my 92 500sel knocks when cold in morning start. it knocks for 15 seconds until oil pressure come up to 3 and knocking ends. I changed oil with
(0w40 mobil1) filter and oil pressure sender. I heard there is a valve in oil system that keeps oil in system once car shut. Any info about that valve or any ideas how to stop knock is apreaciated
Thank you
Victor

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1999 ML430 Silver 135k ml
Smoked LED taillights, Alpine in-dash DVD player, 12" sub, Pioneer components, 2 amps, 4200k HIDs, ML55 headlights, 20" rims, mirror LED blinkers

SOLD. 1996 E320 145k ml. Burgundy

SOLD but miss it everyday 1992 500sel Black
Chime buzzer mod,Alpine CD/MP3 player with stock amp,Euro headlights,S600 grill,20" rims, BEST CAR EVER!

SOLD. 1990 300E White
187k ml,smoked tails,Euro headlights,17rims,Intake,12" sub in first aid kit,alarm/autostart,buzzer mod

a knock (deep) or a tap (higher pitch)?

if it is more of a tap it may just be the valve adjuster, which is not to worry about and often can be solved by a change in oil type.

a knock can be serious.

main bearing noise is not a good thing.

tom w

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Diesel loving autocrossing grandpa Architect. 82 240d, 83 300TD with five speed, 03 Dodge 3/4 ton with cummins six speed; I have had about 33 benzes. I am building a 39 Studebaker Coupe Express pickup street rod at the moment in which I plan to install a 617 and a five speed manual.....or a 64 stude v8.