What is with Rod Bearings dying?

[Patryn]

Guys I spoke with Grooms and they do the rebuild for $1995, plus if you want a lifetime warranty no fault, even if the owner fucks it up. Thats how I read it. The warranty is about $149 extra. I beleive they include a gasket set for around $200 too. Seems like a good option, but I don't have first hand experiance with grooms engines.

[Docdead]

Doesn't this whole thread sound like fun.

I am about to take my crank to the machinist today to be turned. I have all new pistons and rods, so I am also taking everything to be balanced together. Am I wasting my time turning my crank vs getting a new one? I am going to keep an eye on this thread as I do my rebuild. I'm putting the engine together myself, so I guess I will be the one to blame for any mistakes

[OwnGTP/WantRTTT]

Interesting thread but I can’t believe some of the responses.

If an engine goes 5k miles and then spins a bearing, I can almost guarantee that it has nothing to do with the build itself. If the bearings were screwed when installed, they’d be screwed when you first cranked and it and would’ve knocked right away. In this case, I think it’s obvious that tuning and potentially oil contamination were your culprits.

As far as bearings go, give King bearings a try. I’ve had mine in for two years now, about 8k miles and my oil pressure is 18-25 warm idle, 50+ cruise, 90+ WOT. My crank was turned during the rebuild (not due to a spun bearing, just due to it being on the far end of spec) and polished, these bearings are .025 oversize.

I don’t trust Clevite bearings as far as I can throw them. ACL bearings are top notch, my DSM buddies love them. These Kings are proving to work very well and I highly recommend them, I only wish more people would try them out so we can get more feedback on them.

[chargerx3]

Originally Posted by OwnGTP/WantRTTT

Interesting thread but I can’t believe some of the responses.

If an engine goes 5k miles and then spins a bearing, I can almost guarantee that it has nothing to do with the build itself. If the bearings were screwed when installed, they’d be screwed when you first cranked and it and would’ve knocked right away. In this case, I think it’s obvious that tuning and potentially oil contamination were your culprits.

As far as bearings go, give King bearings a try. I’ve had mine in for two years now, about 8k miles and my oil pressure is 18-25 warm idle, 50+ cruise, 90+ WOT. My crank was turned during the rebuild (not due to a spun bearing, just due to it being on the far end of spec) and polished, these bearings are .025 oversize.

I don’t trust Clevite bearings as far as I can throw them. ACL bearings are top notch, my DSM buddies love them. These Kings are proving to work very well and I highly recommend them, I only wish more people would try them out so we can get more feedback on them.

I disagree with your argument that bad rebuilds go bad from the start. I think its subjective to what alterations have been done and the previous strain that has been put on the motor. Im not saying that oil isn't a factor, but i think its only one piece of the big puzzle.

I would love to see some research in the oil contamination theory. every once in a while i see some info on it, but i haven't gotten the answers i was looking for. it would be very interesting to see what percentage of peoples builds actually fail and to what causes.

Its just weird to see so may failures to our motors with roughly 5k miles on them that have been rebuilt by different pro shops. Ive rebuilt motors myself and none of them have spun bearings. why do 3s's then? To is sounds like a flaw in design, or the majority of those who work on them. Blaming oil just seems like the easy way out...

Either way negligence destroys everything.

....on a different note...Does anyone here have a REBUILT 3s motor with over 100k?

[Racer_X]

I have watched this deal go down for a while now. I will throw in my stinky opinion since everyone else has. I think your motor was put together too tight for the oil you were using. That can cause a delayed death to your engine, especially if you were using good/decent oil. You REALLY need to take the thing apart, have the block measured with a micrometer (to .0001") have the crank measured with a micrometer (to .0001") have the rods measured with a micrometer (to .0001 inch) put the crank on V blocks and measure the straightness between all 4 mains (to .0001"), measure the straighness of your block journals (to .0001"), figure out what main and rod bearings you had in the motor and figure out what your minimum clearance was on ALL of them at the bearing crowns, then compare that to OEM recomended limts (given in the service manual). (((This is all assuming you find that all the journals on the crank, rods and mains are in round to .0001" themselves at all points))). Once you do this, I would almost GUARANTEE you that you find something fishy about the initial build that is "just slightly off" from what the service manual mandates...........and that's why most rebuilt engines in these cars go BOOM. There isn't a lot of time or chance for the rods to even GET oil, so the main bearing clearances must be ABSOLUTELY perfect, or your car will die a slow death. Until you do these things, there is a VERY good chance you could just repeat the same mistakes unless you let a machinist that is VERY VERY VERY familiar with these engines rebuild it.

btw..........VERY few machinists will devote this kind of attention to ANY car that isn't in NASCAR or other types of high end racing (hint.......I reccomend you buy some top quality measuring tools of your own and start shopping around for machinists). Mitsubishi did not design this engine with much insurance, so it has to be DEAD RIGHT, or else it will just end up DEAD, no matter how credible the machinist is.

That's my stinky opinion. it's out there if you want it.

[i3igpete]

Originally Posted by chargerx3

why do 3s's then? To is sounds like a flaw in design, or the majority of those who work on them. Blaming oil just seems like the easy way out...

it's inherent to a V6 with our firing order. think about it

[OwnGTP/WantRTTT]

Originally Posted by chargerx3

I disagree with your argument that bad rebuilds go bad from the start. I think its subjective to what alterations have been done and the previous strain that has been put on the motor. Im not saying that oil isn't a factor, but i think its only one piece of the big puzzle.

I would love to see some research in the oil contamination theory. every once in a while i see some info on it, but i haven't gotten the answers i was looking for. it would be very interesting to see what percentage of peoples builds actually fail and to what causes.

Its just weird to see so may failures to our motors with roughly 5k miles on them that have been rebuilt by different pro shops. Ive rebuilt motors myself and none of them have spun bearings. why do 3s's then? To is sounds like a flaw in design, or the majority of those who work on them. Blaming oil just seems like the easy way out...

Either way negligence destroys everything.

....on a different note...Does anyone here have a REBUILT 3s motor with over 100k?

Our engines are nothing special, first and foremost. We have a crank, rods, pistons, and most importantly . . . bearings.

What I am saying and what I have seen from experience, is that build quality will be evident very quickly after you first fire the engine. Bearings are NOT like rings, they do not need to seat or get "broken in". If it is going to spin due to it being out of clearance spec, it will do it regardless.

After 5k miles, I have to believe that an additional variable entered into this equation to make his bearing spin that was not there for the previous 5k.

Oil contamination has been the proven number one cause of spun bearings on ANY engine. Contamination most commonly being fuel entering the crank case and effectively lowering the viscosity of the oil. In this case, contamination coupled with a poor tune that introduced an elevated amount of knock was most likely responsible for the bearing's demise.

The 6G72 is not rocket science and certainly isn't special, people need to stop treating it like it is.

[mikes2nd]

bad rods...

Even when spun, you must make sure the rods are right on spec.

Even when a machine shop says your rods are checked out... guess what? they arent.

My rods were checked out, later one turned out bad. Out of round... Plastiguaging once wont do it on rod. you need to really make sure rods are good and true.

Had a machine shop check them out, obviously they didnt know how to check them out

[chargerx3]

Originally Posted by mikes2nd

bad rods...

Even when spun, you must make sure the rods are right on spec.

Even when a machine shop says your rods are checked out... guess what? they arent.

My rods were checked out, later one turned out bad. Out of round... Plastiguaging once wont do it on rod. you need to really make sure rods are good and true.

Had a machine shop check them out, obviously they didnt know how to check them out

Exactly what i was getting at. Ive had machine shops say one thing and then have to take them to another shop to actually get them properly fixed. I almost destroyed a new motor because of the idiot. Since so many of us 3s guys have spun bearing problems then we should double check our rods, or buy new ones and check their clearances as well.

Thats just my "stinky" opinion.

[SPYDERTT]

I dont have time to read complete post right know, but I know my premature bearing failure was due to fuel contamination. Poor tune and pcv systems were at fault. I am using bearings coated by Calico Coatings this time. The coating is not a cureall but gives added protection and I need all the help I can get. They are a little pricey but I think worth it. I had mine double coated to tighten up clearance a little bit. Mitch