BMW Compact Rally Car Build

[cooljess76]

Ouch! Dave I'm so sorry to see your misfortune. That valve looks so mangled, I can't believe it didn't damage the head. You definitely dodged a bullet there. The piston really doesn't look that bad. I've seen much worse. I think you might be able to get away with it, at least until the bottom end needs a rebuild. I'd turn the crank a couple times and see if that piston reaches the top of it's stroke normally, but other than that, I wouldn't even dremel it. Maybe sand any high spots down to prevent possible valve contact. I'd imagine if the connecting rod was bent, the piston wouldn't reach TDC and you'd probably notice some scoring on the cylinder wall. Did you find any metal in the oil?

[DaveKern]

Originally Posted by cooljess76

Ouch! Dave I'm so sorry to see your misfortune. That valve looks so mangled, I can't believe it didn't damage the head. You definitely dodged a bullet there. The piston really doesn't look that bad. I've seen much worse. I think you might be able to get away with it, at least until the bottom end needs a rebuild. I'd turn the crank a couple times and see if that piston reaches the top of it's stroke normally, but other than that, I wouldn't even dremel it. Maybe sand any high spots down to prevent possible valve contact. I'd imagine if the connecting rod was bent, the piston wouldn't reach TDC and you'd probably notice some scoring on the cylinder wall. Did you find any metal in the oil?

Piston appears to just protrude above the head, same as all the others (we only spun it half a turn in each direction).

Haven't drained the oil yet, but there weren't any marks on the piston wall, or pieces of head or valve missing. We do appear to be missing one of the clampy things that snaps into the valve keeper, but based on proximity to the drain holes in the head, I suspect it fell down into the pan.

Dave

[cooljess76]

As for the motor mounts, that's a pretty simple job. I'd either go with OEM M3 mounts or try to find a bolt-through design. The aluminum motor mount arms are a crappy idea IMO. BMW should've used steel. When I bought my wrecked M3, one of the arms was snapped as well as the transmission crossmember. The opposite rubber motor mount was sheared in half also, so the engine was literally resting on the steering rack.

[DaveKern]

Originally Posted by cooljess76

As for the motor mounts, that's a pretty simple job. I'd either go with OEM M3 mounts or try to find a bolt-through design. The aluminum motor mount arms are a crappy idea IMO. BMW should've used steel. When I bought my wrecked M3, one of the arms was snapped as well as the transmission crossmember. The opposite rubber motor mount was sheared in half also, so the engine was literally resting on the steering rack.

Replaced the torn motor mounts with bolt thru ones from AKG. They're harder, but I don't think there's any way we'll break them. They were on the car for the last two shakedown days and no issues so far.

Agreed on the aluminum arm mounts - going to keep an eye on those, and also used loctite on the bolts this time so hopefully they won't loosen up and move around at all. May eventually look at doing steel ones, but if I do that, I may end up utilizing a different mounting strategy - maybe to the frame rails instead of the front cross memeber.

Dave

[cooljess76]

The only reason I could imagine for them using aluminum arms is so they'll fail before the engine block gives. But I've seen an S54 before where the aluminum arm punched through the block. I used to jump my '94 wrangler all the time and I popped a couple radiators because I had it bolted directly to the chassis. I eventually made metal brackets(straps) which provided enough flex so I didn't crack anymore radiators. Well one time I was driving on the freeway and smelled coolant. I looked around hoping it was someone else's car, but then I noticed steam coming up from the transmission tunnel. I had my shifter boot removed because it let a good amount of heat in the jeep to keep my legs warm and the hole in the floorboard made for a nice spitter. Anyway, long story short, one of those brackets I made had snapped and the fan tore into the radiator. I'd be afraid to mount the engine to the frame rails after seeing what happened to my radiators.

[DaveKern]

Well, long time no update. Kinda bummed this has taken me so long to do, but that's the beauty of project cars - there's time to set them aside and get back to them when there's money to fix 'em.

First the bad news. When we took the head down to the machine shop, the guys found a crack surrounding the valve guide. So, head isn't useable - or it could be, but would require welding work, then more machine work, etc...sounded expensive. So, figured I'd keep an eye out for a good cheap used head.

While I was waiting, I picked up a set of Supertech dual valve springs and retainers. I don't plan on revving it higher than 7k, but having parts in the car that could handle more stress than I plan to put them through seems like a smart move.

I had also considered picking up another used S50, but couldn't find one for a good deal, and also realized I'd have to address the valve retainer issue, and do the oil-pump nut fix as well. After 6 weeks of craigslist and BFC classifieds searching with no good leads, I finally gave up. I decided to bite the bullet and pick up a head that's been rebuilt.

So, with that decided, it's time to dig the rest of the way into the block and get the damaged parts out of there. I borrowed an engine holder thing, and strapped the front of the block to it then got to work.

Next up was to drop the sub-frame and unbolt the power steering pump. Luckily with my revamped power steering lines, I was able to drop the sub-frame far enough out of the way without having to un-do any of the fittings. Pulled all of the bolts out of the oil pan. FWIW, there are two hidden bolts inside the transmission. Once I found those, the pan came off nice & easy:



Removed the baffle to reveal the crank & rods:



Two more bolts, and the rod & piston are out:



Next up is to figure out what bearings I need and meet up with a buddy who's got a spare stock piston.

Dave

[DaveKern]

Time to figure out what bearings I need and if its possible to order up a set for just one rod. The bearings had markings on them.

One said:

03-95
6481

The other had:

03-95
6469

Then on the other side they're both marked the same:

BMW
1284 843 844 (the 843 & 844 are sorta offset, with 843 half a line above the 1284, and the 844 half a line below the 1284).

Did the RealOEM search and found this page:

http://realoem.com/bmw/showparts.do?...19&hg=11&fg=20

Dave

[DaveKern]

Just went out to the car and measured the crank. Got 45.02mm, so looks like I should be trying to find:

05 Bearing shell, blue 45,00MM(0) 6 11241284850 $15.98
06 Bearing shell, red 45,00MM(0) 6 11241284849 $16.49

Am I on the right track?

Bearing thickness is 1.5mm if that matters.

Dave

[Zigfried3]

Originally Posted by pdxmotorhead

Don't forget to cap the shock towers, they are thin metal. I'd do them from the bottom side if your tearing things that far out. Then add the turner upper shock mounts.

Dave

Absolutely cap them if you're going to be doing heavy driving. We learned the hard way that they're somewhat fragile. Lol!

[DaveKern]

Originally Posted by Zigfried3

Absolutely cap them if you're going to be doing heavy driving. We learned the hard way that they're somewhat fragile. Lol!

Rear towers were cut out completely and replaced with a single bolt setup.





Fronts were reinforced with the factory add-on rings which were welded to the underside of the shock towers.

On my "wish" list is removing the engine bay fuse box and relocating them inside with the real purpose being that I want to extend the roll cage through the firewall and have it meet up with the shock towers.

Dave

[urbanmisfit]

Originally Posted by DaveKern

Rear towers were cut out completely and replaced with a single bolt setup.





Fronts were reinforced with the factory add-on rings which were welded to the underside of the shock towers.

On my "wish" list is removing the engine bay fuse box and relocating them inside with the real purpose being that I want to extend the roll cage through the firewall and have it meet up with the shock towers.

Dave

Moving the fuse block is easy if you can snag another harness somewhere so you can maintain colors but it may not be long enough
I changed a Toyota pickup harness from RhD to LHD in an afternoon; some had to be extended to the right or left side; some had to be shortened etc,
Stagger all the joints; solder them and use double wall shrink tube; it has sealant/glue inside it
Make a gizmo using alligator clips to hold the wires while you join them.
And OH!..don't forget to put the piece of shrinktube on before you solder the joint...ask me

[thesk8nmidget]

great thread! just got done reading everything!! cant wait to keep following the updates!

[DaveKern]

Dug into the car a bit more this afternoon and have started replacing the rod bearings. Ran into an issue with my manual...I can't seem to find torque specs when putting the new rod bolts back in.

Did a quick google search and turned up the following, but I'm wondering if anyone could confirm (the 65 degrees seemed a bit odd):

Connecting Rod Bolts (M10x1.25) = Application 5Nm, Jointing 20Nm, Angle 65 Degrees

Thanks,

Dave

[DaveKern]

After 4 months of being down, the BMW fired up tonight. I just let it run for a second or two and was going to look for leaks. Glad that I did because unfortunately I found a big oil leak from somewhere on the back of the head. Looked the damaged head over and found what looked to be the missing bolt, only to find the bolt hole in the new head is a much larger size.

Not sure exactly what year the new head was from...anybody have any ideas on what size it might be? Kind of a tight fit back there for doing any measuring, and pretty sure that I'm not going to have this specialty bolt in my laying around.

Dave

[J!m]

Originally Posted by DaveKern

(the 65 degrees seemed a bit odd):

Connecting Rod Bolts (M10x1.25) = Application 5Nm, Jointing 20Nm, Angle 65 Degrees

Torque angle. Thread them on by hand (5Nm) then tighten to 20Nm with a torque wrench, then turn each nut 65 degrees of rotation from that point.

You use one of these for this:

http://buy1.snapon.com/catalog/item....0&group_ID=980

I see this a lot with newer head bolts, and those typically have to be changed every other time they are torqued, due to stretch (and since you never know, I always get new ones). If you use them too many times, they will break.

Remember to clean/chase all threads and use a light coating of motor oil during assembly.

It sounds as if the rod bolts should be replaced every time, but the dealer can confirm that.

If you went with ARP bolts, go with their torque recommendations.