Orientation of connecting rods on a 2.4l ecotech

[Bill G. Johnson]

I am rebuilding a 2.4l Ecotech. It jumped time and took out 7 valves and three pistons. I replaced the pistons. And new rings. Yes I clocked them. The pistons are going in the right direction. But I was un sure of the connecting rod orientation. A "mechanic" told me about chamfers on the rod caps. But My eyes are not that good. I see that there is printed letters to match up with the rods and caps. It's also on the same side where there is the grooves for aligning the rod bearings. A "mechanic" told me that they face out. Towards the intake side. But I just watched a video of a 2.4 tear down from a Terrain that shows it point towards the exhaust side. Does it matter? I put on a remanufactured head and put all the timing and secondary chains and guides in. Everything lined up with the colored links on each chain with the marks on the corresponding gears. How ever, when I installed the engine and tried to turn the engine over with the crank to line up the flywheel to the torque converter, it wouldn't budge. I'm afraid that I will break the crank shaft bolt. Is it possible that the connecting rods being on backwards is causing this?

 

[90sbuickrescue]

I just went on ebay and looked at a pic of an ecotec 2.4 crankshaft. I don't see any fillets, or radiused edges of the bearing journals. Also, it doesn't make sense to me on any 4 cyl that one side would have a chamfer and one wouldn't, since it only has 1 rod on each crank throw. That would only make sense on a motor with 2 rods on each crank throw. Then the chamfered sides would face outward. (Obviously it would make no sense for the chamfered sides to face toward each other in the center of the bearing.)

There can be other reasons for rods to go in an inline 4 cyl motor a certain way, but not chamfer. If your vision is good enough to see the stamping on the rods, it's good enough to see the chamfer too, if there was any.

So anyway I don't think if the rods are backwards, it would stop the motor from being able to rotate, with the 2.4 ecotec.

What I don't get is how you managed to put the whole thing together without ever turning the crankshaft! Wasn't there a point (or multiple points) where you turned the crank while putting it back together?

 

[Bill G. Johnson]

Yes before I put the head on and attached all new timing gears and chains. When I put the pistons in. Had no problem turning the crank then. Thinking of pulling the head back off and go from there. The head bolts are not yet torqued to yield yet. Your thoughts?

 

[Bill G. Johnson]

I didn't have a problem turning the crank until I put the head on it and all the timing gears and chains. I think I'm just5 going to take the head off and see what's going on. Your thoughts?

 

[90sbuickrescue]

I don't know. It's really hard to diagnose over the internet. The first thing that comes to mind if the cams aren't timed properly and a piston is hitting a valve. I'm not familiar with the ecotec, but I know with a honda 4 cyl, upon reinstalling the cams you wouldn't be able to tighten the cam caps and have a cam push the valves down into the piston hard enough to bend a valve or anything without the cam simply rotating a bit. Then if you went to put the belt on like that, it wouldn't line up right.

If that is what's causing the problem I suppose you'd have to remove the head to inspect the valves, unless they did all seal with compression or leakdown test after you did get it lined up properly.

I'm trying to think what else it could be that would stop the motor from turning, you didn't lock the crank or cams when lining them up with a tool left in there anywhere, did you? If there's something on the flexplate side I'm not thinking of what it could be, and if there's something binding with the chain guides/tensioners I don't know either.

 

[Bill G. Johnson]

I don't know. It's really hard to diagnose over the internet. The first thing that comes to mind if the cams aren't timed properly and a piston is hitting a valve. I'm not familiar with the ecotec, but I know with a honda 4 cyl, upon reinstalling the cams you wouldn't be able to tighten the cam caps and have a cam push the valves down into the piston hard enough to bend a valve or anything without the cam simply rotating a bit. Then if you went to put the belt on like that, it wouldn't line up right.

If that is what's causing the problem I suppose you'd have to remove the head to inspect the valves, unless they did all seal with compression or leakdown test after you did get it lined up properly.

I'm trying to think what else it could be that would stop the motor from turning, you didn't lock the crank or cams when lining them up with a tool left in there anywhere, did you? If there's something on the flexplate side I'm not thinking of what it could be, and if there's something binding with the chain guides/tensioners I don't know either.

I never removed the crank. And the head I got from ZZperformance. It's remanufactured. I have the head off but when I put the crankshaft bolt in and try to turn the crank. It won't budge.

 

[richardnewton]

I thought there were several parts revisions over the DI years (tensioners, phasers, etc?). So make sure you have all the appropriate parts.

The tensioner needs to be deployed manually before starting. There is a process to reset the tensioner back to factory for whatever reasons.

Before starting, should you turn the engine manually at the crank bolt a several times to make sure everything is smooth and no valves are hitting pistons?

This guide might help:

http://www.engineprofessional.com/TB/TB040517-2.pdf

Some tips for different year 2.4L engines:

Timing chain tensioner extended.

After a rebuild from losing the rear main the engine rattled on start up like the timing chain was loose. Putting it back on the lift and peeling the valve and front covers off I find that the tensioner is fully extended and the chain is somewhat loose. Mind you everything having to do with the...

www.terrainforum.net

timing marks

www.chevymalibuforum.com

 

[Bill G. Johnson]

Thank you. Now I had all timing stuff removed. And the head off. And the crank still not move untill I loosened the rod bearing bolts. I removed the pistons and flipped the connecting rods around. Because I seen the little groove in the rod bearings points to the exaust side. I was told by a mechanic that it went the other way, but upon watching a couple of videos on my engine I seen he was wrong and they face towards the exaust side. So I put number 1 and number 4 piston in. Torqued them down 18 ft/pounds then 100 degrees. And now my crank wont turn. Theres nothing but those two connecting rods that are bolted to the crank. Before i put 1 & 4 piston in, I could easily turn the crank with my hand. So I'm kinda lost.

 

[90sbuickrescue]

This kind of work is super detail oriented.

You haven't written if you've replaced the rod bearings, but aside from an unknown assembly error, (each rod cap goes back with the rod it came from for example) it sounds like you might have the wrong bearings. Does this motor have multiple size options for bearings from the factory to stay within set clearances? Some motors do. Color coded bearings.

If you're replacing main and rod bearings you should always plastigauge them to verify clearance. Never just assume it's okay.

If those rod bolts are torque to yield, (the 100 degree spec tells me they likely are) you also must replace them. Or else when you do get it running, it'll throw rods through the block the first time you rev it up. TTY bolts are weak enough to permanently stretch (yield) as they're tightened, so re using them stretches them to failure. Garbage idea from the factory. A lot of people believe they're a scam just to sell more bolts. I would never use any TTY fastener in anything I build.

 

[agaric]

If you're replacing main and rod bearings you should always plastigauge them to verify clearance. Never just assume it's okay.

Look up the other thread that was started about this. Clearances were not checked when reassembling.

 

[G-337896]

I am rebuilding a 2.4l Ecotech. It jumped time and took out 7 valves and three pistons. I replaced the pistons. And new rings. Yes I clocked them. The pistons are going in the right direction. But I was un sure of the connecting rod orientation. A "mechanic" told me about chamfers on the rod caps. But My eyes are not that good. I see that there is printed letters to match up with the rods and caps. It's also on the same side where there is the grooves for aligning the rod bearings. A "mechanic" told me that they face out. Towards the intake side. But I just watched a video of a 2.4 tear down from a Terrain that shows it point towards the exhaust side. Does it matter? I put on a remanufactured head and put all the timing and secondary chains and guides in. Everything lined up with the colored links on each chain with the marks on the corresponding gears. How ever, when I installed the engine and tried to turn the engine over with the crank to line up the flywheel to the torque converter, it wouldn't budge. I'm afraid that I will break the crank shaft bolt. Is it possible that the connecting rods being on backwards is causing this?

I was paintig cars and the owner of the shop rebuilt a v8 motor and could not turn it over i check it out and he had mixed the parts lucky it was repeird once and and it had numbed the caps and rods.