35d worsening gas mileage - solved- thermostat/fan/EGR cooler - DIY with pics

[ZetaTre]

Originally Posted by bawareca

I was thinking to install this bracket,but looks like after instalation the lower(intake) pipe of the EGR starts to break,with very bad effects.In more than a few cases the exhaust gasses escaping from a crack on the bottom pipe burn through the plastic T-stat housing.

What's the source? It's the first time I read this...

[bawareca]

http://www.xoutpost.com/bmw-sav-foru...el-pain-4.html
Post # 38
Plus 2 my customers and a friend in texas.

[ZetaTre]

Originally Posted by bawareca

http://www.xoutpost.com/bmw-sav-foru...el-pain-4.html
Post # 38
Plus 2 my customers and a friend in texas.

Interesting indeed... I may start hang around here a bit more... The other board has a lot more nonsense going on and I miss all these cool stories

[ZetaTre]

I gave some more thoughts about the new bracket being the reason for the rapture and I'm not entirely convinced.

There are 2 bolts that secure the cooler to the head/engine block which make it for a very rigid and solid mounting point. I can't see how the bracket mounted all the way over to the opposite side of the accordion that cracks would affect the rigidity of the accordion itself.

I do, however, have a theory on how it cracks which is improper alignment during assembly of the EGR cooler. Perhaps the cases reported (and others for that matter) had the EGR cooler cracked so as described in the bulletin, it was going to be replaced as part of the bracket installation.

The technician, for example, could have first bolted the cooler to the engine block that secured the two bolts on the flange that connect the cooler to the exhaust manifold. As a result he flange may have not been properly aligned resulting in stressed on the accordion that through the because of the heat cycles ultimately cracked.

I can't recall off the top of my head if INPA/DIS have a specific tightening sequence required, but when I reassembled my cooler after replacing the thermostat I:
1) loosely place the two bolts that attach the cooler to the engine block
2) position the flange and tight the two bolts
3) positioned the clamp over the EGR valve and secured it
4) went back and torqued the two bolts on the flange
5) torqued the two bolts that secure the cooler to the head
That came just as common sense to me since I've been wrenching for some time, but who knows if the ASE and BMW certified monkey at the dealership takes the same care...

Nonetheless, I could be entirely wrong... I'd just be very curious to understand how the bracket on the outlet side of the EGR cooler in question affects the accordion on the inlet...

[bawareca]

Originally Posted by ZetaTre

..

The cases of the accordion cracking are reported after instalation of the bracket,I didnt hear of any original EGR to crack there.The EGR is exposed to a substantial thermal and pressure loads.Especially the accordion is on the hot and pressure side of the turbo.The EGR may go thru many heat cycles while driving in city or mixed as the valve may open or close many times,with delay between the openning and closing.Plus there is a bypass channel inside the EGR which also affects the temperature of the EGR.Originally the upper flex joint is designed to take all the flex,but the recall bracket may change the point where the expansion goes.
Your theory looks plausible too.Like most things in life it could be a mix of both factors.

Good thing is that me and the Norway tuner i am working with should be ready to offer some parts of that kind,along with software correction,for EGR and headache free motoring

EGR block-off kit:

[D5diesel]

Originally Posted by sgrice

I have a 2010 e70 35d with about 79,000 miles. Over the past 6 months or so I've noticed a drop in highway mpg from 31-32 to approx 25-26. After checking out a number of forum discussions (particularly bimmerfest and some European 335d forums), I thought possibly my thermostat was malfunctioning, with resultant low engine temps. Apparently, a low engine temperature can cause a number of issues - poor engine efficiency, plus some say the glow plugs stay on for temps <75 deg cent (may cause eventual early demise of glow plugs), and numerous people say the diesel particulate filter (DPF) regeneration mode requires a temp of 75-80 deg cent. So a low engine temperature for the diesels may cause poor mpg, burn out of glow plugs, and DPF malfunction.

This link on bimmerfest gives an excellent overview of the issue. As said by lpcapital in post #5:

"While on a gasoline car if the engine temperature is a 10 or so degrees lower than optimal nothing major happens, the same is not true with our cars where the regeneration of the DPF occurs only if the coolant temperature is at a particular level, which appears to be 75C. There are plenty of reports of aged thermostats that keep the engine in the low 70s when cruising on freeways. Since the coolant temperature is below the threshold, the DPF doesn't regenerate, it clogs and people lose their mind figuring out what's wrong and start spending thousands to replace DPF and adding washes, remove the DPF all together."

So I utilized the "hidden menu" as discussed in post #17 of the above link to check my operating temp. My temp (like many in other forum postings) was 72-73, and never over 75. BTW, post #17 talks about accessing the hidden menu with the ignition on, but engine off. If you do this, there is obviously no way to monitor coolant temperature while driving. No worries, though, you can access the hidden menu in the same way, but with the engine running. So start the car, idle in the driveway, and have a button pushing frenzy as described in post #17.

The forums I've read express some uncertainty about what the operating temp is supposed to be, but (spoiler alert!) after getting to my thermostat it turns out that "88C" is clearly printed on the thermostat:



And after I replaced the thermostat, my new operating temp was 85-86 deg, and mpg was back to 31-32 on the highway. So I'm pretty pleased. Here is a DIY for this job.

To begin with, you'll need the usual assortment of sockets, including torx sockets, e-torx sockets, and socket extensions (it will be critical to have a roughly 7-8 inch reach from tip of a t-45 socket to end of socket extension(s) to get to the exhaust gas recirculator (EGR) cooler flange bolts). A mirror was a huge help in seeing back into the "guts" of the engine/EGR cooler interface. In addition, I highly recommend a "tight reach ratchet" to get to many of the bolts in tight spaces. Here's a picture of the tight reach getting to a difficult to access clamp bolt - as viewed from the top:



And here's a view of it down in the deep:


There are a lot of connections, so I used bits of blue painter's tape as tags to mark every hose/electrical connector I took apart - that way I made sure I didn't forget to hook something back up. A very short (!) summary of the process is in post #15 of the above bimmerfest link. Understand that you'll need to remove the air ducts (both pre and post MAF), remove the engine cross bar, disconnect coolant hoses, remove the fan/fan shroud, remove EGR cooler (IMO this is the tough part), and now you've got access to the thermostat. It took me a little over 6 hours, though I was moving slowly so as not to make a mistake. Some more details:

Start by removing the engine cross bar, and then disconnect the cable (?others have said this is hood release cable, but I don't know for sure?) that is attached to it. There is an electrical connection bracket attached to the cross bar - this needs to come off too.

The bottom plastic skid plate needs to come off, otherwise the drained radiator fluid will splash (more) and make an even bigger mess.

Next, begin draining most of the radiator. I couldn't find a drain bolt for the radiator, and ended up disconnecting various hoses at various times. I had a scavenger bucket, but (as noted above) still probably 25% went on the floor. Have a bunch of towels around to clean up the mess.

Removing air ducts pre and post MAF - use this Realoem link to see what I'm talking about. You'll want the tight reach ratchet to get to some of these duct clamp bolts. The intake muffler (#1 in this link) is removed by giving a good upward tug on the "legs."

Remove fan/shroud: Remove the electrical connection on passenger side. Also remove the bracket (torx bolt) that holds the air hose coming from the intercooler to the throttle/EGR valve on the driver's side (the air hose I'm talking about is part #12 in this link). Also disconnect this air hose (and it's electrical connection) from the throttle body so it can be pushed out of the way so the fan/shroud can come out. Also remove the main coolant hose that enters the top of the radiator on the driver's side (part #1 in this link). Now you should be able to lift the fan/shroud out without obstructions. There are two flanges (one on driver's side and one on passenger side) about six to eight inches down on either side that slide into slots to keep the fan and shroud in position. Use a screwdriver to press the flange in, and then you can lift the fan/shroud up a couple of inches. Once it's been lifted a few inches, be aware that the flange on the driver's side is hinged, and needs to be flipped inward (photos below will hopefully make this clear) to clear obstructions and allow the fan to be lifted out. Here is an overview pic of the fan/shroud with an arrow pointing to the "flippable flange" -



Here is another up close pic - the "flippable flange" (red arrow) has now been flipped open. The yellow arrow shows the slot mechanism that helps keep the bracket for the charge air hose leading to the throttle (noted above) in position.



Removal of the EGR cooler. The EGR cooler sits above the thermostat. The EGR cooler can be seen in this RealOEM link - it is what hoses 6 and 7 connect to. For another view, it is the big shiny rectangular metal object in the center of this pic:



Undo the various electrical connections, the radiator hoses (6 and 7 as noted in the RealOEM link above), and the circumferential clamp (red arrow in photo above) that connects the cooler to the EGR valve. There was another connection (yellow arrow) that leads to a particularly difficult (for me, at least) electrical connection on the EGR valve. This electrical connection is shown in the next photo:



I expected this electrical connection to easily come apart when the white tab was snapped back. However, I couldn't get it to come apart. Eventually, I was able to get it apart by slipping a very small flat screwdriver blade between the two connection parts as shown in the photo above. Then it disconnected easily. Not sure if I was doing something wrong, but I couldn't get it apart any other way (edit point: be aware the photo above was taken after completion of this job in order to document this (for me) difficult electrical connection. When I was actually doing the job the black plastic "leg" of the intake muffler that is obscuring the view of the screwdriver in the photo had been removed).

Disregarding electrical/vacuum connections, the EGR cooler is held in place by a total of five connection points - the circumferential clamp discussed above, two mounting bolts (easy to see), and by two flange bolts that are hidden underneath (and to the side of) the vacuum pump. The vacuum pump is the large silver circular object sitting above the EGR cooler in the photo above. The two EGR cooler flange bolts were/are the tough part, IMO. I could barely see the top flange bolt by peering in between various vacuum hoses and electrical cables. The only way I could see the bottom flange bolt was with a mirror. The flange bolts are T45. You'll need an extension set that measures roughly 7-8 inches from the tip of the torx socket to the end of the extension set. I could see enough to get the socket into the top bolt, but had to use a mirror and "memory braille" to get into the bottom bolt. Here is an overview picture of the socket/extension/wrench on one of the bolts:




And here is a picture taken that (I hope) demonstrates using the mirror to confirm visualization of the proper placement of the socket on the top flange bolt.


The camera is pointed toward the front of the car, so the reflection in the mirror is toward the rear of the car. The red arrow shows the socket in place on the top flange bolt.

I undid the flange bolts first, then the mounting bolts. The flange bolts stayed in place on the flange as the EGR cooler was removed. I was terribly afraid that once loosened I would drop the flange bolts deep into the engine compartment - never to be found again. So I stuffed a rag under the flange area (poked it into position with a screwdriver) so that if they fell they would be saved by the rag rather than drop down into the abyss.

At this point, I was able to easily lift the EGR cooler out of the way and place it on top of the engine. With the EGR cooler out of the way, the thermostat replacement was straightforward - 2 hoses and 4 bolts (though the rigid water pipe on the driver's side of the thermostat [part #1 on this link from RealOEM] has a positioning bolt (I think it's part #3 from the prior link) that needed to be removed to allow thermostat removal). Here is a picture with the thermostat out and the EGR cooler sitting on top of the engine:



The single red arrow shows where the thermostat was removed. The double red arrows point to the mounting bolts on the EGR cooler. The EGR flange that accepts the bolts I discussed at length above is shown by the yellow arrow. The green arrow leads to the difficult electrical connection I talked about earlier.

Putting back together was not too bad, with a couple of caveats.
1) A lot of connections. Again, I recommend tagging things with tape so you make sure you don't miss something.
2) The EGR cooler flange bolts (again!). You can't reach the flange with your fingers to start the bolts. The bolts have to be attached to the 7-8 inch extension and then carefully (memory braille on the bottom bolt, again) put into position. I didn't want to drop the bolts, so had a cloth in position under the flange to catch a potentially dropped bolt. In addition, I stuck some blue painter's tape on the end of the T45 socket (adhesive toward the socket) and then pressed the bolt onto the socket. The tape gave enough friction so that the bolt was held on quite securely. Here is a pic of what I'm talking about - here I have an e-torx socket attached to the torx socket instead of the bolt, but hopefully you understand:


The EGR cooler flange bolts are not magnetic, so a magnet would be no help in retrieving a dropped bolt.
3)When you put the fan/shroud back in place, be aware there are tabs at the bottom of the shroud that fit into slots near the bottom of the radiator. So (not counting the charge air hose bracket) the fan/shroud has a total of 6 connection points - 2 slots/tabs on the bottom, 2 flaps that clip in on the sides (driver's side has the "flippable flap"mentioned above), and 2 smaller slots/tabs on the top).

As I said, it took me about 6-7 hours, but I was going really slowly. Overall difficulty - I'd rate it as about a 6 on 1-10 scale.

Even though the ultimate goal is a thermostat change, the difficult parts were getting the fan/shroud out, and the EGR cooler out.

As I said, my mileage has improved, and hopefully I've saved my glow plugs and DPF!

Hope the above is helpful.

Stephen
1998 ML 320 - now driven by son #1
2005 e53 3.0 - now driven by son #2
2008 ML320 CDI - now driven by wife
2010 e70 35d - now driven by me

This is all great information, but I think this should have been followed by real readings using a dedicated BMW obdii reader,. What it is the temperature you are getting now for colant? What about the temperature of the coolant in the egr? How has the mileage improved if any?

In addition where is the sensor located that measures the coolant temperature? If it is on the other side of the line it may not confirm that the thermostat is bad.

[bawareca]

Originally Posted by D5diesel

This is all great information, but I think this should have been followed by real readings using a dedicated BMW obdii reader,. What it is the temperature you are getting now for colant? What about the temperature of the coolant in the egr? How has the mileage improved if any?

In addition where is the sensor located that measures the coolant temperature? If it is on the other side of the line it may not confirm that the thermostat is bad.

That was a looooong quote
There is a temperature sensor on the head and on the radiator outlet,standart for modern BMWs.Both values are under different names in the actual values menu,so it is not easy to mismatch them.

[sgrice]

D5diesel - I don't have a dedicated BMW obd reader. I was using the "hidden menu" as described/referred to in my original post. For simplicity, you can see a PDF describing the hidden menu by copying and pasting the following link into your browser address (for some reason I can't make the link shortcut work for this):

http://www.scoopz.com/m5board/E60_Hi...structions.pdf

A link to a similar Bimmerfest posting is here (the PDF is from post #17):

X5 35d engine temperature - Bimmerfest - BMW Forums

The link says it is for an e60, but it works the same on my e70. As I mentioned in my original post, the pdf describes accessing the menu with the ignition on, but engine off. If one does this, though, one does not obtain information while the engine is operating (obviously). No problem, though, just access the menu the same way but with the engine on. To be specific, I monitored coolant temperature on menu 07.00 - as seen on page 12 of the PDF.

So my temps (from menu 07.00) went from 72-73 degrees Centigrade with highway mpg of 25-26 pre-repair, to temps of 84-85 Centigrade with highway mpg of 31-32 after the repair. This is with fairly cold temps in Atlanta recently (ambient temps 20-40 degrees Fahrenheit).

I don't know specifically where the sensor is located that gives the menu 07.00 temperature. I also don't know if there is a sensor that specifically gives EGR coolant temperature. Certainly I couldn't find such a temp in the PDF document noted above.

Hope the info above is helpful.

[blue dragon]

Subscribed....

[ZetaTre]

Originally Posted by sgrice

I don't know specifically where the sensor is located that gives the menu 07.00 temperature. I also don't know if there is a sensor that specifically gives EGR coolant temperature. Certainly I couldn't find such a temp in the PDF document noted above.

The coolant temperature sensor is mounted on the intake side of the cylinder head. The coolant in the M57 flows through the thermostat to the exhaust side, over to the intake side and then out. The temperature shown in the hidden menue is from that sensor.

There is no EGR coolant temperature. There is however a sensor for the exhaust fumes after the high pressure EGR cooler. Our HP EGR has basically 2 tracks: part of the fumes always get cooled and part of the fumes go straight through. The DDE achieved the desired temperature by activating a valve that mixes the two in different ratios. I'm under the impression that there no such thing with the LP EGR since it's only activated once coolant temperature is above a certain temperature.

I believe the bypass in the HP EGR is there not so much to regulate temperature under regular driving condition but to facilitate warmup.

You can read more here, if interested: https://drive.google.com/file/d/0B1e...ew?usp=sharing