mattb16a1civic

well after dealing with erl for several weeks over an issue with the incorrect size of my main bearing, I am now having another issue with acl's. I had about 2300 miles on the engine, pulled some good times at the track and all of a sudden, I get a knock. still seeing 70+ oil psi at about 6700. and mid 11s on afr. Anyways a month later I pull the engine apart and see three pretty clean rod bearings until I get to the 4th. So now is the question what are the chances that I can save my billet rods. I know the pistons are trashed, and I need all new bearings just because its better safe than sorry. and also a crank. Ive never spun a bearing so there are a couple of questions. What caused this? What can I do to prevent this in the future. ERL did all of the machining to the engine, rods, crank etc. Everything speced as it should within clearances after the main issue was resolved (thanks to erl for fixing that and to earl for helping guide me in the right direction to tell them what they made a mistake on) Could this be a mechanical issue with the acl, a possible engine assembly issue on my part, or a crank maching issue on erls. Im not looking to blame anyone, just looking for some answers to help ease my wallet since I just lost my job and this is at least 1500 dollars in parts, not including any machining labor.





Modified by mattb16a1civic at 3:31 AM 8/1/2005


Modified by mattb16a1civic at 1:40 AM 8/2/2005

quickcarl

Bummer , generaly a spun bearing is caused by excess heat and or the oil film breaking down. The crank and bearing are trying to weld together. The crank probably can be ground and the rods re-sized. You have to have a shop check them. Why do you say the pistons are toast? If the skirts are scuffed this could be a sign of a lean condition causing excess heat. If you drove it 2300 miles, you probably got it assembled right, so I would look for something that changed. Driving style, tune up, oil change,etc. If you can save the crank and rods, just buy bearings, pistons, rings, head gasket and machining.

vaporboy12

sorry to hear that

earl

The fact that 3 bearings were perfect and only one spun means it is not a bearing fault. The key thing you said was your pistons were thrashed. This means you were experiencing lean detonation. That detonation beats the hell out of the rod bearing, as it is the softest part of the piston/pin/rod/bearing/crank assembly. After the bearing gets beaten egg shaped, it will just spin on you. Look to this as a tuning issue. I don't care what you say your a/f ratio is or was, that is what caused your problem.

utahbmx

I wouldn't remachine anything. I just underwent almost the same thing, I had the rods remachined and the crank polished with all new bearings and I never got to boost it before they went to crap. Pretty much once you burn a rod that bad I would throw it in the trash and save yourself some more headaches.

vaporboy12

earl you are so smart hehe
you a/f might have been fine but a clogged injector of bad connection on a injector will cause a cylinder to go lean

quickcarl

"The key thing you said was your pistons were thrashed. This means you were experiencing lean detonation."
"generaly a spun bearing is caused by excess heat and or the oil film breaking down." There is no oil film left under the extreme pressure of detonation .
Find the cause before you rebuild it.
"so I would look for something that changed"
"a clogged injector or a bad connection on a injector will cause a cylinder to go lean"

mattb16a1civic

ok since im partially new in all of this I will not argue, instead I will ask questions. i was monitoring knock at all times and never noticed a change over 1.5 volts, even under full load. so would I have noticed a knock voltage variation if I had an injector fail? Also number 4 pistons had damage to one skirt, number three was perfect, number 1 and 2 had slight scuffing on the skirt. This engine did have another mile on it at about 4k rpm in order to get off the interstate, after hearing the knocking noise, in which it went from zero knock out of boost to almost 5 volts. I am in no way blaming anyone or anything, only trying to figure out what happened. Also does anyone know if buying one rod is availabe, I know I can order a single piston, but that isnt really an option for me.

earl

With 3 of 4 pistons showing scuffing, I would look for a lean mixture across the board. The cylinder running the hottest or weakest for what ever reason is always the first to go. You just can't count on knock sensors to warn you or to pull back timing quickly enough.

tony1

Gotta remember, Knock sensors work after the fact, you have to detonate first for a knock sensor to pick anything up. If in fact it didn't show any knock, that only means just that, that it didn't show any knock on the meter. It's possible that slight detonation was present that the meter didn't pick up.

doublej

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by tony1 &raquo;</TD></TR><TR><TD CLASS="quote">Gotta remember, Knock sensors work after the fact, you have to detonate first for a knock sensor to pick anything up. If in fact it didn't show any knock, that only means just that, that it didn't show any knock on the meter. It's possible that slight detonation was present that the meter didn't pick up. </TD></TR></TABLE>

Exactly. That's why the "experienced" tuners know there's more to engine life than just a/f ratio.

The pictured piston has black death from trying to seize, due to tuning issues. As Earl said, overall lean and likely cylinder imbalance. That's a tremendous load on the bearing and it pushes the oil out of it's way resulting in a singled-out bearing failure.

LeGeND4LiFe

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by tony1 &raquo;</TD></TR><TR><TD CLASS="quote">Gotta remember, Knock sensors work after the fact, you have to detonate first for a knock sensor to pick anything up. If in fact it didn't show any knock, that only means just that, that it didn't show any knock on the meter. It's possible that slight detonation was present that the meter didn't pick up. </TD></TR></TABLE>

What's the best way to prevent situations like that then if you can't rely solely on the knock sensors and knock voltage readings?

tony1

Make sure it doesn't detonate. There no simple answer though, there's alot going on inside an engine, and alot of things that have to be right to keep it running. If you want to learn more, i'd suggest EFI101. http://www.efi101.com

stizzit

Sorry to hear this happened to someone else. I myself am taking my time and rebuilding from the exact same thing.

I decided to buy a new crank, rods, and no choice on pistons. I had to dissassemble EVERYTHING and have it all cleaned due to the metal contamination. ITs just about the worst thing you can do it seems. I realize mine was due to a tuning issue and carelessness (very expensive).

I just hope it'll last longer the next time around ...

mattb16a1civic

I really do appreciate everyones input, it really does help. Im doing this almost soley on my own, which means out of my own wallet, and soley on my research. The plans for the dyno were 2 days before I spun the bearing, I know it should have been way sooner, and that is my mistake and waiting for some more parts to come in. I do want to thank earl hes helped me several times, hell I even purchased my valves off of him. I also want to thank everyone else. Im new to aem, new to tuning, and im pretty damn new at engine building as well. I was really hoping to run this at Indiana truck bash this year, I guess its not going to happen, unless I can find a machine shop willing to work with me on this in a timely fashion. Im assuming salvaging my crower rod isnt an acceptable option? and as I asked about, can I buy them in singles?

mrDFWmechanic

damn because of one thing going bad a whole setup is scrwed up

earl

Check with your machine shop to see if they can resize your rod back to stock. It could be fixable. The crank is not fixable for a reasonable price and should be replaced with another used one.

mattb16a1civic

kinda what I was hoping to hear. The crank isnt a big deal, its only a b18a crank, hell the whole long block is 300 bucks or less. Just the rods are the only thing im worried about. Thanks for everyones inputs, Ill try to keep pics up as I reassemble again.