[martinlink]

Hey!

My 535d (same engine as 335d) has been ticking since october. We found metal slivers in the oil filter and decided to do a big end repair. Upon opening the sump, it turned out that one of the turbos had failed and bits of the journal bearing went through the oil pump and destroyed it.

Massive repair bill later (new turbos, crankshaft, rod and main bearings, chains+sprockets, oil pump and cooler, belts and pulleys etc etc) and the car is still ticking!
Tried replacing injectors without luck - still the same.

The knocking has a frequency of exactly half of RPM, so about 350 knocks per minute or roughly 6 per second.

Starting to wonder if it could be a damaged rod or piston? Or has lifter noise been documented on these at all? Car runs fine apart from the noise, compensations are almost equal in INPA. Noise is much louder on cold startups in current weather (deep in the negatives!)

Thanks for any input!

[kbsilver]

I'm not an expert but a frequency of 1/2 the RPM would typically correlate to something in the valvetrain as the cam runs at 1/2 engine speed. And it sounds like something like a valve tap.

Don't think it relates but I had a 540 with a dull knock a bit similar, 1/2 engine speed, the whole time I owned it (70K - 150K miles). Research indicated it was play in the vanos system which other than being annoying, was not detrimental. There were even stories of people rebuilding their vanos to eliminate the noise, only to have it return 20K miles later.

[martinlink]

Thanks for the reply!

I've heard the theory about 1/2 RPM being valvetrain related, then again Youtube is full of vids where burnt or cracked pistons cause a noise with the same frequency...

[Yozh]

Your belt system seems squeaky. Check those too. A failing harmonic balancer can produce knocking. I realize it does not support frequency theory but still should eliminate those possibilities. Other options are poorly seated injectors.

[martinlink]

The first video is from before the big repair - the pulleys and belts have been replaced by now and it's silent.
Injectors also replaced with new crush washers every time.

[BB_cuda]

I can’t support the following with evidence. I hear a tapping noise when our E70is cold for about first 2 minutes after startup. I listened closely and poked around and it doesn’t sound to be injector. I wonder if timing chain slap against cover could be a possibility as that’s the area where I centered down to. I hadn’t measured frequency but quite familiar with devices that can measure this. An accelerometer with output to spectrum analyzer would show these. I used to work in the industry that made these sensors and peripherals that work with them.

[martinlink]

So a few months ago the previous hard knocking was finally diagnosed as an overly worn engine block (cylinders out of round).

The fix of my choice was another rebuild using a cast iron block and crankshaft from a M57tü using the internals from my tü2 engine.

The end result was a nice, smooth, quiet engine, sadly riddled with fueling issues which ended up with not one but two R90 pumps and 4 replaced injectors until it stopped throwing low rail pressure errors on WOT.


Everything was fine for a few months until a few weeks ago I started noticing the engine getting gradually louder. At first, on medium loads at low RPMs between 1300 - 2000 rpm, a slight "clatter" developed, almost too quiet to hear. Then came the smoky start-up. And now, for about a week the engine has been ticking pretty loud, especially (and constantly) during warm-up but also when warm, intermittently.
The engine consumes some oil, around a liter per 2k miles (might still be wearing in the new rings but not sure how much is acceptable and for how long). It has done around 5k since the second rebuild.

I am attaching some videos of the current situation in hopes of a diagnosis or at least some possible options. Maybe someone has had something similar and can guide me on the right track.
Injector compensations are between +-0.7 on idle, up to -1 in D on 3rd cylinder. No excessive vibrations or shaking, but sounds just like one cylinder missing or down on compression when the noise is audible.


1st clip is bone cold engine start-up with clatter and white-blue smoke. Seems to be more on overrun, not during throttle. Bear in mind the car has no DPF, small strip of catalyst and muffler are still in place.

2nd clip is semi warm engine after about 3 miles of driving. This seems to be the worst as the engine might even constantly tick until revs are applied or the engine warms up some more.

3rd clip is a warm engine with the throttle applied between 1200-1500 rpm and you can hear the engine noise change intermittently, especially around the 13-15s mark where a sharp tick develops, then subsides. Same thing happens many times throughout the video.

Thanks for any and all input!