PeachParts Mercedes-Benz Forum - View Single Post - Need help! 617 N/A rattling louder after head gasket replacement

Jarod · #9 10-07-2022, 11:51 AM

My Blue car had a weird sound for a while, turned out to mostly be the cam lobes wearing down and causing the rocker arms to hammer into stuff and rattle around, turns out it was run low on oil due to a turbo drain hemorrhaging oil.

I swapped the cam out, which massively quieted it down, but there was a lingering rhythmic knock sound. I replaced the injector nozzles, and got them all popping within maybe 25psi or so of eachother, then installed them, it had a much louder combustion clatter, which faded a little after running it for a few hundred miles, noise is basically normal I'd say now, and I've driven it thousands of miles with no issues.

Backstory aside, my engine has a little rock at idle like yours does in the video. I have suspected that I need to check my injectors again, or I might have a weak cylinder, or the cam wear has caused something else to have an issue, perhaps one of the plungers/barrels in the injector pump is scored from the oil starvation event.

I wish there was a good way to measure IP output on the car, test if all 5 cylinders are getting equal fuel, but I'm unaware of any way to do that. Maybe a infrared camera and look at the exhaust to see if one hole is colder or hotter than the others?

I wonder if the head gasket going bad on the engine you're working on could have damaged something else, coolant got somewhere it shouldn't or is it possible it hydrolocked even a tiny bit and bent a rod?

A compression test while not terribly fun might give some ideas.
Sorry to ramble, I am curious what the end result is, as it might help me track down my rhythmic rocking that a rack damper did not help.

I feel like that little rock indicates one cylinder is either contributing more than the others, or possibly less.