Am I Being Crazy?

[scott_dodge]

Hey, new member here - I've been reading up on this forum for quite a while. Finally decided to register and contribute.

Basically, I have a '91 318is, Alpine White w/ LSD, with about 226k on it. It's my first bimmer, and I love it.

Now, about a year ago, I bought this for a good price - it was a bit banged up, had been through 4 owners, and I didn't get any maintenance records. I took a bit of a gamble on it, but it hasn't given me any issues at all in the year that I've owned it. It never overheats or anything - the hottest the temp gauge will read is 50%. It does have some chain rattle, and I plan to have the tensioner looked at.

As of late, I've been putting some money in to it. Just did the rear subframe bushings (they were GONE), rear shock tower mounts, and checked the oil pan for bits / loose screws (no metal bits, one small plastic piece, and one screw in the pan). The shocks are fine - the last thing to do is the front control arms.

This has really transformed how the car rides and drives.

I've been driving Japanese cars all my life (Mazdas & Hondas), and I don't really "trust" the e30 yet. I'm just afraid of destroying something, and getting stuck on the side of the road.

However, it hasn't given me any reason to not trust it - the chain noise worries me a bit, but due to the fact that there weren't any metal bits in the oil pan (and the screws have been taken care of), that eases my mind.

Do you think I'm being crazy? Should I just man up, and take it on a 300 mile road trip and see what happens?

I'm not the most mechanically inclined person in the world - I'm fine at diagnosing things, but when it comes time to turn wrenches, I feel a bit over my head.

Would appreciate your input, guys.

[bmwman91]

What sort of timing chain noises are you hearing? It is a noisy motor by nature. If you are hearing any sort of "diesel" or grinding noises, then you have problems. If in doubt, spend the $40 on a new tensioner piston & 5 minutes changing it. Make sure to pop/expand it before installation.

[scott_dodge]

What sort of timing chain noises are you hearing? It is a noisy motor by nature. If you are hearing any sort of "diesel" or grinding noises, then you have problems. If in doubt, spend the $40 on a new tensioner piston & 5 minutes changing it. Make sure to pop/expand it before installation.

The noise is just kind of a rattle. When it's cold during the winter, it sounds like a diesel. It's not a grinding sound. There's definitely some chain noise happening around 2500 - 3k RPM.

I didn't realize the tensioner was so easy to do - I'll just take care of that and see what happens.

[d.hitchcock]

The cold-start diesel noise indicates a problem, imho.

I got my 150k-mile 318is last fall, and when ambient average temps dropped below 50 it started sounding like a diesel on startup. The noise would go away after a minute or so of run time.

I had fairly worn timing sprockets, a broken lower guide, worn tensioner, and the timing was off a bit due to overall wear in the components.

[DesktopDave]

I've had a bunch of Japanese cars over the years.  The BMW isn't a very different beast.  Like most RWD cars, driveline components tend to last longer.   BMWs are just as trustworthy...with a few caveats.  The Bavarians are more expensive at low mileage, but far more likely to run a very long time.

What does strike me as different is BMW's ideal preventative maintenance.  A BMW tends to run a very long time if you replace particular items at judicious intervals regardless of condition (water pumps, radiators and the expansion tank are good examples on the M42).  The Japanese tend to inspect & replace their components depending on mechanical failure.

I'd advise against installing the new tensioner until I had a good look at the rest of the cam drive.  At the very least, pull the cam cover and see what the cam gear teeth look like.  The earlier cars had components that were upgraded to resolve wear problems on the rails.  Later versions of the M42 eliminated the idler gear entirely.

I don't have any hard data to back this up, but IMHO if you have a broken guide (or worse) a dying idler bearing, the new tensioner will put more load on them & potentially accelerate a cam drive failure.

[scott_dodge]

Dave,

Thanks for the response.

Pulling the cam cover is something I'm not entirely comfortable with at this time, although I'd love to have a peek. My thinking behind having the oil pan pulled an inspected was to search for metal bits (from what I understand, bits of the timing chain / gears disintegrating), of which there apparently wasn't any.

My mechanic did say he saw one very small piece of plastic, and that was it.

Am I on the right track here? My thinking was that since the metal bits aren't present, that a timing chain tensioner would be all that is needed. However, you're not the first person who has cautioned against replacing the tensioner when timing components are worn.

What if I simply replaced the timing chain tensioner, and see if that resolves the rattle? And if not, then have the timing gears / chain / idler bearing inspected?

I found a bunch of E30 guys that build track cars in my neighborhood. Maybe I'll just bring a bunch of beer and see if they can give me a hand