Need Help! - 3.6L thru bolt

[Moriartyhlms]

Hello all,
I'm rebuilding a 3.6L engine out of a 90' C2 and can't figure out how to get an o-ring and stepped washer to fit on the lower thru bolt stud at the no. 1 bearing. An o-ring, stepped washer, and nut are supposed to mount here on the right crankcase half, but there's no room!
The gap diameter below the threads on the stud is too narrow to fit in either the o-ring or the necked portion of the stepped washer like it's supposed to. It actually appears that something is bonded into the face of that boss that the stud is poking through. I got a magnet to stick to that face, so whatever it is, it's not aluminum like the rest of the crankcase. And I've counted all of my stepped washers, so unless I forgot to install one on the other through bolts, I don't think it's another stepped washer stuck in there. Any ideas?
-Thanks, Sam

[KTL]

Does the nut & washer above (shown already assembled) have the same problem?

These o-rings here on the 3.6 case are similar to the older engine cases, where the o-ring doesn't truly act like an o-ring should. It acts more like a packing and gets mangled when you install the nut & washer.

There's a thread here on the rebuilding forum where the o-ring lubricant was fiercely debated. In the end, I think the lubricant is less important than ensuring the space beneath the washer, or the o-ring thickness, is important to avoid thrashing the o-ring.

[safe]

It look like you have a stepped washer there...

[Moriartyhlms]

Thanks for the replies, I actually split the case again yesterday to try and figure this out.

The upper number 1 bearing through-bolt that's visible in the picture installed normally without any issues.

And I don't think that's a stepped washer in that lower hole because after taking everything apart again, I counted 24 stepped washers like I was supposed to have. I could try to remove whatever's in that lower through-bolt boss, but I figure it's probably in there for a reason. I'm using all of the same through-bolt hardware over again (except for o-rings), so whatever weird way it was assembled before the tear-down was working...I just failed to take a picture of this exact bolt.

I'm considering just filling that gap with multiple o-rings and a lot of DC 55, then capping it off with a flat washer (not the stepped washer) and the acorn/12-point nut. Please let me know how stupid of an idea that is.

-Thanks

[e3photo]

I just went out to the garage and looked at my spare engine,and you indeed have something already in the hole. They should both be the same and take a step washer. I think that if you take out the thru bolt,you will see a gap where the o-ring would be behind the existing washer. I sent my case out for cleaning,and when I looked at it the other day,there is one step washer stuck in it. I will probably send the case half to Ollies for remedy,as I plan on selling the engine.

Hope this helps.


Emerald

[RedCoupe]

There were some cases in the 1990 C2's that were machined too deep in the o-ring recess on one side. The factory fix was to stuff a second o-ring in the extra deep hole and grind a little bit of of the step washer so it would all fit. There is a tech bulletin about this, but all it says is just to use two o-rings on the same side and it gives the dimension of the thinner step washers. Perhaps your unusual spacer on one of you bolts was an attempt to deal with a mis-machined o-ring recess. I'll see if I can locate the bulletin. If so I'll post the numbers of the affected engines.

[RedCoupe]

Sorry I can't attach the bulletin to this post, but it is Technical Bulletin number 9107 and engines affect are 62L11289 through 62L11307 and 62L12581 through 62L12801 (manual transmission) along with 62L51104 through 62L51140 (Tiptronic). I know all of this because I have one of the engines in this group and it leaks like I have an oil well in my backyard!

[Moriartyhlms]

Mystery solved...mostly.

So I'm a bit of an idiot; just pried a two cent washer out of that through bolt hole, it looks entirely normal now. Only question is how it got there because I can't imagine it was there when I removed the through bolts originally. So it either got stuck in there randomly...which seems pretty much impossible, or my machine shop put it there for some reason...which doesn't make much more sense. Oh well, see picture below if you care, offending washer is displayed on the lip under the stud holes.

Thanks everybody for the help,
Sam

[e3photo]

Glad you got it sorted.


Emerald