Spun A Rod Bearing After 6000 Miles!

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Junior Member
5 months ago i rebuilt my LS/vtec with some better parts, and my machinist used Clevite main and rod bearings, ensuring me they are fine for 8500rpm duty. well after 6000 miles rod #3 spun a bearing. when he took the block apart he said all main bearings look fine, along with rods #1 & 2. rod bearing #4 was flaking, which he says looks like what happens when gas gets into the oil. but since #4 was the only one to show this, gas in the oil can't be the case.

i ran the first 500 miles with dino oil, did a change, and ran an add'l 3000 miles on dino before switching to Mobil 1 Trisynthetic. i never overreved beyond 8500rpm, and when the bearing let go i had just taken it to about 8000 and then shifted into second hard; right when i grabbed 2nd gear i heard a loud pop which was the bearing letting go.

so now after 5 months i have the engine back out and apart, the machinist is telling me it doesn't look like a bearing failure, yet he doesn't know what caused the problem. he's trying to blame it on my stock (shot peened) LS rods, but i don't think that's the problem.

does anyone have any thoughts on what might have caused my problem, and also on if the machinist is trying to screw me or if he's justified in his actions? right now it looks like he won't be paying for anything, even labor to redo it.

sorry for the long post, but i like to fully explain the situation.

for info on my car, go here.
Severla things ca lead to a spun rod bearing...a rod bolt that was not torqued properly...low oil level in the pan...bearings that was clearanced too tight...oil pressure not high enough or not enough flow (you did mention revving to 8500 - what did you do to increase oil pressure and flow?)...oil running too hot...crank flexing (should see slight wearing on the outer edges of your other bearings)...rods flexing (again, you should see the same wear pattern previously described) - so, without seeing your parts it is really difficult to make a real diagnosis.

For what it is worth - I have built 30 Honda race motors in the last 10 years, the only ones (two) that I have ever had bearing problems with were the ones that I built with Clevite Bearings...I had to use them in a pinch and they did not last. Ever other motor that I have built with the OEM bearings have never given me a problem.

Sorry to hear you are having problems.

ok, let me run down the list, and i will try to provide pics tomorrow:

-rod bolt not torqued properly: done by machinist
-low oil level: checked oil the day before, had not dropped more than 1mm on dipstick in last 2000 miles
-bearings clearanced too tight: again, machinist
-oil pressure: i was running a Type R oil pump, this should be sufficient, right?
-oil running too hot: possible, as i have no oil cooler now, but it's sub freezing outside, i'm also running Mobil1 Trisynth, and i had not been running the engine hard before that, just was cruising on hwy
-crank/rods flexing: machinist said no abnormal wear on any bearings but rod#3 & 4

i have a strong feeling it was either that Clevite bearings are crap (and i will no longer use them for sure), or it was improperly clearanced, both of which will be hard to prove to get some reimbursement for my problems

thanks for your input, and i hope my feedback is of some assistance
Honda Color Coded is the only way to go...too many horror stories. And if he can't tell with the block in front of him...get a new tech.
Originally posted by chevy302dz@Jan 7 2003, 03:39 AM
How long did you give the engine to break in before you started shifting at 8500 RPM?

at 6000 miles, you shouldn't have hit it more than twice.

you didn't break it in- it broke on you.

go figure
i broke it in, not going over 3500rpm, for about 1000 miles. that is more than enough time for the engine to break-in, as i've been told my numerous sources. hell, the engine builder said i probably didn't really need to break it in at all, but it's good insurance. you all must be of the school of thinking that it takes 10000 miles to break in an engine?

and there's no need to be an ass, go figure
The crank flexing is a problem created by high revs with a longer/heavier rod of the LS - every crank flexes, it is just a matter to what degree. Since you are using the LS bottom end that was designed for lower RPM usage, the builder should have allowed for this and clearanced the bearings looser. To compensate for the looser bearing, the oil feed hole in the center of the bearing should have been opened up to allow more flow. Get a hold of the other bearings and look very carefully at the edges...take a look at the back of the bearings, are they black?

In general Honda oil pumps are capable of supplying more than three times the volume that is actually needed by the engine - the pressure relief valve opens and dumps the excess volume back into the pan. You can shim the pressure relief valve to attain a higher pressure, but the flow to the bottom end is controlled by the bearing clearances and the supply hole in the bearings. In addition, the head has an oil control jet that sets the volume for your head - on the early motors I know that it as located in the top of the block, I am not sure where yours will be.

Bummer dude - throw that crank away...

The #3 bearing has too much damage to see what was going on and the #4 damage is probably caused from the material that left the #3 and was robbing flow the #4. Do you have any pictures of the #1 & #2 bearings? How about pictures of the center Main Bearing? The center Main Bearing generally starts to show wearing from crank flexing first.

You did say that you had ARP Rod Bolts installed - did the machine shop resize them after they installed the new bolts?

Do you know the order of your rods as they came out of the motor? What I am trying to establish is the relationship of the Rod Bearing Codes and the Crankshaft Bearing Codes...i.e. - B2, C3, etc...

actually, i think i'm gonna put the crank on the wall o shame, along with my block with stripped head bolt holes, broken tools, etc. HAHA

what you're saying about the damage to #4 sounds right to me, i doubt it's from gas in the oil like one of the guys at the shop was saying. i don't have pictures of the other bearings, but i can get them tomorrow probably. i looked at them and the machinist also said that they look normal, only rod #3 and #4 bearings had any abnormal wear on them. what should i look for on the center main bearing, a tapered wear?

i did have ARP rod bolts installed, and at the time he did resize them (or at least said he did, i would expect he did).

i think they marked the rods when they came out, i'd have to go up there and double check when i take pictures tomorrow. i will get pictures of everything along with all the bearing codes on rods/crank/block when i go up there.

thanks a ton for all of your insight and assistance
If they resized the rod, then you will have to find out what each one of them was resized to - the codes on the rods will be of no use...that being said, when the rods are resized, you can find out which code range they fit into and then use the Honda charts to get the appropriate bearing size.

Yes, you are correct in that you want to look at the edges for slight signs of wear. Sometimes it is not very apparent - the surface finish will have just changed slightly. Have you looked at the top of your pistins yet? Depending on your pstin to valve clearance you mave have had some contact between them...

Oh yeah...probably ought to throw away that rod...DOH!

yeah, i knew the rod and crank were a loss as soon as i pulled off the rod cap and saw the bearing split facing down at me. i'm working on finding an LS crank still, but i've already purchased a set of Eagle rods for it. good point about rods being resized as well, i guess there isn't much use at this point in getting bearing codes. i will get a hold of the bearings tomorrow and see if i can tell any abnormal wear on them that the machinist might have missed. i had over 0.1" valve-piston clearance and the top of the #3 piston looked exactly the same as the others, so i don't think there was any contact. that was the second think i looked for once i saw the bearing had spun.

anyone need 3 shot peened LS rods with ARP bolts? heh
i know a lot of people swear by synthetic oil, but i've seen spun rod bearings on motors using synthetic oil and quaker state. synthetic oil seems to be too thin at high rpm's during prolonged usage...a few engine builders here in the tampa area suggest people use castrol. i know cory in particular has seen a lot of motors spin rod bearings and we had an interesting conversation about this...he said while in most cases its the builders fault, by not getting the clearances correct...etc...the wrong oil can contribute to this.

plus oem bearings are the best and i agree with gtpilot on that.
WOw... Habit is a friend of mine we are busting knuckles and turning wrenches all the time ... I just want to give you guys and this board a big Thumbs up .. He has posted this on a few other reputable boards this one by far has given the best Info with little to no BS. .

We will be back and frequent now I’m sure ...

Thanks :worthy: :worthy: