Help Please 340 main bearing cap is cracked

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Chris Martin

Chris Martin

Norton
Joined
May 7, 2006
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Location
Goderich Ontario Canada
Hello all!!! I replaced the oil pump in my 340 and I noticed a hair line crack where the oil pump drive shaft comes through the main bearing cap. Anyone else had this happen? If so is it normal and can I leave it or do I yank the engine, get a different cap and have it line bored? Thanks in advance
 
Since you have the pan off already I think it would be worth your time to take it to a machine shop and have them verify what you see. First time I have heard of this.
 
That does not sound good.... I have not had that happen, but with the time and $ we put in these cars, I would be very paranoid!
 
I'm curious why you are replacing the pump in the first place? Was it for precautionary measures or were you having pressure issues, if the later you may have found your problem right there.
 
The words " main bearing cap is cracked " speak volumes.
I'd have it checked over thoroughly for sure.
You could replace it and have it line bored if it is cracked , but I'd give the entire bottom end a ton of scrutiny before I started making decisions.
 
Thanks all for the advice. I was replacing the pump because I had the oil pan off and figured it may aswell be replaced too. As it turns out, the replacment pump wasn't machined properly so it didnt seat properly in the bearing cap and put too much pressure on it causing the crack. I ended up taking the cap off and put it my milling machine, removed the affected area with an end mill, checked for any other cracks and VIOLA!!! good to go!!! Called Chrysler, vented a bit and they are sending a new pump. I will be sure to mic. this one B4 it goes in. Note to self... don't trust everything that come "ready to install".
 
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