darrencnz 10 Report post Posted June 10, 2015 Hey guys So i've had my M52B28 in my E30 for a while now but have pretty much finished most of the work on it and now it's time to iron out all that list of niggly little issues, i've mentioned a few of them below and would love to know your thoughts and opinons on what might be causing them and ideas to fix them. 1) I've done the M50 2.5L inlet mod and i have the proper conversion kit installed and something i have noticed is that when i turn the car off, i get a hissing sound of built up air somewhere that's trying to escape. If i push the gas pedal down, i can hear it releasing faster so im wondering where that problem is coming from, I wonder if i have connected the small vacuum lines correctly when i did my inlet conversion as all the info about what vacuum linbes to connect were for the M50 engines which have some different inlet bits or it it may be a combination of some of the other questions below so keen to hear your thoughts. 2) I've replaced the brake booster with a VW golf Mk2 and when i did this, i wasn't sure if there should be a one way valve in the 1/2" rubber hose that goes from the booster to the plenum on the inlet, again, is this related to the issue i mentioned above? Quote Share this post Link to post Share on other sites
B.M.W Ltd 950 Report post Posted June 11, 2015 (edited) Yes to both issues... fit the one way valve Edited June 11, 2015 by B.M.W Ltd 1 Quote Share this post Link to post Share on other sites
Guest MP0wer Report post Posted June 11, 2015 sounds like a vacuum issue, recheck the little vac lines. I used the kit from m50manifold from eric in the usa. if you bought it from him, i suggest you get in touch, hes quite helpful. Quote Share this post Link to post Share on other sites
darrencnz 10 Report post Posted June 12, 2015 sounds like a vacuum issue, recheck the little vac lines. I used the kit from m50manifold from eric in the usa. if you bought it from him, i suggest you get in touch, hes quite helpful. Yeah thats what i thought too... I did get it from him but there was very little information about fitting it to the M52's Quote Share this post Link to post Share on other sites
darrencnz 10 Report post Posted June 12, 2015 sounds like a vacuum issue, recheck the little vac lines. I used the kit from m50manifold from eric in the usa. if you bought it from him, i suggest you get in touch, hes quite helpful. I've emailed the guy to see what he says so will wait to hear back but ive also found a forum online where lots of people have mentioned the same thing and everyones seems to think it is normal, like it is just the air escaping out of one of the cylinders and that the reason you ntoice it is because of the removal of all the factory airbox stuff and that theres nothing to worry about? Maybe there isn't but i like to ask others opinions... I've installed the one way valve but havent noticed any difference in anything but thats ok. Quote Share this post Link to post Share on other sites
hybrid 1043 Report post Posted June 12, 2015 My e30/s50 coming from a MKII booster to the pressure rail. You can see the 1 way/filter there. 1 Quote Share this post Link to post Share on other sites
e30ftw 410 Report post Posted June 12, 2015 I was running a one way valve from an m50 when I fitted to my m52. Idea is it keeps the brake booster under vacuum when car is off. Mash the pedal a few times and you lose the pressure anyway 1 Quote Share this post Link to post Share on other sites
darrencnz 10 Report post Posted June 12, 2015 My e30/s50 coming from a MKII booster to the pressure rail. You can see the 1 way/filter there. ^ That looks purty..... I got a one way valve today from cylinder head specialists today, so i've got that sorted. Just received an email from Eric at m50manifold.com and he said the hissing sound is normal, apparantely cos everything is sealed up nicely, its just the pressure equalising... 1 Quote Share this post Link to post Share on other sites
darrencnz 10 Report post Posted June 12, 2015 I was running a one way valve from an m50 when I fitted to my m52. Idea is it keeps the brake booster under vacuum when car is off. Mash the pedal a few times and you lose the pressure anyway That makes sense... Quote Share this post Link to post Share on other sites
hybrid 1043 Report post Posted June 14, 2015 Eric at m50manifold.com and he said the hissing sound is normal, apparantely cos everything is sealed up nicely, its just the pressure equalising... Hmmm doesnt right to me .. If its functioning correctly you shouldn't hear any hissing. Sounds like you still have a leak somewhere. Quote Share this post Link to post Share on other sites
will 169 Report post Posted June 14, 2015 Hmmm doesnt right to me .. If its functioning correctly you shouldn't hear any hissing. Sounds like you still have a leak somewhere. I agree. Get a smoke test done or try target spraying brake cleaner/start ya bastard/similar gunk around the intake system and see if you get an increase in idle speed or change in exhaust emissions (need gas analyser for this). 1 Quote Share this post Link to post Share on other sites
darrencnz 10 Report post Posted June 15, 2015 This is normal. Your system is sealed up now so what you are hearing is the ccv leaking down (equalizing pressure) after there is no longer a vacuum source on the engine.Before you did the swap there was so many leaky spots around the seals there was less overall vacuum in the crank case and when it leaked off after engine shutdown it just went around all the leaky seals instead of through the ccv. If your idle is good and you don't have any other issues I don't think this is anything to worry about. This is the email i received, the car runs fine, idles fine, all the rubbers are in good condition. I'd be interested to hear more opinions or perhaps a solution to the problem would be better. The only thing i am not 100% sure on with this whole setup is the tiny little straw sized vacuum lines because the manual had clear instructions for M50 engines but not so clear instructions for the M52 which is slightly different in how these are connected. Does anyone have this setup and NOT get a hissing sound on shutdown? Cheers Darren Quote Share this post Link to post Share on other sites
e30ftw 410 Report post Posted June 15, 2015 I don't get why you need the kit in the first place. I ran the m50 manifold, m50 TB, e36 Intake boot with 2 bungs, One I fit the IAT sensor into and the other one I fitted the m50 ICV lines but used the m52 ICV. Put a T into it with a tube for the Crank case. Quote Share this post Link to post Share on other sites
darrencnz 10 Report post Posted June 16, 2015 I don't get why you need the kit in the first place. I ran the m50 manifold, m50 TB, e36 Intake boot with 2 bungs, One I fit the IAT sensor into and the other one I fitted the m50 ICV lines but used the m52 ICV. Put a T into it with a tube for the Crank case. Basically, cos at the time i had an M52 engine thats was missing half its bits and pieces, i didnt take the engine out of the car myself, i had never worked on a BMW before and after reading and looking at all the misinformation and hack jobs on the internet i decided that the smartest way to approach this task was to get the kit that had everything i needed. Because of my lack of detailed knowledge of the subtle differences between the M50 and the M52's engine parts, such as fuel rail, throttle body etc, i just wanted a proper solution that was affordable and tidy and this seemed like it... Dont get me wrong, i'm very happy with it, engine runs great, idles nicely, has lots of power, no complaints, just wondering if the sound i am hearing at switch off is... a) normal and nothing to worry about is going to ruin my engine c) i have something in the vaccuum line connected incorrectly d) can be fixed/removed easily Quote Share this post Link to post Share on other sites
darrencnz 10 Report post Posted June 16, 2015 I don't get why you need the kit in the first place. I ran the m50 manifold, m50 TB, e36 Intake boot with 2 bungs, One I fit the IAT sensor into and the other one I fitted the m50 ICV lines but used the m52 ICV. Put a T into it with a tube for the Crank case. I have routed the CCV hose into the oil dipstick rather than venting back into the intake manifold Quote Share this post Link to post Share on other sites
