2012-2015 BMW 3-Series and 4-Series Forum
BMW Garage BMW Meets Register Search Today's Posts Mark Forums Read
BMW 3-Series and 4-Series Forum (F30 / F32) | F30POST > Technical Forums > N47 and N57 Turbodiesel Engine / Drivetrain / Exhaust Modifications > Has anyone done Thermostat Mods to improve warm-up time?
Post Reply
Thread Tools Search this Thread
      10-05-2020, 10:09 AM   #1
First Lieutenant

Drives: BMW 430dX
Join Date: Apr 2018
Location: Sheffield, England

iTrader: (0)

Has anyone done Thermostat Mods to improve warm-up time?

So winter is approaching for us northern hemisphere folk. I'm seeing lots of threads on the forum regarding slow warm-up of our diesel engines. I would love to know if anyone has modified the coolant system to improve this? Ive tinkered with cars for years and often played around with basic coolant systems but this one needs a bit more research!

I recently tried to diagnose a slightly slow warm-up of my 430d (https://f30.bimmerpost.com/forums/sh....php?t=1763280) - what i realized was that despite the thermostat being closed, a lot of hot coolant was still working its way into the radiator.

After 20 mins slow/fast idle it hit 76C Coolant/75C Oil Temp in 12C ambient:
Hose FROM engine block under inlet manifold = HOT
Right side of Radiator = HOT
Left side of Radiator = Warm
Left side return to Thermostat and Water Pump hose = Cold

On my previous (VW) diesels, both coolant hoses and the rad would be stone cold until the Thermostat opened, which indicates to me that our engines have a slight design flaw.

The heat bleed is coming from the block through pipe #1 in the diagram. My thoughts would be that an in-line thermostat with a conservative opening temp (~80C) in that pipe could significantly shorten warm-up time. The only problem would be the return hose to the expansion tank (
#3) and im unsure if blocking this path until warm would have a negative effect.

It'd be great if someone could validate my findings with their engines

Last edited by Eddamoo; 10-05-2020 at 10:28 AM..
Appreciate 0
Post Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

All times are GMT -5. The time now is 08:47 AM.

Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2021, vBulletin Solutions Inc.
1Addicts.com, BIMMERPOST.com, E90Post.com, F30Post.com, M3Post.com, ZPost.com, 5Post.com, 6Post.com, 7Post.com, XBimmers.com logo and trademark are properties of BIMMERPOST