Blew up my LT5, Let the grieving begin.

[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?

[Paul Workman]

I spoke to Marc briefly about your experience, and he told me that in his experience there is a tendancy for people to jump to conclusions - thinking they broke the motor - where he finds that to rarely be the case: something else is causing the problem (problem being spinning a rod or main bearing, that is). Hell, one of my first experiences with the Z was some spark cross-over due to mice having chewed my (LT5) wires. Talk about knock!

Could have injested something, or dropped a valve, or broken dual FW spring... No need to think the worst, is what we're sayin', I recon!!

Whats new? What have ya found??

P.

[scottfab]

Originally Posted by Paul Workman

.....snip....
Whats new? What have ya found??

P.

Yah, we're curious about the outcome.
Hope its just a spark plug fouling or something simple.

[Torchred96]

Ok, I'm back. Thanks for the patience. I read and re-read all of your responses, also looked at some video of OH cam collapsed lifter video on youtube and went back to my engine with a renewed sense of optimism.

Observations: When I start the car (yes i did), there is a definite KNOCK that goes away after OP builds up (oil pressure comes up quickly and is right in the middle of the gauge). The knock then goes away and a ticking noise remains. I can't start the car and listen with a screw driver at the same time so it's hard to tell where the knock is. I would guess that knock and tick is at half the freq of the rpms, because when it goes down to a slow idle, i can follow the cadence of ticks and can rapidly say the word tick tick tick tick as it happens (if that makes sense) ...Another way I could describe the tick it is that I can count up to about 1,2,3 and then my mouth can't quite move that fast...So,at least to me it doesn't sound like it's happening once per revolution, but rather, every other revolution

Oil level is at the ADD mark...I thought i was pretty good at keeping oil in it but the oil pan was damaged at one point and it loses oil through what appears to be a bad jb weld repair. I never noticed any loss of pressure though.

1st. Reassured myself that the front accessories were not spinning and eliminated those as a culprit. i.e. I loosened the belt, started it (i know I know) Though the wp is noisy, it is not the noise in question.

2nd. I thought I may have injested a screw from the throttle plates as I used another type of screw to put them back on after the powdercoat. The screws were still firmly attached to the throttle plates.

3rd. Loosened all plug wires enough to pull them easily when started. I believe all cylinders on the pass. side dropped a few rpms each when wire removed with no discernable change in ticking noise. However, on the driver's side, though it was more difficult to discern, it seems like cylsl 1 and 3 (definitely 1) don't chage rpms much at all. But then 5 and 7 are not much better. There was NO noise difference with the wires pulled that I didnt attribute to the flywheel noise I used to hear when it was Missing due to the injectors, and the ticking remained.

4th. Looked at the harmonic balancer while running. It seems to track fine, no obvious damage or noise coming from it.

Next, I used the screwdriver handle to the ear. I had used a medical stethescope before but I think this trick works better. I think I found the ticking noise on the driver's side cylinders esp (noise directly under cam cover of) number 1, but can hear it all the way down the length of the cam cover on that side. The noise when directly over the number one cylinder sounds like a "thick thick thick", IE, like a slapping tick so I'm guessing it is in the valve train on that side.

ON the pass side, I can hear the tick, but is sounds more like it's traveling through the aluminum engine..It's much more pronounced on the drivers side.

I was going to remove the oil pan this evening, but after I got it jacked up and put on stands, I decided to try one more time and do the above tests.... I hope this is good, or at least better news.

Again pls forgive me for not getting back to you faster. I wanted to assimilate what you guys said, weigh the alternatives (buying a new engine, sell the car (not really an option since I owe too much on it) etc) and also get motivated to jump in ......again.

I haven't cut open the filter or drained the oil, but there are no obvious fragments in the dipstick oil held up to the light.

That's all I got for now. Maybe as Paul said, I may have over reacted and assumed the worst. Hopefully, it's not a rod, main bearing or piston (it definitely doesn't clunk after op is up even if I bring r's up a little bit.. ticking persists at all rpms though.

Any thoughts? Thanks again!!!!!