Author Topic: How to spend $1,000 on a timing chain tensioner (Read 5282 times)

benhanson · « **on:** May 29, 2007, 04:02:15 AM »

So last fall I was driving home and I thought a threw a rod, or busted a piston ring. Car was driving fine when all of the sudden she got quite noisy and lost power. Long story short, I pulled the motor, disassembled and found every timing chain guide either cracked or broken, with several largish chunks in the oil pan.

I'm in Alaska, and apparently I've got a snowball's chance in hell of coming across a used motor up here, so I started perusing the internets. Eventually, I took gamble on a motor that supposedly had 200lbs compression when pulled, and was priced at $700 + $300 freight. Again, being 2700 miles from the mainland doesn't help in this department. Pulled the trigger, with a 90 day warranty I started hoping for the best. BTW 'hoping for the best' in my automotive life has always had mixed results, so I don't recommend it.

A week later I was looking at a 'new' used engine and it didn't look all that bad. Motor was relatively clean and complete minus Alternator, so I new I could at least recoup some money selling parts I wouldn't need anymore. After a few weeks I had the 2nd motor installed, and much to my chagrin the thing was loud as hell when I started it up. Now, as a back story my 318i was loud before. I'd gone as far as posting to forums asking if it was normal for these things to sound like a diesel. I probably even had someone recommend I replace the timing chain tensioner, but I could never accept that this much racket was coming from a loose timing chain. So when I started up this motor and found it to be as loud as my old had been before it "broke", I was thoroughly disappointed.

Needless to say, I dropped $40 on a new tensioner, popped it in and the thing now purrs. This is good news as long as I forget about the fact that the old motor probably would still be kicking if I'd dropped the $40 when I first bought the car.

So the moral of the story, if you buy an M42 and can't believe how much valve train noise there is, replace the timing chain tensioner. For that matter, if there is any replace it. It's $40 and takes about 5 minutes.

bmwman91 · « **Reply #1 on:** May 29, 2007, 11:41:36 AM »

True words! A word of caution though...you might wind up blowing another $500+ if you are not careful. When run without a good tensioner piston for a long time, the chain tends to lose chunks of roller bearing. These bits of hardened steel fall into the oil pan, and have made it into numerous people's oil pans!

Pull the lower oil pan on the new motor and check for debris. If there is anything, clean it out and post pics! Your motor's life really does depend on it! Do it ASAP!

mbtech0 · « **Reply #2 on:** May 29, 2007, 11:52:00 AM »

I'm glad this worked for you. Timing chains can cause all sorts of noise. When they get loose, no matter what the cause, something is going to get broken by the whipping chain. As the chain whips, it breaks the guides & rails, and it stretches as it does this, worsening the problem. Sooner, or later, something crucial breaks.

sheepdog · « **Reply #3 on:** May 29, 2007, 02:02:15 PM »

Quote from: bmwman91;26762

True words! A word of caution though...you might wind up blowing another $500+ if you are not careful. When run without a good tensioner piston for a long time, the chain tends to lose chunks of roller bearing. These bits of hardened steel fall into the oil pan, and have made it into numerous people's oil pans!

Pull the lower oil pan on the new motor and check for debris. If there is anything, clean it out and post pics! Your motor's life really does depend on it! Do it ASAP!

PLEASE head this advice.

This is probably the most important thing on an M42, especially before or after dealing with the timing chain tensioner.

Check for loose pan bolts while you are in there as well.

Jtuner · « **Reply #4 on:** May 29, 2007, 02:06:09 PM »

When I first got my car I had the tensioner issue,, really friggin loud and annoying! $40 bucks later, and it purrs just as mentioned above,, however,, I do still, at abou 3200rpm-4500rpm still have a swishing, like metal rubbing/scraping sound that is really annoying.. It doesn't seem to affect performance, or idle or anything, and its not as loud as when the tensioner was bad, but I'm wondering WTF it is? Guide rails?? I'm sure others have come across the same thing..
Sorry to hear you blew a grand on something you didn't really need, but at least you have replacement parts if you ever need em

Cheers!

Jtuner · « **Reply #5 on:** May 29, 2007, 02:09:33 PM »

Quote from: sheepdog;26773

PLEASE head this advice.

*cough* heed *cough cough* :p

gearheadE30 · « **Reply #6 on:** May 29, 2007, 03:22:20 PM »

^^ sounds like the guides. If the tensioner is worn and the chain flops for any amount of time, the first places it hits are the ends of the guide rails. The bolts holding them in are on the ends, so eventually the material wears away and the chain starts slapping the bolts.

Long story short, you will need new guides (~150) new chain (~70) new tensioner (40) and the time to rebuild it all.

Which is exactly what I am going to do as soon as school gets out. The previous owner put 200k miles on the same chain and tensioner

Alpine003 · « **Reply #7 on:** May 29, 2007, 11:31:16 PM »

To the op, if you ran it with a worn tensioner for a long time, chances are you probably needed to either refresh your motor or get a newer one anyways.

If you found all sorts of debris blocking the oil pickup, there would've been a good chance of some oil starvation possibly leading to premature worn rings, bearings, and more.

Jtuner · « **Reply #8 on:** May 30, 2007, 11:29:13 AM »

Pan looked good when I dropped it at the time of tensioner replacement,, a couple of bolts in there which was scary, but I loctited those sumbitches in there.. No shavings or anything,, I think I got to it before it was a big issue.. well I guess other than my rails getting worn.. I just gotta find the time to do it, and I'll do the rails, gaskets, etc.. time is something I haven't had a lot of lately though lol

bmwman91 · « **Reply #9 on:** May 30, 2007, 11:34:43 AM »

Quote from: Jtuner;26855

sumbitches

For some reason this word always cracks me up.

Oh and how is the pan inspection going Ben?

tjts1 · « **Reply #10 on:** May 30, 2007, 11:37:31 AM »

How many miles on the odometer when chain guides broke?

sheepdog · « **Reply #11 on:** May 30, 2007, 03:03:03 PM »

Quote from: Jtuner;26775

*cough* heed *cough cough* :p

Spell Nazi! :p

sheepdog · « **Reply #12 on:** May 30, 2007, 03:04:58 PM »

Quote from: Jtuner;26774

When I first got my car I had the tensioner issue,, really friggin loud and annoying! $40 bucks later, and it purrs just as mentioned above,, however,, I do still, at abou 3200rpm-4500rpm still have a swishing, like metal rubbing/scraping sound that is really annoying.. It doesn't seem to affect performance, or idle or anything, and its not as loud as when the tensioner was bad, but I'm wondering WTF it is? Guide rails?? I'm sure others have come across the same thing..
Sorry to hear you blew a grand on something you didn't really need, but at least you have replacement parts if you ever need em Cheers!

Mine did the whole 3200-4500 when I got the car and ran it that way for a year. I replaced the tensioner and that is when I had problems.

You may have gotten a bad tensioner, or more likely, you need new sprockets. Usually the crank sprocket is the worst of the bunch.

benhanson · « **Reply #13 on:** May 31, 2007, 02:33:49 AM »

I've got to make time, order gaskets etc. I was prepping this to go back as my daily driver, so the thought of going back to my rattle trap 1980 Volvo 240, with 185K is killing me. If only there was a way to do a visual without dropping the pan! Anyone ever try using magnets below the pan to see if any debris could be pulled toward the front of the pan? I would think a neodymium would be strong enough to pass through the pan. This would just be until I got a pan gasket of course.

Alpine003 · « **Reply #14 on:** May 31, 2007, 10:46:37 AM »

Quote from: benhanson;26888

Anyone ever try using magnets below the pan to see if any debris could be pulled toward the front of the pan? I would think a neodymium would be strong enough to pass through the pan. This would just be until I got a pan gasket of course.

If you had your guides break into pieces, I'm afraid just checking the pan might not be enough. I've included a pic below. Basically, pieces of the chain guide can get stuck in places preventing proper oil flow. As for the magnet, the guide pieces are plastic so it won't do any good in detecting them.

The best thing to do would be to pull the valve cover and get a good flash light and inspect to make sure both your guides aren't missing plastic chunks. Next is to pull the oil lower oil pan to check for any other debris.

Both these procedures aren't bad at all, even a first timer can do it easily in under 2 hours working at a slow pace at the most.

Just make sure you order a new lower pan gasket and possibly a valve cover gasket set if you notice any oil seeping on the side of the cover and/or in the spark plug holes.