Question: LB7 Main Bearing Cap Side Bolts.

BigDaddyDiesel

BigDaddyDiesel

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Feb 14, 2009
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Ok, I broke one on the passenger side right behind the starter. I attempted to back it out with an easy out, but that broke too. Since I was already going through the rest of the engine, (top end is done), I am pulling the engine and wanted to know if anyone else has broken the side bolts and what were you doing when they broke?
 
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custom8726

custom8726

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Feb 25, 2008
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If the bolt broke flush or slightly outside the block you can weld a nut to the bolt and then add a little heat and hopefully back the bolt out. Probably going to be a PITA though, Good luck..
 
BigDaddyDiesel

BigDaddyDiesel

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Feb 14, 2009
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Ok, first of all, sorry for the delay. I was subscribed but the notifications didn't make it home. But, I broke the second from the back on the passenger side. I think it may have been a combination of pulling/hauling with a decent tune coupled with a leaking injector sleeve. At some points on the last run at around 25-2600 rpms it felt as if a cylinder wasn't firing. I am "guessing" that running a hotter tune while hauling along with dead cylinder at times, (about twice that it did that) may have caused just the right vibration to make it happen. I can say I am having a hard time finding someone else that has seen it happen.

So I pulled it apart and sure enough I had antifreeze throughout, and it was NASTY, grey and white milky through the valve train and THICK while draining. I got about 3.4 gallons of super thick crap out of the oil pan. Serviced the top end completely, injectors, silicone fuel lines, cleaned the valve train, etc. When I opened up the bottom end nothing looked bad right off, so I pulled that one bearing cap and wonder of wonders the bearing was dang near flawless! I assumed that with the antifreeze dilution, etc that they would be thrashed! Also, the bell housing is cracked. I have all new bolts, etc. But I now need a bell housing and one bearing cap. I tried using and easy out on that broken bolt and that broke too...
 
BigDaddyDiesel

BigDaddyDiesel

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Feb 14, 2009
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Here are a couple of pics...

Valve train mess...
DmaxPics009.jpg


Valve train clean...
DmaxPics011.jpg


Broken bolt and easy out IN the cap...
DmaxPics020.jpg
 
TheBac

TheBac

Why do I keep doing this?
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Apr 19, 2008
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I am at a loss. What the heck would cause that other than something being amiss with the crank/rotating assembly?
 
403turbo

403turbo

<--It's whats for dinner!
Aug 3, 2009
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What caused the heat discoloration on the rocker arms? Is that normal? I don't remember seeing that on mine when I had it apart.
 
BigDaddyDiesel

BigDaddyDiesel

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Feb 14, 2009
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Most all of those I have seen had the same discoloration on the rocker arms, but I am at a loos as to why that bolt broke. Except for the fact that I was "Forced" (so to speak) into running my hot tune while hauling, but at the time I only had a tri-axle gooseneck behind it running empty. Now, that tune dynoed at 467hp and 856ft lb's tq, but, I didn't think that was enough to caused that.

That is why my "Theory" is that it MAY have been caused by excessive vibration resulting from an injector sleeve dumping antifreeze into a cylinder enough to caused that particular cylinder not to fire. That happened three times on that trip, and may also explain why I had so much antifreeze in the crankcase without having any signs of a blown headgasket in any way shape or form. But, honestly I am stumped. The cap is at the machine shop now to see if they can get the old out and chase the threads so that it can be saved; if not, I am thinking I have two choices.

Choice #1
Replace the block with a stock replacement block if I can find one in good shape.

Choice #2
SoCal Billet caps. Of course with this route I would probably want to ship it to SoCal and go ahead and have them build it with billet throughout.

I guess we will have to just wait and see what the my buddy at the machine shop says when he calls me...
 
BigDaddyDiesel

BigDaddyDiesel

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Feb 14, 2009
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But if the old cap is salvageable, would it be ok to put that one back and run it at least temporarily until I get everything I need? Like I said, the bearings looked good...
 
BigDaddyDiesel

BigDaddyDiesel

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Feb 14, 2009
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Also, if I go with Socal caps, those would need to be line bored instead of just honed? Am I on the right track there? And, if I go that route, understanding that I use the truck for hauling and not for wild tuning, racing or sledpulling; would the added expense of billet everything else to go along with it truly be worth it, to avoid possible piston or other failure?

I run EFI pushing a dynoed 450+hp, and less with a tow tune...
 
Leadfoot

Leadfoot

Needs Bigger Tires!
Dec 27, 2006
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www.matpa.org
That's interesting.

If all the bearings look OK, then I doubt it was from too much power and/or vibration. It could be as simple as it was a 1 in a million defective bolt, 1 in a million defective cap (or threads), or something could have gotten into the threads before/during assembly.

If it were mine, I would have a local machine shop see if the could EDM the broken easy out and bolt out (using the opposite side as a depth and diameter gauge) and then you can gently break the rest of the pieces out with a tap (back and forth, back and forth, etc. removing the chips as often as possible with lots of tap and die lube).

If you do decide to reuse it, at MINIMUM have someone check the alignment of all the caps when torqued down.....

If using a different cap or billet caps it will have to be checked anyways and most likely honed or line bored and honed.

Good luck, let us know how you make out.
 
BigDaddyDiesel

BigDaddyDiesel

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Feb 14, 2009
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Ok, we wound up doing just that. My buddy was able to get the broken easy out tip and the bolt end out of the cap. He chased the threads and the bolt goes in fine and has no "play" or wiggle when fully inserted. It is as tight as the other side. So I am going to try to reuse for now. I do have a small fund for building it, but at this point it is not enough to do all that I want to do when taking it all the way down, I would hate to pay someone to do all that for just the caps and bearings and not do pistons and the rest while I am in there.

Sometimes I hate living on a budget, but I am thankful that I was lucky this time around...

If it doesn't hold up you will all know about it...:rolleyes:
 
BigDaddyDiesel

BigDaddyDiesel

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Feb 14, 2009
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OH, one last interesting tidbit that kind of surprised us as well, when the bolt broke, instead of breaking at the threshold where the cap meets the block, it broke about a 1/4inch deep into the cap. I would imagine that makes the defective bolt more plausible.
 
duratothemax

duratothemax

<--- slippery roads
Aug 28, 2006
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BigDaddyDiesel said:
I run EFI pushing a dynoed 450+hp, and less with a tow tune...
Click to expand...

stop thinking it was HP, your tune, leaking injector, blahblahblah that did this. ;) :)

IMO, it wasnt any of those things.

there are guys running 1500hp and they dont have problems like these. Even guys who run stock main caps/stock main bolts to 1000hp dont have these problems.

It was a 1 in a million freak occurrence, plain and simple....

ben
 
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