[461-69bird]

car cut out on the track at 60ft mark. what I thought was something in the oil pump locking up and breaking the roll pin in the dizzy drive, turned out to be the oil pump shaft broken and a broken crank.

not sure what broke first, the crank or the oil pump shaft which then jammed the crank.

also found what looks like a dowel pin in the pan?

not took it all apart yet to check for any damage but it`s going to be expensive I guess.

[twooldgoats]

What kind of crank was it? I did this years ago with a Chinese cast aftermarket crank in a low 10-second car. I managed to split the block lengthwise as well. I'm sorry you had the problem, but glad no one was hurt. It's good it happened early in the pass.

Jim

[461-69bird]

2007 Eagle cast stroker crank. shifting at 5500 crossing line at 5800 until this year when had to switch to shorter slicks and the 3 runs before it broke, shifting at 5500 crossing line at 6100.

block looks intact, didn`t spill any fluids

[BruceWilkie]

Dowel in pan is NOT encouraging sign. Not a fan of the cast china cranks... IMO they are inferior to factory cast cranks.
Sucks when things break.

[461-69bird]

Originally Posted by BruceWilkie

Dowel in pan is NOT encouraging sign.

where has that come from Bruce?

[quick67bird]

Originally Posted by 461-69bird

where has that come from Bruce?

From what I have seen when a main dowel is in the pan then the block usually has a crack. Sorry for you problems.

[461-69bird]

Originally Posted by quick67bird

From what I have seen when a main dowel is in the pan then the block usually has a crack. Sorry for you problems.

oh ok thanks

[Tom Vaught]

Dowell holds the main cap in the proper location.

For you to find a dowell in the oil pan the dowell had to come out of the block/cap it was locating. It is "trapped" in its location normally.

Expect some interesting findings when you get the engine apart and everything gone over on the block. If the main caps split without hurting the block other caps can be installed (line bored/honed), and possibly you can save the block.

Tom V.

[461-69bird]

ok thanks Tom

[steve25]

I would not run one of those aftermarket cast Cranks without getting it Cryo treated for added strength, pure and simple!

[461-69bird]

a few more pics.

the dowel was from number 2 mains and the crank broke at number 5. what I did notice taking it apart, there are studs for number 2 and 4 and number 2 were loose after undoing the nuts, I could unscrew the studs by hand.

block looks intact but I will get it checked professionally before I decide what to do.

[461-69bird]

looks like it was eating the thrust bearing. this was changed in 2008, never saw any gold in the oil changes though and I had just done one 2 days before this happened.

the cam was in great condition and all the con rod bearings were good as well.

[firechickenman]

That #2 dowel pin may have fallen out at any time since the pan was off the last time. Looks like the cap may have been moving around some. How tight does the dowel fit in the block?

Main studs should not be tight in the block. If you could remove the studs by hand after the nuts were loosened, that's normal.

Looks like you might have gotten very lucky. How did the oil pump drive come out of place? Is the shaft locating pin missing from the oil pump?

[461-69bird]

I didn`t try the dowel as it had broken off and didn`t think to.

interesting about the studs as the number 4 ones I couldn`t undo.

not sure on the pump drive, but there are no pins on it, it`s smooth and looks like they`ve been ground off. is that what you do if it has to be installed from the top?

[Tom Vaught]

Originally Posted by firechickenman

That #2 dowel pin may have fallen out at any time since the pan was off the last time. Looks like the cap may have been moving around some. How tight does the dowel fit in the block?

Main studs should not be tight in the block. If you could remove the studs by hand after the nuts were loosened, that's normal.

Looks like you might have gotten very lucky. How did the oil pump drive come out of place? Is the shaft locating pin missing from the oil pump?

[ Post #1 FCMan: "car cut out on the track at 60ft mark. what I thought was something in the oil pump locking up and breaking the roll pin in the dizzy drive, turned out to be the oil pump shaft broken and a broken crank.

not sure what broke first, the crank or the oil pump shaft which then jammed the crank."]

The Number#2 main sees the stress in the engine first. Have seen several engines (cast main caps) where the #2 main cap was split up the main fastener hole. Your pics show no evidence of that happening in this case.

The crank does not normally break at the #5 main location.

Yours did which makes me think that the oil pump shaft got jammed up in the #5 crank counterweight area. If the block checks out you can put steel caps on the block is the block shows no other damage. Inspect the block for the oil pump shaft guide (cast in the block) still being there and in good shape.

Brian H broke the oil pump shaft guide on his IA-2 Block when he had a engine failure some years ago.

Tom Vaught

[461-69bird]

Tom

do you mean I shouldn`t use the existing main caps if the block is ok? also that shaft guide, what`s it made of?

thanks, Rick

[RA462]

I broke a factory "N" 455 crank about the same point on the track once. It was like I killed the ignition. No bang just stopped. I broke the #5 rod journal right off the crank. In our opinion the journal fillets should have been larger creating a stress concentration piont. The power from all the cylinders has to go through that #5 rod journal since the resistance on the engine is the flex plate. Just my 2 cents. Sorry about your engine.

[screamingchief]

I can easily see some excess heat (ie: blue'ing) in the area of the break around that rod journal/counterweight.

My WAG,it spit the OP shaft outta it,then it obviously lost oil pressure,rod grabbed the crank,bam broken crank,only odd part here is the OP says the rod bearing itself looked ok.

Was the big end of that specific rod discolored @ all???

That discoloration is away from (opposite side of) the main journal that has the thrust bearing on it,but despite that (one way or the other) I feel that the thrust issue could be the root cause of the crank breaking here.

Now were that the case,how about this chain of events,in this scenario the excessive thrust could easily be what took out the OP shaft,that's a no-brainer,that back counterweight is like right there,so that seems easy enough to see happening,I just dont think we'd see that obvious heat discoloration if the shaft jammed in there and caused the crank to break.

And the dowel pin is sorta the same deal.

I mean you can clearly see that specific main cap was fretting,and that's likely why the dowel fell out.

I dunno,looks to me like a couple of different things were going on @ the same time here.

Thrust is all outta whack,crank is sawing back & forth in the block,that causes the cap fretting situation first,so yeah it drops the dowel outta there,eventually the rearmost counterweight takes out the OP shaft,instant loss of oil pressure,then bam a rod grabs the crank,and the crank breaks.

Just curious,what casting no. is this block?

If it's a 557 block,that might explain some of this.



Bret P.

[Tom Vaught]

Have to agree that a lot of things were going on with this engine that could have contributed to the crank failing.

We had some cap/block fretting on the 863 HP boosted engine with 2 bolt caps and studs. The theory now is that the dowel pin register was not good enough on that deal.

Maybe the OP can post up the pictures of the main and rod bearings for us.

Tom V.

If it was a 557 block ........Tick Tock.

[461-69bird]

Brett

no this was a 72 block. all the con rod bearings were fine as were the crank journals themselves. yes the thrust bearings were worn but no other damage.

this happened at the 1-2 shift at 60ft mark.

I`ve had problems with it shearing the roll pins on the dizzy gear drive, would that have been caused by the crank moving due to the thrust wear?