Noisy injectors?

[Black 535i]

I just had the big service 2 done last week and the car runs great now. My only concern is that there is a ticking coming from the valve area. It is not the valves since they were adjusted properly. Could the injectors actually be that noisy that one could hear them? Does anyone else experience this? It is a ticking at any speed that I can hear but it does not increase with speed but remains constant.

[Gayle]

I just had the big service 2 done last week and the car runs great now. My only concern is that there is a ticking coming from the valve area. It is not the valves since they were adjusted properly. Could the injectors actually be that noisy that one could hear them? Does anyone else experience this? It is a ticking at any speed that I can hear but it does not increase with speed but remains constant.


I am interested in what people say to this post. I am a sound snob and I am wondering about valve noise. I have read in other threads that it is normal in these cars but I want to know more.

How many miles does your baby have?

[genphreak]

Yes, injector ticks increase with motor RPM (and so does the valve chatter of course).

Old injectors are noisy- when were they last removed and cleaned (or replaced)? If you don't know they might need attention.

If the car has good power and no other problems I wouldn't worry. Treatments seldom really fix it, but might get some temproary releif. Its better to take them out and do it properly or buy a new set. http://www.fiveomotorsport.com/Injector_SetsBMW.asp are good. Then again, if they were no good your mechanic might well have worked it out and told you.

I believe its often gunk in the injector's input filter or a buildup in the actual nozzle/s, it depends a lot on fuel quality and whether there is rust in the tank/lines- common if the car is left to stand in an area of high diurnal range (daily temperature change).

Hint: Check your fuel consumption- it always shows there. :) GP

[Bill R.]

noise, if the eccentrics are worn its very difficult to get the correct feel when adjusting the valves.... As far as the injectors go, the rubber seals on them top and bottom serve more than one purpose.They not only seal the hole the injector is plugged into, they all tend to insulate the injector so noise doesn't transfer and well as insulate from heat transfer.. If the rubber seals are hard and old then they transmit more noise that you may hear.. Take a piece of tubing or a long screwdriver that you can hold against the valve cover and on the injectors to try and pinpoint where the sound is coming from..






I just had the big service 2 done last week and the car runs great now. My only concern is that there is a ticking coming from the valve area. It is not the valves since they were adjusted properly. Could the injectors actually be that noisy that one could hear them? Does anyone else experience this? It is a ticking at any speed that I can hear but it does not increase with speed but remains constant.

[Blitzkrieg Bob]

Leave them in.

You'll probably get many miles out of a ticking injector before it begins leaking or sticking.

I have one injector that is much louder then the valve train, and it is begining to go...leaks out and floods the engine every once in a while.

But I picked up a replacement set at Five-O motorsports for @ $170.00, now I just need the time to stick em in.

[Kalevera]

I've spent a lot of time chasing sounds around in my car, as well. After meticulously going over the valves a number of times and replacing the eccentrics/related hardware, not much changed. There's some metal on metal clinking inherent in the design, as others have said.

More recently, I swapped the injectors with a set of design II 19# units, as many others have done. I didn't think it would do much, and it didn't. One thing that can be done to confirm that the injectors *aren't* making the noise is to get the car on a Modic III or GT1 and fire them. The M30 has banked injection: sets of three are fired together, with two firings for each cylinder's cycle (50% of gas at each injection).

I theorize that what people think are "noisy" injectors is actually just the three injector combinations firing at once, versus the more consistent injector click heard on a sequential MPI motor.

So, before swapping injectors: fire them on a diagnostic computer and compare the sound to what you're hearing while the car is running. In my car's case, the sound was negligable, albeit the injectors were caked in carbon.

My current prognosis on the car is a sincere case of carbon buildup. I'm trying to decide what to do about it, if anything. A good BG intake cleaning should do the trick, though.


best, whit

[genphreak]

When I rebuilt my car's cylinder head this was the case on mine. The pintle caps on the injectors were very deteriorated, but all except one still sprayed 'ok'. The carbon buildup on the pistons was under 2mm thick plus the head had buildup inside the chambers so the overall volume of each chamber was reduced by perhaps 1.0-1.5 cubic cm (1/2 a cubic inch).

I was tempted to leave it to keep the compression up a bit, (we have better gas than when they made these cars) but I ended up secumbing to the temptation to match those precision honed bores (exhibiting no wear) with smooth, shiny piston tops... :(

I bet it makes no difference at all... :) GP

[Kalevera]

Nick, was the head shaved/the fatter head gasket used, regardless? That'dve dropped compression. Not by much, but you know :)


best, whit

[genphreak]

Interesting point about hardened O-rings transferring more noise too. When I replaced my Type IIs with Type IIIs, things quietened down a lot... heaps in fact.

I suspect the Type III's one-piece moulded body helps this too. :) GP

[Black 535i]

... this car in question has 194,000 miles and as far as I know the injectors have never been changed. Would running some BG44K next oil change quiet things down?



Interesting point about hardened O-rings transferring more noise too. When I replaced my Type IIs with Type IIIs, things quietened down a lot... heaps in fact.

I suspect the Type III's one-piece moulded body helps this too. :) GP

[genphreak]

Nick, was the head shaved/the fatter head gasket used, regardless? That'dve dropped compression. Not by much, but you know :) Hey Whit, something was taken off it, but in my machinist's words 'nothing to even think of'... (it was not warped at all) so I used the standard head gasket. But perhaps I could clawing back some compression here... I doubt it'd be worth a mention though :( She runs on 91-98 octane without a ping. I am yet to install a high-octane chip yet.

Actually with petrol the price it is going I am thinking I'll convert to Peanut oil... any idea what glow-plugs will fit an M30? :D

[genphreak]

I'd follow Bill R's suggestion first... I doubt any cleaner will calm the noise, but its worth a try. You probably know, but cleaner has detergents in it that can break down your oil, so its often a good idea to use it a tank before you are due to change the oil. Thing is at 194k any wear item that hasn't been changed should be; Oxy sensor, AFM, injectors, injection rubbers, temp sensors, ignition wires etc. Check your cam and eccentrics- I'd suspect them for wear as others have suggested... esp due to the 'noise' factor. Usually only a couple in the middle can wear- new eccentrics and rockers ($15 each set) can help... every now and then there is a new cam on eBay should you see you need one- there's a TRW one there recently starting at $1.00 but you can expect $100... they are $139 list. Since you just had your mechanic adjust the valves ask him- did they all REALLY come into adjustment properly? Did the cam have any wear (grooves on the lobes) - that sort of thing. If he is adamant its ok (and knows these engines) then its your injectors making the noise. :) GP

[Bill R.]

feel okay, its just that the drag suddenly increases alot on your feeler gauge when you make a slight adjustment, since they wear a flat on the eccentric when you rotate it slightly you suddenly have a sharp corner where the worn flat converts to the rest of the round eccentric.. So if your mechanic doesn't actually remove the eccentrics and look at them he can't tell... thats why i would first use a mechanics stethoscope or screwdriver handle to pinpoint which injector or valve adjuster your hearing and then if needed remove that eccentric and inspect.








I'd follow Bill R's suggestion first... I doubt any cleaner will calm the noise, but its worth a try. You probably know, but cleaner has detergents in it that can break down your oil, so its often a good idea to use it a tank before you are due to change the oil. Thing is at 194k any wear item that hasn't been changed should be; Oxy sensor, AFM, injectors, injection rubbers, temp sensors, ignition wires etc. Check your cam and eccentrics- I'd suspect them for wear as others have suggested... esp due to the 'noise' factor. Usually only a couple in the middle can wear- new eccentrics and rockers ($15 each set) can help... every now and then there is a new cam on eBay should you see you need one- there's a TRW one there recently starting at $1.00 but you can expect $100... they are $139 list. Since you just had your mechanic adjust the valves ask him- did they all REALLY come into adjustment properly? Did the cam have any wear (grooves on the lobes) - that sort of thing. If he is adamant its ok (and knows these engines) then its your injectors making the noise. :) GP

[Black 535i]

I will see what he says about these suggestions.


feel okay, its just that the drag suddenly increases alot on your feeler gauge when you make a slight adjustment, since they wear a flat on the eccentric when you rotate it slightly you suddenly have a sharp corner where the worn flat converts to the rest of the round eccentric.. So if your mechanic doesn't actually remove the eccentrics and look at them he can't tell... thats why i would first use a mechanics stethoscope or screwdriver handle to pinpoint which injector or valve adjuster your hearing and then if needed remove that eccentric and inspect.

[MJ535]

I changed the injectors in my 89 535 to new Bosch 19.4 lb 4-jet injectors (not too tough a job) and it was MUCH quieter and idled and ran more smoothly. I highly recommend it.

Mark