Blew up my LT5, Let the grieving begin.

[mike100]

Originally Posted by bad-zr1

One other thing you can try if you have eliminated the accessories is to remove one plug wire at a time. Use insulated pliers and have them loose before hand. It will identify what cylinder is causing the noise if it's in the bottom end. If the noise stays the same I would suspect something besides the rod or piston.
Good luck

yes, this- an easy enough quick test that will tell you if the lower end is suspect.

[tf95ZR1]

Originally Posted by Torchred96

Wait, I did do one other thing...In order to eliminate the accessories as the culprit, I took all the tension from the serpentine belt with a 1/2 ratchet. It looked like all the accessories stopped spinning, but the noise remained.

Do you really want to run the engine if you think its something major?



Inspecting the spark plugs seems like a good, safe start to me.

P.S. Technical Section?

[CamP]

Drain the oil, filter it through a paint strainer and look for bronze and/or aluminum bearing material.

[robbz28]

Originally Posted by CamP

Drain the oil, filter it through a paint strainer and look for bronze and/or aluminum bearing material.

I concur...should be shavings or possibly chunks. Possibly should ne oil in the water or water in the oil depending on how "bad" the engineay be blown...if your oil is clean then i think your chances of it being a bad internal.component decreases a lot...

[scottfab]

Of course running the engine seems risky but then we can't hear the knock from here (maybe record it and post? I have a "sound library" of issues dating back to before this forum started)

Checking oil for crap and plug inspection seems very prudent.

[Hib Halverson]

Marc doesn't do calibrations with no rev limiter so, unless you did a "wrong gear" downshift, you didn't overrev.

Since the engine is already making noise, as long as you've got oil pressure--I assume you do--there's little harm in starting the engine, letting it idle then pulling plug wires to see if the noise changes. Also, the suggestion to pull the oil filter and cut it open is a good one. Finally, drain the oil and see what comes out.

There are lots of things besides bearings which can cause knocking sounds.

Bad DM flywheel.
Cracked or broken piston.
faulty cam chain tensioner

How many miles on the engine?

[Paul Workman]

Originally Posted by Hib Halverson

Marc doesn't do calibrations with no rev limiter so, unless you did a "wrong gear" downshift, you didn't overrev.

Since the engine is already making noise, as long as you've got oil pressure--I assume you do--there's little harm in starting the engine, letting it idle then pulling plug wires to see if the noise changes. Also, the suggestion to pull the oil filter and cut it open is a good one. Finally, drain the oil and see what comes out.

There are lots of things besides bearings which can cause knocking sounds.

Bad DM flywheel.
Cracked or broken piston.
faulty cam chain tensioner

How many miles on the engine?

I agree. Add to the list, harmonic balancer...
And I agree w/ Cliff re turning the engine (by hand) while listening w/ a stethoscope.
Draining the oil to see what comes out If it is clean, you're golden.
Pulling plug wires is risky on an LT5 in that the plug wires are so close to the ECM wire harness. I'm just sayin...

P.

[Torchred96]

Hey guys, whatever I did to my motor was done by me. Please don't misunderstand my post as putting blame on anyone else. I was the one who ported the plenum and IH knowing full well what problems with inconsistencies in size can cause and how it would affect rpms as well as inherent risks of modifying a factory motor with 135k miles on it. This is my second car and I consider it one of my hobbies or past times. So, looking at it from a positive perspective, Now I get to play and learn, expensively. In fact, I bought the car initially thinking it had a bad rod bearing that turned out to be injectors. I am ahead in my mind in this car. The rest of her is is GREAT shape. Someone really loved her in her 135k miles, and at only $8800, I am the beneficiary of all that lovin.

Now, I haven't been able to get into the motor yet, but I promise to keep you updated when I do. Thanks for all the responses.

It is quite possible I over revved previously when downshifting but it has run normal since that downshift. Although I never slam the downshift my speed may have been inappropriate. Remember, prior to owning this car approximately 3000 miles ago, i had never driven or felt an LT5. Not knowing the tach numbers, I have no reference to say what "felt" normal. Though I could and should have taken the time to find out what maximum mph was for each gear as a substitute for the tach, that's hindsight now.

Again, when I get to it, I will definitely keep you all posted. thanks again for you help and condolences. And this Phoenix will rise again!

[scottfab]

Originally Posted by Torchred96

snip......

It is quite possible I over revved previously when downshifting but it has run normal since that downshift. Although I never slam the downshift my speed may have been inappropriate. Remember, prior to owning this car approximately 3000 miles ago, i had never driven or felt an LT5. Not knowing the tach numbers, I have no reference to say what "felt" normal. Though I could and should have taken the time to find out what maximum mph was for each gear as a substitute for the tach, that's hindsight now.

I over revved my LT5 once soon after buying it. I was in the bad
habit on my 4 speed from 3rd to 2nd by pulling down and as far left
as the shifter would go before pulling it into 2nd. Doing that on the
ZF6 results in a 5th to 2nd shift if you misjudge what gear you're in.
The thing definitely saw 8000rpm and maybe more.
No negative results but it was an "oh sh%t" moment.

Originally Posted by Torchred96

Again, when I get to it, I will definitely keep you all posted. thanks again for you help and condolences. And this Phoenix will rise again!

It'd be great to see pics of every step you take in the order you do it.
I wouldn't slam the engine down on the H-balancer ever. If it's not damaged it will be.

[USAFPILOT]

i drive my car hard every time I am behind the wheel; I am just waiting for the day to come, but it never does. I rev to over 7K all day and it seems she only gets stronger. I have only felt the rev limiter once. I doubt you really hurt it. Now maybe under hard cornering low on oil, something could happen. Other than that these engines in stock form are nearly bullet proof.

dive into it yet?