118d main Thermostat and EGR thermostat change.

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rob-the-viking
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118d main Thermostat and EGR thermostat change.

Post by rob-the-viking » Sun Jan 22, 2012 5:28 pm

The car is a 2005 118d with the M47TU engine, other varients of this lump (such as the 120d) may differ to this!

Symptoms

The first sign that something was not quite right was fuel consumption dropping by about 20%. After I checked the tyre pressures were all OK, I began to suspect a faulty stat. To confirm this, you need to access the hidden menus with in the OBD. Here is a guide to get you into the menus. Once you are in there and have unlocked the rest of the menus using step 19, you need to scroll through to step 7 which will tell you your coolant temperature. Obviously this will vary slightly as you are driving. In my case, the temp never went about 85 degrees, no matter how hard or gently I drive the car. You should see temperatures of up to about 92-93 degrees once the car is warmed up. The clue to the fault is seen in the photo below.

Image

The thermostat is rated at 88 degrees, so it has failed open as it's designed to, which means the DDE thinks the engine is still in warm up mode all the time so pumps in more fuel. (At least that's how I understand it!)

So I decided to bite the bullet and replace both the EGR and the main thermostat. Cost for the parts was about £73 delivered, thanks to Kev and Tony @ Cotswold BMW for their excellent service again!

Parts needed

EGR stat part # 1171 7787870
Main Thermostat part # 1151 7805811

Tools and other stuff needed

Nothing too unusual, but you'll need

5mm allen key and T40 torx drive to fit onto a socket. A standard allen key or torx won't give you the leverage you need to undo various nuts.
Usual selection of sockets and extension bars, screwdrivers etc
Blue roll
At least 3L of coolant!

The Fix

Before you start, you need to take a couple of things into consideration.

1. You are going to spill coolant on the ground, so if you've just spent thousands on getting your driveway resurfaced, you might want to do it elsewhere.
2. You will have your hands in the engine bay so best to do this when the engine is cold!
3. You will have your hands in the engine bay and be dumping water and coolant into it, which leads me to the start....

1. Disconnect the -ve battery terminal, remember that you will need to get back into the boot later to reconnect it so don't shut the boot fully! Otherwise you'll be crawling in through the back seat to pull the emergency boot release!

2. Remove engine accoustic cover - 2 x 5mm allen bolts, and slide it forward towards you, also remove front air guide, 2 x T20 screws. See red dots below!

Image

3. Unplug electric fan connector (Shown in green), 1 x T20 bold at the top L/H side of the fan as you look at it, (Shown in red) and there is a little plastic catch half way down on the R/H side you need to hold open as you slide the fan upwards (Shown in yellow).

Image

4. Remove air feed to turbo. 2 x 5mm allen bolts at the top, the turbo end is a push fit and there is another breather pipe half way down which is also a push fit. Pipe marked yellow, allen bolts marked in red

Image

5. Next, because BMW hide the main thermostat behind the EGR cooler, to remove the stat you first have to remove the EGR cooler. First, undo and remove the two jubilee clips that hold the ERG exhaust pipe on. Shown on the pic below in blue, EGR cooler is yellow and EGR thermostat is red.

Image

Then remove the EGR exhaust pipe, to make this easier to remove, unplug the EGR air feed.

Here is where it starts to get wet, so to try and minimise this I packed the engine bay with blue roll and bunged up the exposed turbo air feed, as you can see above.

6. Disconnect the coolant inlet pipe that feeds the ERG thermostat and outlet pipe (jubilee clip) and remove the hoses. Let the blue stuff flow! Clips shown in yellow below. Also remove the 10mm nut that secures the coolant hose to the block, shown in green.

Image

7. Remove 2 x T40 bolts that attach the EGR cooler above the turbo

Image

8. Remove 3 x H5 bolts that attach the EGR cooler to the front of the engine, and remove the EGR cooler with EGR thermostat attached.

Image

9. Once EGR cooler is removed, undo 2 bolts that attach the thermostat to it and replace the EGR thermostat for the new one, remember to fit the new 'O' ring that comes with it.

Image

10. Release the retaining clips that hold the hoses on to either side of the thermostat and disconnect them. You will spill more coolant here for sure!

Image

11. Remove the 4 x 10mm bolts that attach the thermostat to the waterpump, remove thermostat and install replacement item!

Image

12. Reattach stat hoses and reassembly is the reverse of the above!

Whilst the access was good I had a feel of the turbo and checked for play, there was none, 60k and it feels fine.

Image

13. Once the engine is rebuilt, leave the top accoustic cover off for access to bleed screws.

14. Fill and bleed the coolant system as BMW advise below.

M47TU:
Note:
When adding coolant, it is absolutely essential to adhere to the following sequence:
1) Remove cap from expansion tank (ET)
2) Open all vent plugs:
Radiator feed - ET branch piece
Coolant return pipe
EGR cooler thermostat
Heating cooler feed
3) Add coolant slowly
4) Close vent plugs on coolant return pipe and on radiator feed (ET branch piece) after coolant emerges
5) Fill ET with coolant up to edge
6) Close vent plugs on EGR cooler thermostat and on heating cooler feed (no emergence of coolant during filling procedure)
7) Start engine (idling), set heater to maximum and fan to low stage (if necessary, top up coolant to max. fill level)
8] Close ET cap, press accelerator pedal several times up to approx. 2500 rpm
9) Remove ET cap and if necessary top up coolant to max. cold fill level
10) Run engine at idle for approx. 5 minutes with open ET (until bubble-free coolant can be seen to emerge in ET); if required, top up coolant to max. cold fill level
11) Close ET cap

Took it out for a run and checked the coolant temp after a few miles.

Image

It wasn't going past 85 previously, so hopefully that will be the fault fixed. I'll report back with an update to fuel consunption. Also, for a laugh, I'm going to phone BMW for a quote to do the above work. Place your bets now please!
Last edited by rob-the-viking on Tue Jan 31, 2012 10:50 pm, edited 1 time in total.

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Re: 118d main Thermostat and EGR thermostat change.

Post by marco_polo » Mon Jan 23, 2012 3:18 pm

Thanks for the write up Rob; a nice, thorough job.

You've reminded me to check my coolant temp too.
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Re: 118d main Thermostat and EGR thermostat change.

Post by rob-the-viking » Mon Jan 23, 2012 6:08 pm

My pleasure mate.

Incidently i phoned BMW.....

To supply and fit both stats, (£70 in parts and £15 in coolant) how much do you think?




Are you sitting down?





£517:50 !!!!!!!!!!



Yes you read that right! Hopefully this thread can save a few folk some cash.

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Re: 118d main Thermostat and EGR thermostat change.

Post by matt_long247 » Mon Jan 23, 2012 6:21 pm

Brilliant write up. Mines been abit poor on fuel since I've had it. Will have to check this next time I go out. Cheers!
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Re: 118d main Thermostat and EGR thermostat change.

Post by rob-the-viking » Mon Jan 23, 2012 6:41 pm

The procedure i linked to is a little complicated to access the hidden OBC menus. Here's what worked for me.

Prior to attempting this you need to work out the code for your car. To do this simply add up the last 5 digits of your VIN. So if it ends in 12345 then 1+2+3+4+5 means your code is 15 and so on.

1. Insert key and start engine
2. Press and hold trip reset button in the corner of the dash for 10 seconds. Ignore the warnings that pop up.
3. You should be greeted by the last 7 of the cars vin on the dash
4. Press the trip reset button repeatedly to get menu 19 displayed, it should say 'lock on'

(if when you press the trip button it changes to 01.01 instead of 02.00, you will need to press and hold the trip button for 2 seconds to toggle to the L/H digits.)

5. After a couple of seconds the window will change to say code 00
6. Press the trip reset button repeatedly until your code is reached
7. After a couple more seconds it will take you back to step 01.00
8. Press the trip reset button till you reach test 07.00 which will display your coolant temp (KTMP MOM).

(after unlocking it, it might change to 01.01 instead of 02.00 again, so you may need to press and hold the trip button for 2 seconds to toggle to the L/H digits like before.)

To exit, switch off the engine. This will lock itself again though, so you need to unlock the rest of the menu steps again if you need the hidden menus.

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Re: 118d main Thermostat and EGR thermostat change.

Post by marco_polo » Mon Jan 23, 2012 11:08 pm

Ah crap, mine didn't get above 80C on my way home tonight. It is cold out though.

I'll try again tomorrow, doesn't look good though. :(
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Re: 118d main Thermostat and EGR thermostat change.

Post by rob-the-viking » Mon Jan 23, 2012 11:25 pm

How long and how enthisiastic was the drive mate? 80 is pretty low mind, is your consumption down?

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Re: 118d main Thermostat and EGR thermostat change.

Post by marco_polo » Mon Jan 23, 2012 11:34 pm

Yes, it's dropped.

I used to get 47+ in the summer, 45+ in the winter. She's down to 42 currently.

My thermostat is the same part number as yours, so it should be running around at 88ish, not 79/80.

Gonna try tomorrow. There's a steep 2 mile long hill up to Brands Hatch, I'll floor it up there, won't ever get much warmer than that.
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Re: 118d main Thermostat and EGR thermostat change.

Post by rob-the-viking » Mon Jan 23, 2012 11:40 pm

Looks like another failed stat mate. Thing is, unless you check the coolant temp often, reduced consumption is the only sign. No warning lights or fault codes anywhere. If you've never changed the EGR stat, i'd do that too, only £30 ish and you have it detached from the engine, it adds 2 minutes to the job. The clip that holds the coolant feed.onto it can be a little fiddley to reattach though!

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Re: 118d main Thermostat and EGR thermostat change.

Post by marco_polo » Tue Jan 24, 2012 2:16 pm

Got her up to 81°C, but she soon normalised to 79° again. It's not too cold out today either, about 7°.

'Stats look dead, unless it's my temp sensor! I'll start with the stats, job for Saturday.

Which coolant did you go for Rob?
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Re: 118d main Thermostat and EGR thermostat change.

Post by marco_polo » Tue Jan 24, 2012 4:48 pm

Not to worry, I've ordered both stats and 3 litres of BMW coolant from BmMiniParts. £85 delivered also. :)
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Re: 118d main Thermostat and EGR thermostat change.

Post by rob-the-viking » Tue Jan 24, 2012 6:19 pm

If the temp sensor was dead, it'd not work right up to 80 and then fail, it's be deac across the range. Sorry I didn't get back to you, had to teach today. Sure you don't want the throw £517 at the dealer and have them do it? :lol: It's easy enough to do mate, it'll take you about 2 hours i'd guess. If tyhe guide i wrote is wrong or out of sequence, please let me know!

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Re: 118d main Thermostat and EGR thermostat change.

Post by eighteentee » Thu Jan 26, 2012 3:05 pm

This is an excellent post and one I'm sure affects a lot of diesel 1-ers out there. I'm guessing this also causes the soot because of the unburnt fuel which also adds to the EGR clogging issue?
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Re: 118d main Thermostat and EGR thermostat change.

Post by marco_polo » Thu Jan 26, 2012 3:10 pm

Yes, this would quicken the build up of soot in the EGR.
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Re: 118d main Thermostat and EGR thermostat change.

Post by rob-the-viking » Thu Jan 26, 2012 6:02 pm

Economy has shot up by about 7mpg after this job, with fuel prices on the up, this is a win!

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