I think it's Dwight Hinton to whom we owe the blame for coining this phrase. I can't take credit. I'm not a mechanic, just a happy and interested owner who's looking after his car. Therefore, my experiences are only relevant to the models I've owned - 300E's and my newly-beloved 500E. The racka-racka is specific to the 500E's 119 V8 - no indications on either my wife's '93 300TE or the '89 300E we traded for it. Having said that - my racka-racka was first diagnosed as a loose timing chain, which made sense at 104K miles. I had it replaced, with the usual tensioner and rails, but the noise was still there. That's when I started following this thread so closely. In fact, next having replaced the check valve in the oil filter housing, I still hear the noise infrequently - like when I skip a day driving the car (stone cold and plenty of time to leak back through the check valve). So I'm thinking of having the pan dropped next time and the relief valve serviced/replaced, like Dwight did.
Krasuskyp - The check valve in the 119 V8 engine is a large-ish spring plunger mechanism (1"+ bore) that is in the oil filter housing (the base to which the cover is screwed). It's not part of the oil filter cartridge. And I can't imagine a company MORE concerned about their reputation right now than Firestone! I'll bet they do just fine. Whatever it takes, so long as you change your oil often. I use the EZ Lube down the street for my Tahoe - they use Mobil 1 too. I just don't expect them to stock the oil filter for my MB's. They say they will happily install a filter if I bring it in. Maybe Firestone will do likewise for you! Just watch to make sure they don't bugger the threads.
So I think I'm on the proper path for my V8:
1 - Replace the timing chain, tensioner, and rails, as a preventive maintenance on high mileage engines.
2 - If the racka-racka keeps racketing, replace the check valve in the oil filter housing - there is a design upgrade that makes for a more reliable seal. It's cheaper than attending to the oil pump pressure relief valve. Dwight gives the info for this back up this thread.
3rd - If there's still a racket, or you just can't stop yourself from trying to keep your car perfect, replace the pressure relief valve at the oil pump. This requires dropping the pan.
I don't know that it's a given that all 3 steps will always be required. I've done the first two so far and most of the noise is gone. Dwight went to the third step and his noise is finally gone (hope it STAYS gone Dwight!)
This is a summary of actions on this thread and prior threads - read back up this one and search for others. The CD-ROM manual shows diagrams of the parts and assemblies, which are referenced more than once in these threads. May all our engines be quiet one day!
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