Intermittent top tapping G230 petrol

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Jdring
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Location: South of Oxford, UK. 87' 230GE SWB Manual, 89' 230GE SWB Auto, 2012 G350Bluetec LWB
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Here is one for you experienced mechanics.

I have a 230GE which has tappet noise on one cylinder, sounds like #3, which is intermittent.  It feels like oil circulation as it comes and goes.  It came on more in the winter and is less the more it is used.   It doesn't seem to be linked to engine temperature.  It does seem linked to cornering.  Oil was mildly low and topped up with a litre to the max line

I am wondering if it could be a cracked rocker which works it way intermittently into a good place and then slips out of position?  But that is complete guesswork.  What experience do you all have with this?   If it was oil pump, it would probably affect lube to all rockers?

Just wondering before I put it into a shop to investigate.

 

 

 

Arnie
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Re: Intermittent top tapping G230 petrol

 

Hello,

If you have an M102 engine, as in the W463, then the issue may be a sticking hydraulic tappet. This might be cured by running a synthetic oil, such as Mobil 1 0W-40, which has a high concentration of detergents, or using an engine flushing oil followed by an oil change.

If you have the older, M115 engine (as in the W460, you might wish to first check the valve clearance and adjust if necessary.

 

Jdring
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Location: South of Oxford, UK. 87' 230GE SWB Manual, 89' 230GE SWB Auto, 2012 G350Bluetec LWB
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Re: Intermittent top tapping G230 petrol

Thanks.  It's an 89 W460 engine, and if the tappet/valve clearance was wrong I don't think it would come and go just like that.

Giving the engine some revs doesn't help at all, suggesting it is not a weak oil circulation pump.  Maybe the valve seat/fixing is moving about if that is possible.  Perhaps a threaded retainingn bolt?

Arnie
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Re: Intermittent top tapping G230 petrol

It could be a partially-blocked oil spray bar not properly lubricating one of the tappets or a loose screw, as you say, but I think it's no use guessing.  If it sounds like a tappet noise from No.3, just remove the valve cover and check.