It looks to me like the engine starved for oil at some point. Was the oil level up at full at all times? If the engine starved for oil even for an instant, the damage is done and you're on borrowed time.

 

the oil level never went down. I even checked the oil the night before the motor went and it was great.

 

Interesting thread... 5-30 Mobil One oil causes failure ?

 

It wasn't mobil 1

 

Sorry... I saw your post where you mentioned changing over to 5-30 synthethic and then post # 35 with the Mobil One comment...

I wouldn't think changing from 10-30 dino (for break-in) to 5-30 synthetic would be the root cause of bearing failure.

 

I certainly wouldn't think that either. What really concerns me though is that all of the rods look like they got hot and same with the main bearings, and the whole time I had oil pressure. I never completely lost pressure, it just went down dramatically when the knocking started.

 

the oil starvation may have came from loose bearing clearances, and thin oil. when a large area is filled with a very thin subsatance it is likely to squish out easier. i dont understand why some people belive a higher horspower engine needs to have more clearance. it doesent help as far as higher rpm its actually worse. it just beats the **** out of the bearing pulling it to btd and like wise going to tdc.

 

Just want to keep this alive. Any other engine builders have opinions on this?

 

Here is a copy of the blueprint sheet.

 

looks like it was built too loose to me

 

Do you have pictures of the big end of the rods? And maybe some pictures of the rod bearings?

Have you removed the cam yet?

I hate to see you ask a general question to engine builders on the internet.

Your going to get everyone in here with their own opinions. I agree with Mikey that it appears that there was not enough oil pressure to maintain a oil wedge in the bearings
It comes down to finding out what happened first. That is the tough part.

How aggresive was the tune? How much timing? A/F ratio?

Also you need to measure the journals at 90 degree points. You need to be sure that the journals are round and that the crank was straight.

Many of the off shore crankshafts need work before they can be properly installed.

Good luck with your situation.

Robin

 

Cam is out and looks brand new still. The tune was not aggressive to me. I had 0 knock to speak of and Even had Texas Speed look over the file and make some adjustments to my Idle, but other than that they said it looked good..
The crank has been checked and does have a little bit of bend after or near the #5and #6 rod rod journal.
I can definately get more pics. The rod bearings look just like the main bearings. Lots of hot spots and scoring.

 

You'd be incorrect...

Specs sheet from Clevite:

 

I disagree, but then again it's my opinion.

Robin

 

My guess is that's where the issue lies.

 

How much is a "little bit of a bend"???


And how much heat was/is in the rod journals on the crank?


If it got hot enough you will never know if it was a result of the problem or if it WAS the problem.

OK on the tune, I had to ask because some people have a little rattle or detonation and never know it. You would see signs on the rings as well as the pistons if that were the case. That can kill rod bearings which would lead to the same result.

I am not going to venture an opinion, I wanted to pose some things for you to consider.

Again good luck!


Robin

 

So your saying with all the measurements across the board all over the place a supposedly renownd company like Tsp cant keep the clearances within a .0001. Is this hard to ask for. For a STREET engine this is too loose for a race engine its medioker. If i built an engine like this i would be laughed out of town. I was taught to keep it within .0001 of each other. That guide is according to clevite not gm, i have a build book and ill post the correct clearances in here.

 

the dark spots were pollish off by the rod, and there was .007 bend at the no4 main journal. no.6 rod journal was ground .030 out of round. the only way to get the crank in a ok state is to pre-heat it weld it and post heat. but it will never be what it was.

 

My clearances with clevite is more than this and I have no oiling issues even with turbos! I've always been fought a short block build issue shows up quickly, not after 6k miles!

I would absolutely trust TSP and Robin. Between those guys they've probably built thousands of ls engines.

How can you possibly tell the crank wasn't bent from the heat of spinning the bearings. Did you run the TSP spec oil?

Just thinking out loud, but if Tsp, clevite, and Robin from m like the clearances, I'd trust them.

Don't make the mistake of letting a unknown shop work on your ls, send back to TSP. I bet even after 6k miles they'll still give you huge discounts fixing it. Those guys are some of the most stand up guys I know!!

 

I am not going to get into a pissing match about engine clearance numbers.

In MY opinon, the clearances were fine.

And if you can get all your bearings the same and within .0001 then I am happy for you and your customers.

I tend to dwell on things that I have deemed more important than those kind of numbers. To each his own I guess.

I think that you have enough information to make an educated guess at what the problem was.

It appears that since you are local you have other motives than to help solve a problem.

Why were you not involved in the build the first time?

Have a great day!

Robin