86 420SEL Light ticking noise from engine

[jodeven]

Hi,

Looking for some thoughts on potential cause and direction to pursue. My 86 420SEL, 90K miles has just developed a light ticking sound. Sounds like the noise is comming from under the valve covers. The ticking noise is variable in nature i.e comes and goes and soft and louder, however at it loudest I would say it is still fairly quite. My first thought was hydraulic valve lifters are collapsing thereby increasing lash and noise. The variable nature of the sound is why I thought this. However, after reading many posts on timing chains and camshafts, I wonder, if the noise is an early indication of fun times ahead.

I have been a professional auto technician for 15 years (Chrysler Products), however, no experience with Mercedes vehicles. So, I would say I probably could do any type repair.

Any ideas would be welcome

Thanks

Joe

[david s poole]

yes its lifters get some lucas h.d. oil additive 2 qts for your engine and the noise will go away.take off valve covers and replace gaskets and fit new oil tube kits to oil rail as insurance.while covers off check valve timing[chain stretch]and look at rails to see if they need replacing.

[gmercoleza]

Hi David, my 85 380SE has a similar intermittent light ticking - definitely from the valve train and definitely oil related as it is not present until the oil has warmed up. Can the M116 in this car also benefit from the things you suggested?

[Tomguy]

All m116 and m117 engines benefit from periodic cleaning of the cam oiler tubes, and replacement of the plastic bits at that time. Make SURE to replace those plastic timing chain guide rails on the top end of the engine - $40 in parts or $3000 in valvetrain rebuild - your call!

[86560SEL]

Oh... can the guides/rails be changed when just the valve covers are removed, or is it more involved than that? My 268K 380 has that ticking as well.

Originally Posted by Tomguy

Make SURE to replace those plastic timing chain guide rails on the top end of the engine - $40 in parts or $3000 in valvetrain rebuild - your call!

[jodeven]

Thanks for the info. Will try the Lucas oil treatment and report back.

Joe

[davestlouis]

My 420 has developed a slight tick, but it goes away when I turn off the climate control or put it on ECON, so I assume my A/C compressor is getting noisy.