m a x i m u s

Once in a while, my engine will make a noise right before firing up. Sounds like when a car is stalling out, you know, that clunker clunking sound. Same sound when a car has run-on. But it only happens for a nano second and then the engine starts. Basically, I don't get that crisp engine fire up, feels sloppy, if that makes any sense. This happens at random times, even after running the car and then shutting it off for a few minutes and then starting it again. What can this be? Could it be a bad battery?

HBC350

Sounds like a momentary instance of spark knock or detonation. Maybe an injector bleeding down into one cylinder while engine is off.

Could also be a loose flywheel? Although unlikely, I've seen it before on other cars. The old Porsche 964's (totally different flywheel design) used to make some hallacious racket when their dual mass flywheels started to grenade.

SROC276

Could be bad gas, or in my case a bad fuel check valve and fuel pump. That was happening before I started having misfires and the engine would shake. Could be a lot of thing but would suggest checking fuel pressures as a precaution. Hopefully not the same issue I ran into. Took a yr from those kind of start ups before I had bigger start up issues.

Merc63

Cam adjusters are going bad

m a x i m u s

Thanks, guys. Maybe it is bad gas. Maybe cam adjuster; I've had the left intake and exhaust adjusters replaced as well as the right intake adjuster, and the sound does come from the right bank, so maybe time to change the right exhaust adjuster.

Has anyone else had cam adjuster issues? A friend of mine who has an MB shop (not local to me) says the cam adjusters go bad frequently, but I haven't seen anyone posting about it here.

Merc63

Yes they go bad, I've replaced them. Should do them all not just one at a time.

m a x i m u s

I thought doing them all at once would be better as well, but this was all warranty work, so understandably, they replaced them as needed. How often are you seeing these needing replacement? 20k miles?

Merc63

Both m156s I had needed them around 60k km.

You might have loud lifters too. They can clack on startup hot and cold.

m a x i m u s

Thanks. Sounds about right. I had mine done at 32k miles, 35k and 50k. And now this one, presumably, at 52k.

rmt52

if what you hear is the same as what I hear every now and then, then I doubt it's the cam adjusters as I've had all four replaced and I still get that brief clunk noise on startup every now and then. very hard to predictably replicate the noise though.