A couple of gremlins

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 

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.

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!!

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

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 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.

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