HOW TO DO AN ADVANCED SEARCH.

Mon Jul 08, 2013 3:56 pm by Admin


For the benefit of 944Hybrids users there are two search functions available for you to use.
The purpose of this sticky is to explain the "Advanced Search" function because it is much more powerful and is the best choice when researching information.

When you log on to the site a list of options is shown in a line at the top of the page. One option is labelled "Search", use this option (NOT the search box lower down on the right).

After you click on the upper search option, a drop down box appears. At the bottom of this box is a radio button marked "Advanced …

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Rebuilt engine threw three rods

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Rebuilt engine threw three rods

Post  jpkinerk on Sat Nov 18, 2017 6:58 pm

Well, after all the tweaks and wrench time, I had three awesome track weekends at Mid-Ohio and Putnam. Unfortunately on the third, the below happened. I had the block professionally machines along with crank, rods, pistons, cam installed and then built it up from the short block myself. No smoke, ran real strong (385 rwhp) and ran cool too. Both the oil and coolant temps were normal during my track sessions. I also was running a new oil cooler as well.

Anyway, I had some friends who think it vapor locked, but I can't think of any other reason it would throw three rods. Anyone had something like this happen before?

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jpkinerk

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Re: Rebuilt engine threw three rods

Post  sharkey on Sat Nov 18, 2017 10:28 pm

ouch, thats a bad day of racing right there.

you should be able to look at the pieces and get an idea what may have happened. how do the rod bearings look, are they hot, any material transfer, etc? what about the rod bolts, did it break the heads, stretch the bolts or pull the threads out of the rod? also have a look at the pistons, any signs of detonation? also, how was the oil pressure? does it dip at all in the corners? do you run an accusump? i know some ls heads are known for holding oil in the top end and in road race situations can cause oil starvation.

sharkey

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Re: Rebuilt engine threw three rods

Post  Rich L. on Sun Nov 19, 2017 1:08 pm

Oh Man that sucks! Sorry Dude. Agreed on doing some postmortem on the internals. Maybe send some of the oil, if you can recover enough, off for analysis by Blackstone.

A friend let me participate in rebuilding an Audi engine years back. I was surprised by the amount of fussy little steps in getting all the clearances and tensions correct. Mine ended up skook'em but another buddy's engine done by the same guy with the same recipe never ran quite right.

Rich
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Rich L.

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Re: Rebuilt engine threw three rods

Post  jpkinerk on Fri Nov 24, 2017 6:22 pm

Well, a buddy and I dug into it and it definitely oil starved. Here's the rundown.

Rod bearing look bad, all marred up.
Rods themselves broke, none of the rod bolts gave out (ARP)
No signs of detonation I can see, but two of the cylinders had white scorched intake valves
Oil pressure was good all day, I'll admit I wasn't checking in the sweepers though
No accusump

I didn't know about the LS1 heads holding oil on turns, that combined with my (new) oil cooler opening up, might have lowered the oil just enough in the pan to let the pickup take a big gulp of air.

We may never know...

sharkey wrote:ouch, thats a bad day of racing right there.

you should be able to look at the pieces and get an idea what may have happened. how do the rod bearings look, are they hot, any material transfer, etc? what about the rod bolts, did it break the heads, stretch the bolts or pull the threads out of the rod? also have a look at the pistons, any signs of detonation? also, how was the oil pressure? does it dip at all in the corners? do you run an accusump? i know some ls heads are known for holding oil in the top end and in road race situations can cause oil starvation.
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Re: Rebuilt engine threw three rods

Post  sharkey on Fri Nov 24, 2017 10:13 pm

im not sure what heads specifically have oil return issues, for some reason i think it was rectangle port heads, but im really not sure. its something you should do some research on though. i remember hearing about someone local to me having unexplained bearing failures in an LS engine, and that was the cause, and they added some external oil return lines to fix it.

if your not running an accusump id recommend it in the future.

sharkey

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Re: Rebuilt engine threw three rods

Post  zeusrotty on Tue Nov 28, 2017 9:34 am

Sorry man. That’s rough. Wondering if the oil cooler has a thermostat on it or before it? Is it routed correctly? Could air in the lines have stopped oil flow? Was there oil in the intake?

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Re: Rebuilt engine threw three rods

Post  Rich L. on Thu Nov 30, 2017 1:41 pm

"White scorched intakes" is from running lean, right? I had a bit of that on one spark plug out of 8 when I changed them. A buddy suggested changing my dead-head fuel rail to a return system.

Back to oil, I do have a Accusump and run fully-synthetic 5/40 weight oil. Not to drag this thread into an oil argument... but what oil were you running? The pooling in the heads is often blamed on too heavy an oil, the LS1 cars' manuals specify 5/30.

Rich
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Re: Rebuilt engine threw three rods

Post  jpkinerk on Sun Dec 10, 2017 7:45 pm

I was running Driven Racing 10-40. I also am wondering the same thing about air in the lines causing it to oil starve. The cooler setup was new to the car the week prior to this track event.

I guess that was just a boner move on my part. I had no idea air could get trapped like that. I had made sure to have the fittings pointed upward on the cooler just for that reason, but I guess that's not enough.

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Re: Rebuilt engine threw three rods

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