Author Topic: The Little Motor That Won't Stop Breaking [+PICS] (Read 8256 times)

bmwman91 · « **on:** July 03, 2011, 08:11:57 PM »

(In the motor's defense, I think that a good 50% of the issues I have had are my own doing somehow...including this one)

As some may recall, I overhauled the motor a month or so ago. All went well & it has been driving better than ever, for the most part. I noticed a buzzing sound that seemed to be coming from the glove box a few days after the rebuild. It almost sounded like rapid electrical arcing, but it only occurred between 2900 & 3100RPM. Electrical issues aren't usually that speed-dependent. If I had the windows down & was next to a wall or something, I'd also hear some sort of rattling at those engine speeds. Hmmm.

(troubleshooting / noticing issues is probably the only area where adding tons of sound deadening to the cabin & hood have made life harder)

Anyway, I sort of had my suspicions about the cause. When I was putting the motor back together, the top bolt of the driver's side timing chain guide stripped in the head. I have NO idea why I didn't repair that when I was in there...I was 2.5days & almost 40 hours in, and I think I was just too tired of working on it to make a rational decision there. I think I tossed some Loc-Tite on it & kept going lol.

When my thermostat housing cracked a couple of weeks ago I bled the system and noted a very very loud clicking noise at around 3000RPM. It was coming from somewhere on the front of the motor. No externally-accessible bits were loose or seemed like plausible culprits. Well, that seemed like one more piece of evidence pointing to the stripped bolt moving around, probably hitting the timing cover. It was loud enough that I could see it making it through the glove box lol.

So I finally decided to test my hypothesis this morning. I popped the valve cover & took a peak. Sure enough, the bolt & threaded adjuster sleeve were backed all the way out & up against the timing case cover. It looks like this coming weekend's project is to install a helicoil there. Thankfully, the adjuster sleeve thing is big enough that I can get the drill & helicoil through there, so I won't have to pull the lower timing case cover. Thermostat housing & upper timing case cover gaskets are on-order now.

I seem to be this car's worst enemy! Honda Civics keep appealing more & more (or maybe just a car I haven't ever touched)!

keflaman · « **Reply #1 on:** July 03, 2011, 08:58:57 PM »

Aw, don't be too hard on yourself and starting talking all Honda and stuff. They have their problems too and I'm sure you could screw something up on them as well.:p

bmwman91 · « **Reply #2 on:** July 03, 2011, 10:20:08 PM »

No doubt. My fiancee has probably gotten away with $600 in maintenance in 7 years simply because I haven't felt like working on it!

If I had a garage, I'd pick up a Civic for commuting & keep the 318iS for tinkering. I keep threatening to rid myself of it, but I have some sort of sick attachment apparently! I suppose that I do owe my engineering career to the E30 for the most part. It seems to be habitually collecting "interest payments" on that though haha.

dj91318is · « **Reply #3 on:** July 04, 2011, 05:57:22 PM »

If you fiend a BMW! turn key no worry, Please let me know! Every one needs a back up. Good luck on your repair.

DesktopDave · « **Reply #4 on:** July 05, 2011, 07:27:54 AM »

I drive the wife's minivan when mine is down for maintenance. I have a spare e30 as well, but that one's in worse shape than the M42!

I've had a lot of Japanese cars that I liked, but they just don't do it for me like the Bavarians do. The new crop of hot hatches is superb...MazdaSpeed 3, Civic Si, VW GTI, etc. put our poor cars to utter shame all 'round. But (it's hard to put my finger on exactly why) I just prefer the general feel of the BMW.

bmwman91 · « **Reply #5 on:** July 05, 2011, 12:50:28 PM »

Yeah, I can't exactly say WHY I want to keep the car. There are a ton of faster, more reliable cars out there. There's just something about the old-school German attitude *****ded in these cars that I love. That and the smell old German cars have...

I think I have roped a friend into helping me this coming weekend. I just need to fire up the BBQ & toss some meat on...boo hoo. All he has to do is hold the shop-vac hose while I drill out the stripped hole & tap it anyway.

DesktopDave · « **Reply #6 on:** July 05, 2011, 05:53:45 PM »

I've come to the conclusion that it's either the *****ded attitude or the shop chemicals. They might be the exact same thing...

DesktopDave · « **Reply #7 on:** July 05, 2011, 05:56:50 PM »

Em-bedded gets pwned by the bad word filter!?!?

LOL!!!

92BMW318is · « **Reply #8 on:** July 07, 2011, 08:14:03 AM »

Quote from: DesktopDave;105090

Em-bedded gets pwned by the bad word filter!?!?

LOL!!!

yea i posted a thread in "Off-topic discussion" saying M42Club should allow em-bedding videos on youtube and it got censored.. i thought "wtf" http://www.m42club.com/forums/showthread.php?t=13626

bmwman91 · « **Reply #9 on:** December 11, 2011, 02:50:59 AM »

Well, I repaired the stripped threads for the timing chain guide a while back. It definitely fixed the awful noise that came from the bolt running against the upper timing case cover. If I had let this go long enough, it would have worn through the cover! The bolt would have fallen out, and the spacer thing would have fallen into the timing chain assembly (ka-BOOM!). The depression you see below was almost 1mm deep!

When I popped the valve cover, this is what I could see. Hmm...a bolt isn't where it is supposed to be.

The bolt (well, socket cap screw, but bolt is easier) threads were all mashed up, as were those on the spacer. Replacing the bolt was easy since it is a standard size. The spacer, however, is very non-standard (M12x0.75 thread). Good luck finding a die for THAT!

After thinking for a few minutes, I decided to make a replacement on the lathe. Although it has English-thread lead screws, a 0.75mm thread pitch is very close to 34 threads per inch, which the lathe can do without any problem. After a few more moments of thought, I figured, "I am doing this the hard way." So instead, I got a #4 (fine) triangular file, stuck the "good" end of the spacer into a 0.5" collet and ran the file through the threads to clean them up. This worked just fine, since the threads in the chain guide were undamaged.

Now, before continuing I needed to install a helicoil into the head. Removing the timing chain was not on my list of "stuff I want to do today" and the drill bit/helicoil insertion tool fit through the guide spacer hole. To contain the chips. I taped some hose to the shop-vac and had it sucking the work area.

Here is the stripped hole, waiting to be drilled-out and have a helicoil installed.

Anyway, I reassembled it all and the terrible noise was mostly gone. I have been annoyed by the noise that is still there for weeks, and I finally started chasing it down today. That'll be another post though.

bmwman91 · « **Reply #10 on:** December 11, 2011, 03:02:01 AM »

Today I replaced the entire driver's side guide rail. The metal bushing at the top seemed to be a little loose in the plastic body, and I though that it may have been causing the persisting rattling noise (not nearly as bad at the loose bolt, but still a nasty noise). It was good to get in there & double-check all of the bolts & screws from when I overhauled the timing case earlier this year. That crank damper bolt really isn't all that terrible to deal with either (I used to HATE it)...the starter motor loosens it after 4-5 smacks of a breaker bar onto a wooden block. A 1/2" steel plate that I machined holes into bolts to the crank hub & lets me put 240 ft-lbs of torque on easily, too.

Anyway, I couldn't see anything else in there that would cause the nasty rattling noise. So I put it all back together. Sure enough, at 3100RPM the nasty noise was still there. So much for my theory about the loose bushing in the guide rail!

I DID notice that the timing chain tensioner piston felt "weak" when I reinstalled it. Normally, when you get a new one, pop it open and then install it (you SHOULD pop it open first), it is sort of a pain to press it up to the head to start threading the cap. This one was super easy to install, indicating that the internal spring was funked up. This tensioner only has 50k-60k miles on it, and I wouldn't expect it to be crapped out so fast, but it does seem like it could be the culprit here.

The bad noise I near does sound like timing chain slap, or SOMETHING in the top/front of the motor having to do with slop in there. Maybe the tensioner isn't doing its job and the cams can flop around a little, and I am hearing lobes smacking lifters or something. Really, even with a loose tensioner, I can't really figure out what makes all that darn noise, other than the cams being unconstrained and their lobes slapping lifters.

So, I getting long-winded and should stop. A new tensioner, along with a bunch of odds & ends, are on order from Pelican Parts. I hope that this will remedy my ugly noise once and for all. Uugh...why can't I be like the average car owner & be completely oblivious to any problems, short of a wheel falling off?!

DesktopDave · « **Reply #11 on:** December 11, 2011, 08:34:32 AM »

You're very proactive about getting that repaired...I wonder how many other M42's died from the same faults?

Isn't that sleeve/bushing/insert for sale as well? With such an odd pitch did you have trouble finding a correctly sized heli-coil insert?

bmwman91 · « **Reply #12 on:** December 11, 2011, 03:29:15 PM »

The bolt that goes through the sleeve and into the head is just a regular M6x1 thread. The sleeve just spaces the chain guide from the head. The sleeve threads into the top of the guide.

I ended up replacing it all anyway lol. I must be addicted to working on this darn car.

spanish_pants · « **Reply #13 on:** December 12, 2011, 03:40:21 AM »

Glad to see you did this before it turned into something expensive.
Trust me, it happened to me. It turns out the threaded hole in the head cracked, ripped the bolt from the guide and sent it flying out of the front cover.
It made a hell of a mess on the way out. The PO decided it was too expensive to fix and just welded the hole in the cover.
Funny thing is i drove it about 50,000 kms this way with no problems. I gave it hell too.
Either it�s a robust motor or i was lucky.

bmwman91 · « **Reply #14 on:** December 13, 2011, 03:14:20 AM »

LOL

So, the bolt came loose and wore through the upper valve cover?! That's one of those stories that is almost unbelievable.

It's good to hear that the guide held up well otherwise. Did any of the other plastic screw bosses break off of the guide? It seems like those would be under a lot of stress. Was it the original guide (metal sheath, as opposed to being plastic like the newer ones)?