PeachParts Mercedes-Benz Forum - View Single Post - 500E still Racka Racka's on cold start up????

Mark Stetson · #18 08-31-2001, 12:47 AM

You are the greatest, Dwight! Thanks for your help. I noticed a drop in my hot idle oil pressure yesterday - before then it was 1.5 bar in drive at idle (500rpm), then yesterday it went down to 1 bar. I was afraid it was associated with the pressure relief valve, since I'm still hearing a little racka-racka (about half a second, intermittently now). A half quart of oil (Mobil 1 15W50), however, brought the dipstick up to just over halfway, and brought the hot idle oil pressure back to 1.5 bar. My low oil level sender never came on - I think it only turns on when the oil is down a quart, right?.

BTW, this might sound stupid, but I have the hardest time getting accurate readings off that dipstick. I check it in the morning, cold, on level ground. I bought a new dipstick 'cause the old one had a cracked top and wouldn't seat right, but the oil level still varies on the stick depending on how long I leave it "dipped" after I wipe it. I leave it in ten seconds now, and that gives me a consistent reading. If I just "plunge and pull", it reads a lot lower. Am I doing it right?

Now that simply adding oil solved my hot idle low oil pressure, I'm a lot less scared, but I still think I'll ask my service guys to drop the pan and check the pressure relief valve next time I bring it in. Maybe they'll find the right parts!

Stummala - most of the racka-racka victims hear it only when cold. Mine did a racka-racka, however, one time only after a three hour sit. It scared me! Usually it takes more. The check valve is an easier deal - replace that first, I reckon, then keep going if you need to. Do a search here for more threads on this topic, in the Hot Rods forum as well as here in Tech Help.

Krasuskyp - The 119 engine in the 500E has both a check valve in the oil filter housing (accessible by pulling the oil filter housing) and a pressure relief valve in the oil pump housing (inside the oil pan). I assume that's the same for all 119 V8'S. The racka-racka that this thread addresses is caused, as I understand, by low oil pressure to the variable valve timing gear, which is located where Stummala describes his sound. Does your 2.3-16 have similar valve gear? Does that imply that Cosworth carried over a rare German design error?