Having issues with the crank not turning after installing rod bearings in a 2.4l ecotech

Bill_Johnson

I have a 2.4l ecotech engine in a 2017 Buick Verano. The head is off. I put in new pistons and rings new rod bearings in . No timing chains are hooked up. Just the number 1 & 4 piston rod bearings are connected to the crank. Before when there was nothing tightened to the crank. I could easily turn it by hand. After tightening the rod bearings for pistons 1 & 4 to spec 18 ft/pounds then 100 degrees. The crank wont turn now. Not even with a breaker bar. Which I didnt do too hard cause I shouldn't have to. I had to replace all the rod bearings that I put in the first time and the crank wouldn't turn. And I tried to force it and found out in doing so it scarred my rod bearings. So after putting in new rod bearing and tightening the rod bearings for piston 1 and 4. The crank wont turn. I don't have a clue at this point whats going. Anybody have an idea as to what is going on?

thecardoc3

The bearing clearance has to be too tight. One possibility could be a little debris behind one of the bearing inserts. Everyone always worries about dirt on the crankshaft side of the bearing, but dirt behind a bearing doesn't allow it to sit properly in the rod or cap and reduces the clearance and locks the crankshaft up. Right now, you don't know which one is at fault, so pick one and unbolt the rod and remove the cap. Push the rod away from the crank and see if it turns. If so then you have the one that has the problem, if not repeat with the other one.

Did you measure the bearing clearance with plasti-gage? You would use the green as the specification is .0011~.0029 (basically 1-3 thousandths of an inch). A lot of people like to try to skip this step, but it is the builder's responsibility to ensure that everything is correct. The connecting rod journal of the crankshaft should measure 1.9291" ~ 1.9297". When you see that only the ten thousandths digit changes and that is only five ten-thousandths (5/10,000") you get an idea how precise everything has to be.

Let us know what the bearing clearance measures and if there was any debris between a bearing insert and the rod or rod cap.

The link below is for plasti-gage (.001"~.003"). Follow the instructions to use it. Let me know if you have any questions.


https://www.amazon.com/Powerbuilt-648441-Plastic-gauge/dp/B002INTX3C/ref=sr_1_2?crid=269ZJD8VDO6PV&dib=eyJ2IjoiMSJ9.-QxZXw4aXg0DlZ6yYlcr1gA9XsxIgC2GC5EfxzGIdfoZVImCPwO9A0nHgV4_FH_ERdn-DjI_MaB9EYLteEXvzdCF3ScLEo6W3KNAbDibC62qnEBD67rG5yiKu38kJrEj7ZvZbQeN3J9XiNtqBPk9YhztL8j2qlvTN6C_13WtL_BHxMTBDisWjowvwm3x7hmdDMdRgceVWwiIhLPELQgliIkMwCqTIT92eGnmXregG9o.-IrcO8yt2t3oPA3syWkH9nLS5PDawDU9kpqD-ghJAgA&dib_tag=se&keywords=plastigage&qid=1721340715&sprefix=plastigage,aps,84&sr=8-2

Bill_Johnson

Is this measurement best done with the engine out of the car or can it be done with the engine in the car?

Bill_Johnson

And is this guage better than a feeler gauge? and can you use the feeler guage?

thecardoc3

Bill_Johnson said:

Is this measurement best done with the engine out of the car or can it be done with the engine in the car?

It can be done either in or out, but it's far easier to deal with any problems found if the engine is not in the car.

Bill_Johnson said:

And is this guage better than a feeler gauge? and can you use the feeler guage?

You cannot use a feeler gage to measure bearing clearance. To use the plasti-gage, you cut a piece of it and lay it across the crank journal. Then you install the cap and torque the rod bolts (or nuts) to spec. This crushes the plasti-gage between the bearing and the journal. Now you take the cap back off and get ready to compare how much it "squished" against the crankshaft. If you look at the packaging for the plasti-gage, the different size rectangles are the measuring scale. The greater the amount that the plastic squeezes, the tighter the bearing clearance.

Here I have enlarged the package.

Here is a video showing the process.
https://www.youtube.com/watch?v=q3pHb-qXZc8

Bill_Johnson

Sorry for not responding sooner. The crank journal measured 1.9294 approx using a 2 inch micromoter. The rod bearing ID is 1.9275 using a digital caliper that was torqued to specs . So the difference being .0019 aproxx. There is no debri interfering. I used the plasti-gage and it crushed it. in the green at .001 And yes I torqued to specs.

thecardoc3

Were you able to turn the crankshaft once the rod caps were removed?

Bill_Johnson

yes. i could do so with the caps tightened a little. But if I crank them down, even just one of them, then it doesnt turn.

thecardoc3

Bill_Johnson said:

yes. i could do so with the caps tightened a little. But if I crank them down, even just one of them, then it doesnt turn.

Did you pull the bearings and inspect for anything on the backside of the bearings? At .001 clearance they shouldn't cause the crank to lock up. Did you plasti-gage all of them?