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VW Polo 1.2 3cyl BMD 2005 - High oil consumption after head rebuild - Unresolved #

Posted by David Evason on October 30, 2013, 11:57 pm

Year of Manufacture *: 2005
Engine Size and Code *: 1.2 BMD

Good evening gentlemen,
Just after a bit of help with a VW Polo that ive got in.
Usual story of low compression on two of the cylinders, so head off to engine shop and they confirm that valve guides are shot.
Now head back on, new timing chain and full service and the car back with customer.
Two weeks later vehicle is back in with a misfire, whiteish smoke and slight oil smell.
Spark plugs out, I noticed that all of them were contaminated with oil. Compression test all good at around 250 psi each. 17"Hg of vacuum. No oil on dipstick.
Plugs cleaned up, refitted and running quite sweet. Now what I noticed is that if I pull off the oil filler cap its a bit tighter than usual and comes off with a pop then the misfire counters start rising as it runs rough.
What im wondering is is have I missed anything obvious when rebuilding it that can commonly happen if your not familiar with this engine ?
I'm thinking that I may have a problem with rings aswell.
Test plan for tomorrow is a leak down test.
The main problem I've got is I think the customer thinks im trying to pull the wool over their eyes !
Thanks, Dave

Re: vw polo 1.2, 3cyl - High Oil Consumption After Head

Posted by James Eardley <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=ukat3143' width='330' height='300' border=0 style='border:none;'> on October 31, 2013, 9:31 am, in reply to "vw polo 1.2, 3cyl - High Oil Consumption After Head"

Hi David

Do you mean the oil cap is hard do get off due to it being sucked back on?

If so I would look into the PCV system... There should be a slight vacuum in the sump but not full manifold vacuum.

This could also explain how the oil is getting into the cylinders too.

James

Re: vw polo 1.2, 3cyl - High Oil Consumption After Head

Posted by Alan Ganter <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=ukat3444' width='330' height='300' border=0 style='border:none;'> on November 4, 2013, 11:25 pm, in reply to "Re: vw polo 1.2, 3cyl - High Oil Consumption After Head"

Did the exhaust valve guides get replaced ?

Re: VW Polo 1.2 3cyl BMD 2005 - High oil consumption after head rebuild #

Posted by Alan Ganter <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=ukat3444' width='330' height='300' border=0 style='border:none;'> on November 4, 2013, 11:30 pm, in reply to "VW Polo 1.2 3cyl BMD 2005 - High oil consumption after head rebuild #"

Sorry just reread the post and i see the valve guides were replaced. Im guessing this is burning oil after it has warmed up. In which case the oil control rings are likely to be siezed into the pistons. There are no rebuid specs for the bottom end. And VW official line is a new bottom end.

Re: VW Polo 1.2 3cyl BMD 2005 - High oil consumption after head rebuild #

Posted by Russell Davey <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT2748' width='330' height='300' border=0 style='border:none;'> on November 5, 2013, 10:56 am, in reply to "VW Polo 1.2 3cyl BMD 2005 - High oil consumption after head rebuild #"
Andy Davey

Hi David, had this issue a few times with these 3 cylinder engines (AWY's mainly). 100% its the rings.

Tell your customer that you'd done such a good job making the top end of his engine 'gas tight' that it has now highlighted a deficiency in his bottom end which you weren't to know about unless you had fully dismantled his engine the first time around $$$$$$ (obviously the clever #### may question why you never suggested this at the time of the rebuild, so tread carefully)

Our main line of work is cylinder head related and every single job we take on, we always suggest to the owner that the pistons are removed for inspection. 95% of them turn it down but at least my arse is covered.

Not 100% sure about the BMD's, but parts are available for the AWY's and can be rebuilt (even though VW say otherwise)PM me your reg no if you want me to check parts availability.

Russ

Re: VW Polo 1.2 3cyl BMD 2005 - High oil consumption after head rebuild #

Posted by David evason <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=ukat3433' width='330' height='300' border=0 style='border:none;'> on November 5, 2013, 10:24 pm, in reply to "Re: VW Polo 1.2 3cyl BMD 2005 - High oil consumption after head rebuild #"

Evening gents, thanks for the replies,
James the oil cap has a very slight vacuum on it if you like but it's not hard to get off like the vauxhall type fault.
I've checked out the PCV and it's all working correctly and I found some info that confirms that these will run rougher with the oil cap off.

Alan your quite correct it's after it has warmed up about 10/15 mins later it will start to misfire. I was starting to think the same thing regarding the rings stuck as the oil quality that I drained out was appalling.
I should ve really thought about this first !!!

Thanks Russell that's pretty much what I've explained to them but I told them that because of the low compression and the head fault that there was no way of me really finding that fault until it was 100% gas tight and if there was no fault found with the head then I would've looked to the rings anyway.

Does this happen to many of the 3cyl engines as I've had a corsa 3cyl that's pretty much bit me on the arse like this one has. It doesn't half make you question yourself sometimes.

I shall be in future making customers aware of potential problems !!! Another learning curve for me anyway !!

I wouldn't mind but I did this job dirt cheap as well trying to help her out !

I think she's going to trade it in anyway now. I'll keep you all posted !

Thanks again for the advice

Re: VW Polo 1.2 3cyl BMD 2005 - High oil consumption after head rebuild #

Posted by Matt Seabrook <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=ukat3462' width='330' height='300' border=0 style='border:none;'> on November 9, 2013, 8:45 am, in reply to "Re: VW Polo 1.2 3cyl BMD 2005 - High oil consumption after head rebuild #"
Matt Seabrook

It's a long shot but has worked for me more than once. Try a Forte clean and protect and gas treatment with another oil change. The customer may have made the decision to trade it though. Only thing is the bottom end may be so bad due to lack of maintenance that its *&~"ed now anyway. Best of luck with the car and not loosing a customer.

Unresolved #

Posted by David evason on November 9, 2013, 9:27 pm, in reply to "Re: VW Polo 1.2 3cyl BMD 2005 - High oil consumption after head rebuild #"
Edited by board administrator November 15, 2013, 2:22 pm

Thanks Matt,
I did suggest this option was available regarding the treatment but as it was not a 100% fix then they were not willing to spend anymore money on it. She did realise that due to the lack of servicing that this may have contributed to the bottom end failing.
After a clean up of the plugs the vehicle was collected and taken to the nearest car superstore !

Can this be listed as a fixed or unresolved please.

Thanks for everyone's input .
Dave

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