2G Help with rod bearings!

[Covoss]

I keep spinning rod bearings the crank has been milled hoping for some tips and maybe a number for a brain to scratch .

 

[DSMPT]

You have to rebuild the engine properly. Just keep replacing the bearings and cutting the journals won't solve the issue. Once you spin rod bearings, the rod big end roundness is out of spec. Like they get oval. You have to recondition rods and maybe the block too.
Many factors would cause spun bearings but another common cause is oil pressure related. Like you have forgotten to block off the balance shaft oil feed hole if you eliminated them.

 

[Covoss]

I believe our lack of assembly lube may have been the problem we have checked our specs with rads. And are within limits, will update if I spin it again!

 

[curt-s]

The engine was assembled dry?
Oof.
That doesn't explain "KEEPS spinning rod bearings"
I hope whomever assembled it before didn't check it this last time.

 

[DSMPT]

I believe our lack of assembly lube may have been the problem we have checked our specs with rads. And are within limits, will update if I spin it again!

Did you disassemble the engine and inspect all the parts? How did you check the clearance?
I don't mean to discourage you but it doesn't really matter what caused the last spun bearings. As I mentioned above that once you spin bearings, the only way to break the vicious circle of replacing bearings is by inspecting/cleaning all the parts and rebuilding the engine properly. Otherwise you would spin again sooner or later.

 

[Covoss]

That's what I've heard as well, this is last try before complete tear down. But no it was just assembled using oil instead of assembly. We have been dropping the pan to inspect the crank. We have mostly caught it before it had the chance to make audible noise due to stethoscopes. Hoping it didn't cause any more damage then scuffing the crank.

 

[jed344]

Have to figure out why its spinning. Then anything that touches oil coolers turbo ect all needs gone threw. Then when everything needs checked. I rarely use plasti as i prefer to mic the crank then torque the rods and mains and measure with bore gauges so i know exactly what it is. We even then once all done with assembly lube will prime it by spinning the oil pump so nothing is dry when the motor first cranks.

 

[Covoss]

I believe it spun due to a clogged port, the car had sat for 15 years, after an oil change it was too dry is our guess. After that we basically started it dry now we are at 50 miles or so with it just babying it with break in fluid.

 

[jed344]

Well we do not baby the break in ourselves. Usually 1 heat cycle varying rpm from 2-3,500pm till warm then shut it off. Gives up time to check tune settings, leaks re torque stuff hot. After that it goes right to boost and decel in gear so the vacuum helps seat the rings. Granted these are motors that get raced and ran hard. This method checking leak down and compression test we have seen rings fully seated within 50 miles sometimes less. Have also in a pinch done this and first drive the motors see well above 600. Badly built any amount of break in wont fix. Everything needs torn apart now cleaned and checked either way. I ALWAYS wire brush every single oil port and galley every motor. You would be shocked how much junk comes out of a crank after coming back from the machine shop.

 

[Covoss]

Fair enough, yeah I'm just getting into the 4g63t, kind of crazy how much power these things can put out. But sounds good it needs done anyway I'll let y'all know thank ya!

 

[curt-s]

The more power, the more exact you need to be in machining, tolerances, and assembly. Throwing it haphazardly together and hoping for the best is a fast ticket to " the 4g63 sucks dsms suck it doesnt run on sand wsWTFTF?T?" territory. Not saying you're doing that but so far the impression is it's being re-assembled after spinning rod bearings without investigating why and looking at it very closely.

You can use oil to assemble most parts, you don't need assembly lube. Assembly lube just sticks better and some have anti-wear additives in there already to give a bit of a boost. However, most engines to this day are assembled with oil. Bearing-journal interface is fine to use oil because it gets trapped. After the first time you start the engine, you only have oil there anyway and will until the day the engine dies.

On cam/rocker lobes, assembly lube works better because it sticks to the surfaces.

 

[Covoss]

No I get you, honestly, I don't see how people can have a lack of respect for these engines after seeing what they're capable of. And I'm not expecting it to be perfect yet. Has previously stated it has been sitting for 15 years. The fact that it runs it all is amazing.

 

[97egl]

I keep spinning rod bearings the crank has been milled hoping for some tips and maybe a number for a brain to scratch

Not a put down but just to clarify for your future reference crankshafts get turned and/or polished. Milling is done to flat surfaces like head/flywheels/block decks ect.

If you had the crank turned are you sure you are putting undersized bearings in?

Also are you spinning the rod bearings or are they just knocking? Spinning is where the bearing halves are literally turned in the rod and usually melted together.

If you have SPUN a bearing there is VERY VERY little chance just a new bearing will last even for a couple hundred miles in the rod without the rod being machined or getting a new rod. If you just had a worn bearing that's knocking but not spun you can probably get away with just replacing the bearing and it will last for a little while. How long? Depends on how bad the crank or rod is out of round.

 

[Covoss]

No you're right. It is turned instead of milled. I always get them backwards even with rotors . You would think with it being round I would get it. The first one spun after an oil change and the two halves were on the same side but after inspecting the rod still from the bottom. The rod seemed fine The second was just the knocking That's when we checked it, luckily I come from a family of machinists so we have all the tools to properly check surfaces. We ordered decent bearings instead of cheap bearings just in case their machines were off. As far as the rod and the crank we look to be in good position. Like I've said if it spins again it'll be a complete engine tear down, honestly it's needs to happen either way. Thank you guys again!

 

[curt-s]

No I get you, honestly, I don't see how people can have a lack of respect for these engines after seeing what they're capable of. And I'm not expecting it to be perfect yet. Has previously stated it has been sitting for 15 years. The fact that it runs it all is amazing.

No you're right. It is turned instead of milled. I always get them backwards even with rotors . You would think with it being round I would get it. The first one spun after an oil change and the two halves were on the same side but after inspecting the rod still from the bottom. The rod seemed fine The second was just the knocking That's when we checked it, luckily I come from a family of machinists so we have all the tools to properly check surfaces. We ordered decent bearings instead of cheap bearings just in case their machines were off. As far as the rod and the crank we look to be in good position. Like I've said if it spins again it'll be a complete engine tear down, honestly it's needs to happen either way. Thank you guys again!

We will definitely try to help but these two statements are at odds with each other. After sitting for 15 years, it should have been torn down and every inch checked by visual inspection and measurement.
Best of luck going forward but it needs to be done proper starting from this moment. Well, not this moment, many moments ago.