Broken Crank...

[Luckymc420]

95 3100
I was driving home from the gym and car started to knock really bad but still ran. I went maybe 200 more feet before i got it to a parking spot. Car was not ran much longer maybe 2 min to find out if it was an ACC drive problem. Anyways pulled it home. Pulled engine out removed pan and I think it is #2 rod cap spot is where the break is.
Question is:
Id like to have an idea of why it broke. No engine mods. All stock. Engine was rebuilt about 7 years ago. Everything was check. Did find a piston bad but was replaced. New oil pump and lifters. Crank turned. Also new timing chain.
Had no major engine problems before this...
I have done some shopping for a new crank, oil pump, timing cover gaskets, and oil pan gasket. Runs about $400.

Any ideas comments?

[Money pit Beretta]

It looks very thin. What brand was it?

[1990BerettaGTZ2.3L]

I did that in my chevelle when I had the 350 in it that's now in my truck but my old Saginaw 4 speed was starting to go out and by noise I mean it was wining like I had 10 superchargers running together and I had 2 miles til home and it locked up at 40mph and snapped my crank in half

[berettaboi]

that's interesting! you said there was a bad piston when you "rebuilt" it before, was the con. rod for that piston on that spot on the crank? likely whatever caused that bad piston may have fractured that spot, or maybe the machine shop took a little too much meat off? (hard to believe, but i guess all shops are not equal).

crazy either way. i would just buy a 3400 and plop it in, but you have already said you don't mind tearing into it.

[Luckymc420]

Well I don't remember why we replaced the piston but it was just that. Not sure what one. The engine was rebuilt after the lower intake gasket blew.
I did see this wear but I think its from the crank breaking.




I don't want to put in a 3400 in this car.
Not sure on the brand Money.
Some bearings had a grove in them but also thinking maybe crank break did it. The rest have some copper showing.

[3X00-Modified]

Thats crank thrust/walk wear... Do any of the crank bearings have a thrust collar on them? are they heavily worn? if not they used the wrong bearings when assembling.

Notice the third bearing back has a thrust collar on it.



Does yours have this?

Depending on where that wear is yes it could have been caused when the crank broke, but that would only be true if that wear is ONLY on the first main bearing cap, any one behind that and the thrust bearing wasn't working right.

Turning the crank should not have caused that, but yes if you did have a bad piston/rod assy you could have hairline cracked the crank from that and then it just gave out.

Also why not put a 3400 in it... it will be cheaper and a direct drop in.

[1990BerettaGTZ2.3L]

If he did a 3400 would he have to upgrade to obd2 to tune it to run right in his car though if he went that route I'm just curious because I wish I did it when I had my 95

[Money pit Beretta]

It's better to do so, but you don't have to Ryan.

By the way Luckymc420 has a 3400 in his project car. I don't think he wants to go through that again on the DD car.

[3X00-Modified]

Woody's 95 3400 swapped Z26 ran the fastest time of all 3400 swaps and he was never able to tune it... so no you don't have to. The displacement change is not enough to screw up what the 95 3100 ECU has for a tune, it can adjust for it for the most part and work fine as a DD... its only if you start to mod the 3400 is when you want the tuning capabilities.

[Luckymc420]

Yeah forgot to say that was the front bearing cap. If you look real close you can see the side of the bearing. As for the thrust washers yes we did put those in.

You can see the top thrust in that picture.
As for the bad piston and rod deal. It was in 05 and I really don't remember what # it was. I thought you can put dye on the crank to find the crack. Anyways.
I am wondering can I still use that bearing cap. I mean It didn't really get into it.
Well when my car broke I had to figure out what was wrong so I had an idea on how much this was going to cost. Before I found out what it was I told myself if its over 700 then I will prolly get rid of it. I have priced out the lower end rebuild and its under 400. That's before my works discount. I don't think Ill find a decent 3400 around here for that little. And Im kinda on a time factor since the car I am using now is not mine. I know its very odd I broke it but just wanted to get some peoples input on what could have incase its something else that caused it.

[berettaboi]

you can likely find a 3400 powered car ready for scrap due to rust or other issues that you can part out yourself and scrap and get close to if not more than what you paid for it out of it... this involves more time and work though...

[3X00-Modified]

You can re-use that cap, and if that was cylinder 1 then that's defiantly from after it broke.