[TDIwyse]

335DEE, when you were replacing your multiple EGR cooler failures, and when you tried to bypass the EGR cooler, how carefull were you in bleeding air out of the coolant system? The symptoms you describe with the coolant temp swings sound like a classic "air in coolant system" issue that could result from air entering the system when the coolant path was opened to remove/replace/bypass the EGR cooler.

Just one of many examples of the symptoms:

http://www.autotraderclassics.com/ca...l!-81952.xhtml

"The hallmark of an air bound cooling system is a temperature gauge reading that swings from hotter than normal to colder than normal while the engine is running. This can happen over a matter of time as little as 30 seconds to as long as a few minutes. The system is usually greeted with a like swing in heater output, from very hot to very cold."

As I look at the coolant setup on this car versus the systems on the US trucks, where EGR cooler removal is common, I'm not seeing how a properly bleed system should produce this problem when the EGR cooler is removed.

Also, regarding the theory on cracking EGR coolers due to heat on the exhaust side and the EGR valve being closed ... Under full fueling conditions the EGR valve is closed by the DDE, so heat build up at the exhaust side should be the same, and since the EGR is closed, there will be minimal heat gradient across the EGR. After full fueling is over, and the EGR opens to allow some exhaust to flow into the intake, the temperature gradient across the EGR cooler will then become greater because there will now be lower temp at the intake side, but the exhaust side should be essentially the same temp whether or not the EGR is open (since it's right by the exhaust side, it will see similar temps to whatever the exhaust is producing).

I'm wondering how many of the cracked EGR coolers where a result of air in the coolant system versus the EGR closed coding? Just wondering, as I've been running at ~400 hp level (based on 1/4 mile trap speeds and times) for quite some time without any EGR cooler issues. But I am using H2O injection to control EGT's that might be lower than what these "stage 2" systems produce? Just curious, what are your EGT's at max fueling conditions?

[dixy2k]

Originally Posted by TDIwyse

Under full fueling conditions the EGR valve is closed by the DDE, so heat build up at the exhaust side should be the same, and since the EGR is closed, there will be minimal heat gradient across the EGR. After full fueling is over, and the EGR opens to allow some exhaust to flow into the intake, the temperature gradient across the EGR cooler will then become greater because there will now be lower temp at the intake side, but the exhaust side should be essentially the same temp whether or not the EGR is open (since it's right by the exhaust side, it will see similar temps to whatever the exhaust is producing).

I raised this issue a few threads back, but I think I also answered in the same post.

It is possible to have an intact cooler due to the brief period of time while the engine is under WOT vs driving it all the time with the EGR valve closed and the EGR cooler functioning normally.

I think the repeated heating-cooling effect on the cooler puts a lot of stress on it and over time it develops cracks.

[dixy2k]

I tend to agree with your theory in the case of complete EGR cooler removal. Without any further knowledge of the cooling system in this car I just don't see how the simple removal of the EGR cooler could produce wild swings in the cooling system temperature.

[F32Fleet]

Originally Posted by TDIwyse

335DEE, when you were replacing your multiple EGR cooler failures, and when you tried to bypass the EGR cooler, how carefull were you in bleeding air out of the coolant system? The symptoms you describe with the coolant temp swings sound like a classic "air in coolant system" issue that could result from air entering the system when the coolant path was opened to remove/replace/bypass the EGR cooler.

Just one of many examples of the symptoms:

http://www.autotraderclassics.com/ca...l!-81952.xhtml

"The hallmark of an air bound cooling system is a temperature gauge reading that swings from hotter than normal to colder than normal while the engine is running. This can happen over a matter of time as little as 30 seconds to as long as a few minutes. The system is usually greeted with a like swing in heater output, from very hot to very cold."

As I look at the coolant setup on this car versus the systems on the US trucks, where EGR cooler removal is common, I'm not seeing how a properly bleed system should produce this problem when the EGR cooler is removed.

Also, regarding the theory on cracking EGR coolers due to heat on the exhaust side and the EGR valve being closed ... Under full fueling conditions the EGR valve is closed by the DDE, so heat build up at the exhaust side should be the same, and since the EGR is closed, there will be minimal heat gradient across the EGR. After full fueling is over, and the EGR opens to allow some exhaust to flow into the intake, the temperature gradient across the EGR cooler will then become greater because there will now be lower temp at the intake side, but the exhaust side should be essentially the same temp whether or not the EGR is open (since it's right by the exhaust side, it will see similar temps to whatever the exhaust is producing).

I'm wondering how many of the cracked EGR coolers where a result of air in the coolant system versus the EGR closed coding? Just wondering, as I've been running at ~400 hp level (based on 1/4 mile trap speeds and times) for quite some time without any EGR cooler issues. But I am using H2O injection to control EGT's that might be lower than what these "stage 2" systems produce? Just curious, what are your EGT's at max fueling conditions?

Correctly if I'm wrong but fuel fueling scenarios are few and far between. Do we know that the temps on the exhaust side of the cooler are the same regardless of whether the EGR is open/closed? I would think with EGR open some heat is being drawn to the intake side.

[TDIwyse]

Originally Posted by Socom

Correctly if I'm wrong but fuel fueling scenarios are few and far between. Do we know that the temps on the exhaust side of the cooler are the same regardless of whether the EGR is open/closed? I would think with EGR open some heat is being drawn to the intake side.

Unless you're on a track and/or towing something, full fueling scenarios will quickly lead to a revoked license...

Guess my question/thought was that regardless of the EGR valve being open or closed, the exhaust side temp will be basically the same as its physically near the extreme EGT's pre-turbo. Even when the EGR opens again after full fueling and a small (relative to the total air being pumped by the engine) amount of exhaust flows through the EGR path to the inlet (you now have a bigger temperature gradient across the valve compared to a lower temp gradient when the valve was closed) but the hot side should still be nearly as hot due to the heat retention in the exhaust/turbo area. Or at least that's what seems to make sense to me? However, I have no quantifiable measured data on this one way or the other...

Either way, since there's lots of posts about stock cars cracking their EGR coolers, it appears to be a marginal design at best. And running higher EGT's due to burning more fuel for more power would definitely make this situation worse. I'm just not sure I follow the theory for why leaving the EGR on would help?

[F32Fleet]

Originally Posted by TDIwyse

Unless you're on a track and/or towing something, full fueling scenarios will quickly lead to a revoked license...

Guess my question/thought was that regardless of the EGR valve being open or closed, the exhaust side temp will be basically the same as its physically near the extreme EGT's pre-turbo. Even when the EGR opens again after full fueling and a small (relative to the total air being pumped by the engine) amount of exhaust flows through the EGR path to the inlet (you now have a bigger temperature gradient across the valve compared to a lower temp gradient when the valve was closed) but the hot side should still be nearly as hot due to the heat retention in the exhaust/turbo area. Or at least that's what seems to make sense to me? However, I have no quantifiable measured data on this one way or the other...

Either way, since there's lots of posts about stock cars cracking their EGR coolers, it appears to be a marginal design at best. And running higher EGT's due to burning more fuel for more power would definitely make this situation worse. I'm just not sure I follow the theory for why leaving the EGR on would help?

Gotcha and did u say your 35d was running 400hp ?

[TDIwyse]

Originally Posted by Socom

Gotcha and did u say your 35d was running 400hp ?

Well, hitting a trap speed of 110 mph and ET's of 12.6 on the dragstrip, based on vehicle weight, puts it in that range.

The 12.65 was documented here (also has a link to youtube video of a previous run with a 109.7 mph and 12.6'ish run)

http://www.dragtimes.com/BMW--335d-Drag-Racing.html

Got a 110.18 trap speed from this Fall. Wasn't pushing the launch very hard, just wanted to measure the top end due a new mod. I'll see if I can find that slip.

[TDIwyse]

Found it.

[Mproved]

This makes me question the reliability of these cars at stage 2 levels...hit or miss?

[Hoooper]

reliability is going to take a hit when you start to really apply the juice. Considering the reliability is already a bit spotty and can depend on your luck, id say its not the pinnacle of modded reliability but still not a DSM. Aside from cracked EGR coolers nothing else has really shown up in any significant amount.

[335DEE]

Originally Posted by TDIwyse

335DEE, when you were replacing your multiple EGR cooler failures, and when you tried to bypass the EGR cooler, how carefull were you in bleeding air out of the coolant system? The symptoms you describe with the coolant temp swings sound like a classic "air in coolant system" issue that could result from air entering the system when the coolant path was opened to remove/replace/bypass the EGR cooler.

Bleeding these systems is a tricky job and takes a lot of time. It's not just a case of dumping water in and opening bleed screws. There is a set procedure to follow.

If you are going for removal of egr cooler, I'll be following your progress.
Both my main stat and egr stat were brand new when I made my attempt so I can rule out the weakened stats. On the flip side I can't rule out a sticking egr stat although new it's long been a suspicion that it is stuck closed. Never tested though.

Originally Posted by TDIwyse

Just curious, what are your EGT's at max fueling conditions?

Unfortunately I cannot read my egr. I asked you about this in a previous thread ages ago in a different thread. I don't have the option in my Inpa and it's not available in my 'torque' app. I think I put it down to having an early 2006 model with the older style k - line protocol system. Unless there are the specific PID's I can enter into torque, that's not going to happen for me.

[335DEE]

Originally Posted by dixy2k

I tend to agree with your theory in the case of complete EGR cooler removal. Without any further knowledge of the cooling system in this car I just don't see how the simple removal of the EGR cooler could produce wild swings in the cooling system temperature.

The US version of the 335d has a more advanced EGR cooling system.The X5 35d is different again !.
The euro version just has a mechanical thermostat to control the flow of coolant. The US version has an electronic temperature control with positional feedback off the actuator so it can give more precise control. Good if you leave it to do it's job , not so good if you want to interfere with it!

I have a document that explains the US version of the 335d , you guys probably already have it , but it's an interesting read. Shame it doesn't compare the euro version with what the US has --> http://goo.gl/G00PNe

I have access to temperature data logging equipment and have considered thermal mapping the EGR system , whats stopped me is how to actually physically attach the sensors to various parts of the EGR , obviously you cant just zip tie sensors to the outside of the system. A) the ties would melt in about 3 seconds and b) it's getting good thermal contact between the sensor and the metal casing in the first instance. C) Getting a correlation between throttle position/RPM and the temperature data recorded. Not a massive issue but another stumbling block.

[TDIwyse]

Originally Posted by 335DEE

Bleeding these systems is a tricky job and takes a lot of time. It's not just a case of dumping water in and opening bleed screws. There is a set procedure to follow.

Thanks for that insight. Do you have a link to what that procedure is? I have a faint memory of it involving needing to turn on the electric water pump with the engine off for one of the multiple steps?

Originally Posted by 335DEE

If you are going for removal of egr cooler, I'll be following your progress.
Both my main stat and egr stat were brand new when I made my attempt so I can rule out the weakened stats. On the flip side I can't rule out a sticking egr stat although new it's long been a suspicion that it is stuck closed. Never tested though.

At this point I'm a bit gun shy as my car has been down for quite some time (~3 wks due to shipping my DPF overseas, and now my accelerator pedal issue) and just want to be able to drive it... But I'll definitely post anything related to this if/when I try it.

Originally Posted by 335DEE

Unfortunately I cannot read my egr. I asked you about this in a previous thread ages ago in a different thread. I don't have the option in my Inpa and it's not available in my 'torque' app. I think I put it down to having an early 2006 model with the older style k - line protocol system. Unless there are the specific PID's I can enter into torque, that's not going to happen for me.

That's unfortunate. Having access to the EGT's would be helpful in knowing how much thermal stress the cooler is being subject too. You could always drill and tap an aftermarket EGT probe in there somewhere and add a gauge in the cockpit?

[335DEE]

Originally Posted by TDIwyse

That's unfortunate. Having access to the EGT's would be helpful in knowing how much thermal stress the cooler is being subject too. You could always drill and tap an aftermarket EGT probe in there somewhere and add a gauge in the cockpit?

The procedure I was told was from a BMW mech, i'll see if he can get one down on paper.

As far as drilling holes and adding 3rd part dials ...

I hate my car right now !
I've replaced gearbox , turbo's all associated pipework and actuators, pretty much the complete vacuum control system , seals ,pipes , controllers, thermostats , sensors the lot as well as the run of the mill stuff .. tyres brakes oil etc . I have spent a small fortune on this car to keep it on the road. When the DPF failed, having it mapped and DPF bypass fitted was the cheapest option ( apart from fitting a s/h DPF with no guarantees). Now with all the unforeseen issues with cracked EGR coolers ( purchase of and time fitting ) , the final straw for me and this car was the hydro locking and bending of a con rod when the last but 1 EGR failed in spectacular fashion.

As it happens and it's quite important to note , the hydrolock occurred not when driving ( boost and coolant pressure would counteract each other ) but when the car was turned off and the coolant still under pressure seeping out over a period of time which then pooled. Starting the car with this amount of fluid in the system must have somehow found it's way into the inlet. ( bearing in mind that the compression is that high you'd only need a thimble full of water to do the damage)

Sadly my wallet cannot take any more shit. I'm still driving it with it's bent rod as a form of punishment for causing me so much grief... and it's already paid me back for doing that , reckon the master cylinder seals have gone as the pedals gone all spongy and can push the pedal to the floor if I hold it under pressure for long enough.. not a vacuum problem because it's all been replaced.

When I have the cash to fix it the con rod .. it's getting repaired then chopped in for something else. I love the 35d there isn't a car on the market that can give impressive power, torque and MPG in the same sentence but it's like having a high maintenance trophy wife. It feels great when your out and about, but the behind the scenes wallet raping just isn't worth the grief.

[335dFan]

Originally Posted by 335DEE

I love the 35d there isn't a car on the market that can give impressive power, torque and MPG in the same sentence but it's like having a high maintenance trophy wife. It feels great when your out and about, but the behind the scenes wallet raping just isn't worth the grief.

Hahahaha! This is a great analogy! So great I had to share it with my wife.

[TDIwyse]

Ouch. Sounds like a mess. If I lived close by I'd buy you a beer ... or 10.

[335DEE]

Originally Posted by TDIwyse

Ouch. Sounds like a mess. If I lived close by I'd buy you a beer ... or 10.

Haha .. i'd need a few .. that's for sure.

The car has definitely got a personality and it's definitely a woman . I constantly lavish all these new parts on it. Then it goes on it's monthly cycle , goes all moody and demands more cash is spent....

I've initiated divorce proceedings !!

[TDIwyse]

Originally Posted by 335DEE

...
If you are going for removal of egr cooler, I'll be following your progress.
Both my main stat and egr stat were brand new when I made my attempt so I can rule out the weakened stats. On the flip side I can't rule out a sticking egr stat although new it's long been a suspicion that it is stuck closed. Never tested though.
...

Just reporting back on this. I've got a little over 100 miles on the EGR cooler delete and not seeing any weird coolant behavior. Here's a log of this morning's run for a ~41 mile mostly interstate run. Perhaps the US version with its different setup allows the bypass to work where the euro version doesn't?

[335DEE]

Originally Posted by TDIwyse

Just reporting back on this. I've got a little over 100 miles on the EGR cooler delete and not seeing any weird coolant behavior. Here's a log of this morning's run for a ~41 mile mostly interstate run. Perhaps the US version with its different setup allows the bypass to work where the euro version doesn't?

Interesting!

Do you have any photos of the engine after you have done the work?

[TDIwyse]

Originally Posted by 335DEE

Interesting!

Do you have any photos of the engine after you have done the work?

There's a lot of info in the DPF Delete thread: http://www.e90post.com/forums/showthread.php?t=904968

The last several pages has pictures and more details.