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Mike, Technician
Category: Mazda
Satisfied Customers: 39198
Experience:  Tech Expert
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Hi there. I have a 2007 Mazda 6 Diesel 143bhp. There has been

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Hi there. I have a 2007 Mazda 6 Diesel 143bhp. There has been a tapping noise from the engine for some time now, but only when under acceleration. I brought it to my main dealer and he said that the noise is coming from the vacuum housing and that part alone would cost @ 700! "Its still working ok, so you could keep going until it eventually goes and then get it replaced", he said!? (The DPF light has been flashing for a while and he said that there was a build up of soot so he did a forced re-gen. All warning lights are off now which is fine, but the tapping noise is even louder now!?). This just doesn't seem right to me. Ok, he is probably trying to save me the cost, but surely an audible 'tapping' noise from the engine must mean something is wrong?? Any ideas please as I am not sure what to do next?? Thanks.
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Hi .

Okay a tapping noise could be many things .

Please do the following so we can determine what the tapping is .

First check the engine oil is on the top level .
Run engine until you have it at operating temp.

Then raise the engine rev's to 3000rpm and hold for 10 minutes ,does the tapping get quiter or stay the same ,does it get louder and faster with the engine speed .

Rgds Greg
Customer: replied 3 years ago.

Hi Greg,

When the oil is at temperature, the oil is at an acceptable level, i.e. there is the 'low' mark, the 'top' mark and above the top mark 'x' its halfway between 'top' and 'x' (apparently once it reaches this you change the oil). I have run the engine and firstly, the tapping is only really audible when the car is under load and not when idling. Sometimes its louder than other times and this can happen instantly. The sound of tapping sounds more like 'pinking' when outside the car. When I ran the car as you asked you could hear the tapping but much fainter than when under load. Hope this is not too confusing. Thanks, Milo

Hard to say . sorry have to opt out and open this for anmother expert .

Rgds Greg
Customer: replied 3 years ago.

Ok. Thanks, Milo.

Hi Milo,
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Customer: replied 3 years ago.

Hello, I don't mind waiting another day or two, but no longer.Thanks, Milo.

Hello and Welcome...

My name is ***** ***** I have been asked to help you from here -

Before I lay anything down here... you said the dealer said the noise was coming from the "vacuum housing" -- Is this the one that works the brakes / engine vacuum etc...? Im just trying to be sure as obviously I cant see it / be there..?

Too - he has evidently spent some time checking this - so thats what I need to go off...rather than just dismissing we need to be sure on that --

Also - what mileage has the car done?

Does it blow excess smoke at all out the exhaust when this happens? If so - what colour?

Rgds - MIKE..........................................
Customer: replied 3 years ago.

Hi Mike, just reading your message now. I didn't talk to the technician directly, but the secretary who read it off the sheet. I must clarify as it actually says the 'vacuum pump' is where it was coming from. It sounds like a tapping from inside the car and bad 'pinking' from outside. I have been under the bonnet with the plastic cover off the top of the engine and with someone gently revving the engine, it sounds to me it is coming from the top of the engine. The car has 85,000 miles. No smoke ever coming from the exhaust. (I had changed the oil and filter last year and my motor factor gave me what I was told was the right spec 5w30 AECA A1/B1. The DPF light was flashing far a while recently and then the engine management light came on and it went into limp mode. When I brought I to the dealer he said it was a built up of soot and did a forced regen. All ok then, but he didn't question the oil. I found out later that it should only be 5W30 AECA C1 only as this is low ash oil specifically for the DPF. Just changed to this oil don't know whether this would make any difference?

Driving today, it seems that if the car is driven gently, there is little or no tapping, if its driven hard, the same, but I does make the noise when driven normally??.

Hope this helps. Milo.

Customer: replied 3 years ago.

Hi Mike,

Did you receive my last email on 08/09? If so, any ideas??

Hi again...

This is MIKE - My apologies as I was off yesterday...

Milo, I think you are on to something there with the oil - for sure you had the wrong oil before - this does need the low ash oil... and too - this could well be causing the valve train / tappets to go sticky and not operate properly causing the tapping.

Now that you have changed the oil and you say its not as bad it could well be freeing up in use with the proper oil - I would see how it goes over the next few days ( mileage dependent ) and you may well find it goes altogether.

IF not - then I would suggest have the tappet clearances checked - these are the manual adjustable type on this engine -

IF you still have the issue after that - then the vac pump will need further investigation - but from what you have described, I would suggest to work through as above on this....

All the best Milo -

Im very pleased to have helped you - Do let me know if you need anything more --

*** Meanwhile - - >>>> Please do click on the "OK/ Excellent ratings" for me - Thank you in advance for that...

You can and are most welcome to get back to me anytime you might need - clicking the OK ratings does not close you out at all..

Kind Rgds, MIKE.
Mike, Technician
Category: Mazda
Satisfied Customers: 39198
Experience: Tech Expert
Mike and other Mazda Specialists are ready to help you
Customer: replied 3 years ago.

Hi Mike. Thanks for the reply. Somehow I don't think it's the valves. The noise seems nonexistent at idle and when driven hard! Its seems to be getting worse like bad pinking. I'd like to know what the vacuum pump is used for and why it would be tapping/rattling? (according to the Mazda technician). I read on an online forum that vacuum pump is oil pressure fed from a port in the centre of camshaft. Sometimes the injector washers leak and blow carbon into the rocker box.

Carbon gets washed down and picked up blocking the oil strainer.

The sump should be dropped and the strainer should be cleaned every 40k miles! maybe I'll try this? Milo.

Hi there Milo -

Thank you for your reply... No not the actual valves Milo - rather the tappets - when I said valve train , thats what I meant sorry.

It could be pinking - a diagnostic test is best for that - as the knock sensor circuit controls that and that should pick that up if thats at fault...

The vacuum pump is used to provide power to various vacuum powered circuits- but mainly the brake servo unit... You will see the pipe going from it to the brake unit -and on some version dependent, you have smaller micro pipes branching off - usually to the turbo valves and so on.. The vacuum pump is mechanical inside and when worn - much like an oil pump, it can clatter...or start rattling as some would call it. What I would suggest there Milo would be to - while its doing it , place a long screwdriver to the vac pump - on it.. and the other end in your ear - firmly placed. If you hear the noise accentuated, then you can be sure its that -- it works like a Docs stethoscope !

In the case of the need for the sump to be dropped to clean a clogged oil strainer - first signs of the need for that are the oil pressure light staying - or coming on in use... so I wouldn't be worrying about that really if thats not happening,.

I hope that helps you further Milo let me know how you get on.

Best Rgds, MIKE.
Customer: replied 3 years ago.

Thanks for that Mike.

I was always under the impression (or was told by a dealer) that modern cars didn't 'pink" anymore as the ecu etc. Anyway, now you have explained the vacuum pump, it's purpose and how it goes wrong it makes more sense, (I have noticed that the ABS when driving on the motorway is more 'pronounced' recently, ie rather than a gentle oscillating feeling in the break pedal when applied, it feels more like there is a slight buckle in the wheel/s (even though there is not). Also, the engine has started to 'hunt' at idle, i.e. it drops revs for a second or two and then goes back to normal for about 4 seconds and repeats...

It would be great to do the test with the screw driver you mentioned, but the 'pinking/rattling' sound only really happens when you are driving (i.e. have the engine under load) and not all the way through the revs either). I'll try to get someone to gently rev the car and see if I can get the noise to happen and try the test.This is really frustrating! Thanks again, Mike.

By the way, Mike, Iam new to this site. I have given (maybe prematurely) a good rating (would like to give higher), I assume that this means you will get paid etc, is there anything else I need to do?

Hi again Milo -

Thank you for your reply...

What you have been told re pinking is not fully true at all... that was the intention...but its not an exact science.. pinking is still a problem with some - albeit not as bad as it was. But the timing is Ecu controlled yes... but that doesn't make it infallible ;)

I do think that your issues may well be with the vac pump - from here... but yes - thats a good idea to have a helper, try and test it that way... I should have suggested that !

Re the ratings - you can give the ratings when and as often as you like Milo - we appreciate all the ok / excellent ratings , as it helps us of course for our time etc.. So if you wish, you can click on the Excellent rating after you have this reply from me... if you do that - I thank you now ;)

All the best with the car Milo...

Kind Rgds, MIKE.
Mike, Technician
Category: Mazda
Satisfied Customers: 39198
Experience: Tech Expert
Mike and other Mazda Specialists are ready to help you