Rod knock or nailing
 

In the past week my 240D has developed a very bad sounding engine. I am trying to determine if it is a nailing injector or something worse. I can hear it very clearly inside the car while driving but the car sounds mostly normal at idle. The car has a known 136k miles and a good maintenance history but it did sit unused for about 5 years from 2001-2006. New to me injectors from a known good source. Oil analysis shows slightly elevated iron but very elevated copper.

Here is a video from under the hood.

March 22 part 3 - YouTube

And under the car.

March 22 part 4 - YouTube


Any thoughts?

Does not sound like nailing to me. Sorry I can't offer any more help. Can you listen with a stethoscope? A long ratchet extension or wooden dowel? That might help you to pinpoint the location of the sound.
Others will have many more ideas....

only one place elevated copper can come from... bearings.

I don't hear any rod or main banging... it sounds like a fueling issue, perhaps some air in the lines? I'd have the injectors re popped. you may have developed a leaker.

Check that the air filter housing is properly seated as well. My '87's intake tube from the filter housing to turbo inlet was loose a bit and it sounded like that.

Well that is good news. I can handle fuel issues but rebuilding an engine is above my pay grade i think.

Don I will check the air cleaner mounts as well. The airbox seems to be secure but I suppose they could still be bad.

X2 on what Joe said.

Sounds to me like u have a broken rubber foot on the air cleaner housing. The air cleaner might be bumping against the valve cover.

Question about the 2nd video:
I just want to know though why you were "going" on the tire. Do you have a new dog that you are trying to teach how to wash the brake dust off??:D

That sounds a lot like my '83 did a few months ago. The bolts at the exhaust flange had disappeared. The pipe hadn't dropped, but the connection was leaking. I think it sounds louder than it should if it were a loose air cleaner. Both possibilities are easy to rule out.

mounts,exhaust....
 

something is rubbing onto something it seems....


.

I just did an inspection of the exhaust system and it looks like you may be on to something with this suggestion. The exhaust is split right by the flange and leaking there so that might be what I'm hearing. If not it is causing the exhaust smell in the cabin :rolleyes:

Sounds normal to me.

This being a 616 and because of the high copper count. Plus the tendancy of the first rod bearing going bad is a known issue.

You can remove the lower oil pan. Check and plastic gauge the number one bearing if unsure and change it out if worn. Since the engine is not really hammering you should hopefully find no crank journal damage.

I did not hear a seriously damaged bearing in your videos. Are you absolutly positive the milage on that engine is as low as you mention? If that bearing is not really good make sure to check your fuel pressure in the base of the injection pump as well.

I know this may turn out to have little to do with your present concern. Still I suspect but doing the above could save you some real misery ahead.

Actually at least the fuel pressure should be checked on any 616 especially soon after it is aquired. Nothing has really changed my mind much so far to eliminate the long term low fuel pressure as perhaps contributing to excess number one rod bearing and cylinder wear.

This low pressure can be simply caused by running with partially clogged fuel filters. I have almost decided that leaving the secondary fuel filter in service till it shows actual signs of flow loss may be about the worse thing we can do to the 616 engines. Or may be on a par with not changing the oil often enough because of the excess soot generation of these indirect injection engines.

A weak lift pump and remember the pressure out put of the 616 lift pump is lower than the turbo 617s even when new. So the fuel filters are more signifigant as a potential restriction . The actual fuel pressure in the base of the injection pump will fall off easier than a 617 turbo as the fuel filter aquires the same amount of junk. Plus of course a really dirty tank filter could also reduce fuel pressure. These cars run much better at 18-19 pounds fuel pressure anyways. That the fuel pressure relief valve can deteriorate with time is also fairly common now.

I had a thought stirring in the back of my mind recently to really justify the permanent installation of a fuel pressure gauge. Or add another reason to do so to those that already exist.

Also a reason materialised to either install a good lift pump from a 617 turbo engine or put a tubo engines fuel output pressure determining spring in the 616 lift pump. I think I have covered that reason earlier in this post.

If fuel pressure falls on the highway to very low values. When you go to pass it may fall further and further limiting passing ability. In a good functional supply system you want to see the 18-19 pounds maintained at speeds and loads that are in far excess of seeing that pressure at idle.

I simply feel that because of age many 616 and 617 Fuel supply systems are not totally up to scratch after all these years. Since we did not buy the cars new we may not know what we are missing. Zero to sixty mph times can be an indicator as well. If your 616 is substandard this may be a good simple way to find out it is.

I am not stealing your thread either. Your videos and descriptions of the current issue are good. There is just not enough there to make any form of really accurate determination. Unless I believe am missing something.

Except for the high copper content of the oil sample you sent out. I thought that if it were my car I would investigate this a little. Even if it turns out not to be noise you are hearing currently.

How many miles on the oil in the engine that you sent out a test sample on? What was the viscosity rating of it? If by any chance you have the last oil filter I might also examine it carefully. Although even if that rod bearing were wearing it might be far too early to catch anything in the oil filter. When the bearing seriously delaminates or squeezes out the babitt material is when you can expect physical evidence.

Can you determine how much copper in parts per million or whatever form of description was used . Compared to what is the normal expected amount would have been. If it is several times higher you pretty much should have a serious look. Once wear gets started it accelerates at an ever increasing rate usually. All the above are just my opinions though.

I am guessing that is not an injector / nailing sound. Sounds either it is coming from inside your VC or the passenger side of your engine. I would be concerned, however. I did not see your AC shake like a singer sewing machine so I am thinking its not a mount.

Any exhaust leak under the hood is going to make a big racket. Whatever the outcome, this needs to be addressed. I'd also take the time to check the manifold bolts and look for signs of a leaky gasket.

The bad oil analysis results may or may not be related to the current issue, but it can't be ignored. It doesn't sound like you have a rod knock to me, but other noise may be masking a budding issue. I'd wait just long enough to get another good sample to submit for another oil test, but only if repairing exhaust leaks restores the engine to what it sounded like before it became a concern. If a second test yields the same results, then it would be most prudent to inspect the bearings.

Call me
 

Please call me now if possible. phone: 248-850-7027


.