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aaronamerica
07-25-2010, 06:24 PM
ok just put together the bottom end with scatt rods along with all new bearings, so long story short I've driven the car for exactly 266miles and drove perfectly smooth but then all a sudden the motor started knocking[=(], so i get the car towed home and find cyl. 2 spun the rod bearing


this pic I put a used bearing set out of my stock rod just to see will it fit but obvious this rod is toast... the new bearing was in the bottom of the oil pan all in pieces
http://i4.photobucket.com/albums/y102/aaronamericahall/rod1.jpg

what the heck happened here???[headbang]

http://i4.photobucket.com/albums/y102/aaronamericahall/rod.jpg

I dont know what to do, i certainly dont have no more money to put in this car [=(]

Can this be fixed with out pulling my motor out again?

Jake39454
07-25-2010, 06:32 PM
You are going to need a new crank. I wouldn't cut that crank since thicker bearings aren't exactly ideal for performance applications, especially one like this with high output per cylinder. Chances are the oil clearance was too large or too small. I just built a motor and measured .0035 rod bearing clearance with ACL race bearings, which is too much. The rod would've been banging around on the crank and beating up the bearing under high loads, eventually spinning the bearing. And too tight will spin a bearing for obvious reasons due to lack of boundary lubrication.

This time around measure all the rods to make sure big end diameter is the same, measure all the clearances and keep it all very clean during assembly...

geeky
07-25-2010, 06:59 PM
Did you build the motor yourself or was it built for you?

brockallentaylo
07-25-2010, 07:35 PM
You are going to need a new crank and 1 new rod, plus that block and head is going to have to be completely disassembled and cleaned or you will have issues again later from the debris.

When I mess with rods/cranks I always.

1 Mark everything so journals and caps don't get mixed up. Pull the crank, set it on a bench, torque rod caps with bearings installed (not installed on the crank). Make measurements on crank and rods, do the math to check the fit. Take everything apart.

2 Assemble the rods onto the crank and torque with no lube so I can spin them and make sure they pass my "feel" test (no binding when spun by hand and a slight side to side "wiggle" but no slop otherwise). Take it apart again.

3 Assemble the rods onto the crank and torque with plastigauge installed. Take it apart again and check plastigauge readings.

4 Clean off plastigauge and install everything in the block with lube spinning the crank by hand after each main cap and rod cap are torqued to check the amount of drag.

5 Drink whiskey.

Not everybody does it this way but this is how I do it and have never had a problem (over 100 bottom ends fiddled with here). I have seen so many "hobby mechanics" mess it up and I always feel bad for them because I know how much work they have ahead of them to get it all to work properly for the long run again. If you have never done crank work I would HIGHLY suggest to let a pro measure and install the rods and crank into the block or be there when you do it. Please don't waste your time trying to reuse or resize your crank or that rod with a different bearing size, you will regret it. Good luck to you.

Keep in mind that one rod cap belongs to one rod and connot be used with another (they are sized with the cap bolted on to it's mating rod), and make sure you don't put the cap on backwards, generally the locking tabs go on the same side of the rod, which I see is not the case in the pic of your damaged rod.

A4Rob
07-25-2010, 08:26 PM
Can this be fixed with out pulling my motor out again?


100% No. Sorry to hear about your troubles :-(

grillhands
07-25-2010, 08:42 PM
Dam that's such a horrible feeling when something like this happens.

Jake39454
07-25-2010, 08:46 PM
Keep in mind that one rod cap belongs to one rod and connot be used with another (they are sized with the cap bolted on to it's mating rod), and make sure you don't put the cap on backwards, generally the locking tabs go on the same side of the rod, which I see is not the case in the pic of your damaged rod.

The rod bearings do appear to be tang to tang in the picture...

brockallentaylo
07-25-2010, 09:31 PM
The rod bearings do appear to be tang to tang in the picture...

Oops, I see that now, just barely.

Finneid90
07-26-2010, 07:47 AM
Been there done that. It sucks! :(

aaronamerica
07-26-2010, 09:02 AM
You are going to need a new crank. I wouldn't cut that crank since thicker bearings aren't exactly ideal for performance applications, especially one like this with high output per cylinder. Chances are the oil clearance was too large or too small. I just built a motor and measured .0035 rod bearing clearance with ACL race bearings, which is too much. The rod would've been banging around on the crank and beating up the bearing under high loads, eventually spinning the bearing. And too tight will spin a bearing for obvious reasons due to lack of boundary lubrication.

This time around measure all the rods to make sure big end diameter is the same, measure all the clearances and keep it all very clean during assembly...

So what you end up doing? Did you get oversize bearings

Jake39454
07-26-2010, 09:06 AM
So what you end up doing? Did you get oversize bearings

No, I ordered OEM sized bearings from King Bearings that put me back in the .002-.0025 range. The ACL race's were .001 extra clearance

aaronamerica
07-26-2010, 10:53 AM
Did you build the motor yourself or was it built for you?

It was built for me

belinko
07-26-2010, 03:38 PM
Take it back and have them fix it!

terraflata
07-26-2010, 03:42 PM
Take it back and have them fix it!

Better have a paper that says garauntee on it!

belinko
07-26-2010, 04:31 PM
Based on the information provided it seems that the assembly process, caused the failure.

If an engine builder doesn't stand behind their own work, then the engine shouldn't have been built there.

2001A4QUATTRO
07-26-2010, 04:46 PM
^^^ Agreed and yet so many high performance shops say that the engines are built for high performance and are not warrantied. GL

aaronamerica
07-27-2010, 05:51 PM
Well I ordered a new rod and I guess I will pull the motor this weekend

I'm looking for a crank if anybody selling one.

blacka4
07-27-2010, 07:39 PM
You can repair this without pulling hte motor in my mind. you just have to pull the crank out. have it checked, but I think you are going to need a new one, the head will have to come off and be cleaned and checked. also you are going to have to flush the oil passages for debris

v dub'n
07-27-2010, 08:52 PM
the motor is gonna have to come out and if you are replacing the crank give the block a line hone.

aaronamerica
07-28-2010, 03:48 PM
Will a 2001 a4 crank fit in my 98 a4 AEB block?

2001A4QUATTRO
07-28-2010, 04:23 PM
^No