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Turbocharged Engine Thermostat Replacement
 

Pelican Technical Article:

Turbocharged Engine Thermostat Replacement

Nick Czerula

Time:

3 hours3 hrs

Tab:

$150

Talent:

****

Tools:

Set of sockets 10, 11, 13mm, screwdrivers

Applicable Models:

R56 MINI Cooper S Hatchback (2007-11)

Parts Required:

Thermostat, hoses, engine coolant

Hot Tip:

Work with a cool engine

Performance Gain:

Car will cool down again or restore function of heater

Complementary Modification:

Change radiator hoses and/or water pipes.

The MINI R56 cooling system is filled through the plastic coolant expansion tank (or coolant reservoir) at the right front of the engine compartment. There is no cap on the radiator. Other components of the cooling system consist of:

  • Belt driven coolant pump bolted to the right side of the engine block.
  • Turbocharged engines: Electric coolant pump bolted to the left front of the engine block.
  • Turbocharged engines: Engine oil cooler attached to oil filter housing.
  • Electric cooling fan attached to rear of radiator. The cooling fan is controlled by the engine control module (ECM) via an output final stage.
  • Electrically heated thermostat.
  • Automatic transmission cooler (heat exchanger).
  • Coolant temperature sensor at cylinder head.
  • Coolant hose and lines.

The engine control module (ECM) (DME) controls and monitors operation of the thermostat. Controlling the thermostat function according to a map allows the engine management system (DME) to raise engine operating temperature quickly and precisely to the optimal range and to maintain it there for maximum efficiency and minimum emissions.

If a fault occurs in the thermostat, a fault code is stored in the ECM, usually with a description of "Map cooling circuit". A fault code can be present yet the vehicle will lack any cooling system issues, such as overheating. This is because the thermostat has a fail-safe mechanical function as well. If you have this fault code, replace your thermostat and bleed your cooling system. Other symptoms of a faulty thermostat are engine overheating, slow to warm up and lack of heat.

In this article I will describe how to replace the thermostat in your N14 MINI turbocharged engine. Be sure to work with a cool engine and confirm the cooling system lacks pressure before opening the cooling system.

NOTE: Now is a really good time to inspect and change out your water pipes. They are made of plastic and often crack over time or get baked onto the water pump due to heat in this area. 

Keep in mind that when your car was serviced before, parts may have been replaced with different size fasteners used in the replacement. The sizes of the nuts and bolts we give may be different from what you have, so be prepared with different size sockets and wrenches.

Protect your eyes, hands and body from fluids, dust and debris while working on your vehicle. If you're working with the electrical system, disconnect the battery before beginning. Always catch fluids in appropriate containers and properly dispose of any fluid waste. Recycle parts, packaging and fluids when possible. Do not work on your vehicle if you feel the task is beyond your ability.

Vehicle models change and evolve, as they grow older, so the vehicle shown in our illustrations may vary slightly from yours. If something seems different, let us know and share your info to help other users. Do you have questions or want to add to the article? Leave a comment below. When leaving a comment, please leave your vehicle information.

Drain the cooling system. See our tech article on cooling system draining and filling.

Working at the crankcase breather heating element, release the tab (red arrow) and disconnect the electrical connector.
Figure 1

Working at the crankcase breather heating element, release the tab (red arrow) and disconnect the electrical connector.

Then lift it up to detach the hose lock (red arrows) at the valve cover.
Figure 2

Then lift it up to detach the hose lock (red arrows) at the valve cover.

Remove the hose from the valve cover (red arrow).
Figure 3

Remove the hose from the valve cover (red arrow).

Working at the vacuum pump, press the brake booster line release tab (red arrow) and pull the vacuum line straight off the pump.
Figure 4

Working at the vacuum pump, press the brake booster line release tab (red arrow) and pull the vacuum line straight off the pump.

Loosen the intake air duct hose clamps (red arrows).
Figure 5

Loosen the intake air duct hose clamps (red arrows).

Remove the intake air duct from the turbocharger, then the intake air housing.
Figure 6

Remove the intake air duct from the turbocharger, then the intake air housing.

Disconnect the electrical connectors for the oil pressure sensor (red arrow) and the coolant temperature sensor housing (green arrow).
Figure 7

Disconnect the electrical connectors for the oil pressure sensor (red arrow) and the coolant temperature sensor housing (green arrow). Use a pick to pull the connector tab up and slide the connectors straight off.

Working at the left rear of the cylinder head, release the tab and disconnect the camshaft sensor electrical connector (red arrow).
Figure 8

Working at the left rear of the cylinder head, release the tab and disconnect the camshaft sensor electrical connector (red arrow). The intake sensor is shown. If your vehicle has an exhaust sensor, disconnect it too.

Remove the wiring harness housing (red arrow) from the mounting bracket (green arrow) by sliding it straight up.
Figure 9

Remove the wiring harness housing (red arrow) from the mounting bracket (green arrow) by sliding it straight up. Place it aside and out of the way.

Working at the front thermostat hoses, use hose clamp pliers (inset) to remove the hose clamps (red arrows).
Figure 10

Working at the front thermostat hoses, use hose clamp pliers (inset) to remove the hose clamps (red arrows). Slide the clamps away from the thermostat.

Pull the hoses (red arrows) straight off.
Figure 11

Pull the hoses (red arrows) straight off.

Working at the back of the thermostat, remove the hose using hose clamp pliers (green arrow).
Figure 12

Working at the back of the thermostat, remove the hose using hose clamp pliers (green arrow). Slide the clamps away from the thermostat and pull the hose straight off. Use a pick to pull the connector tab (red arrow) down (it's on the bottom), and slide the connector straight off.

Working at the back of the thermostat, remove the hose (green arrow) using sliding jaw pliers (red arrow).
Figure 13

Working at the back of the thermostat, remove the hose (green arrow) using sliding jaw pliers (red arrow). Slide the clamps away from the thermostat and pull the hose straight off.

Working at the back of the thermostat (green arrow) under the intake manifold (yellow arrow), remove the metal clip (red arrow) by pulling it straight up.
Figure 14

Working at the back of the thermostat (green arrow) under the intake manifold (yellow arrow), remove the metal clip (red arrow) by pulling it straight up.

This photo shows the clip removed from the thermostat (red arrow).
Figure 15

This photo shows the clip removed from the thermostat (red arrow).

Remove the three 10mm thermostat mounting fasteners (red arrows).
Figure 16

Remove the three 10mm thermostat mounting fasteners (red arrows). The rear fastener has a socket on it in the photo. Once the fasteners are removed, you will have to remove the small front hose clamp (green arrow).

Using hose clamp pliers (red arrow) slide the clamp away from the thermostat and pull the hose straight off.
Figure 17

Using hose clamp pliers (red arrow) slide the clamp away from the thermostat and pull the hose straight off. You will have to pull the hose off as you remove the thermostat from the engine.

This photo shows the thermostat fastener locations (red arrows).
Figure 18

This photo shows the thermostat fastener locations (red arrows).

Slide the small hose off the thermostat and remove the thermostat from the engine.
Figure 19

Slide the small hose off the thermostat and remove the thermostat from the engine.

Using a plastic scraper and a Scotch-Brite pad, clean the thermostat sealing surface.
Figure 20

Using a plastic scraper and a Scotch-Brite pad, clean the thermostat sealing surface. It is important not to use a metal scraper or razor blade here. You could damage the sealing surface and the thermostat seal (red arrow) will not seat properly, resulting in a leak. Once clean, confirm the sealing surface isn't pitted. It if is, it may not seal correctly. You may have to add some epoxy and sand it down to get a smooth and even sealing surface. I see this happen more on high mileage under-maintained MINIs. Replace the small hose (green arrow) if needed. Install the new thermostat and evenly tighten all the fasteners. Install the coolant hoses. Listen for an audible click to confirm the rear clip engages. Connect the thermostat and sensor electrical connectors. Install the cooling fan and fill and bleed the cooling system. Remember to check the cooling system for leaks and top up the coolant when complete.

Comments and Suggestions:
Jose Luis Comments: Hi, great info here, I'm using this tutorial to find out why my Peugeot 3008 turbo takes a lot of time to warm up mini and Peugeot are using same engine at least on the turbo version. May the thermostat be stuck on open position? I know they usually stay closed when fail and causing engine overheating. Thanks.
January 23, 2018
  Followup from the Pelican Staff: Yes, likely stuck open thermostat. - Nick at Pelican Parts  
OldHoopsJunkie Comments: Regarding putting the clip back on the connection with the coolant pipe: Easiest part of the job. I had the air filter housing off and the fat intake tube off as well, so the clip was easy to set in place and push.
January 22, 2018
  Followup from the Pelican Staff: Thanks for the Info. We appreciate it.
- Nick at Pelican Parts
 
OldHoopsJunkie Comments: These instructions are great, but they treat the re-installation as if it were simple. Far from it. Re-installation is much more difficult than removal:
1. The far end of the coolant pipe, at the water pump, is almost certain to break or crack if it's old. So it should be replaced.
2. Re-inserting the coolant pipe is tricky. It has to be in the right position in three ways, independent of each other:
A. Far enough in which is difficult to see.
B. Rotated perfectly because it has a little indentation on the thermostat end, which has to match up perfectly with a nub on the thermo housing - and OF COURSE they are on the bottom, where you can't see them, so it's a bit of trial and error with the coolant tube constantly falling back out of the water pump.
C. The thermo housing end of the pipe must be in exactly the right high/low, left/right position in order to slide the thermo housing into it.

Also, pushing the pipe in and pushing the thermo housing into the pipe, with new o-rings, required more strength than I have. I could not do it manually, given the wretched angles at which pushing was required. I recommend that for this and other DIY projects involving o-rings, always have silicone grease not spray!!! lubricant on hand. Coolant as the lubricant? Good luck.

To get the pipe to go into the water pump, I had to use a screwdriver as a lever at the thermostat end, which risked breaking the pipe. I then used a pry bar and padding to push the thermostat housing into the pipe while holding it in position with the other hand.

Yes, the job is easier if you want to risk leaving that fragile coolant pipe and its old o-ring in place and risk having to do this job all over again in zero miles when you find out that jostling the old coolant pipe even slightly caused it to crack at the far end. But the right way is to also buy and replace the pipe, and use silicone and no other grease on the o-rings. Other greases, and silicone spray, cause the o-rings to swell, and then, you've have a swell time trying to get them in.

I did not have to remove the intake housing to put the coolant pipe back in. In fact, I can’t see how that would make it easier.

Mechanically, this job is simple. In terms of grunt work, the degree of difficulty is a 9 out of 10. A horrible little job caused by BMW using plastic parts in hard-to-reach places which are subject to a lot of heat and vibration.
January 22, 2018
  Followup from the Pelican Staff: Thanks for sharing your repair process and experience. These type of comments add so much to the Pelican tech community.
- Nick at Pelican Parts
 
Bill Comments: Is there a way to detect the source of a leak in that area? I have a leak which hisses under pressure. Already replace the return hose assembly from the turbo; that wasn't it. The leak is in that area, but I can't see it. Car has 51k miles. Is it a likely possibility that the thermostat housing would develop a crack at that mileage?
January 15, 2018
  Followup from the Pelican Staff: You can pressure test cooling system, then use a mirror to look in hidden places for the leak.

Any plastic component can crack. - Nick at Pelican Parts
 
Major need Comments: I just performed this job and there was never a clip between the thermostat and the water pipe. I replaced it back without the clip. Will there be any major problems?
November 18, 2017
  Followup from the Pelican Staff: There should be a clip. Give The Pelican Parts parts specialists a call at 1-888-280-7799. They can figure out what part or repair kit you need.
- Nick at Pelican Parts
 
greg Comments: cant get the clip back in then i dropped. it kept popping up when i pushed it down. will order a clip and a pipe.
November 9, 2017
  Followup from the Pelican Staff: PIpe probably not seated all the way. - Nick at Pelican Parts  
JIM Comments: Great help article, Pelican. It's taken me over a week, sometimes spoending wghole afternoons just trying to remove one clip, but I'm getting there. New thermostyat bolted in place, but the clip sirclip? thing that secures the thermostat to the big pipe at the rear won't go bacjk in. I've spent 2 days trying and I'm getting to the point where, "put a half kilo of epoxy glue on it and sell the car" stage - any suggestions would be most welcome!
May 7, 2017
  Followup from the Pelican Staff: The clip should be in the pipe when the thermostat is installed. Lubricate the pipe and t-stat o-ring with clean coolant. Then support pipe and press them together until you hear a click. - Nick at Pelican Parts  
P8ntballa Comments: Just did this on my mini Cooper. Your guide made it very easy to do. I don't know what I would do without this website to fix my mini. Its saved me thousands of dollars and your parts are sold at a great price as well.
Thank you so much!
April 8, 2017
  Followup from the Pelican Staff: Thanks for the feedback. Glad we could help.
- Nick at Pelican Parts
 
Borracho bean Comments: Wooooo that was brutal, I just took off the thermostat and I found it funny that there was no metal pin connecting the water pipe and thermostat. It was glued together! So yes as I pulled on the connection my water pipe came out, and I'm glad it did. The end of it that connects to the water pump was completely destroyed, like crumble in my hands destroyed. So now I await the water pipe and a new pin. Thanks for the help so far!
March 14, 2017
  Followup from the Pelican Staff: WHOA. Glued in - NOT GOOD.

Glad you got it worked out. - Nick at Pelican Parts
 
Back street garden mechanic Comments: Hi guys. Just replaced my wife's 2007 cooper R56 thermostat . Thanks to your directions! After 3 days had a new error code: $7E8 engine, as well as : $79 A/T. When I clicked on these it stated "Engine coolant temp sensor 1",and "circuit low". But after many hrs on the web, nothing. Any ideas?
December 15, 2016
  Followup from the Pelican Staff: Check if the sensor was damaged during the thermostat repair. http://www.pelicanparts.com/techarticles/MINI_R56/86-ENGINE-Coolant_Temperature_and_Oil_Pressure_Sensor_Replacement/86-ENGINE-Coolant_Temperature_and_Oil_Pressure_Sensor_Replacement.htm - Nick at Pelican Parts  
Skua Comments: Thanks for the tips,
Easily took the thermostat out an hour ago. Ordered a new one from Pelican at half the price Mini dealer sells it here in Spain. I think that maybe will have to change that pipe as well as Retired Miner, that pipe looks slightly dirt and now I suspect the leak was from that coupling instead of the thermostat to the block coupling. Anyway that will probably be a work for the mechanic since I cant lift the car and work from below. Will also change the water pump in that case.
It is a great help for me to read your articles. since then I serviced my Boxster 987 and now this Mini I bought to my son as a Christmas present, hope I have it fixed in time!
December 1, 2016
  Followup from the Pelican Staff: Thanks for the feedback. Glad we could help.
- Nick at Pelican Parts
 
Retired Miner Comments: This article is good
Except you do not mention that the difficult removal of the thermostat from the water pipe from the water pump to the thermostat can dislodge the pipe from the water pump end and damage the pipe and O-ring. After a successful thermostat remove and replace I had a leak at the water pump end and had to remove the thermostat again to remove the water pipe. I have ordered the pipe and any suggestions on installation of the water pipe would be welcome. Thanks for the great articles and pictures even seasoned mechanics benefit from precise instructions and good pictures. I can take pictures of the damaged pipe if you need them to amend your tech article.
November 23, 2016
  Followup from the Pelican Staff: The thermostat should not difficult to remove. Unless someone used an adhesive when installing the one you are trying to remove. I would like to see photos of the themrostat side of pipe. - Nick at Pelican Parts  
Primevci Comments: Thanks this write up helped allot
July 9, 2016
  Followup from the Pelican Staff: Thanks for the feedback. Glad we could help.
- Nick at Pelican Parts
 

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Page last updated: Wed 2/21/2018 03:09:39 AM