Before I get started; yes, I've searched and yes, I've read, alot.

With that said I'm so disheartened about this problem I've resorted to making a thread and seeing if I can get some help on my specific issue.

Anyways... Initally my problem started as a light knock at high RPMs. The knock would continue down to about 2,500rpms and then stop. It got to the point where the engine would knock the entire time is was ignited. This is at 120,000 miles, so I decided to pull the engine out and just rebuild the entire thing. Upon opening up the engine, I found just what I expected, 2 shot rod bearings. One was broken in half and the other was cracked and well on its way to breaking.

So I ordered 2 new rods (mistake, I know), a new crankshaft and bearings etc etc etc.

Put the whole thing back together along with new gaskets, followed the service manual down to the T. It ran great for about 2 weeks untill....


On the way home from work one day it started knocking REALLY bad, A LOT worse than it had before... so I pulled over and had it towed home the next day, it was that bad.

This time I decided to just drop the oil pan off and try and replace just the rod bearings.... Not happening. The suckers were MELTED to the rods on #1 and #4, it was terrible. However, the 2 new pistons (#2 and #3) were fine. So I pulled the entire engine out AGAIN. This time I replace everything, new crankshaft, 2 new rods, and a complete bearing set.

I took the rods, bearings, and crank to a machine shop and had them check the oil clearances for me. He said that I had bearings too large (.5) and gave me smaller ones (.25).

Put it all back together and yet again......... (yes for the 3rd time) I've got a very slight knocking....


Am I missing something??? I'm incredibly disheartened by the entire thing, I love my car and really hate not being able to fix a problem... from my reading the only thing I might have done wrong is touch face of the bearings, which may repel the oil?

I just can't possibly understand what I'm doing wrong... Please help me


Cliffs:
Engine was knocking, found 2 bad bearings and rods
Replaced 2 rods and all bearings (2 new rods, 2 old rods, new crank, new bearings)
Combination of old rods and new bearings completely melted
Combination of new rods and new bearings were 100% clean
Replaced 2 rods and all bearings (2 new rods, 2 semi-new unharmed rods, new crank, new bearing)
Engine knocking again at high RPMs

either an ignition issue, or you had it rebuilt wrong.

my opinion, start fresh.

fressh following:
crank (polished by machine shop)
everything measured.
rods polished
new bearings
new pistons
new rings
overbore on block
plastigauge everything
feeler gauge rings on pistons
check, recheck everything

bet you'll solve the problem after that one :)

Originally posted by 420agreenvilleSC
either an ignition issue, or you had it rebuilt wrong. my opinion, start fresh. fressh following: crank (polished by machine shop) everything measured. rods polished new bearings new pistons new rings overbore on block plastigauge everything feeler gauge rings on pistons check, recheck everything bet you'll solve the problem after that one :)

What would an ignition issue have to do with rod bearings?

And the last time I rebuilt everything was new, pistons, rods, crank, rings, bearings, everything.

if you're engine's knocking, then it has to do w/ ur spark doe doe brain

Originally posted by 420agreenvilleSC
if you're engine's knocking, then it has to do w/ ur spark doe doe brain

So a combustion problem is causing the rod bearings to break??

I don't understand what you're getting at... please elaborate

I think he is talking about the timing being advanced too far. Causing the fuel to ignite too early causing the motor to knock. Dino will hopefully chime in with something more constructive than what I can give.

I doubt its an ignition problem, especially if you're still on the stock ECU. if you're consistently destroying rod bearings, you may have an oil pressure issue. What is your hot curb oil pressure? Do you know?

Originally posted by 420agreenvilleSC
if you're engine's knocking, then it has to do w/ ur spark doe doe brain

Seriously doubtful doe doe brain. :rolleyes
I don't think he needs to buy everything new again when his post clearly stated that he just did!

OP- Is the oil pump original? Have you checked your oil pressure? You have an oiling problem. check/replace the oil pump and check the oil pickup. If the bearings are starving for oil then they will spin almost instantly. As long as your crank journal faces are ok you can replace the bearings with the correct size, you don't need to keep replacing the crank with new ones. Fix your oil problem, replace the bearings, plastigauge or have the shortblock assembled. Run it.

Originally posted by djtrickee

Originally posted by 420agreenvilleSC if you're engine's knocking, then it has to do w/ ur spark doe doe brain

Seriously doubtful doe doe brain. :rolleyes I don't think he needs to buy everything new again when his post clearly stated that he just did! OP- Is the oil pump original? Have you checked your oil pressure? You have an oiling problem. check/replace the oil pump and check the oil pickup. If the bearings are starving for oil then they will spin almost instantly. As long as your crank journal faces are ok you can replace the bearings with the correct size, you don't need to keep replacing the crank with new ones. Fix your oil problem, replace the bearings, plastigauge or have the shortblock assembled. Run it.

I did replace the oil pump the first time I rebuilt the whole thing myself... the second (most recent) time I rebuilt it I had to replace the crank because the bearings were so bad I figured I might as well.

This is where I think my problem is as well... I just can't figure out how I can possibly have an oil issue when I just recently replaced the oil pump.

As for oil pressure I am unsure... my car is an RS so as you know my gauges are extremely limited and I don't know of any ways to check it without one :(