engine and drivetrain 1 Step Forward, 3 Steps Back On My M10 Rebuild

[BMtroubleyou]

Hello everyone,

 

It's been awhile since i've posted, however now I could use the good minds of all I can gather. I blew my headgasket a few weeks ago and took a good look at my M10 in my 75' 02 and noticed about every gasket and seal was leaking. I than decided to pull the engine out and clean/reseal everything.

 

Everything shy of the valves and pistons is taken apart, and to my suprise the old owner has decided to cut several corners. 3 of the 6 waterpump bolts to the timing cover were sheared off, than drilled out and tapped with two easy outs snapped off inside. I also discovered that the timing chain and oil pump chain were very loose and floppy and ordered new ones. I discovered the old owner also swapped 320i sprockets and chains on the 2002 engine because the chains I received from bavauto have links that are twice the size of the ones on here currently.

 

The part# for the bavauto oil pump chain shows as 11411716989. I have a sneaking suspiscion the one I need is different than that

 

My dillema now is if I should pay to have the broken bolts and taps milled out, or find someone who will sell me their timing cover for cheap with all the bolt holes intact. I also have talked with Bavauto, and Bellevue BMW (local bmw dealership) and they claim there is only one type of oil pump chain that will go on 2002's and 320i's, and its the one they sent me. ***Major headache now***

 

I will appreciate all the help I can get on this one.

 

Thank you

 

(O=00=O)

[schoir]

Do you have closeup photos of the timing cover/water pump showing the sheared off bolts and broken ez out taps?

 

In some instances, especially since you have the engine out and access is not compromised, it's not that difficult to get the broken bolts and taps out.  You would need a carbide cutter for your Dremel tool, a set of reverse drill bits and a MAPP gas torch to have any chance of success.  Again, it depends on the individual situation and closeup photos would help in evaluating that possibility.

 

Also, you might take some small comfort in that once you fix these little horrors you will have found and corrected the source of a lot of leaks.

 

Regards, Maurice.

Edited January 15, 2014 by schoir

[Tommy]

It shouldn't be hard to find somebody willing to sell good timing cover. It may be easier after all.

 

The chain problem sounds weird. There really shouldn't be more than one chain that fits.

Pictures might help to understand what's the case.

 

  Tommy

[BMtroubleyou]

so here's a close look at what i'm working with. It's all the smaller bolts towards the open cavity area of the waterpump. You can see the top right 10mm bolt hole is very honed out. I managed to drill through that one with a traditional drill bit and attempted putting another easy-out extractor in however i could feel it near it's threshold of snapping. You can also see what the hole is supposed to look like comparing it to the far right hole.

 

[DaHose]

Your timing cover looks salvageable to me. I also think you should be able to do this at home and don't need to have a machine shop do it.

 

Grind the bolt surface flat, center punch and get some left twist drill bits.  As you work your way up in sizes, the vibration and friction of the bit will loosen the remaining bolt thread and back it out.  At worst, you end up drilling one or two sizes bigger and put in threadserts. 

 

Jose

[schoir]

Good photos.

 

Those look EXACTLY like what I ran into with the exhaust manifold bolts on my '97 Boxster when I installed headers.  The advantage you have here is that you don't have to get under the car and work facing straight up at the underside of the engine.  I wrote this up on a Boxster website and I'll post the link if I can find it.

 

The trick with the one at 8 o'clock, with the piece of the tap stuck in it, is to remove enough material from the side of one of the cut-outs of the broken tap such that the tap will become loosened.  From your photo, it looks like you can definitely fit the Dremel tungsten carbide cutter in that broken bolt with the tap in it at about 11 o'clock.  Once you have removed just a little of the old bolt material, you can lightly strike the side of that broken tap with a very small chisel in a clockwise direction and it should come loose.  Once you have the piece of tap out, you can evaluate whether you have to use the carbide cutter again to get whatever hole is already existing in the middle of the broken bolt to be centered.  Once you get the hole inside the broken bolt to be dead center, you can heat up the surrounding area and use successively bigger reverse drill bits.  If you have your hole dead center you can get a reverse drill bit in there that is very close to then just leaving the bolt threads in there and by that point, they usually back out and come spinning out onto the bit, especially if you have been soaking it with PB Blaster or equivalent and then later apply heat to the surrounding area.

 

The bolt hole at one o'clock can definitely be handled by first using the Dremel tungsten carbide cutter to hollow out more of the inside of the bolt towards the right and down so that you can get an enlarged hole that is dead center.  Then you can proceed as above.

 

The key with the broken bolt at 11 o'clock is to try to get a very small drill bit DEAD CENTER and work your way out from there.  Again, if you find that you are not dead center once you get up to about a 1/8th drill bit you can work your way to dead center again by enlarging the hole with the tungsten carbide cutter in the Dremel.

 

The Dremel part number is 9903.  You could also use 9904.  They both have rounded tips so they don't grab and run away on you.

 

Regards, Maurice.

[DaHose]

I forgot to tell you the welders way.

 

Get a nut that is just a tiny bit bigger than the bolt and drop it over the piece of bolt sticking out.  Now weld the bolt to the nut from the inside.  The high, focused heat will cycle the expansion of the bolt and loosen rust or galling.  You can then get a socket on it and back it out (hopefully).

 

Jose

[oldguy]

won't be able to check till this weekend but I probably have a timing cover laying around.

 

pay for the UPS to box it and freight it..  it's yours.

[RussTii]

Regarding the oil pump chain, for some reason one or all of the aftermarket suppliers are providing a chain that is significantly wider than the correct part an M10 requires. We had a number of these show up from various sources, finally got the correct part through the local dealer. May cost more than aftermarket but it appears to be the correct width and length.

[Mike Self]

One more thought on removing the broken bolts/taps etc...if you booger up the 6mm threads removing whatever's stuck in the hole, there's enough meat in the aluminum to re-tap for a 7x1 mm bolt.  Commonly available size.  And when replacing, use stainless steel bolts, or at least coat the threads of your new bolts with an anti-sieze paste.  Then when you replace the water pump ten years from now, they'll come right out without a fight.

 

cheers

mike

[Preyupy]

Give me a call at the shop, I have a bunch of front covers and you can have one.  I'm in Redmond

Byron at Vintage Racing Motors  425-869-8112

[mike472]

If you drill this out you are best off using a drill press to keep the hole straight and not veer off the mark.  Dont use a hand drill.   Grind flat and center punch.   With any luck and a left hand drill bit a little smaller then the hole, whats left of the bolt should start spinning out as you get to the bottom.  Mike's idea of drilling out to the next size up isn't bad either if you booger up the remaining threads in the cover.

[AceAndrew]

Regarding the oil pump chain, for some reason one or all of the aftermarket suppliers are providing a chain that is significantly wider than the correct part an M10 requires

 

Not all suppliers.  What you're getting is an S14 Timing chain.  Discovered this several months ago, and now I keep only the correct oem chain (and shims) on the shelf.

Edited January 16, 2014 by AceAndrew

[Hans]

I, d be inclined to find another cover with good threads. Mote predictable outcome. Check two front holes too .....the ones for upper case.

[TobyB]

Go see Byron.

 

He's worth the trip!  

(and he has at least a few covers from me!)

Take your old one- sometimes they've been milled.

 

THEN try saving yours- when it goes bad, you can toss it in the green bin and laugh.

Or save it, and learn a new useful set of skills.

 

And Andrew beat me to it- sounds like an M3/S14 chain.

The BMW chain's not all THAT expensive, and it's good.

 

This happens a lot, these days.

 

Oh, you do know that you can shim the pump to tighten the chain, right?

 

t