Quote:
Originally Posted by Edmund
I got a 2001 W210 E240 automatic about 2 weeks ago. There was a tapping sound coming from the engine so I sent it in to have the valvelifters replaced. The mechanic replaced all 12 valvelifters and informed me that the engine is still making the tapping sound. He reckons this is due to the engine running at very high temperatures causing the top of the pistons to shrink. Now I have to decide between replacing all 6 pistons or buying a secondhand engine.
I know the alluminium tops of the pistons can be deformed due to very high temperatures. But how does this cause the tapping sound that sounds exactly like valvelifters...
Is this guy just trying to squeeze money out of me?
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I think he probably all ready has !! The mech should have been able to tell the piston noise from the lifters.
When the motor got too hot it has probably damaged the pistons.
When the pistons get too hot they expand too much & then deform as the bore does not expand as much. When the pistons cool back, they are out of shape & so piston noise. Does it breath a lot or use much oil? if not Just drive it!! fix the overheating problem first.
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1967 230-6 auto parts car. rust bucket.
1980 300D now parts car 800k miles
1984 300D 500k miles 
1987 250td 160k miles English import 
2001 jeep turbo diesel 130k miles 
1998 jeep tdi ~ followed me home. Needs a turbo.
1968 Ford F750 truck. 6-354 diesel conversion.
Other toys ~J.D.,Cat & GM ~ mainly earth moving
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