28A0 Code Diagnostic... Wastegate Reservoir

bmdubya1198 · 07-15-2021, 10:40 PM

I'm working on diagnosing my cousin's X5 35i 28A0 code, and I read in this BMW TIS article that I can apply vacuum to the wastegate actuator vacuum reservoir to test for leak down. When I do this, it seems to leak down fairly quickly. I pumped it up to about 5-6 in-hg, then it took probably 3-5 seconds to leak back down to zero.
When I did this, I had just smoke tested the intake tract for vacuum leaks, so it was still holding smoke at this point. Before connecting the hose from my vacuum hand pump, there was NO smoke coming from the vacuum port. When I pumped, it was pulling smoke through there. I'm assuming this is a diaphragm, and it's to be expected? Or is there a small crack that it's pulling from, which would be causing the fast leak down?

According to the owner (who has had it for about 3-4 weeks now) the previous owner changed the valve cover in October of last year. It's an aftermarket one so I know it's likely to be the culprit here. Otherwise, I can't find any other issues. No other vacuum leaks, and the PCV/CCV did NOT suck in any smoke when I tested that.

Can anybody confirm the behavior of these wastegate reservoirs?

TunafishE93 · 07-15-2021, 10:59 PM

The reservoir should hold vacuum. Are you testing one valve cover vacuum port and blocking the other? The other needs to be blocked for the test.

bmdubya1198 · 07-16-2021, 09:58 AM

Quote:

Originally Posted by TunafishE93

The reservoir should hold vacuum. Are you testing one valve cover vacuum port and blocking the other? The other needs to be blocked for the test.

Ah, that's what I didn't do. I'll check it again later with the other port plugged.

bmdubya1198 · 07-17-2021, 12:14 AM

I plugged off the other port earlier and tested it, and while it leaked down slower, but it still leaked down. I also noticed it was pulling oil through when I pumped the vacuum pump. I have a feeling this isn’t exactly how it was designed... am I wrong?
Interestingly enough, the car isn’t down on power from what I can feel. It’s super sluggish to get going from a stop, but from what I can tell that’s normal and software-related. My E90 was similar.

bmdubya1198 · 07-19-2021, 12:21 AM

Anybody?

drwillb · 07-19-2021, 10:25 AM

Sounds like you need a new valve cover. Oil is getting sucked up into the built in/integral vacuum galleys of the cover.

bmdubya1198 · 07-19-2021, 10:41 AM

Quote:

Originally Posted by drwillb

Sounds like you need a new valve cover. Oil is getting sucked up into the built in/integral vacuum galleys of the cover.

That's what I was thinking. So I'd be correct in thinking that these vacuum chambers are supposed to be separate from the inside of the valve cover? They're closed off and should NOT have contact with oil?

wheela · 07-19-2021, 11:38 AM

Quote:

Originally Posted by bmdubya1198

That's what I was thinking. So I'd be correct in thinking that these vacuum chambers are supposed to be separate from the inside of the valve cover? They're closed off and should NOT have contact with oil?

That's correct, there shouldn't be any oil in the vacuum chamber on the valve cover. In addition to sucking oil in through that crack, that is also going to be a source of the vacuum leak. So unless there are additional leaks somewhere else, I think you found the cause of your vacuum leak

TheGoodTheBadTheUgly · 07-19-2021, 12:41 PM

Yes the chambers should be separate because the introduction of oil would mean that the boost solenoid won't be able to reach and pull the specific vacuum wanted which will affect how much the wastegate will close.

bmdubya1198 · 07-19-2021, 12:50 PM

Okay, that confirms my suspicions! Thanks guys!

I'll let him know he needs a valve cover. That would be the leak, since I can't find any other leaks.

drwillb · 07-19-2021, 05:12 PM

Quote:

Originally Posted by bmdubya1198

Okay, that confirms my suspicions! Thanks guys!

I'll let him know he needs a valve cover. That would be the leak, since I can't find any other leaks.

I’d replace the boost solenoid as well. It’s probably got a fair amount of oil in it.

bmdubya1198 · 07-20-2021, 12:21 AM

Quote:

Originally Posted by drwillb

I’d replace the boost solenoid as well. It’s probably got a fair amount of oil in it.

I’ll add that to the list!

Nitolin79 · 06-22-2023, 08:42 PM

Quote:

Originally Posted by bmdubya1198

That's what I was thinking. So I'd be correct in thinking that these vacuum chambers are supposed to be separate from the inside of the valve cover? They're closed off and should NOT have contact with oil?

I have a question I have the same issue and I was reading your post about the oil coming out from those nipples from the wastegate reseivor , is this normal ? Or we shouldn’t have oil in it pictures here

Nitolin79 · 06-22-2023, 08:43 PM

How do I upload pictures ?

bmdubya1198 · 06-23-2023, 09:42 AM

Quote:

Originally Posted by Nitolin79

I have a question I have the same issue and I was reading your post about the oil coming out from those nipples from the wastegate reseivor , is this normal ? Or we shouldn’t have oil in it pictures here

There should NOT be oil coming from the wastegate reservoir. It is supposed to be closed off from the inside of the valve cover.

To upload pictures, scroll down on the posting page and select "manage attachments".

07-15-2021, 10:40 PM	#1
bmdubya1198 Private First Class 38 Rep 180 Posts Drives: E39/E46/E53/E30... Join Date: Apr 2020 Location: Charlotte, NC iTrader: (0)	28A0 Code Diagnostic... Wastegate Reservoir I'm working on diagnosing my cousin's X5 35i 28A0 code, and I read in this BMW TIS article that I can apply vacuum to the wastegate actuator vacuum reservoir to test for leak down. When I do this, it seems to leak down fairly quickly. I pumped it up to about 5-6 in-hg, then it took probably 3-5 seconds to leak back down to zero. When I did this, I had just smoke tested the intake tract for vacuum leaks, so it was still holding smoke at this point. Before connecting the hose from my vacuum hand pump, there was NO smoke coming from the vacuum port. When I pumped, it was pulling smoke through there. I'm assuming this is a diaphragm, and it's to be expected? Or is there a small crack that it's pulling from, which would be causing the fast leak down? According to the owner (who has had it for about 3-4 weeks now) the previous owner changed the valve cover in October of last year. It's an aftermarket one so I know it's likely to be the culprit here. Otherwise, I can't find any other issues. No other vacuum leaks, and the PCV/CCV did NOT suck in any smoke when I tested that. Can anybody confirm the behavior of these wastegate reservoirs? __________________ 1999 528iT 2003 X5 3.0i 2001 330Ci 5MT 2007 335i/6 (brother's) 2006 330i (sold)
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07-15-2021, 10:59 PM	#2
TunafishE93 Major 418 Rep 1,152 Posts Drives: BMW 335i Join Date: Dec 2019 Location: NV iTrader: (0)	The reservoir should hold vacuum. Are you testing one valve cover vacuum port and blocking the other? The other needs to be blocked for the test.
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07-17-2021, 12:14 AM	#4
bmdubya1198 Private First Class 38 Rep 180 Posts Drives: E39/E46/E53/E30... Join Date: Apr 2020 Location: Charlotte, NC iTrader: (0)	I plugged off the other port earlier and tested it, and while it leaked down slower, but it still leaked down. I also noticed it was pulling oil through when I pumped the vacuum pump. I have a feeling this isn’t exactly how it was designed... am I wrong? Interestingly enough, the car isn’t down on power from what I can feel. It’s super sluggish to get going from a stop, but from what I can tell that’s normal and software-related. My E90 was similar. __________________ 1999 528iT 2003 X5 3.0i 2001 330Ci 5MT 2007 335i/6 (brother's) 2006 330i (sold)
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07-19-2021, 12:21 AM	#5
bmdubya1198 Private First Class 38 Rep 180 Posts Drives: E39/E46/E53/E30... Join Date: Apr 2020 Location: Charlotte, NC iTrader: (0)	Anybody? __________________ 1999 528iT 2003 X5 3.0i 2001 330Ci 5MT 2007 335i/6 (brother's) 2006 330i (sold)
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07-19-2021, 10:25 AM	#6
drwillb BMW Fan 290 Rep 838 Posts Drives: e30 M3, e30 M3, e46 M3 Join Date: Aug 2008 Location: northern NJ iTrader: (4)	Sounds like you need a new valve cover. Oil is getting sucked up into the built in/integral vacuum galleys of the cover. __________________ 2012 135i Mods: air scoops, CP, K&N filter, PS1, ADE FMIC, BMW PE, JB4, 1M front body, full M3 suspension front and rear, M3 brakes front and rear, M3 rear subframe and LSD Owned so far: 88 M3 x 2, 95 325is, 95 M3 x 2, 06 Mini Cooper S, 08 335 xi, 09 Z4 35i, 01 M3, 12 135i
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07-19-2021, 12:41 PM	#9
TheGoodTheBadTheUgly Captain 258 Rep 674 Posts Drives: 2011 E90 335i xDrive Join Date: Feb 2018 Location: Gatineau iTrader: (0)	Yes the chambers should be separate because the introduction of oil would mean that the boost solenoid won't be able to reach and pull the specific vacuum wanted which will affect how much the wastegate will close. __________________ TOTALED \| 2011 E90 335i xDrive - BMS Cold Air Intake - ETS Charge Pipe - ETS 7" FMIC - MHD Stage 2+ - GFB DV+ - PE Mod - VRSF Catless Downpipe - xDelete - xHP Stage 3 2015 E84 X1 35i M-Sport
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07-19-2021, 12:50 PM	#10
bmdubya1198 Private First Class 38 Rep 180 Posts Drives: E39/E46/E53/E30... Join Date: Apr 2020 Location: Charlotte, NC iTrader: (0)	Okay, that confirms my suspicions! Thanks guys! I'll let him know he needs a valve cover. That would be the leak, since I can't find any other leaks. __________________ 1999 528iT 2003 X5 3.0i 2001 330Ci 5MT 2007 335i/6 (brother's) 2006 330i (sold)
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06-22-2023, 08:43 PM	#14
Nitolin79 New Member 0 Rep 8 Posts Drives: 2012 BMW X5 35i Join Date: Apr 2022 Location: New Jersey iTrader: (0)	How do I upload pictures ?
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