Replacing lower timing chain guides: an epic adventure

[joey79]

I was experiencing a rattle between 1200-1400 rpm. Pulled valve cover and diagnosed broken lower timing chain guide on the non-tensioner side. Bummer, but whatever. Order some parts, start the tear-down. All goes smooth until I get the timing cover off and see that the holes in the block that the mounting bolts thread into are stripped.






So I arm myself with some tools. 90 degree drill chuck, since there's no room in there. Several sizes of drill bits (19/64, 5/16, 21/64). I wanted to do this gradually, as to not risk snapping a bit off in the block, or destroying the hole. Finally, a thread repair insert kit. Brand is "V-Coil", but they're similar to heli-coil, etc. V-Coil is made in Germany, so can't go wrong, right?






Used an old t-shirt and some magnets to catch shavings. I then drilled out the holes, working my way from smallest to largest drill bit. I had to ghetto rig my tap handle to work around the crankshaft and head. Using the tap provided with the v-coil kit, I tapped the holes going slowly, using lots of lube, backing the tap out to clean it several times per hole.






Freshly tapped holes.






Threaded the v-coil inserts into newly tapped holes.








Dry fit the mouting bolts and chain guide. Plan on using red loctite on these bastards.






Here are the old guides. I broke the tensioner guide removing it. It was quite brittle, and I ended up gashing my knuckle on it (note blood in first picture). One of the mounting bolts is still in the oil pan. I'll try to fish it out with a magnet. If not, it will stay there until I get around to doing my oil pan gasket.

[das borgen]

That is an exceedingly rare failure on an E36.

Great work reviving it, OP.

[joey79]

Yeah, I did notice that the new mounting bolts I got from the dealer had a wider hex on the bases than the originals. The new ones are 15mm, originals looked to be 12 or 13mm. Maybe the revised part will be less likely to fail in this fashion. The threads are only M8x1mm (fine thread) and about 5/16" long.

[cabdolla]

Joey, important question since I have to replace my chain cover. Did you have to remove the VANOS and upper chain gears to get access to the top two bolts that hold the chain cover onto the head, or could you get them out with the chain gears still in place?

[joey79]

There are actually 3 bolts that hold the timing cover to the head. You can see the center hole in this diagram.



I honestly don't know if the vanos and cam gears have to come out to get to them. I was removing all that stuff anyway to replace my upper guide and tensioner. I know that center bolt goes through the upper guide into the head, and it's kind of under the upper tensioner.

[cabdolla]

Thanks, when you put the cover back on did you put any RTV on the edges of the cover along with new gasket material? Unfortunately, the BMW TIS appears to be down.

[joey79]

I haven't put the cover back on yet, but I'm 99% sure I remember TIS stating to only put a bead in the upper corners. I think Bentley says the same as well as a thin coating on the upper surface that contacts the head gasket. I'll check Bentley again when I get home.

[cabdolla]

There is no more BMW TIS website!! (Panic attack)

[joey79]

Yeah, I wonder what the hell happened to the TIS website. Been down for a few days now.

Here's a shot from the Bentley manual. No mention of RTV'ing the whole gasket. Also, the picture to the left shows the middle timing cover bolt.

[joey79]

I just put everything back together today and figured I'd answer some questions.

Joey, important question since I have to replace my chain cover. Did you have to remove the VANOS and upper chain gears to get access to the top two bolts that hold the chain cover onto the head, or could you get them out with the chain gears still in place?

Once it was all back together, I was able to get a socket onto all three of the bolts. The one on the left looked like it might be a tight squeeze getting the bolt out, but it looks possible.

Thanks, when you put the cover back on did you put any RTV on the edges of the cover along with new gasket material? Unfortunately, the BMW TIS appears to be down.

I ended up putting a very thin layer of RTV on both sides of the timing cover gasket.

[Eric93se]

pics please

[joey79]

I didn't take any pictures during reassembly. The three bolts mentioned are shown in the bentley screenshot above. They're still accessible with the cam gears and vanos in place.

[Eric93se]

Peerblock was blocking the img host, lol. Now I see, very nice job!

[cabdolla]

I just put everything back together today and figured I'd answer some questions.

To be clear, I am not concerned about getting a socket into the well (it will fit), but having clearance to get the socket in there when the cams and sprockets are still on the car. I played around with an M50 in the junk yard, and there was no way - zero - to get those three bolts off without removing the VANOS and the intake cam.