engine rattle

due to a dicky MAF sensor, my car will regularly run badly.

when starting from cold, it seems to run on three cylinders for about a minute, then splutters and runs perfectly fine with no other signs of ill health.

however, while waiting for the engine to come right, it makes a chug, chug, chug noise. between the chugs, theres a low clack type noise. i'm a little worried about this. the last time i heard this was in an engine with a knackered big end bearing. it also makes the same noise on the last couple of revs after switching the ignition off.

two seperate bmw indies have said the engine fine, but not in the context of this clacking noise.

my brother reckons it could be a worn engine mounting. any thoughts?

excluding the chugging, it is noise free when cold. it does only seem to be the motion of the engine causing the rattle.

as a further development, it actually seems to be the underneath of the car that the noise is coming from. it seems to be the driver's footwell, actually. i had my back box changed recently and it didn't do much to change the exhaust volume. could it be the cat maybe??

another possibility, but it may not explain the loud exhaust hum.

would a knackered cat rattle? i think it's time to go back to the exhaust centre...

 

(how bout a more specific question on exhausts, having done a little poking on the forum- assuming i have the infamous cat heatshield rattle, has a concensus been found on the solution. Removal??

Edited by beemerfool

If the engine is stalling it will move side to side quite a bit. This along with a "soft" mount could be causing the exaust or something to bang of the bunder body.

Disconnect the MAF if you think its at fault. The car will run smooth enough with out it. If the problem still exists with the MAF disconected then its something else.

Mick

absolutely right. pressed clutch, noise went away. switched off engine, no rattle. what does this mean, is there a repair in order??

thinking about it now i'm a little confuddled because on one hand it could be exhaust related because i can hear rattling when going over rough roads and the exhaust sounds boomy. on the other hand, it most definitely disappeared when the clutch was pressed.

(peter, i plan to get the MAF sensor as soon as reasonably possible but i'm convinced that the rattle is not direcly related and the chugging is just highlighting something that's already there. i have no reason to believe this other than the rattle sounds similar. i may end up eating humble pie, though)

ps. i'm assuming nothing yet til i can get the car looked at, but, if it was a layshaft, how can it be rectified?

Edited by beemerfool

beemerfool wrote: due to a dicky MAF sensor, my car will regularly run badly. when starting from cold, it seems to run on three cylinders for about a minute, then splutters and runs perfectly fine with no other signs of ill health. however, while waiting for the engine to come right, it makes a chug, chug, chug noise. between the chugs, theres a low clack type noise. i'm a little worried about this. the last time i heard this was in an engine with a knackered big end bearing. it also makes the same noise on the last couple of revs after switching the ignition off. two seperate bmw indies have said the engine fine, but not in the context of this clacking noise. my brother reckons it could be a worn engine mounting. any thoughts?

Hi,

I'm sorry if this sounds cruel...

You say that 2 indies have said that there's nothing to worry about...
You say you have a faulty MAF...
You then ask about a noise...

Hmmmm...

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1. Fix the MAF
2. Why 2 indies???
3. If one of them will take you as a customer again - ask them about your rattle...

------------------------------------------------------------ ---

When you have someone you trust - stay with them...

My twopence worth...
BMWcare
bmwcare@eircom.net

beemerfool wrote: due to a dicky MAF sensor, my car will regularly run badly. when starting from cold, it seems to run on three cylinders for about a minute, then splutters and runs perfectly fine with no other signs of ill health. however, while waiting for the engine to come right, it makes a chug, chug, chug noise. between the chugs, theres a low clack type noise.

You state that the "chug, chug, chug" and a "low clack" while WAITING FOR THE ENGINE TO COME RIGHT...

Maybe I'm overstepping the mark - but YOU STATE that the noise is there when the engine is not running right... When the "chugs" stop - does your noise stop?

Also, you state that the "poxy MAF" is faulty. If it is - change it.
Never mind the €1k you spent. If you leave a faulty MAF like that it will eventually destroy your CAT and possibly sensors... Your money, decide yourself.

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If it's insulting your intelligence, I apologise. But your post would lead anyone looking at it logically to deal with the MAF first.

Regarding the missed brake disks etc. - that's totally out of order, it should have been seen.

In addition, if the people dealing with your car are so incompetent - how do you know the MAF is "dicky"?

BMWcare

Suit yourself...

The proper way to diagnose your RATTLE is to eliminate unnecessary vibrations. As you're not looking at it like that. We differ.

Just wondering...
Nah, nevermind - you probably will get all upset about spending money ;)

BMWcare

it's not the maf

the noise goes when you press the clutch

clear?

differ all you want but the car is only worth a couple of grand. What really makes no sense is to throw good money after bad. if the gearbox is falling out of it, it actually makes more sense to scrap it. what's the point of sending a brand new maf sensor to the scrapyard?

bmwcare, we're going round in circles here, could you do me a favour and read all the previous posts so you can gain a more rounded view of this topic. if you have any opinions or advice on my newfound gearbox/ clutch issue i'll be glad to hear them. i would ask that if you don't, please refrain from turning an autocondriac's desperate attempt to gain an insight into what may only be a common bmw "ism" into an opportunity for childish bickering. we all rely on these forums as a place to increase our knowledge of our chosen cars.

i have had more than my fair share of misfortune up to and including what is now my ninth car. i could write books on the trials and tribulations i've gone through and i'm affronted that you should sink to the point of insinuating that i'm too miserly to fix the sensor. To me, there's no such thing as don't bother fixing it, sell it on before it gets worse or pretend the problem's not there. every car i've sold on has been tip top. i've had re-sprays, engine re-builds, gearbox re-builds, windscreens, shocks, clutches, exhausts, chassis re-aligned, and so on. you name it, i've had it done. i have the money for all the maf sensors in the world, but not if the car is bound for the scrapyard. 

what's most valuable to me is my time- i certainly don't have time to start changing parts on a speculative basis, especially when i'm so sure of the issue. i have had gearbox/ clutch problems in the past. i've known plenty of mechanics who will tell you 'go away and try that' only to re-visit the same problem repeatedly. this is far more frustrating than the original problem and the expense.

if the gearbox isn't knackered, or is fixable, the sensor will be done then, not before i know whether or not the car has a fatal fault.

i am not determined to have the last word here but i will not humour any more squabbling. afterall, i am the only one here who has scrutinised the car and you have to give me some credit that i know what i'm talking about.

for your convenience i will consider this issue closed and i won't be posting in this topic again.