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Is it cheaper to replace engine or fix a rod knock?

Old Dec 29, 2010, 10:11 PM
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Is it cheaper to replace engine or fix a rod knock?

Whatsup EvoM,

My car has been stored away for winter due to a rod knock from the engine. Car has completely stock engine. My question is will it be cheaper to replace engine or fix the internal problems? Any advice or opinion will be appreciated.
Old Dec 29, 2010, 10:14 PM
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Originally Posted by CMoney
Whatsup EvoM,

My car has been stored away for winter due to a rod knock from the engine. Car has completely stock engine. My question is will it be cheaper to replace engine or fix the internal problems? Any advice or opinion will be appreciated.
Cheaper to buy a longblock and just drop it in the car and go.. Then sell off any extras that are good on your rod knocked motor.. For a little more you can fix yours and end up with a built motor but you only asked for cheapest way to get back on the road..

Also if you want to just get rid of the car we buy them as it sits blown..

Mike
Old Dec 30, 2010, 12:31 PM
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Because your crank may be damage, I would have to lean to either build it (Inspect Crank) or do what Awd says
Old Dec 30, 2010, 12:50 PM
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build the motor hands down when mine was acting up and I did not know why no evo shops buy me i pull the whole thing and dropped a 2.4 in there and moved on. no point in messing with it perfect excuse to go built motor for sure and as mike stated sell off old parts as I did.
Old Dec 30, 2010, 04:12 PM
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As great as it is to just drop in a new engine and go, why don't you assess the damage first. If your crank is still in good shape, you may be able to get it cleaned up and polished and put slightly thicker bearings in there if needed. The engine will still have to come out of the car but in terms of cost, a little machining to clean up the crank and rod plus bearings is much cheaper than another engine. If the crank is no good, then you can go the new engine route. My two cents. -A

Last edited by Adrewzki; Dec 30, 2010 at 04:14 PM.
Old Dec 30, 2010, 06:12 PM
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If its got rod knock (and it indeed is the rod knocking, not a cracked piston) then you will at the very least need an entire new crankshaft and a full set of bearings. This is way cheaper than an entire new engine, but the only way you are going to be able to tell what was destroyed is to pop the pan and examine the crank and maybe remove the cylinder head. Good luck!
Old Dec 31, 2010, 06:47 AM
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just because you have a rod knock doesnt mean your crank will need to be replaced. I had spun a rod bearing and was able to reuse my crank when the motor was built. obviously after being polished.

but yes it is cheaper to replace with another long block. I went with a built shortblock because its like having a brand new motor and could be happier
Old Dec 31, 2010, 11:17 AM
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Yeah i will update this thread after i get my car fully inspected. I'm sure if has to do with something internal as it has the sound rattling from inside so i suspect it is a rod knock from videos posted on youtube.
Old Dec 31, 2010, 11:50 AM
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somebody mentioned polishing crank then using oversized bearings dont be dumb enough to do that. get new motor safest route
Old Dec 31, 2010, 01:44 PM
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How much would a used shortblock cost?
Old Nov 8, 2015, 12:12 PM
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2012 mazda 3 I rod knock

I was wonder what's the best idea to do with my rod knock on my car? I want to either trade the car in or fix it
. What could I do?
Old Nov 8, 2015, 01:41 PM
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If you have the time and ability, pull the motor down and inspect it yourself, that won't cost you anything. Then decide the best way to go. If it was me and I would want to save money too. If the bore was still good, I'd buy a stroker kit and install it myself. Then I'd save up and do the head and cams, then the next stage I'd go a Fp red and so, as a staged approach
Old Nov 9, 2015, 10:04 AM
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rod knock on a 2012 mazda 3? Should be under warranty unless you didn't change the oil...
Old Nov 9, 2015, 10:17 AM
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Originally Posted by Jonno99
If you have the time and ability, pull the motor down and inspect it yourself, that won't cost you anything. Then decide the best way to go. If it was me and I would want to save money too. If the bore was still good, I'd buy a stroker kit and install it myself. Then I'd save up and do the head and cams, then the next stage I'd go a Fp red and so, as a staged approach
I agree with Jonno here,


Drop the oil pan, pull the head, and check for damage. If it's little to none, that would be a perfect platform for a stroker.

-pal215
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