my 3.1 had been making a wierd knocking. yesterday i pulled the pass. side head off and #1 cyl. looked a little oil-ie. we decided that it was probably rings. today, i pulled the other head then we pulled the motor out and completely apart. we found a few metal shavings in the oil pan but cannont find where they came from. what we found...3 pistons had been lightly hitting crank counter weights due to a custom setup running 2.8 pistons (different wrist pin location). that should be a big problem to fix. rod bearings and main bearings are shot...why? the motor only has about 1,200 miles on it, max. oil pressure shows 40-45 at idle and jumps to about 60psi anywhere off idle. motor has been run pretty hard but why are my bearings gone so guick? everything was assembled correctly and to spec. also, piston rings are shot but i think that they were cheap rings to begin with. the cam is "walking" too, it has about a 1/4" play, any cam buttons or anything available? so, i guess i need to check into a HV oil pump, better rings, new valve stem seals, and a cam button. any recommendations? anything that can be done to the crank or block to improve oil flow?

 

look into new cam bearings while you're at it. 1/4" play in cam, damn, I wonder your lifters weren't fudged up as well.

Why are you using 2.8 pistons anyway? Were the specs of the bearings checked before final engine assembly? sounds & looks like they're out.

Did vortex rebuild teh engine? j/k

 

ouch, no my dad and i built the engine. i haven't totally checked the cam bearings but i will do that. lifters SEEMED to be ok. uhh....i assume they are 2.8 pistons but the nice .100" pop up allowed me to cut them and get a dome to boost the CR a lot. they were in another motor that i bought and they were +.030" which i needed and wanted. i don't guess you could say that the bearings were checked (measured) before we put them in but we put in it what came out of it, only new obviously. we don't really understand what was causing the wear. my dad has built lots of motors all through out his life so, he knows what to look for and is teaching me everything.

 

You don't need a HV oil pump, you have plenty of pressure. What you need to do is MIC or platic gauge everything before you buy any more parts.

 

HV oil pump won't fix anything and could cause more problem. how do you know it was built to spec? what was the thrust measurement? rod side clearance? how could the pistons hit the crank after it was running and you didn't know that when you did the assembly? and if the pistons hit the crank how can you say it was assembled right, it wasn't.

 

oops....i mean 12,000 miles not 1,200. everything was fine when we put the motor together. there was lots of cutom work in the motor so don't tell me that my motor was not built correctly. clearance was very close but everything did clear. the wear on the bottom of the pistons was very minor, nothing hit hard enough to break anything. it wasn't until the bearings wore out that the pistons rubbed the crank. why would a HV oil pump cause problems??

 

Here's my ten cents on this.

I have been TOLD that a high volume oil pump, used in conjunction with a STOCK oil pan can cause oil starvation- the pump can suck the stock 4 quart pan to the point the pickup sucks air before the oil can drian back to the bottom of the pan.

I would examine the bearings carefully, look online, some where there has to be a site with pictures of bearing failure types and causes of them. I bet Clevite or some other bearing manufacturer has this.

At this point it's just speculation the failure was caused by oil starvation. I would tear the block down COMPLETELY and run a bore brush, solvent and air through every oil rifle drilling in it.

Check the oil filter base, see it's not blocked with something, for the amount of damage you experienced it's hard to say what happened first, but most engines have a means of bypassing the oil filter when it becomes too clogged with debris.

Your pistons contacting the counterwieghts is probably a result of the bearing failure, no cause.

Have you checked your harmonic balancer? Last year we had a very expensive failure in a marine diesel because the balancer failed, not externally visible, but it was a fluid filled dampner and the jelly like oil leaked out. This was masked by engine oil leaks, and shortly after an in frame overhaul (pistons, cylinder sleeves, rod bearings, valve job) a main bearing spun. The rod bearings that came out had some wear but not excessive, and the mains were not inspected (fatal error!) as they were on back order and the custormer was in a hurry to get his toy ready for the next big garmefishing tournament. It ran great for 11 hours. Sure we could have argued that we didn't touch the harmonic balancer, but then it was a case of "you worked on it last" so we ate the repair.

Keep us posted.

Eric

 

If a stock pump is some how not providing enough oil I would use an adjustable one before a HV for the same reasons above and more.

 

Eric (or anyone), how does the motor sound with a spun bearing? I'd assuming a grinding noise?

AM91, so the 2.8 pistons are taller, with a lower wrist pin, than 3.1 pistons? I'm having trouble visualizing that... ? I thought the pistons and wrist pin location would've been the same between 2.8 and 3.1 - oh wait never mind, the 3.1 is a stroked 2.8. So the pistons must've been different. How close was the interference? Have the pistons been nicking the crank all this time?

 

I would bet the pistons started nicking the counterwieghts after the rod bearings went away. I have seen diesels with a top end knock, I find the piston has kissed the valve face, and get into it deeper and find a rod bearing had failed, allowing a lot more slop between conrod and crankshaft, the piston doesn't move upward or downward exactly when the crank throw does anymore and gets a bit out of synch with the valves, crankshaft counterwieghts etc.

Eric

 

pretty much what eric said, once the bearing got wore out i guess is when it started hitting. got a rering kit on the way with moly rings and new bearings and gaskets. hopefully get the motor back together end of the week or so cause i'm leaving next wed. and will be gone about a week. i'm gonna try to get the motor back in the car before i go but it may not get back in until i get back.

 

Hey Aim- in a post about a guy's 2.8 buildup you mentioned thast at 10.75:1 CR you "spark knock all the time"

THATS probably where your trashed bearings came from!!! Sure, theHV oil pup/stock pan combo didn't help but I'll bet the spark knock had a lot to do with it. Unfortunately nobody has come up with software to burn 3.1 chips so you can change the spark table. I know it makes good power and sounds wicked on the exhaust note but you may need to de-tune that thing a shade to make the bottom end live on pump gas.

Eric

 

time out eric. go back and reread all of that. "spark knock all the time." i never said that. i said mine spark knocks sometimes. if it did it all the time, i would cut the timing on it, i'm not stupid. i've never heard of spark knock hurting bearings and my bearings were not trashed, they showed some wear. enough wear that i wanted to put new ones in it, not reuse the old ones. would you like for me to take pictures of them so that you can see that they are not trashed, spun, and are each still fully intact?? i DO NOT have a HV oil pump in my motor...reread the top, i was asking about putting one in it. there is software to burn chips for the 3.1,s computer, there currently is no software to scan it. Pasky13, on this board is creating software to do that. it does not need to be de-tuned, it just needs to be tuned a little better...fuel curve and spark curve need to be smoothed out and adjusted properly. trust me, i know what i'm running and i've checked into what i need to do with it. if you want to make anymore false accusations about my setup please be prepared to be corrected.

edit: also, you may ask Doward or Vortex, they were at my house last night and saw all of the internals from my motor seeing as how it is completely disassembled right now. ask them if anything is trashed...

 

Whoa!

Sorry man, I appologize if anything I said was taken as an accusation. I meant absolutely no slight against any of your tuning or engine building ability, I was thinking of possible causes as to the failure, if I incorrectly connected the dots I stand corrected.

Actually I will be coming through the area on a trip to Tampa on the 3-4th of January and was hoping I could see the projects and perhaps provide a couple cases of grain and hops lubricant as a token of my humility.

Peace?

Eric

 

sorry, i was already in a bad mood when i typed that... no big deal. i probably took some of the stuff another way than you meant but i did see where you had "quoted" some stuff that wasn't exactly what i said. if you're gonna be in the area, PM me or something. if i have the camaro all back together and have a few miles on it, i wouldn't mind meeting up, i'll take ya for a right in it. and, i promise i'm normally not grumpy like i was earlier.

 

No prob, I'll PM ya the day before I'm going to be around and give you my cell #

Eric

 

Did you have the crankshaft balanced?

 

Hey! I dont come here that much... someone PM a bloke when he's gotta defend himself..


And the 2.8 when it spun sounded like a broomstick in a fan... bad knocking.

And Alan, you totally rawk dude.. you pulled thru in a clinch and saved the day. And yeah, everything is apart, including some of the most immaculate pistons ive seen.
Like I said, stop by the shop if you need anything... we're dying to try out our new toys/tools.. so let us know if you need anything fabbed up. Again, you are a small round candy in the form of a life saver.:hail: :hail: :hail:

As far as cam bearings... if you have someone press them in, they may charge a lil more cuz on those blocks you cant access them from the bottom..

 

no, i didn't get the crank balanced. i have a friend i'm gonna check with on that stuff.

 

ok, good news...the car is up and running again. i got to drive it again for the first time on friday. i went out of town for about a week is why it took soo long. it has probably 180 miles on it now and is doing great. i got on it a couple of times today and it seems good and strong.

edit: check out my cardomain site, http://www.cardomain.com/memberpage/471476 to see how i smoothed out the oil passage on the rear main cap. should help improve oil flow. i think its on page 4 where i have that pic. i plan to post pics of my powder coated headers and oil pan off the motor and the assembled motor before installation,...