Herbmiester 924 Report post Posted January 11, 2022 Hoping someone can shed some light here. My E70 40D has a hard brake pedal when I go to start the vehicle in the morning. When starting it the pedal does not drop down as you would expect and remains hard with what would appear to be no vacuum assistance. When the car is warmed up the fault disappears and I get vacuum assistance again. If I drive with the hard brake pedal I often get a half engine power warning that goes away after about a minute or two, and when it goes away I get the vacuum assistance back again. I have replaced the brake booster seal, where the vacuum pipe enters the booster, and initially this fixed the problem, but now its back again. I am thinking perhaps its the one way check valve but would appreciate any advice. I do find it somewhat odd that when the vehicle warms up the issue goes away. Quote Share this post Link to post Share on other sites
Herbmiester 924 Report post Posted January 11, 2022 After further investigation there is no actual vacuum when the vehicle is first started. I checked the one way valve with a simple blow suck test and it was fine. I then disconnected the main hard line on the passengers side and tested for vacuum, there was none. So the vacuum pump may be at fault? Quote Share this post Link to post Share on other sites
aja540i 1906 Report post Posted January 11, 2022 I would guess vacuum pump or plumbing. Quote Share this post Link to post Share on other sites
Herbmiester 924 Report post Posted January 12, 2022 (edited) 1 hour ago, aja540i said: I would guess vacuum pump or plumbing. The pipe I haven't tested is the one off the vacuum pump, its a bit tricky to get too but I guess it has to be done. Fixing/replacing the vacuum pump looks expensive Edited January 12, 2022 by Herbmiester Quote Share this post Link to post Share on other sites
Herbmiester 924 Report post Posted January 14, 2022 I have trolled the internet but found very little on whey I have no vacuum, I f anyone has any thoughts I would be happy to hear them. Quote Share this post Link to post Share on other sites
dirtydoogle 383 Report post Posted January 14, 2022 It could just be a matter of cleaning the pump, they are a vane type pump as far as I know, so definitely potential for it to stick the vanes when cold. Have you tried giving it a little rev after start up? Quote Share this post Link to post Share on other sites
Herbmiester 924 Report post Posted January 14, 2022 2 minutes ago, dirtydoogle said: It could just be a matter of cleaning the pump, they are a vane type pump as far as I know, so definitely potential for it to stick the vanes when cold. Have you tried giving it a little rev after start up? Thanks for that I will try that and see what happens. Quote Share this post Link to post Share on other sites
Herbmiester 924 Report post Posted January 14, 2022 42 minutes ago, Herbmiester said: Thanks for that I will try that and see what happens. Any thoughts on how to clean it? Looking at real OEM I cant quite work out if its a separate unit or not. Quote Share this post Link to post Share on other sites
dirtydoogle 383 Report post Posted January 14, 2022 34 minutes ago, Herbmiester said: Any thoughts on how to clean it? Looking at real OEM I cant quite work out if its a separate unit or not. That could be problematic, I was thinking of m57 pumps, n57 appears to be in the sump. I would say the only chance of it fixing itself is lots of long drives and clean oils Quote Share this post Link to post Share on other sites
jon dee 500 Report post Posted January 14, 2022 Was looking at this... https://www.nomaallim.com/brake-vacuum-pump-maintenance.html as the pump in the article appears to be similar to the type of pump used by BMW on many engines. Don't know if it applies to your E70 though. However, if it is this style of pump there does not seem to be any possibility of the vane sticking as both ends are constantly in contact with the wall as it rotates. The tips of the vane have seals, so the possibility of seal wear exists. An alternative hypothesis for your issue would be a vacuum leak in the booster. If the check valve is good the booster should still be holding some vacuum after the vehicle has been sitting. Do you get the hard pedal after you have driven enough to get normal braking back and then shut the engine off for a few minutes ? Or do you get normal pedal when re-starting ? Cheers... Quote Share this post Link to post Share on other sites
Herbmiester 924 Report post Posted January 15, 2022 37 minutes ago, jon dee said: Was looking at this... https://www.nomaallim.com/brake-vacuum-pump-maintenance.html as the pump in the article appears to be similar to the type of pump used by BMW on many engines. Don't know if it applies to your E70 though. However, if it is this style of pump there does not seem to be any possibility of the vane sticking as both ends are constantly in contact with the wall as it rotates. The tips of the vane have seals, so the possibility of seal wear exists. An alternative hypothesis for your issue would be a vacuum leak in the booster. If the check valve is good the booster should still be holding some vacuum after the vehicle has been sitting. Do you get the hard pedal after you have driven enough to get normal braking back and then shut the engine off for a few minutes ? Or do you get normal pedal when re-starting ? Cheers... I dont think the booster has a leak because when I removed the vacuum hose there was a big hiss indicating I had broken a seal. That said the pedal was still firm-ish. Will check to see if there are any codes just in case there is another issue. Quote Share this post Link to post Share on other sites
jon dee 500 Report post Posted January 15, 2022 This part 11 66 7 791 232 appears to fit if your vehicle is one of these... BMW X5 (E70) (Year of Construction 02.2007 - 03.2010, 211 - 286 PS, Diesel) 3.0 d, Year of Construction 02.2007 - 09.2008, 2993 ccm, 211 PS, 3.0 sd, Year of Construction 10.2007 - 03.2010, 2993 ccm, 286 PS. And the pump mounts to the end of a camshaft one end of the head Cheers... Quote Share this post Link to post Share on other sites
Herbmiester 924 Report post Posted January 15, 2022 17 minutes ago, jon dee said: This part 11 66 7 791 232 appears to fit if your vehicle is one of these... BMW X5 (E70) (Year of Construction 02.2007 - 03.2010, 211 - 286 PS, Diesel) 3.0 d, Year of Construction 02.2007 - 09.2008, 2993 ccm, 211 PS, 3.0 sd, Year of Construction 10.2007 - 03.2010, 2993 ccm, 286 PS. And the pump mounts to the end of a camshaft one end of the head Cheers... That looks like an M57 pump not an N57 pump. Quote Share this post Link to post Share on other sites
F10er 65 Report post Posted January 15, 2022 42 minutes ago, Herbmiester said: That looks like an M57 pump not an N57 pump. I've had a bit of experience with the vacuum systems on the n57. On one vehicle i found there was a check valve in the vacuum line near where it enters the sump. Tried to get a new valve but it was ex Germany (2 month wait) so i ended up disassembling the valve. I found it was full of carbon, (probably due to the ridiculously long BMW service intervals) so i cleaned it and refitted. That fixed the issue. I'll try to find the valve on ETK and get you a part number. Could be worth checking on your car. FYI, i remember it was a real prick to get at the valve, so prepare yourself for some cursing and anger. 1 Quote Share this post Link to post Share on other sites
jon dee 500 Report post Posted January 15, 2022 (edited) Could be.... I know less than nothing about X5's of any species. Th web page from which I obtained that wisdom is labeled as Vacuum pump with tubes BMW X5 3.0sd E70 SAV Europe M57N2. But if the 40 in you model code means 4 litres then you probably do have a different engine. Cheers... Oops... my bad, I didn't read your reply correctly. I haven't memorised all the engine codes yet Edited January 15, 2022 by jon dee Quote Share this post Link to post Share on other sites
Herbmiester 924 Report post Posted January 15, 2022 1 minute ago, F10er said: I've had a bit of experience with the vacuum systems on the n57. On one vehicle i found there was a check valve in the vacuum line near where it enters the sump. Tried to get a new valve but it was ex Germany (2 month wait) so i ended up disassembling the valve. I found it was full of carbon, (probably due to the ridiculously long BMW service intervals) so i cleaned it and refitted. That fixed the issue. I'll try to find the valve on ETK and get you a part number. Could be worth checking on your car. FYI, i remember it was a real prick to get at the valve, so prepare yourself for some cursing and anger. Thanks that makes a lot of sense, Time to pull the belly pan off. Quote Share this post Link to post Share on other sites
Herbmiester 924 Report post Posted January 15, 2022 1 minute ago, jon dee said: Could be.... I know less than nothing about X5's of any species. Th web page from which I obtained that wisdom is labeled as Vacuum pump with tubes BMW X5 3.0sd E70 SAV Europe M57N2. But if the 40 in you model code means 4 litres then you probably do have a different engine. Cheers... Yeah the M engines are completely different to the N engines. Quote Share this post Link to post Share on other sites
Herbmiester 924 Report post Posted January 15, 2022 13 minutes ago, F10er said: I've had a bit of experience with the vacuum systems on the n57. On one vehicle i found there was a check valve in the vacuum line near where it enters the sump. Tried to get a new valve but it was ex Germany (2 month wait) so i ended up disassembling the valve. I found it was full of carbon, (probably due to the ridiculously long BMW service intervals) so i cleaned it and refitted. That fixed the issue. I'll try to find the valve on ETK and get you a part number. Could be worth checking on your car. FYI, i remember it was a real prick to get at the valve, so prepare yourself for some cursing and anger. Do you think I could get away with spraying a bit of carbon cleaner into the hose and letting it seep down into the pump? My thoughts are this might displace oil or grease and end up causing even more issues, not sure where the vacuum vents to? Quote Share this post Link to post Share on other sites
F10er 65 Report post Posted January 15, 2022 You can access it from the top. Its at the back of the block, just below the high pressure fuel pump. I think i removed the air filter housing and a few other bits. Its circled on this pic in red. Quote Share this post Link to post Share on other sites
F10er 65 Report post Posted January 15, 2022 I probably wouldn't do that as it will end up inside the vacuum pump, and i think they have plastic parts inside them. I remember there was a series of small holes around the circumference if the valve and they were all but blocked. The carbon was quite hard so i doubt carb cleaner would remove it. Quote Share this post Link to post Share on other sites
Herbmiester 924 Report post Posted January 15, 2022 Ah I see now, thanks for that. Quote Share this post Link to post Share on other sites
Herbmiester 924 Report post Posted January 15, 2022 I gather the check valve is in the bottom of the hose that goes into the block? Quote Share this post Link to post Share on other sites
F10er 65 Report post Posted January 15, 2022 That's the one. My memory is a bit hazy as it was a few years ago but i think part of the valve was inside the hole in the block as well. If you post some pics of it here when you have removed the vac pipe from the block, it might jog my memory a bit. The part number is 11664725082 1 Quote Share this post Link to post Share on other sites
Heple 0 Report post Posted May 5 Hi did you get any further with this, got the same issue on my F15 X5 30d with the N57 issue. Going to remove the pipe and check it. Craig Quote Share this post Link to post Share on other sites
Herbmiester 924 Report post Posted May 9 I never quite got to the bottom of it. It would do it occasionally and in the end I sold it to a dealer. Quote Share this post Link to post Share on other sites
