I'm posting this up for a friend of mine as he doesn't have access to a computer at the moment.

He has recently rebuilt his motor and the rod bearings keep eating themselves up and causing rod knock.

Details on the build that matter are:

4g64 block- was taken to a machine shop with the crank and they checked the specs and all was good

He is using Acl bearings.

After initial start up with the turbo tuff rods he started to hear a knock around 2500 rpm. Turned the car off and pulled the pan to find that the bearings were scored and one of them had got hot.

He then purchased some cheap scat rods and new bearings just to make sure that the tolerances were right and that the surfaces were fresh.

the same thing happened again.

here are the images of the bearings.

new bearings on the left and 100k mile oem on the right



all of the new bearings





he is stumped at this point and looking for any type of input

 

are the rods bolts over torqued?

 

Looks like trash got into the bearings. Is this a build after the engine blew up? Did he use a new oil cooler for the rebuild or even flush the old one out? Was the block hot tanked and the oil passages completely cleaned ? Were the clearances checked to make sure they were correct during both installs?

Just saying...

 

Did it have good oil pressure?

 

Clearances were checked initially, but not after the bearings spun with turbo tuff rods. Not hot tanked after the first set of bearings. Could be from excess from cooler, couldn't get all of shavings out. It's my car.

 

Oil pressure was great at idle and during cruise. Never lost any pressure. Checked surfaces on journal and they aren't smooth anymore so I need a new crank anyways

 

Feel ya....sory to hear about the crank....Replace the oil cooler with brand new and new lines. U might want to clean the oil feed lines to the turbo in case dirt got into there. Wouldnt want to replace a turbo on top of the issues you have now.

Since you have to rebuild everything, clean the whole block again. Get the new oil cooler and lines and flush the turbo oil line liberally. Use plenty of assembly lube and make sure to check all clearance on the rods and mains prior to assembly. Oh and dont forget to replace the thrust bearings with new ones either :-)

 

Well not sure what your problem was the first time, but if you just slapped new rods on the old crank that spun those bearings im sure there was clearance issues. Pull it, hot tank it, new bearings and crank. Get rid of that old oil cooler also.

Make sure you check all clearances.

 

That's the plan now, new crank, bearings and get block cleaned. Thanks for all the input

 

Don't forget a new oil cooler!

 

Or none at all

 

or delete it

 

damn, tree'd lol

 

Prob delete it to get it all running and then buy one later.

 

did you have camcover sand blasted?