As a few of you have read, I recently had a few jobs done on the car to get her through the MOT which has now passed thank goodness! But I have a couple of new issues which may be as a result of having the engine loom unplugged and the intake manifold off as well as various vacuum, breather and fuel pipes.

One thing I have noticed since everything going back together is a hissing noise inside the car coming from the front passenger area behind the dashboard. The weird thing is, when at idle you can hear it clearly but it seems when I accelerate, the hissing noise gets less the harder I accelerate! so if I pull away gently, the hissing noise quietens slightly but if I floor it, the noise completely disappears. I cannot smell anything strange so I'm not sure it's a gas leak from the aircon (but the system is empty and doesn't run anyway) the only thing I can think of is some kind of vacuum escaping? I cannot fathom out what might be there that would use a vacuum nor can I feel any difference in performance (suggesting no loss of vacuum) or anything different from when it first went in.

Also, second issue, I did have a warning come up a few times intermittently which was DIP BEAM - LICENCE PLATE LAMP - TAIL LIGHT - BRAKE LIGHTS. Some of these came upon their own, mainly the licence plate or brake light ones but I did also have all at the same time a couple of journeys. I only had the brake light one come up yesterday and today. Before I left work this evening, I changed the brake light bulb as it seems I only get the problem after pressing the brakes but not always straight away. I thought there may be a dodgy filament that was back feeding and causing a bad signal bringing on all sorts of issues. Both bulbs looked a bit blackened and the filaments looked burnt though they still worked but I replaced them anyway. Half way home after several presses of the brakes, the BRAKE LIGHTS message came up again but when I had a car sitting behind me, I pressed the pedal several times and I could see the red glow coming on and off so I know they are working.

As the rear of the car hasn't been touched and the problem has only been since having everything at the front apart I'm wondering what could cause such a thing to happen.

All pointers and suggestions welcomed please!

One final thing, I want to replace the loom for the crank sensor from the plug at the sensor right back to the pins on the ECU plug. I have asked a guy at BMW and he said he'll need a part number off the plug to match it up? Sounds bizarre to me because I can look terminals and pins up for our vehicles though I have had a look on realoem and come to the same conclusion. Would anyone know or know how to find these part numbers without me having to take the plug apart? Also before I go searching, anyone know where exactly the crank sensor is on the M60 engine? I have a feeling it's at about 10 o'clock if you had the engine out and flywheel facing you?

Cheers

Mike 

Mike happy to see you got the car back on the road

Reference the warning lights message, I had a similar problem on my 1997 E39 touring. It would throw up "check fog lights", "check brake lights" when they would be working. Mine would normally come up whilst driving the car throughout the journey a couple of times. Also it would make a "bong" sound when i'd switch the car off. Like yourself I checked the lamps and everything was fine.

I had a mobile mechanic come and and connect his diagnostic machine to the ECU. He called up the faults and all the above where listed. He asked me if I was getting the "bong" sound when i would switch the car off. I confirmed this with him and he proceeded to clear the faults. He done a through check of the faults and once the car had been reset it ran fine. Since then, touch wood I havent had any more electrical faults.

What i'm trying to say is that if you havnt already done so, get a mate to check your ECU for any fault codes and it may be a good idea just to clear the ECU from any non related faults and see if that brings any joy. Its the cheapest place to start. The electrics on the Beemers dont improve with time either. A mate of mine who works for BMW still says they get loads of E46, E60, and later model cars comming in from customers complaining of cars syaing there brake lights arent working when infact they do. Dodgie contacts or something he said.

Sorry for the long reply and again if this hasnt been any help.

Imran.    

Tail gate wiring loom wearing at the hinge? 

Poor battery condition can throw up a lot of weird electrical faults.  How's the battery?

Regarding the hissing sound - from what you describe it sounds like a definite vacuum leak to me. When the throttle's closed the vacuum's at its greatest, so the hissing sound would be loud. Flooring the accelerator will take the vacuum away and so the hissing sound would disappear!

I hope I'm wrong, but from what I've read in the past the intake manifold gasket makes a loud hissing sound when it's leaking and the noise could well be coming in through the firewall.

As for the electrics, as others have said I still it would be best to just get someone to plug the car into a diagnostic machine and get it all reset and checked out.

The crank sensor reads the teeth off the flywheel so definatley down the back. I did have a look today and I think I can see it on the opposite side to where I said, more like 2 o'clock rather than 10. I can see a shielded wire going down to about that area.

On another note, I had a fiddle with fuses and the LKM module as well as relays and plugs around that area. I basically replaced a few fuses on the lights and re-seated the LKM and all the relays. The problem didn't re-present itself on the way home. It didn't do it on the way to work either but then I didn't have my lights on which seems to be the common denominator. I guess I'll just wait and see. I have heard of clearing fault codes can sometimes clear faults too. Perhaps it's worth a try too.

Still can't identify the hissing sound though. Weird!

Mike

Crispy-d wrote: Regarding the hissing sound - from what you describe it sounds like a definite vacuum leak to me. When the throttle's closed the vacuum's at its greatest, so the hissing sound would be loud. Flooring the accelerator will take the vacuum away and so the hissing sound would disappear! I hope I'm wrong, but from what I've read in the past the intake manifold gasket makes a loud hissing sound when it's leaking and the noise could well be coming in through the firewall. As for the electrics, as others have said I still it would be best to just get someone to plug the car into a diagnostic machine and get it all reset and checked out.

Well it was a thought of mine but if it's losing vacuum, it would more than likely run really rough. You also cannot hear it when the bonnet is up and you listen in to the engine!!

Hmmm... you'd definitely hear it with the bonnet open. Well I'll have to have a look at mine tomorrow and see if I can find any pipes around that area.

Also I think refridgerant is pretty nasty stuff so you don't really want that leaking into you passenger compartment :)

Crispy-d wrote: Hmmm... you'd definitely hear it with the bonnet open. Well I'll have to have a look at mine tomorrow and see if I can find any pipes around that area. Also I think refridgerant is pretty nasty stuff so you don't really want that leaking into you passenger compartment :)

It's definatley not refridgerant because my aircon has been empty for about 2 years now!

I've had a look for pipes. I can see vacuum pipes on the engine side but nothing in the footwell or glovebox. The car seems no different than before so whatever it is doesn't seem to be detrimental to the performance or running of the engine.

Cheers for the diagram, as I thought, the sensor is at 10 o'clock but a bugger to see.

As for the hissing, when I got to work the other day I put my head down in the passenger footwell and the hissing sound seems like its coming from behind the glovebox. I thought at first it may be the speaker hissing but I pu my ear to it and could hear it coming further up inside the footwell. I cannot get my head far enough up inside and when I open the glovebox it doesn't get any louder but it's definatley coming from around that area. I can see wires behind there but no pipes. I have had the bonnet up when idling and I cannot hear anything different from before I had the manifold off.

I notice there is a master cylinder on the bulkhead which I assume is for the brakes? As the brakes are servo assisted, could it be an air leak from here as it's in the right area. I haven't had a listen in this area under the bonnet yet as I've only just thought of it but I will and see if I can hear anything down there.

Confused!

Mike

It's at the front? Ok, I didn't realise! they are usually at the back, I stand corrected!!

Should be easier to see the wires then hopefully.

I thought I was being paranoid but my brakes have felt a little different but I thought that may be because of the new pads bedding in. They work fine but sometimes it seems the pedal feels a tad different, sometimes harder and sometimes a little softer. You are worrying me now! Maybe I should get someone to have a look.

Mike

Anyone have diagrams or can tell me where the vacuum pipes for the brakes are routed? At least this way I can check them all. I just wonder if where all the manifold, pipes and wires are routed, one of the vacuum pipes got disturbed or trapped when everything was replaced.

I know what I'll be doing at lunchtime tomorrow!

Mike

I had a look at mine today and it's easy enough to see the crank sensor and to get to it - there's a large, toothed wheel behind the main pulley on the crank on the front of the engine and the sensor is at 10 O'Clock if you're looking in from the front of the car.

If I were you and could find the time I would trace all the vacuum pipes going to and from the manifold and as Jetset said just spray brake cleaner around with the engine switched on to find any leaks.

Really, to save yourself all this worry you could just get it looked at by a proper BMW technician. Then again I understand it's expensive and throwing cash at it might not be an option just yet!

It could just be a disturbed vacuum line or the manifold gasket (or crack!!) is still leaking and although you can't hear it over the engine it might be directing the hiss straight back at the firewall, which could be why you're hearing it so clearly inside. If you've got good lambda sensors then the engine will still run with a small intake leak, but would obviously not help the idle.

I hear what you are saying crispy but the guy who fixed my car will feel guilty enough of causing another issue so as I've paid him hard earned cash, no doubt he'll feel obliged to rectify the problem. At the end of the day, I know some cars have their differences but essentially a car is a car so a mechanic should be able to sort things out, might just take a bit longer than someone who is a specialist. Anyway, the last e34 rolled off the production line in '94/'95 How many technicians who work for BMW now have any experience of them!!

At my place we have a good retention of technicians but only 3 out of the 15 will have experienced vehicles over 16 years old and one of them is out technical specialist who just gets involved in the hardcore problems/electrics etc so only 2 of them would work on a vehicle that old. If I drove my car to BMW tomorrow I will see from the look on their faces they'll be thinking "What the F*** is that doing in here!"

Anyway, I'll set about checking over the car tomorrow and let you know of my findings.

Hi, I noticed you had posted while I was writing my last post! I've just been looking for diagrams but can't find any at the moment, at least not of our engine bays. I also seem to remember my brake booster being on the driver's side but I could well be wrong!

That's strange what you say about your dealer - perhaps we're a bit behind times here in Suffolk but they are always happy to see me going in to see them and bug them with questions (considering I give them very little money other than for parts, for which they normally give me a 10% discount anyway!) and the technician I usually talk to is a mature chap who's worked with BMW for over 20 years now, so he says. The way he talks about my car without even looking at it though I believe him!

The specialist I mentioned earlier has just one technician and he started at BMW in the late '80s and so is also very clued up. Then my local mechanic who I entrust all the jobs that I can't do to worked at both Volvo and BMW throughout the '90s and so has always been perfect for me! Perhaps I'm in a lucky position but I wouldn't use anyone else.

I have, in the past taken my car to other garages when my mechanic's busy to ask for advice and frankly they didn't have a clue. Yes, they are mechanics, but my brother-in-law is a lecturer and trains mechanics and I've seen what he teaches and is in the syllabus.....! I'll say no more, but following a manual when you have a good set of tools is not a difficult task and that's what I try to do now! Having someone that really knows a specific car not only saves time (as you did suggest) but also will often result in correct diagnosis and, more often than not, will save you money. I love my brother-in-law like my own syblings, but I wouldn't let him touch my car :)

Still, your chap's started it so you might as well let him finish! I will have my glovebox out tomorrow as I'm looking for a ZV module to plug a keyless entry/alarm system into and so will poke around for anything that looks like a vacuum pipe! Best of luck for tomorrow!

Well guys, top job yet again. As suggested, I checked the running the afore mentioned crank pulley and when I shone a light on it, it is not running true at all. If you were to look at it straight on, it would run ever so slightly oval causing the distance rom the CPS to the pulley teeth to be irregular. It's quite obvious to see so it's most certainly my revving problem but I'm now thinking that it may be the cause of my misfire too. When you see it running, the vibration rhythm seems to coinside with the timing of the misfire.

Now for the bads news, it's a dealer part only and comes in at a bargain price of £281 + VAT

I simply cannot afford that amount now so it looks like a decent second hand one will have to do.

PM coming your way bulletproof!!!

Mike

bulletproofbomb wrote: Mike, Do you have ASC+T? If you do then the brake system is full hyraulic, with no vacuum assistance. I think the principle site for vacuum leaks will be the PCV assy, though there is also a line to the fuel pressure regulator on the end of the fuel rail (on the RHS of the vehicle, facing towards the firewall). I would have thought the manifold area would make more noise, but perhaps we need an audio clip... ? I'd nose around real oem a bit as it shows the various systems that have vacuum lines (several...)

Mine has ASC yes. I have come to teh conclusion that the pedal is harder so I have to apply more braking pressure so get the brakes to come on. I have had a few staps at emergency stop just to test them and they stop fine but I just have to put more effort in to it. When the engine is off the pedal is solid so there must be some type of assistance whether vacuum or something else?

I've had the glovebox off and the hissing noise is louder but I stil cannot see any pipes!

Mike

The noise does not change when I have the flaps open or closed, the vents open or closed and the heater motor on or off, the noise remains constant. The only one factor that dissipates the sound is when I'm accelerating. It doesn't even go when I rev from idle, it still remains constant, it only seems to fade when I'm actually in gear, moving and as I said before, the further I floor it, the more the sound disappears.

I'm still totally at a loss. I will try and get a sound recording tomorrow and maybe a picture to show where the sound is strongest. I just hope the manifold won't need stripping again

Mike

I'm convinced it's a vacuum leak near the rear left side of the manifold area - but the vacuum in the manifold definitely decreases as you open the throttle, as it allows more air in :) so the noise should get quieter.

It could well be the PCV gasket, the crack in the manifold (hope not though) or any of the little vacuum pipes round there. As Jetset says, take the cover off and just have a damned good listen and spray brake cleaner or something around the area. I'm sure you'll find something.

EDIT: Oh, sorry Jetset - just seen your edit!

I haven't put the accoustic cover back on yet as I have unfinished business under it!

I spoke to a mechanic at my place and he has said if there was a gap somewhere in the manifold, the sound of the engine would be louder like as if my exhaust was blowing a little and there would more likely be a loss of power when flooring it. He didn't totally rule it out but said it was unlikely. I am totally happy with the repair I made on the manifold. I used plastic resin glue which was like a soft paste when I applied it and I smoothed it along the crack right along the outside whcih totally sealed it. Then I squeezed a thin bead of black mastic (which is really thick, sticky glue/sealant that is used for many automotive applications as it's a lot like silicone but oil, fuel and heat resistant and once it's on you will never get it off!) and I used my finger to spread it along the inside many times so it gave an elastic seal from the inside. I also did the PCV valve up whith the manifold off so I could see if it moved when I tightened it and it didnt budge so I'm very confident on my repair. (Well, 99% lol!)

I'm working tomorrow and I know the guy in charge in the workshop is our technical specialist who is also a good friend. I'll grovel to him to try and help me find the source of the problem and thrash out some theories with him.

I'll also try the brake cleaner test too just to be sure!

Cheers guys, I'll let you know what I find tomorrow, if anything!

Mike

Hmmm - well I hope he's talking about the exhaust manifold then because the inlet manifold is the one with the vacuum!! and is the one that will hiss when it has a leak. It's the exhaust manifold that will blow and be quite loud if it's leaking.

Also, the problem with our engines is that they are so torquey and monstrous anyway that even if there is a problem and not running on full power it's actually quite hard to tell! The only time I've ever noticed a true difference in performane was when I renewed the spark plugs and it seemed like a different engine and felt so responsive and so much more potent at high revs.

Back to topic though...! (Sorry) I'm sure that your seal is good, just throwing out possibilites! It could be something completely different, but just from everything you've described I think the first thing you should try is to test for leaks around that rear left area of the air intake manifold and all connected lines. Once that's done and you can be sure it isn't that, then it'll be easier to let it go and think of other things :)

I'm still a bit concerned that you've been told by a mechanic that it's very unlikely, because most people will tell you that a hissing sound from the engine bay of a V8 BMW is MOST likely to be the inlet manifold gasket because they are prone to going. And considering that's just been tampered with it's the first thing I'd have thought he would think of!! Anyway, I hope you find something tomorrow - good luck!

I have heard vehicles run with inlet manifolds off and the engine is a lot louder. If you look on realoem.com, the intake is actually called the intake 'muffler' it smoothes the airflow going into the cylinders and also covers the actual part the air is sucked in past the valves. This process is quite loud and the intake manifold does muffle the sound. If there was a significant leak, the engine would be louder and I'd be losing a lot of vacuum causing all sorts of fuelling issues.

This is why my thoughts are simliar to jetset's, I'm thinking either a vacuum pipe is leaking (though I did renew some of these when replacing the PCV) or a pipe is possibly trapped. One thought that just ocurred to me now.... there are two pipes coming off the PCV valve. One one the drivers side that goes onto a fuel pressure valve on the rail and on the passenger side it goes off down under the nearside somewhere (passenger footwell area) The pipe on the passenger side was totallyperished and would not have survived being re-attached so I took a normal length of vacuum pipe and used that. When I took the old pipe off, it looked like there was a tiny little piece of plastic tubing half way down the pipe with an internal diameter of about 2-3mm. The mechanic said it looked like a joiner which must have been used previously and had broken off leaving a piece in the pipe. My thought now is, could this have been some type of restrictor that was meant to be there? if the vacuum has to suck through a smaller gap, it makes it more powerful does it not? My theory is, could this be causing the vacuum to be sucking too much and causing an imbalance?

It's only an aside theory but wondered if anyone else noticed this in their pipe?

Didn't manage to look on Saturday. I have been using a work van so not had the car either. I'll do the brake cleaner test tomorrow.

Mike

Ah right, I see you are talking about something completely different - the intake manifold is not a muffler but simply (actually quite complicatedly!) directs the airflow into each intake port. As said, without this the engine would simply not run - if it was the intake manifold (and not the silencer or air filter housing) that was removed from the engine that you heard then it was either a diesel or it had individual throttle housings (an M5 perhaps...?) or individual carburettors. The only additional noises you will get with an open intake system are a slight sucking/hissing noise from the throttle valve and induction noise when at half throttle or more. My old motorbike used to give off a little valve-tap as well but I don't think that would be noticeable on a car.

My thoughts are are also similar to Jetset's still and all of the vacuum lines around that area become very week after 15 years of service. Let us know how the brake cleaner test goes.

I have 2 small pipes, one goes to the fuel valve, the other off and down to the passenger side, I too also have the larger blanked off one and also the one that runs under the nearside of the manifold which comes from the crankcase to the PCV valve.

Along with a mechanic, we have both inspected all vacuum pipes and sprayed liberal amounts of brake cleaner all along them as well as around and across the entire manifold but it didn't cause any difference in the running. My mechanic seems to think the hissing pipe goes under the carpet and disappears along with the wiring loom towards the back of the car and cannot see any connection with the strange feling on the brake pedal. Just to eliminate it, I have fully bled the brakes also replacing the fluid which has made no difference. There is a pipe that runs along the front of the engine which is a pre-formed plasic pipe. This was disconnected during the manifold removal. As it's plastic and some of it is hard to se, I'm going to remove it tomorrow and inspect it to ascertain whether it may have a hairline fracture along it which may be causing the issue.

Not sure if it works with petrols but I know the guys have run some of the vans at work after an engine re-build with the intakes completely off as it's easier to detect any running issues before the final parts are re-assembled so I was just going on this theory about the noise as these run much louder with the intakes off. Having said that, I am now confident after the brake cleaner test that I have no intake leaks.

Mike

Took off a pipe that runs along the front of the engine from just under the throttle housing and goes along to the accumulater down the n/s/f. The pipe seemed to have a small nick in it where I think it's been rubbing. I sealed it up with a few wraps of duck tape and checked the rubber pipes and hose clips. All is ok but still the hard pedal. Tomorrow I'm going to take the other pipe off that goes from the accumulator to the master cylinder in the hope that I'll find something conclusive there.

Getting really fed up now

Right, finally the end of one conundrum <spelling?)  I am now very sure what the hissing noise is and why it's only just started. The pipe my mechanic thought went along with the dash wiring and under the carpet is a red herring!  There is a pipe and it does run behind the glovebox but it goes behind a metal plate then seems to come out the other side (as my mechanic thought) but with my bony little fingers, I managed to feel along the pipe and realised it turns downwards at 90 degrees then swells into a rubber dome about 1 inch across. The 'pipe' coming out the other side is actually electrical sheathing for some wires which also run along the same route as the pipe but nothing to do with it in any shape or form.

So back to the rubber dome, this sits directly above an opening which comes out behind the glovebox. The opening is making a hissing noise which when I cover it stops!  if I remember correctly, it's something to do with the climate control and measures the air temp in the car?

The pipe that BPB mentions is blanked off on his car (lack of climate control?), on my car it's one of the old perished pipes that I replaced and it goes into the bulkhead directly behind the glovebox! I therefore assume that there is a unit which uses the vacuum to suck in air so that it can measure the temperature to allow it to control the temp inside the car.

It's just started hissing because it was obviously not working at all before due to lack of vacuum but I'm now wondering if the pipe I took off which had something stuck in it was acting as a restriction or muffler and so wasn't so loud?

Now with that sorted and knowing my brakes are not linked to the hissing I can turn my full attention to the brakes. Now as you mention it BPB, the pipe I  described does have a little sort of valve unit on the end of it. I'll have a look on realoem and see if I can spot it to cast more theories in to the mix.

Together, we'll get to the bottom of this.

Mike

For some reason once I upload the pics I can't write below them so apologies for the wasted space. Anyway, though difficult to get to, I'm fairly sure I can ID most of the stuff on here as being fitted to my car. The only bit I cannot find is the pipe I mention and the bit on the end you mentioned BPB. Any ideas on what it may come under? I have searched all the brakes unless it's listed elsewhere?

Any other ideas of what to check as most of these pipes are fairly well covered so may involve stripping other things out to get to it all.

I'll try and get her up on a ramp this week and see if it's any easier to see from underneath.

Mike

Well it's funny you should say that because I looked at the fuel vent today and took it off. There was some thick sticky yellow goo on the plug and when you blow through that valve it sort of rattles like if you were blowing a thick liquid through a straw.

I wonder if this could be at fault then?

Those pics above are of the brake accumulator and pressure regulator so I thought if any of the seals on these have been disturbed there may be a small leak somewhere.

So this fuel vent valve could be a possibility then?

I'll see if I can take a pic of the thing I mention in my dash that is hissing.

Mike

I cleaned the vent valve and even bridged it out of the circuit which made abosolutely no difference so I have now eliminated that.

I have aircon (though BMW said it doesn't show on their system so perhaps a retrofit?) and the pipe I mentioned that goes from PCV valve through the bulkhead is definatley something to do with the heater because as it comes through the bulkhead it seems to connect into a small plastic cylinder which has two rubber pipes coming off it. One goes to the drivers side and the other to the passenger side and they both seem to run into the heater housing. When I spoke to a guy at BMW today and I started to tell him about the vacumm pipes coming through the bulkhead pipes, he finished my sentance and said 'the ones for the heater' and he confirmed what I'd found. I also tried pitting the small restrictor back on the pipe where it comes out of the PCV valve and it still works fine but the hissing has gone.

That eliminated, I still have the braking issue. I have now traced all the pipes along from the accumulator to the pressure regulator and the the mastercylinder. They are all very thick and hard rubber or metal and none look perished or loose in any way. Apart from taking it all apart (which BPB swerved me away from and quite right too!) I'm at a total loss.

I really can't afford checking it into a garage but I'm going to do some sniffing, persuading and even begging to get anyone who knows these cars to tell me all they know! I've worked in the motor trade for 13 years, I'm sure I must have a connection somewhere that can tell me something!

I'm going to take some pictures tomorrow to show you which bits I've done what to in the hope it may shed some new light on something.

Mike

I have shown the vacuum pipe I have been on about all this time! You can see it coming from the PCV valve and it loops under a water pipe then into a grommet in the bulkhead. (PIC 1)

In the second picture you can see the other side of where the pipe comes through, into a plastic tubular housing where two vacuum pipes come out, one goes off to the drivers side and the other is shown in the third picture as routing along to the dome shaped rubber (hidden but outlined in red in pic 4) then you can see the opening where the pipe sucks from.