Strange rattling noise

[alkaba]

Hello,
i have recently swapped an M44B19 into my E30 (from E36). Everything worked fine, but the cold starts were always a pain in the ass. Now it became even worse. It started to make a very strange rattling noise when it is cold, it sounds like something is resonating through the engine. I think it could be the timing chain or the tensioner. It also has a dramatic loss of power when its cold. After ca. 2 minutes of driving becomes the engine quiet and has its full power.
Do you think it is comming from the chain?
Here is a video of it: http://www.youtube.com/watch?v=-1AgW4oM5tI
Thank you

[ti_tony]

That's a cool swap. What weight oil are you running. Maybe the tensioner is taking too long to pump up.

If the tensioner is worn or won't pump up does that retard the timing by a couple degrees?

[bmwman91]

Two things:

1) The really bad idle is probably a vacuum leak. Even small ones will make it run poorly, especially on cold starts / idle.

2) The noise is probably related to the timing chain. I recommend replacing the tensioner piston...$40US and 5 minutes are all it takes, and it could save the entire engine. The tensioner should pump up immediately, so the spring inside is probably worn out. When you replace it, push on it to release it BEFORE putting it into the engine so that the chain is not completely loose at first. It is a little harder to install this way, but it is safer to do so.

You also seem to have a noisy valve train. I would try running 4 quarts of 15W-50 synthetic oil + 1 quart of Rislone engine oil detergent. That can help to get old, gummy oil residue out of things. Change it after ~5000 miles and then just run 5 quarts of oil like usual. I usually change my oil every 10000 miles when running full synthetic, and the filter every 5000.

Also look into getting a magnetic oil pan drain plug. Aside from trapping iron/steel metal shavings, it is also a good visual indicator for when things are wearing improperly. Using one has saved me a couple of times now by trapping large metal debris from failed roller bearings and such.

[alkaba]

Thank you very much for the answers! I will buy a new tensioner and replace the oil.
BTW I have checked the intake system and everything around it and I didn't found any leak.
My friend told me, that the water temperature sensor could be the problem. I will try to replace it tomorrow.

[bmwman91]

Hmm, it is possible that it is the temperature sender. Usually the sensor itself is fine; the wire breaks at the connector, which is a fairly easy/free repair to DIY.

[alkaba]

It was the temperature sensor You are great! The dashboard and DME connector were swaped, so the DME was getting a bad temperature signal. I connected it correctly and it works like a charm plus the rattling noise is gone It was getting the whole time lean mixture, now it runns like hell