Spun Bearing: What Causes it? 'Cause it's a bbbb bad thing!

[lifer]

Well, International Diesel finished fault analyzing the engine I returned. Bottom line - spun bearing took out crank, block, and both heads.

My in-warranty cost: $750 to get another 506 dbl-D long block, including shipping both ways from Cali to NY.



My question: what causes spun bearings? What can I do to avoid it with the new engine? 'cause it's a baaaaaaad thing!:(

[DmaxMaverick]

Several things can cause a spun bearing. Most common is lack of oil pressure and/or flow, like no oil, an angle that starved the pump, pump pick-up damaged, flawed, or fell off, bad oil pump (what was the pressure prior to failure?) or the oil just went away somehow. This is assuming the build was done correctly. Too much or too little bearing clearance, bearings installed incorrectly, poorly prepared crank, or poor assembly practice are others, among others.

Why money out of your pocket for a warranty replacement? Unless you ran it out of oil, the cause was 100% their fault, either by a poor build or defective components.

[lifer]

Int. Diesel claimed that I overheated the engine per the heat tag. I checked with Recon who supplies Autozone and Kragen among others and they have a warranty cutoff of 255F heat tag temp. I.D. is lower. I didn't have a problem paying some though. Got it for Kmart price and expected Kmart customer service. Haven't been disappointed.

Thanks for the bearing info. Oil level and press was good. Probably got lightly diluted after the heads broke, but I think that was after the bearing went. I think the bearing was loading down the engine and causing the overheating. Just my 2c.

[DmaxMaverick]

It's a cause/effect thing. You are probably right. It was the spun bearing, or the cause of the spun bearing, that created any overheat condition. Did you notice excessive heat on the gage or feel? If not, it was internal, and related to the spun bearing, or the cause of it. If the engine was assembled properly, it should not have overheated in any case. You would have noticed it for sure. 255° is way off the scale, and hard to miss. That hot, and the engine would have "limped" (OBD II)

[lifer]

I did notice the engine getting over 210F during a trial run with the empty 5k toy hauler the weekend before the blowout. I took the rig down into the desert at midnight (60'sF) and pulled it back out at the crack of dawn (maybe 70F). The gauge temp was good going into the desert, climbed over 210F climbing up the hills out of the desert. Had to keep the speed under 25 mph in order to hold the temp under 210F. I have a digital temp gauge on my pod to monitor water temp on the passenger head near #8 cylinder. The gauge starts flashing the numbers when it reaches a preset value which I set at 210F. (I've always got an eye on the temperature since I blew my first engine with the temp railed to the right by not watching the dash gauge.)

Called Heath Diesel about the 25 mph thing and Ian said that seemed high considering the reman'ed engine and all the mods on it. Said they normally don't tow until after 2k breakin though.

[Robyn]

I am assuming the engine was a rebuilt.
OK not all rebuilts are worth much.
If the tech that put it together failed to tighten a rod or main correctly this can cause a failure. As long as the engine was assembled correctly then it can be a failed part/parts
There is always a reason, the trick is to find out what that reason is/was

If the rods were resized and the crush on the bearing shell was not right then a bearing can spin. Wrong bearing size (too tight) cab do it.
Unfortunately they are probably not going to make the pieces available for anyone to poke around with. I have seen a piece or crud plug a oil hole in a bearing and then its gone.

The 6.5 delivers oil up to the lifter galleries and from there it flows to an anulus groove behind each cam bearing and from there to the mains. The mains are grooved on the top shell and that delivers oil to the passages in the crank and then to the rods.
Far better to bottom oil an engine first but thats the way it is. Many of todays V8's are top oilers though and do fine as long as things are in good shape.

Doing a post mortem on a failed engine is no different than what is done at the Morgue.
You look everything over and weigh, measure and look for things that are amiss and then piece together why it happened.
A loss of oil will show up fairly obvious. Then was it a low level or a failure of a pump ect that caused it.
Was it a rod or main and were the bolts still torqued. (many times the engine gets thrashed so bad that it can be hard to tell)

The builder/seller is going to put the blame on the customer if they can.

Sorry to hear of your loss. :(

Good luck

Robyn

[lifer]

Thanks Robyn,

I do appreciate your expert opinions. I believe it was a main because at first they couldn't detect any cracks after magnafluxing, but then they said after further inspection, the block could no longer be used - the bearing journal(s) were too scarred from the spun bearing to be able to machine down and fill with oversize bearings. The crank was also scarred beyond use by the bearing.

One thought that occurred to me - couldn't metal be weld deposited into the journal, then machined back? I know they sometimes fix injection molds that way.

I didn't get any more detail than that. They volunteered to ship the bare block back to me, but I declined (got enough junk in my garage).

[tommac95]

>couldn't metal be weld deposited into the journal, then machined back?

the OEM cranks are cast/nodular iron ... not good to weld

[Robyn]

The crank is toast if its scored that much. Depending on the extent of the main bearing saddle damage, there are times that the caps can be cut and the mainline remachined back to size.
If the main bore was really thrashed then the block becomes a door stop.
No way that these block can withstand welding.
One its not worth the cost and two the structural integrity of these little blocks is just not there.

Shame it went away though. would be nice to know what happened.

Good luck

Robyn

[JohnC]

So let me get this straight: they said you overheated the engine and this caused a spun bearing? And what do you meant by "the heads broke"?

From what I've heard so far it sounds like you got hosed...