help with a loose rod
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Registered User
Joined: Feb 2007
Posts: 79
help with a loose rod
i have a 1969 396 and one of the rods came loose. everyone i have talked to said the best way is to have a complete engine rebuild. but is there a better/ cheaper way? and if i do get the engine overhauled about how much should it run me. just an estimate so i know im not getting over charged. thanks.
Registered User
Joined: Jul 2007
Posts: 2
From: ohio
rods just dont come loose so you need to have this torn down and see what is going on in there. did it break a rod bolt?, did the rod bolts just stretch from over reving?, what happen to the rod bearing?, where is all the little pieces of metal? you will find all this out when you get inside of it. as for how much that is hard to say how long has it been since it was rebuilt? if it just needs bearings and gaskets and all new rod bolts (that is a must) i would say around 1500 but if it needs bored (you will need new pistons),decked and all that i would say around 2500. that is before you decide that since your that far to put in a aftermarket cam, intake, different carb, roller rockers the list goes on lol
Registered User
Joined: May 2006
Posts: 65
From: Las cruces New Mexico
Guessing on the cost of a rebuild is kind of like guessing what the price of gas will be in 2 months. We hope it will be less expensive, but in all probability it will be expensive.
The cost depends on what needs to be done. However it is not always clear if what needs to be done is something worth doing or not. It is very easy to get caught up in "bench racing" advice and do things that, for a particular situation, are a waste of money.
My advise is to read and research. Then decide for yourself if for the intended use of the engine you really need to do something.
Many of us have gotten caught up in the game and thrown $hundreds into motors that may not have added anything to meet the goals of the project.
So do the home work and decide for your self what you expect from the project. Expect to make some concessions, as the cost of some things out way the gains...
as to the rod....
If the rod came loose, the first question shouldn't be how much to fix it, but why did it come loose in the first place? Rods coming "Loose" are not a common occurrence....more likely the bearing died...
Either way the crank will in all likelihood need to be straightened and turned...and the rods will at least need to be resized...
Think of it this way
In an engine cruising along at 2000 rpms, the rod must stop and change directions 4000 times in a minute (once at the top of the stroke, and once at the bottom of the stroke)....thats around 67 times a second....the film of oil between the crank and bearing transfer huge loads between the crank and the bearing surface...whenthe rod comes loose, the oil film literally goes away and the bearing and the crank come into contact. so even if you heard it knock, and could turn it off in 5 seconds, (and it usually takes longer for the oh crape warning to go off in the brain), the rod banged the crank 200 to 300 times... not a good thing.
If it were mine and a rod had come loose, it would be a full rebuild.
As the adage goes…
If you don't have time and money to do it right the first time,
Then how are you going to find the time and money to do it over the second time??
G
The cost depends on what needs to be done. However it is not always clear if what needs to be done is something worth doing or not. It is very easy to get caught up in "bench racing" advice and do things that, for a particular situation, are a waste of money.
My advise is to read and research. Then decide for yourself if for the intended use of the engine you really need to do something.
Many of us have gotten caught up in the game and thrown $hundreds into motors that may not have added anything to meet the goals of the project.
So do the home work and decide for your self what you expect from the project. Expect to make some concessions, as the cost of some things out way the gains...
as to the rod....
If the rod came loose, the first question shouldn't be how much to fix it, but why did it come loose in the first place? Rods coming "Loose" are not a common occurrence....more likely the bearing died...
Either way the crank will in all likelihood need to be straightened and turned...and the rods will at least need to be resized...
Think of it this way
In an engine cruising along at 2000 rpms, the rod must stop and change directions 4000 times in a minute (once at the top of the stroke, and once at the bottom of the stroke)....thats around 67 times a second....the film of oil between the crank and bearing transfer huge loads between the crank and the bearing surface...whenthe rod comes loose, the oil film literally goes away and the bearing and the crank come into contact. so even if you heard it knock, and could turn it off in 5 seconds, (and it usually takes longer for the oh crape warning to go off in the brain), the rod banged the crank 200 to 300 times... not a good thing.
If it were mine and a rod had come loose, it would be a full rebuild.
As the adage goes…
If you don't have time and money to do it right the first time,
Then how are you going to find the time and money to do it over the second time??
G
Thread Starter
Registered User
Joined: Feb 2007
Posts: 79
thanks for the advice everyone. i called a place the other day and they did some research and got an estimate of 3500. i told them to get lost. i have seen 396's on ebay for half of that. another place suggested i get a new engine, but i am really attached to this motor. but one poster mentioned 1500-2500, that seems a little more affordable, i just need to find a place that will do it for that much.
oooo the things we do for are cars.
oooo the things we do for are cars.
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