What is with Rod Bearings dying?

[UTRacerX9]

Originally Posted by Patryn

I'm only referring to the cars that I've worked on in person, or some of my own. Yeah, I'm aware of this bearing issue with others though on lower mileage blocks. It would just be nice if we can get some ideas together maybe even get a vendor involved in R&D to see if there is and economical way to solve bearing issues, and a spun bearing trashing the crank.

That is what Grooms did, and they offer a full shortblock with many changes to the oiling passages, squirters, etc.

PM TurboBob, I think he bought one, and he could detail the changes better than I.

As far as I know though, we don't have any "improved" parts we can just slap on our engines. A high volume oil pump has been on the wish list for many of us for years, for now, we only have Supercar's custom oil pan. It certainly doesn't hurt to have it, but I think our main problem is with oil delivery, not supply.

[UTRacerX9]

Originally Posted by chargerx3

Keep looking into this and get back with us on any added info. I too have heard of it, but never seen any examples.

Well I don't plan on spinning a bearing any time soon (knock on wood.)

However I am positive that for an engine that will never see above 25 psi of boost, crossdrilling a crank would have no ill effects with warping or cracking. If the stock crank can handle 30+ psi on numerous drag visits with shots of nitrous on top of that as proven by 3SX, I think my solution would be perfect.

[Patryn]

"We were able to get the car on the dyno today. We battled knock all day and just found that your knock sensor had a short in it and was randomly grounding out"
"We encountered an issue today during dyno tuning. Despite running only 8PSI and AFR's in the 10's, your car has developed a lower end knock. At this point we will not be able to dyno tune the car until this issue is resolved."

Thats all I know from the tuner. The car drove fine to the shop, other than the idle being a pain and an exhaust leak. I didn't rev high or run more than 5-6psi. I wasn't logging knock on the way there, as I had just replaced the clutch and apparently during the process managed to scuff the knock sensor wire. Tuner did fix this however, so I would assume they were logging knock. Anyways, I won't know until I or the machine shop disassembles the engine.

Anyways, cross drilling the crank could be worth a try. I'll have to defer that to the machinist though, as machining is not my area of expertise.

[RisingSun]

I personally have experienced the post spun bearing rebuild to immediate spun bearing. I had replaced only the rod that had spun (#4). All other rod bearings were found to be worn evenly during the tear down. Clearance checks (plasti-gauge--yes, I know it's not perfect) with turned crank (forged), showed within book specs. Completed assembly, started engine, idled for 5 minutes, drained oil. Replaced filter, refilled oil, took for short drive. 12 miles, and my engine started making the stangest racket. Removed oil pan, found excessive play in #1 rod. Tore motor completely down and found that bearing had spun again. Sent all rods and crank to machinist. Machinist had found that rods were out of round----not top to bottom but side to side. He did find that to be very curious. Possible that is clearances were checked with plasti-gauge, and not by micrometer and/or calipers, that you may very well have had an out of round issue. By the way, 3 of the rods were out of round in this way--- .002 greater clearance side to side, than top to bottom.
Personal lesson, for me, is to always have every rod resized with the crank that I will be using.

[cbehnken]

This wouldn't have anything to do with engines that seem to spin bearings under low load, but it is an idea.

We know that our rods are fairly strong and can hold as much as 600AWHP for quite a while without fairly if you do not knock. Maybe though, before the rod actually fails it is flexing enough to distort the shape of the bearing and bam spun bearing.

Just an idea...

[Patryn]

Could be the case. I do know the machinest used a caliper. However you may be correct, maybe it is best to just replace all the rods anyway. In this next rebuild its going to be very through and through, if I have to stand over the person doing the machining. For sure I'll see if there aren't any other ways to increase oiling to the bearings too, such as the crossdrilled crank.

[chargerx3]

Originally Posted by Patryn

Could be the case. I do know the machinest used a caliper. However you may be correct, maybe it is best to just replace all the rods anyway. In this next rebuild its going to be very through and through, if I have to stand over the person doing the machining. For sure I'll see if there aren't any other ways to increase oiling to the bearings too, such as the crossdrilled crank.

just so i sleep well at nite will you just promise to get new rods? I wouldnt run yours again. oh and check the new ones before installing them.

[Import Power]

which rod did you spin last time?

[silky]

how much do these rebuilds cost? Might as well just get a factory shortblock if you have to worry about the quality of rebuilds!

[jwetzler]

Originally Posted by TurboBob

the squirters must be replaced during a rebuild. They have a poppet valve in them and they stick open when they get old.

When Grooms did my engine they reduced the squirter size to reduce the oil diversion. I had my 91 TT engine rebuilt by them using a (used) 2G forged crank. They had the Clevite engineers look at the oil paths in the engine and made some modifications based on their feedback. Its run flawlessly for 10K miles.

Bob

Am I the only one that read this and found it interesting? Bob, how much did grooms charge you in all to do all of the above?