Engine 850: B5234T/2.3/20v/T5: - End of tether - tapping problem?!

ozmorgan · Sep 7th, 2010, 22:25

Please forgive long post, I am on the brink of tears, or more likely the scrap yard:

'95 850 T5, nasty tapping from top LHS of engine in time with revs. Audible in cabin under acceleration. Equally loud hot and cold, but only present when in Drive/reverse not neutral. When coasting, it goes away. Performance/ fuel economy good, (average 36mpg at 70mph around the M25 last week).

I have now spent a fortune and it's worse than ever : Tappets x 20, injectors x 5, tps, cps, lambda, MAF, fuel pump. Any suggestions as to what it might be I will investigate - at the try anything stage.

2 New symptoms, when accelerating at constant revs (eg auto box doing the work) the engine has started ever so slightly hunting - eg the revs will dip very very slightly momentarily. Barely noticeable. Also, when starting from cold/lukewarm it starts but sounds like it's going to die, revs hunting between 800/1100 and sounding rough as hell. Revving briefly to 1500 cures it.

If the ecu is allowing pinking to occur, after 5 months would the engine still be running?! It has been getting worse as it has gone on. Could the ecu itself be knackered?

Otherwise, any ideas? The car is facing extinction, despite the vast quantities of fine parts it has consumed!

Shortstuff · Sep 7th, 2010, 22:40

Only time I've come across the hunting problem was on a Primera and it turned out to be the MAF and Lambda sensor but as you've changed those along with other sensors on the car I'd say it points to the ECU itself

but can't say for sure

The tapping a strange 1 too. It probably sounds silly but have you check the oil level and grade (I'm going to run and hide under the sofa for a min

) or I'd be thinking it could be the cams as yet again on an old Primera of mine I had a tapping sound like you've described and that only happened when the engine was idling

Hope thats of some help and sorry if it sounds like stating the obvious with the oil

strbryan · Sep 7th, 2010, 22:50

I would suggest that it could be a bearing "shell" has gone...

Have you dropped the oil to see if there is any metal fragments in the oil?

ozmorgan · Sep 8th, 2010, 08:36

Thank you for those suggestions -

If the ecu is at fault would it throw a warning light?

The MAF sensor and Lambda sensor were a used pair, (though recently replaced on someone else's car) As such, they are still in the questionable zone.

No worries, the 'is the oil right' question is always the place to start! The oil has been changed a couple of times since it started tapping, to no avail. It did not even improve it. I always use 10/40 Magnatec.

Can the cams wear beyond the point of the tappet compensating for it? I stupidly did not measure them up when I changed tappets.

When I have been changing the oil I haven't noticed any metal, but then I haven't been looking for it - I'll drain it through a sieve and see what comes up. Once it is drained I'll drop the sump and rod caps and hold my breath.

The car has had regular oil changes and relatively gentle use, it will be upsetting if a shell has failed. Would there be any other tell tales (smoke etc) if that is the problem?

Oli · Sep 8th, 2010, 08:52

Hi,

This is a long shot, but very easy to try:

I think you mean that the noise is only present when you're driving and not when revving the engine in neutral. So:

Remove the centre cap on both front wheels to expose the centre nut. Tighten both nuts up. Go for a drive.

fingers crossed.

Oli

ozmorgan · Sep 8th, 2010, 09:32

OH MY GOD IT'S FIXED!

After only 6 months, 5 injectors, 20 tappets, a potentiometer, flywheel position sensor, MAF sensor, Lambda sensor, fuel pump, fuel filter, spark plugs and leads, dizzy cap and turbo boost valve, it is no longer tapping.

The camshaft position sensor was knackered.

lyron · Sep 8th, 2010, 18:53

well done, glad you got it sorted in the end,hope you have some fun now instead of grief. lynda & ron.

ozmorgan · Sep 8th, 2010, 21:31

Spoke too soon. Am most definitely crying (it's the onions I tell you)...

Tapping has come back when cold. Goes a bit when hot, but give it any lick and it returns.

Definitely improved/reduced by new cam pos. sensor.

If the knock sensors were knackered would it throw up a warning light? Equally can the ecu get muddled as to what the correct mix is? When totally coasting at 30, the mpg doesn't go above 60mpg, which makes me think something isn't doing its job. If anyone with a working car could check that against their's I'd be hugely grateful.

It's becoming clear that she no longer enjoys life and wishes for a quick dispatch.

Sep 7th, 2010, 22:25	#1
ozmorgan Junior Member Last Online: Aug 5th, 2015 21:40 Join Date: Jun 2009 Location: Oxford	End of tether - tapping problem?! Please forgive long post, I am on the brink of tears, or more likely the scrap yard: '95 850 T5, nasty tapping from top LHS of engine in time with revs. Audible in cabin under acceleration. Equally loud hot and cold, but only present when in Drive/reverse not neutral. When coasting, it goes away. Performance/ fuel economy good, (average 36mpg at 70mph around the M25 last week). I have now spent a fortune and it's worse than ever : Tappets x 20, injectors x 5, tps, cps, lambda, MAF, fuel pump. Any suggestions as to what it might be I will investigate - at the try anything stage. 2 New symptoms, when accelerating at constant revs (eg auto box doing the work) the engine has started ever so slightly hunting - eg the revs will dip very very slightly momentarily. Barely noticeable. Also, when starting from cold/lukewarm it starts but sounds like it's going to die, revs hunting between 800/1100 and sounding rough as hell. Revving briefly to 1500 cures it. If the ecu is allowing pinking to occur, after 5 months would the engine still be running?! It has been getting worse as it has gone on. Could the ecu itself be knackered? Otherwise, any ideas? The car is facing extinction, despite the vast quantities of fine parts it has consumed!

Sep 8th, 2010, 08:52	#5
Oli VOC Member Last Online: Mar 8th, 2016 14:28 Join Date: Jan 2006 Location: Sevenoaks View Photos By: Oli	Long shot Hi, This is a long shot, but very easy to try: I think you mean that the noise is only present when you're driving and not when revving the engine in neutral. So: Remove the centre cap on both front wheels to expose the centre nut. Tighten both nuts up. Go for a drive. fingers crossed. Oli __________________ V70R AWD Phase III (pure and simple, but now with OEM Strutbrace!) - Sadly broken. Needed replacement engine (B5244T2) - Almost fixed :-)! 850 2.5 10v CD (home for lost toys - brilliant and trusty car) XC90 T6 AWD - boy it was fun in the snow...

Sep 7th, 2010, 22:40	#2
Shortstuff Senior Member Last Online: Dec 5th, 2013 17:48 Join Date: Dec 2009 Location: carlin how, saltburn by the sea	Only time I've come across the hunting problem was on a Primera and it turned out to be the MAF and Lambda sensor but as you've changed those along with other sensors on the car I'd say it points to the ECU itself but can't say for sure The tapping a strange 1 too. It probably sounds silly but have you check the oil level and grade (I'm going to run and hide under the sofa for a min ) or I'd be thinking it could be the cams as yet again on an old Primera of mine I had a tapping sound like you've described and that only happened when the engine was idling Hope thats of some help and sorry if it sounds like stating the obvious with the oil

Sep 7th, 2010, 22:50	#3
strbryan I've Been Banned Last Online: Nov 2nd, 2016 18:20 Join Date: Nov 2006 Location: Coppull View Photos By: strbryan	I would suggest that it could be a bearing "shell" has gone... Have you dropped the oil to see if there is any metal fragments in the oil?

Sep 8th, 2010, 08:36	#4
ozmorgan Junior Member Last Online: Aug 5th, 2015 21:40 Join Date: Jun 2009 Location: Oxford	Thank you for those suggestions - If the ecu is at fault would it throw a warning light? The MAF sensor and Lambda sensor were a used pair, (though recently replaced on someone else's car) As such, they are still in the questionable zone. No worries, the 'is the oil right' question is always the place to start! The oil has been changed a couple of times since it started tapping, to no avail. It did not even improve it. I always use 10/40 Magnatec. Can the cams wear beyond the point of the tappet compensating for it? I stupidly did not measure them up when I changed tappets. When I have been changing the oil I haven't noticed any metal, but then I haven't been looking for it - I'll drain it through a sieve and see what comes up. Once it is drained I'll drop the sump and rod caps and hold my breath. The car has had regular oil changes and relatively gentle use, it will be upsetting if a shell has failed. Would there be any other tell tales (smoke etc) if that is the problem?

Sep 8th, 2010, 09:32	#6
ozmorgan Junior Member Last Online: Aug 5th, 2015 21:40 Join Date: Jun 2009 Location: Oxford	OH MY GOD IT'S FIXED! After only 6 months, 5 injectors, 20 tappets, a potentiometer, flywheel position sensor, MAF sensor, Lambda sensor, fuel pump, fuel filter, spark plugs and leads, dizzy cap and turbo boost valve, it is no longer tapping. The camshaft position sensor was knackered.

Sep 8th, 2010, 18:53	#7
lyron Premier Member Last Online: May 4th, 2020 10:57 Join Date: Nov 2009 Location: ibstock liectershire	well done, glad you got it sorted in the end,hope you have some fun now instead of grief. lynda & ron.

Sep 8th, 2010, 21:31	#8
ozmorgan Junior Member Last Online: Aug 5th, 2015 21:40 Join Date: Jun 2009 Location: Oxford	Spoke too soon. Am most definitely crying (it's the onions I tell you)... Tapping has come back when cold. Goes a bit when hot, but give it any lick and it returns. Definitely improved/reduced by new cam pos. sensor. If the knock sensors were knackered would it throw up a warning light? Equally can the ecu get muddled as to what the correct mix is? When totally coasting at 30, the mpg doesn't go above 60mpg, which makes me think something isn't doing its job. If anyone with a working car could check that against their's I'd be hugely grateful. It's becoming clear that she no longer enjoys life and wishes for a quick dispatch.

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