I got my car back late last week with the fresh motor and broke it in over the weekend putting about 400 miles on it. Tonight I was taking a friend for a ride and heard a funny noise that I thought might be the alternator or a belt. I pulled over and opened the hood and recognized it right away ... somehow the engine spun another rod bearing. sick, sick, sick, this sucks! wtf! This shop is known for building top of the line race engines and they stand behind their work so they'll fix it.
I'm just wondering what caused it. They told me not to worry about breaking it in and to just drive it like it had 10k miles on it. The engine had break in oil in it and they were very adamant about not putting in synthetic because they have a low opinion of synthetic.
I always let the engine warm up and I've been watching the oil and coolant temps - oil ran at 206* for the first couple hundred miles then started climbing little by little and was at 225* when the bearing went. Coolant ran at 180-190* and was around 200* when the bearing went.
I know that no one breaks in motors with synthetic oil and the shop told me not to use it at all in the motor but is it possible that the oil broke down and that's why the bearing went? Everything was balanced and everything was new except for the block and the crank which had been turned. Now I'm thinking it's time for a 383 - what's a 383 at .060 over? is that a 396?

396 here I come!

 

detonation is the number 1 killer of rod bearings...

 

oiling problem maybe

 

it could be any number of things... bad machine work, bad bearing, detonation, oil pump failure.

dino oil (or break in oil as you are calling it) is ok, really.

But if it was me, I would switch to synthetic, if only due to their ability to not break down in heat.

Your oil did not fail, if anything, it was a failure in the system...

 

That sucks.
The 383 is 0.030 over. I think max you can go is 0.040 over in most shortblocks. Definitly tear it down and find out what happened....sorry!

 

sorry to hear...keep us updated so we all can learn from it!

 

Sorry to hear

 

It shouldn't be detonation because the engine was running very rich to compensate for missing o2 sensors ... unless my stock fuel pump couldn't keep up and supply enough fuel at high RPM's?

I'm wondering - I thought that what contributed to the bearing failure the first time was my friend letting dirt and stuff fall in the motor when he was cleaning with the intake off. I thought that some of this gunk probably plugged up oil delivery to the bearing that failed.

I'm really starting to wonder if I have a bad oil pump and this contributed to my problem. I'll be interested in seeing which rod bearing failed and if it's the same one that went last time. I think the crank has been turned down as far as it can go that's why I'm thinking it's time for a 383.

I think I'm going to upgrade the fuel pump and the oil pump this time just to be safe - I consistantly had good oil pressure but I guess that's not a guarantee that I had good oil pressure at 6k or 6500 rpm's. I'm not sure how to test my fuel pressure at high rpm's without putting the car on a dyno to use my fuel rail guage since I don't have an in car gauge.

thanks for the input guys!

 

Curious, if it was detonation. He was running my chip which is not extremely aggressive as far as the timing maps go. Even if the timing was a hair too aggressive the knock sensors should have picked up on it and backed off the timing.

I've seen much worse abused engines survive major detonation (you know the stuff you can actually hear and feel.) I've gotta lean towards assembly error or mechanical failure.

Curious you said that shop doesn't like synthetic oil, do they mean EVER or just for the break in. I agree you shouldn't run synthetic on the break in, but it's an extremely proven technology.

 

OUCH!!! I'm sorry to hear that. keep us posted on the results.

 

Stuff happens-spun a rod bearing on a balanced motor once-one thing I've always done is to put a new oil pump in with any major rebuild. I lean toward bad rod. Your temps don't seem to have been out of line at all. Oh-and unless things have changed I think max. over is .060 that's referring to bore. on the crank, I'd replace it if it had to be turned anymore than 10 under.

 

Damn. So the shop will cover all expenses?

 

You had an engine built by a top of the line machine shop that does race engines and they did not demand a new oil pump? Back when I was racing a spun bearing was almost always caused by a lean condition. If you feel the fuel pump is not keeping up on the top end then there's your problem. Whatever you do, put in a new high volume oil pump and get the fuel pump checked out.

 

The oil did not break down because of high temps. The water temps are on the low side of good, and the same with the oil temp. It IS interesting that the oil temps increased. Were you driving in warmer weather? Different traffic conditions? Harder driving? Was this the original oil? I have noticed that the first load of oil in a new engine gets real thin, real fast. I never drive a car with the same oil as the initial fire up oil. And I change the second batch of oil pretty quickly. I like to flush any contaminants of the overhaul. Could the oil have had excess gasoline or water (or antifreeze) in it? All of the previous post's suggestions are worth considering. The 383 is a .030" over 350 block with a 3.75" stroke. Few 350 blocks will stand a .060" overbore. If it would, it the result would be something less than 390 cid (388? 389?). You can do the math. The typical 396 is the 383 bore (4.030") with a 3.875" stroke.

Stay away from a high volume oil pump unless you are going to build the engine with "race engine" loose bearing clearances. Which is NOT a good idea for a street engine. DO check the fuel pressure. It is a simple matter to run a hose to a gauge on the outside of the windshield to make sure there is adequate pressure throughout the rpm range.

RACE ON!!!

 

They strongly dislike synthetic oil I don't know if it's just because they're old school. They reccomended that I not use it at all even after break in because they said synthetic oil goes right past the rings. Personally I've seen tests done on oil and believe there are a lot of benefits to synthetic but I'm not going to argue with these guys.

I just got off the phone with the shop and it turns out they put in a new crank and oil pump. They reused two rods but they checked them out so that shouldn't have been the problem. They said they think it sounds more like a main bearing (and they would probably know better than me) but I think it sounds exactly like the rod bearing that failed last time.

Yes, they full guarantee their motors for a year/10k miles so they're going to take care of me. The only thing they don't cover is pulling the motor and dropping it back in but I haven't talked to them about that yet. I took the car over to the shop last night right after it happened.

 

I would not want to run a motor with a .060 over bore, at least not without sleaves...

 

Sorry to hear that your having problems.

Was the motor run at all prior to you getting it. If not, you should have changed the oil SEVERAL times prior to putting that many miles on it.

The oil in a new motor breaks down EXTREMELY fast. Both my 434 and Dads 555 motor went through 20w50 catrol oil in the first ~10 miles. To the point if you got on them at all your oil pressure would fall. We knew this ahead of time and only planned on putting a small amount of miles on the first oil.

On mine I actually started it up got to operating temp, took it for a 10 mile drive into town, drained and changed oil. The oil when it came out looked like water. I did this scenerio about 3 times in the first week. Each time the oil looked better and I put a few more miles on each batch.

My guess is that your oil broke down to the point of it not giving adequate lubrication, and eventually the bearing surface gualled to the crank and spun the bearing. DO NOT RUN THE MOTOR ANYMORE - its possible that you might now have hurt too much and can change out the bearing with some luck.

Furthermore, I don't follow the non-synthetic theory. Obviously for the first 1000 miles or so I wouldn't use it, but after that there is nothing better you can do for your motor. The synthetic oil DOES NOT break down as the conventional oils do. I can assure you that the bearing would not have spun with the synthetic (most likely), but your motor (rings) will not properly seat cause of its superior lubricating properties.

Next motor, change the oil every 20 or so miles for the first 3 or so times. Too much is not going to hurt anyhting. Too little you will have the problems your having.

 

The high oil temp may have been an indicator that the bearing was coming apart. I had a sudden increase in oil tempurature like that once and it was followed moments later a rapid drop in oil pressure and then by a broken connecting rod. Unfortunatley I was not in a position to shut down.

Just a guess.............

 

Sorry about the engine...Keep us posted on the results.

 

Oil at 225* isn't high. I regularly see 235. What caught my eye, however, was the increase from the 200 range to the 220 range. That is why I asked about the operating environment. I agree, if there were no good reason for the increase, it could have been for warning the failure.

RACE ON!!!