After a 7 month rebuild i had finally got my car back on the road and running all was good. Well roughly a month ago i installed oil pressure gauge and got some unusally low readings 10 at idle 30 at cruising speeds. Shortly after installing the gauge 2 or 3 days i started to get some valvetrain noise so i parked it immediately. Well last night i pulled the oil pan out and started checking everything out.... pump, rod bearings, and plugs for the 2.3 swap. well i pulled #1 and checked the clearances with plastigauge and it looked the same as when i was putting the bottom end together. Same for #2. Then i get to #3 and lone and behold i have another spun rod bearing. (insert massive cursing rant here) Well not 100% sure if it would make a difference i checked the clearances and they are the same as when i put the bottom end together.

Now my questions is would a spun rod bearing be enough to kill my oil pressure that much? Compared to the normal of 25 at idle and 65ish at WOT.

Btw #4 was perfect as well and the rod journal looked perfect on #3 the only part that was "spun" was the outside of the bearing and that had a very slight score on the rod cap.

Thanks for all the help guys!!!

Yes a spun bearing 9anywhere in the motor) can show a low oil pressure readings. Sucks sorry to hear it.



FU Tuning

Thats what i thought but just making sure i wasnt missing anything. Im gonna replace all the bearings and see what happens.

I also have 15psi at idle and 30-40 at wot, i just change the oil pump and it has the same oil pressure. I also have the 2.3 pump. so maybe i spun a bearing??? how do i know if i spun a bearing or no? when i start the engine it kinda knock, but when its hot you dont ear it anymore or at least very little. i have read here that forged pistons do that! i just wanna be sure, is it a spun bearing or pistons?
now if i have to change the bearing with crank, i will have to drop the tranny and timing chain cover right? damn i dont feel like doing all that in the driveway......

To check and see if you spun a rod bearing youre going to have to take the oil pan out and pull all the rod caps off and check each individual bearing and see if any of them are spun.... That does not require pulling the timing chain or transmission only the oil pan....

what would happen if you keep driving on a spun rod bearing??? and what are some sighs of spun rod bearings???

Paul Tjepkes wrote:what would happen if you keep driving on a spun rod bearing??? and what are some sighs of spun rod bearings???

You wont drive with a spun rod bearing. The engine will seize up.



- 2004 Cavalier - 124k, owned since new

more then likely you would put a rod through the block.... Symptoms would be a loud knocking noise from the bottom of the engine that get progressively louder as the rpms go up. If you keep driving with it the less and less of the currents parts that are in there are reusable as things will start to break.

so both of you guys have the 2.3 oil pump swap and you are spinning bearing? who assembled your bottom end? what size oil feed did you use, and what kind of oil do you use?


HP Tuners | Garrett T3/T04B | 2.5" Charge Pipes | 2.5" Downpipe | 650 Injectors | HO Manifold | Addco front/rear | Motor Mounts | HKS SSQV | Spec stage 3 | AEM UEGO Wideband | Team Green LSD | FMIC | 2.3 cams | 2.3 oil pump swap | 280WHP | Now ECOTECED

i dont think i spun the bearings. I did assembled my engine. the noise is there only before it gets to operating temp, after that, it doesn't make any thicking noise. the guy that machined my block drill a 3/8 holes for the oil pump, and i use Mobil1 sunthetic 5w30.

i think the book specs for a 2.4 are 10 psi at idle and 30 at 3000. it sounds low but im sure i read that in the hanes manual. look up the 2.3 specs and see.

spec for 2.3 are 15psi at idle and 30 at 2000, then 10 more psi for each 1000rpm.

ge_forcez22 wrote:so both of you guys have the 2.3 oil pump swap and you are spinning bearing? who assembled your bottom end? what size oil feed did you use, and what kind of oil do you use?

I assembled it. oil feed... if your talking about turbo none as of right now because im not turbo... oil pump... if i remeber correctly 3/8 was drilled by the machinist. Since i barely had 300 miles on the engine i was using 10-30 dino oil.

hmmm, 3/8" oil feed should be good, thats what I have. But how something car wreck in 300 miles, did you let it ide at all? I know before like 500miles I was told very stricly that the engine should not idle.

I assume if you assembled it and your name is "wrench monkey" this is not the first engine you have assembled, so it was all properly measured and ground to spec and proper bearings were used. Did you get your oilpan lowered with the 2.3 pump? if not it might have starved your pump causing low Oil pressure.

did you have to shim you oil pump up to increase backlash? was your oil pump brand new?


HP Tuners | Garrett T3/T04B | 2.5" Charge Pipes | 2.5" Downpipe | 650 Injectors | HO Manifold | Addco front/rear | Motor Mounts | HKS SSQV | Spec stage 3 | AEM UEGO Wideband | Team Green LSD | FMIC | 2.3 cams | 2.3 oil pump swap | 280WHP | Now ECOTECED

Just because you have low oil pressure does not mean you have a spun rod bearing. I think you took what I said before a little far. Bearing wear can cause low oil pressure. You can have bearing wear and no spun rod bearing. If you have a spun rod bearing you will know. It will be pretty loud. The noise you are talking about at start up could be valve rattle, or the rods you have, so if it is not there after warm I would not be too concerned. Spun rod bearings get worse as you drive and louder. You could keep driving it and drive weeks or more on a spun bearing. Drove a 96 grand am 2.4 almost 3 weeks before anyone could figure out what the noise was. Yes the motor could seize, but not likely. yes it could throw a rod through the block, could also start hitting the head as well.



FU Tuning

ge_forcez22 wrote:hmmm, 3/8" oil feed should be good, thats what I have. But how something car wreck in 300 miles, did you let it ide at all? I know before like 500miles I was told very stricly that the engine should not idle.

I assume if you assembled it and your name is "wrench monkey" this is not the first engine you have assembled, so it was all properly measured and ground to spec and proper bearings were used. Did you get your oilpan lowered with the 2.3 pump? if not it might have starved your pump causing low Oil pressure.

did you have to shim you oil pump up to increase backlash? was your oil pump brand new?

The only idleing i did was city driving at stoplights and stop and go traffic. also for a while when i would let the turbo cool.

Thanks for the assumption, but this was my first engine build with the the help of a gm service manual my father a mechanic that works on concrete trucks and some research.

The company that ground my crank has a good rep and knows what there doing... but i did double check there work by plastigauging every main and rod journal. I had it ground to 20 thousandths over and got the clevite 77 bearings to match. I got my oil pan modified by todd miller. and i did not need to shim the brand new oil pump as the backlash was in spec according to the gm service manual.

hmmm, why did you replace your existing engine? was there anything wrong with it? did it spin a bearing too? (spun #3 again)

did you reuse any parts that could have been worn and lowered your oil pressure and caused the problem the first time? possibly the lifters or a bad top end gasket (including but no limited to the head gasket). At 300 miles, did a plug from the 2.3 oil pump swap fall out?

I am really digging deep, to all the problems that I have had nightmares of @!#$ wrecking on my car, lol, but I hope something can be found, so this can be avoided in the future, and if you find the problem be sure to post the result.

What size oil feed do you have? the oil feed "reducer" should be super super tiny,like 1/8" IIRC. was it smoking at all?




HP Tuners | Garrett T3/T04B | 2.5" Charge Pipes | 2.5" Downpipe | 650 Injectors | HO Manifold | Addco front/rear | Motor Mounts | HKS SSQV | Spec stage 3 | AEM UEGO Wideband | Team Green LSD | FMIC | 2.3 cams | 2.3 oil pump swap | 280WHP | Now ECOTECED

yes i spun the #3 originally. I reused the head and lifters and when i had everything apart and visually inspected all the lifters for cracks... i know i should have replaced them. I replaced all gaskets with new and am using arp headstuds with a cometic gasket. i get black smoke out of the tailpipe from runing too rich with the brown top injectors tuned back with HPT. All the plugs for the 2.3 swap are all in and tight. After looking at my feed line for the turbo the reducer was no where to be found leaving me to wonder if it was ever there. oh and i did reuse my cams.

if you have aim hit me up: honda89preludesi or yahoo at honda89preludesi

hmmm, I only have hotmail (msn) which is ge_forcez22@hotmail.com but I will only be online for another hour or so, but, hmmmm, do you know why you spun the bearing in the first place? did they hot tank your block? this is digging way out in left field, but what if a casting burr broke off and is clogging that oil passage.

If it was turboed right before you spun your first bearing... maybe the turbo with no restrictor could have caused low oil pressure, causing things to run dry.


HP Tuners | Garrett T3/T04B | 2.5" Charge Pipes | 2.5" Downpipe | 650 Injectors | HO Manifold | Addco front/rear | Motor Mounts | HKS SSQV | Spec stage 3 | AEM UEGO Wideband | Team Green LSD | FMIC | 2.3 cams | 2.3 oil pump swap | 280WHP | Now ECOTECED

Were the bearing saddles damaged at all ? In other words the part where the bearing halves sit was anything at all messed up ? On your bearings there are those little tabs to keep then from spinning, well its not unheard of for there to be a small nick taken out more then should be and that allows the bearing to spin more easily. I've had to replace 2 small block chevy engines because of this problem.


Have the bearing saddles checked to make sure your not throwing good money after bad.

And sorry to hear it man, good luck though.






Semper Fi SAINT. May you rest in peace.

actually the piece that sticks out on the bearing that holds it in place is the only part that was messed up from it spinning aka the saddles

Then theres your problem, you need a new block. Your just gonna keep spinning bearings cause that area is damaged.


Sorry to hear it man but at least now you'll be able to start fresh without the fear of that happening again, well once you pick up a new block that is.


Good luck man, that sucks.





Semper Fi SAINT. May you rest in peace.

hmmm how would i need a new block if the bearing i spun is on the connecting rod journal and doest not come in contact with the block? i wish i had a pic of the bearing i spun...

OH my bad ! I thought you said MAIN bearing! lol! duhhhh! lol! Ok so its a little less painfull then. You need a new rod. I'd also get the other 3 miked to check them for any run out ( out of roundness ) and if they check out ok then just replace the bad one. Is the crank ok ?


Geez man sorry I thought you said main bearing ! my bad man, my bad.





Semper Fi SAINT. May you rest in peace.

Its the rod... dont worry tho.. LOL. ill check everything then.