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Matt, Mechanical Engineer
Category: BMW
Satisfied Customers: 22909
Experience:  BEng hons Mech engineering, in auto industry 22 years
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I have just bought a bmw 1 series as anniversary present for

Customer Question

I have just bought a bmw 1 series as anniversary present for my wife. Its a 2006 model, diesel, auto. Paid £6000 but I did not check it properly. It had full bmw service history. Upon driving it home, I not when stationary, and the car was in "drive" the car jerked slightly. The jerking happened every 2/3 seconds, and gradually got a little stronger. When I put it in "neutral" or "park", it was ok.



I drove it home, and a friend of mine had a look. He then noticed oil leaking somewhere on the engine too.


I have just spent my savings on the car. I wanted a reliable, good car for wife to take son to school in as we had just sold a smaller car to purchase a more reliable strong car. And now the previous owner will not even answer phone? Please advise, I cannot afford to pay any more money.

Submitted: 3 years ago.
Category: BMW
Expert:  Matt replied 3 years ago.


I'm assuming that there are no check engine or other fault lights on so
this could be an airleak after the airflow meter, any air dragged in here isn't 'seen' by the ECU and so not compensated for and can lean the engine out and can also allow the engine to rev up when not desired causing rough running.
As its a mechanical fault it tends not to turn on the fault light and you can sometimes hear a 'hissing' noise with the engine running.

Check the hose clips for tightness and inspect the trunking for any cracks or splits and also all the vacuum system, the small bore pipes and fittings for cracks and missing parts.

The best way to locate a leak is to have the engine running and warm and then spray lighter gas /propane around each joint in turn. If the engine rev's up you've found your leak.
Now you might think that spraying lighter gas around a hot engine isn’t wise, however the flash /ignition point of gas is about 400°C so you need a naked flame or spark to set it off and I’ve used this method for many years without incident.
Work your way through each possible joint one at a time and you should find it. I use a slightly flattened piece of brake pipe and some rubber hose from the can of lighter gas to provide a spraying 'wand' and allow a direct blast of gas into each area, especially those difficult to reach with large implements.

if thats OK I'd also check over the transmisson
I'd take a look at the colour of the transmission oil it should be a dark red colour if its black then its needs changing together with its oil filter. Also check its level with the gearbox warm and just after you've moved the selector through all the positions leaving it for a few seconds in each one and then back to park.

You can top up the box through the side fill plug if required and make sure you use the correct oil for your car as the fluids are not all the same. Some manufacturers recommended a change of the type of fluid - Speak to the local dealer and parts dept - they will advise you on the updated fluid to use..

If that’s all OK then check all the electrical connections of the gearbox, remove each connector in turn and spray with contact cleaner. Check that the wiring to the gearbox is in good condition with no chafing or frayed wire

Customer: replied 3 years ago.

Thank for all these tips.


I don't think i'll be able to do all this though as i am not a mechanic..




Expert:  Matt replied 3 years ago.
Hello John


however the air leak test is pretty easy to do

if you open the bonnet and loacte the large plastic box that houses the air filter the air flow meter is jsut after that and forms part of the air intake pipework that runs back to the engine

a visual inspection from here can often spot a cracked or leaking hose

also if you really don't fancy tring this then any garage can tackle the job in under an hour

what I'd suggest is to locate a BMW specialist in your area and ask them about the issue, form your description I think we're talking abotu an hours labour

their labour rate will be a lot lower than the dealers but you'll get the same level of expertise

if you let me know your wherabouts I'll try and reccommend someone
Customer: replied 3 years ago.

Thank you...Location...Ealing braodway, w5 3ta

Expert:  Matt replied 3 years ago.
Hello John

try these firms