Rod bearing problem!!

[Mike M]

Hey! I have recently run into a rattle in my Lancer Shelby (89 2.5) that turned out to be a bad rod bearing. The motor only has a couple hundred kilometers on it. I have only checked the one so far but I will check and replace the others. #2 was the only noticeably loose one that I could feel. The rod itself and the crankshaft look OK.

Here is a picture to explain my question better:


I've seen worn bearings before... either shiny or worn down to the brass (?). I have not seen the type of wear at the edge of the bearing halves where they meet. Is this a problem that has to do with torque? Either too much or too little squish? The bearing on the left in the picture is the top bearing and is starting to show some brass and also has a scratch in the bearing (totally news to be, looks like something that would have been scratched before assembly).

This motor was built about 10-11 months ago as I had intentions of driving the car last year. Rods were resized with ARPs installed (machinist was told the torque spec and given ARP lube), the crank is also turned .25mm. The block was assembled by yours truly and assembly lube was used, clearances were all checked and OK. Within the week before the car ran the oil pump was primed by using a drill on the intermediate shaft until pressure developed. Before the vehicle was started the coil and injectors were unplugged and the motor cranked until oil pressure came up - which didn't take much time at all. The motor did sit for a long time, but... I did all I could.

Anyways, I don't want this to be a freak problem. I don't want it to turn into a badly resized rod or a machinist error with the ARP torque/lube. I should be fine to reassemble and check clearances? I mean, thats pretty much what I plan on doing. I just want some advice on what may have caused the bearing failure.

Thanks very much, any input is appreciated!! For more on my car and its build and completion, you can check out my other build thread (yea, this is a shameless plug for anyone who hasn't looked at it, lawl!!) http://www.turbo-mopar.com/forums/sh...ad.php?t=23674

[WickedShelby88]

Check everything again with plastigauge. If you have a bore gauge use it on the rod and mic the crank journals. it looks like something wasn't torqued right or something is out of round.

[John B]

Check the tangs to see if they are crunched. Sometimes the bearing halves rotate slightly as you put the cap on and the tangs get pinched when you torque it down..

[overlordsshadow]

Wow Mike. I call you two days ago thinking your car is finally up and running and now you go and break it.

[88_pacifica]

Wow Mike. I call you two days ago thinking your car is finally up and running and now you go and break it.

Well duh... It's a TD.

[overlordsshadow]

I'm thinking someone didn't resize the rods. Hope they do it right to mine. Mike, did Continental do yours?

[Mike M]

Not Continental. They were resized, my only concern is that when the rods were resized is that they were not torqued correctly with the ARP lube, so then when I torque them properly with the lube the torque is now different from when they were resized - possibly distorting the rod slightly.

As for the tangs, they look like they might be slightly squished but I didn't have a good look or anything to compare it to. I have new bearing shells and I am going out to pull the other ones right away to see. I'll decide soon enough whether I'm just gonna put the new bearings in (and check clearances) and hope for the best.

[turbovanman²]

Do you have a better top pic?

Do the bearings list the oversize on the back of the shell?

When you install the bearing into the rod, is it a nice firm install or they just kind of fall into place?

Did you do an oil pressure test when it was running?

[Mike M]

Here is a better top picture, its the same picture in high rez - if you'd like another shot I can show you as well. (linked because its huge)

http://img153.imageshack.us/img153/6...bearingvk3.jpg

You can see the V shaped scratch in the bearing in this pic. Also when looking at it one of the tabs (I believe the top shell) does look a little squished... the tab looks like its slightly lower then the rest of the flat part of the bearing half (if you know what I'm getting at) - but the other tab on the lower shell looks ok.

The old bearings are .25mm oversize, as are my replacement bearings. The bearings are a snug fit. I've built a small number of motors and nothing was out of the ordinary with this one. By no means am I am a pro but I've gone through all these steps before.

I have not done a mechanical oil pressure test. I have an Autometer oil pressure gauge they reads 10-12psi @ hot idle, ~50psi when cold. Reason I have the Autometer is because the cluster is screwy (this goes way back to my previous motor which had absolutely no oil pressure issues) - it drops off the charts randomly, even with a new sender. Before I got my Autometer gauge I did do a mechanical test back in the day and it confirmed that it was also in the 10-12 @ idle, and my Autometer gauge reads exactly the same with this motor as it did the old one. I have no reason at all to believe its a lack of oil pressure. I'm more concerned with the discolored/worn looking part of the shell right at the bearing halves as I mentioned.

Thanks for any input! I'll be rechecking clearance on #2 very shortly here and will pull another bearing to have a look at it as well.

[overlordsshadow]

Mike, if you don't mind me asking, who did do the work?

[turbovanman²]

What did the plastiguage say?

Thats definatley lack of oil or too loose bearings.

[Mike M]

Well now I'm really upset. I went and wiggled #3 a little harder - its loose too. Good chance #1 and #4 are as well but they are sitting at TDC. Do you know what or where to get the spec for the crank journals are Simon? I'm going to buy a micrometer right away.

Popped #3 off and it has a noticeable groove in the bearing down to the brass.

As if this whole thing doesn't throw a big damn wrench into my plans, I better F'n not have to get the motor pulled and fixed. Car show is 16 days away, and I still needs outside work done to the car and some serious detailing.

Josh - it was Zaran.

[overlordsshadow]

Mike,

What car show are you going to?

Re: Zaran. I've not had much luck with him although I know he's been doing engines pretty well his whole life. He for sure put in the intermediate shaft bearing in wrong on me once and has never had a good attitude, at least towards me about doing 4 cylinder engines, and suggests that they will always blow up when power is put to them. He's even told me that the pistons are not needed when doing boring, although I believe you are supposed to have them there and match them incase some are slightly different? I hope he did you good on your block. Seems our city is having nothing but trouble with our TD's, but we'll get a pack out by summer.

P.S. I'm making a custom intake for my car for the bigger valve head ABS is doing for me. Know any of the guys around here that have done that, or the best place for cheaper aluminum pipe?

P.S.S Looks like me and you are of the few left storing parts for these cars so if you're ever looking for something let me know.

[WickedShelby88]

So far its seeming like half of the TD's are down due to negligence in the machining area or assemble not what we have been doing. I can understand a guy being old school, what I can't under stand is half-a--ing an engine just because its a 4 cylinder. I keep going back to this car, but its cause it was done right. My SVO's original engine blew up because the guy I bought it from didn't have the rods checked for cracks and one broke. This time he did it right and bought new crowers, pistons had the crank polished, engine .030 over etc. Yes it wasn't exactly cheap, but that engine could bounce off the rev limiter between shifts like no other I had ever ran and was still very solid 28k after the build and my crazy arse driving.
anyhoo just keep plugging away and measure everything.. Everything to make darn sure something wasn't done wrong. I usually check crank journals in 9 different places basically 3 times in three locations across the journal to check for wear on the middle, outsides, and out of round. Especially when something like that is turned and in the case of rod resizing a dial bore gauge in an invaluable tool. Thats all we use when we machine the bores of parts along with having a mic alongside to make darn sure the spec we read is right. Then if everything is ok next comes the plastiguage to be able to tell if your clearances are correct when the rod meets the journal. At this rate I'd check your mains, unless they are standard size in which case you are probably ok.

[johnl]

Mike - Can you describe the "rattle?" Did it sound almost as if it was in the top end? I've got a rattle, after a rebuild too.

[Mike M]

Well the only thing good thats going to come out of today.... the micrometer set was on sale.

Took measurements and have some math done here.

Connecting rod measurement (taken in multiple places) is 1.948" (49.47mm).

Stock spec (MP book) is 49.979mm-50.005mm, lets call it 49.99mm.

49.99mm - 49.47mm = 0.52mm (the amount turned off the crank).

Anyone else caught on yet?

I popped a main bearing cap off as well, I could not measure it with a micrometer but I got a reading with my vernier caliper (as a ballpark measurement for some math).

Main crank journal measures 2.35" (59.69mm).

Stock spec (MP Book) is 59.987mm-60.013mm, lets call it 60mm.

60.00mm - 59.69mm = 0.31mm (the amount turned off the crank)

Thats alot closer to .25mm (.010") than .50mm and I also used my caliper which could represent some error.

The main bearing didn't look brand new, it had LIGHT scuffing on it. It may be fine, but I will post pictures and get some input.

So, for those who didn't catch on. I posted earlier I have installed .25mm bearings in the rods (and mains) where my math clearly tells me they should have .50mm bearings.

Now, this makes me mad, not only at myself but my machinist whom I clearly remember telling me the crank was turned 10/10 (.25mm/.25mm). Now I have no explanation on how the hell my plasti-gauging missed this, its not like I'd never done this before and if I had a clearance that big... whatever, I can't even explain it and it was obviously about 10-11 months ago this was done as I mentioned so its a little foggy.

So, I will update again soon and grab some pictures.

Josh - its only the biggest car show in Regina Majestics. And I don't know where to get aluminum pipe.

John... at this point I don't know what to say, it just sounds like a rod knock! It starts about 2000RPM+ (I think it sticks around but on my car it gets drowned out by the exhaust by 3500-4k. It sounded kinda bottom end, it didn't hammer hard like I've heard some rod knocks - I was in denial that it might be the start of a lifter going. Just a consistent deepish rattle in the right RPM. It could be heard faintly while driving, or fairly audible when revving underhood. At first I checked for an individual rod knock (rev engine up and pull plug wires one at a time to locate a bad bearing) but it was always there, so I had a sad feeling that it might be more than one bearing.

I'll update again in a little bit. Any other input welcome =)

[MiniMopar]

I'm a bit confused on one point...perhaps something I am not aware of, but I wouldn't expect the rod to be undersize like that. I thought that when cutting down a crank the undersize bearing thickness makes up the difference, not the rod end. Is that the ID of the rod end or the ID of the rod end with a bearing in it?

Edit: or is that the OD of the journal that you are measuring?

[overlordsshadow]

Mike, shouldn't .25mm all around = .25 on top +.25 on bottom = .50mm total difference?

[Mike M]

I'm a bit confused on one point...perhaps something I am not aware of, but I wouldn't expect the rod to be undersize like that. I thought that when cutting down a crank the undersize bearing thickness makes up the difference, not the rod end. Is that the ID of the rod end or the ID of the rod end with a bearing in it?

Edit: or is that the OD of the journal that you are measuring?

Yes, its the OD of the journals I'm measuring. The rods are still hanging from the pistons, without pulling them from the motor and torquing the caps on I wouldn't be able to check the ID of the rods.

I know what you are getting at Josh but I don't think thats the case. I don't think thats the way these are measured (plus it doesn't jive with my math). If you cut a crank .25mm you take .25mm total, not off the top and bottom to equal .50mm.

Either way, this whole situation sucks. Went back and looked at the main bearing under some light (not just under the car) and its almost all shiny, and even a little bit of brass showing.

http://img527.imageshack.us/img527/7...earing2ry7.jpg

http://img527.imageshack.us/img527/7...earing3sz5.jpg

Any way ya look at it, I think I'll be pulling the motor out so I can take the crank out and have it rechecked (polished or turned again), more new (correct) bearings ordered.

[overlordsshadow]

Thats crappy man. I'm not sure if we have a real machinist in this town besides the guys at ABS, but they are too damned busy. Good luck with that man. I'd offer to come help but hopefully I have my own to put together asap and I've got my house to deal with. Not to mention the fact that you are more than capable and probably have someone helping you already.