 AM
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Originally Posted by Zulu95 View Post
it just sits there looking cool.
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Old 02-13-2020, 08:26 AM
The German The German is offline
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Gotcha. I'm not concerned though with when the water pump turns on or off. I'm looking for the thermostat to open at a lower temperature allowing coolant to flow into the radiator. I believe the stock thermostat opens at 105c and I would like to replace it with a 90c. Thus lowering the operating temperature of the engine from 221 degrees to around 194 degrees.
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Old 02-13-2020, 08:39 AM
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Doug Huffman Doug Huffman is online now
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ECU DME controlled thermostat and coolant pump

N55 has an electrically mapped controlled by the ECU thermostat in addition to an ECU controlled variable speed electric coolant pump.

Quote:
The Digital Engine Electronics (DME) regulate the following temperature range:

Economy mode: 108 C
Normal mode: 104 C
High mode: 95 C
High mode and control operation by characteristic map thermostat: 90C.
I doubt that YOU will find an electrically heated thermostat for a particular engine ALSO with a non-standard wax-pellet motor - itself very high tech.

Quote:
. The wax element of the characteristic map thermostat contains a heater resistor. The Digital Engine Electronics (DME) supplies the heater resistor with current. This causes the wax element to expand and close the cylinder head inlet against the spring pressure of a spring. The spring has the task of pressing the characteristic map thermostat back into its rest position when the wax element cools down. With the engine cold, the coolant circuit runs via the cylinder head inlet and characteristic map thermostat to the return line towards the coolant pump.

The Digital Engine Electronics (DME) activate the heating element via a characteristic map depending on the current driving situation.

https://www.newtis.info/tisv2/a/en/e...oling/F7kt8r2W
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Last edited by Doug Huffman; 02-13-2020 at 08:53 AM.
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Old 02-13-2020, 09:30 AM
ArgentoCarNut ArgentoCarNut is online now
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It seems like the change the OP is looking to make can probably be accomplished through programming rather than replacing hardware.


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Old 02-13-2020, 10:17 AM
The German The German is offline
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This is good information. Thank you. If I could find someone to reprogram my ECU, so the engine temp stays out of both the economy mode and normal modes and stay in high mode or lower (90c seems to work great on the N62). It would save the internal rubber and plastic parts in our engines. Rubber and plastic won't last long at 108c...

Last edited by The German; 02-13-2020 at 10:18 AM.
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Old 02-13-2020, 10:24 AM
deroy deroy is offline
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If you always drive it like you stole it, itll always be in high mode. Much more fun than a laptop solution.


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Old 02-13-2020, 10:42 AM
smassey321 smassey321 is offline
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Quote:
Originally Posted by The German View Post
This is good information. Thank you. If I could find someone to reprogram my ECU, so the engine temp stays out of both the economy mode and normal modes and stay in high mode or lower (90c seems to work great on the N62). It would save the internal rubber and plastic parts in our engines. Rubber and plastic won't last long at 108c...
There really is no need to do this. I just restored all the rubber/plastic on my 15-year-old N52. Only 2 hoses were close to failing. Both the thermostat and upper radiator hose hook to the top of the head with plastic fittings. This is where the hottest fluid exits the engine. Those were the only 2 that were bad. N52 runs hotter than N55.

112C ECO mode (economy)
105C Normal mode
95C High mode
80C High + mapped thermostat mode
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Old 02-13-2020, 10:55 AM
The German The German is offline
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Possibly not as much of a problem on the N52, but lowering the temp prolongs the coolant system as well by reducing pressure. Also keeps the transmission cooler.
For the potential benefits of lowering the temperature in my opinion it's not worth it to run it hotter for the potential economy benefits. There's a reason the Toyota's are considered to be so reliable, it's because they run much lower engine operating temperatures. The high temps of our cars likely aren't doing us any favors in terms of reliability.
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