Scoobie

iTrader: (8)

Folks the wife drove our LT1 Camaro today for the first time ever, lol. She was taking it down to the DMV to have them "read the VIN" to get permanent plates put on. She said she started it and it was fine, pulled out onto the road, made it to third gear and suddenly she heard a bang and then she said it sounded like she was "dragging something". The car died and she coasted it into a parking lot where she called her dad. Her dad popped the hood and all looked well, he is fairly mechanically inclined. They looked under the car and nothing is dragging. He attempted to start it and he told her to tell me that it sounds as if it has "lost compression"

The car was towed to my brothers car audio shop pending inspection by a mechanic. I am in Afghanistan for 7 more months. Your thoughts? My wife drove our 07 Z06 at least 100 times and she's driven our 99 Z28 at least 50 times without issue so I don't think it was the "driver".

pancho toco loco

iTrader: (8)

Maybe a case of the opti going out. The inner workings could have broken apart, bang couldve been a back fire so to speak

Scoobie

iTrader: (8)

That is likely. When the car came out of storage it had a slight miss. Replaced the plugs and wires when I had Kooks Headers installed. Didn't fix it so I had the Opti replaced with an OEM replacement. That was a month ago and maybe 2 miles on the Odometer since the install. Would a "blown" Opti cause the vehicle to instantly die? Father in law says it wants to turn over but sound as if it has no compression. At first I thought timing chain failure.

Rob94hawk

iTrader: (1)

My thoughts right there. I wouldn't turn it over again just in case. Time to start pulling things off. Opti, timing cover. Pull the valve covers off and take a look. Check the valves and springs.

TwoFast4Lv

iTrader: (8)

Yes I have had new opti's let go just like that. Check for spark at the plugs before you start tearing in to far

GIZMO

iTrader: (8)

I would pull the valve covers before I turned it over to make sure that nothing is obviously out of wack.

SS RRR

iTrader: (2)

There has been chatter back and forth whether or not the LT1 is an interference or non-interference motor. Reason I say that is, like stated, it's entirely possible the timing chain broke. This happened to a friend of mine and he threw another chain on without taking the heads off and he was fine. Engine was completely stock with bolt-ons. If the timing chain did actually break, I would take the heads off and make sure no valves actually did come into contact. Broken chain is the only thing that really explains an engine sounding like it's lost compression.
Good luck, fella.

rich5368

iTrader: (2)

I agree totally on the fact that a broken chain explains the loss of compression sound. That's exactly what it sounded like when the timing belt let go only wife's car.

1961ba427

iTrader: (26)

Some LT1's (and other engines I'm sure) just crank over very quickly. When my ICM went out last week my car just shut off and would spin and spin. Several of the guys at work (GM dealership) said it sounded like it was cranking with no compression and the timing chain had probably broken. I told them it always cranked really strongly. The timing chain (LT4) was installed about 7k miles ago when I did heads/cam. Mine is a stock short block and original starter (98k miles) with 52cc chambers and .026" Victor gaskets for around 11.5:1. (I don't remember exactly what it calculated at off the top of my head.)
I've always heard that LT1's, sbc, and bbc aren't interference engines, but when the chain broke on one of our big blocks (under light load....pulled out of driveway and started up a hill) it bent a couple valves. I've heard of plenty that didn't damage anything also....so I guess "it depends" is the only correct answer.
I'd unsrew the oil filler tube and peek to see if the rockers are moving when it's cranked.
I'd also grab a test light and multimeter and see if your opti checks out. It really helped me narrow down my ICM being the problem. Also, make sure it has fuel pressure. It's possible the loud pop was a lean backfire.

GreenBlood55

iTrader: (1)

Wife 1 Lt1 0

TwoFast4Lv

iTrader: (8)

LT1, SBC, BBC, LSx and most chevy V8 engines are INTERFERANCE engines. Most Motors are not

you may get lucky and not hurt the valves to bad but they WILL hit the pistons if you keep trying.

The reason they spin over like they have no compression if they loose spark is because they are not fighting the Spark Before TDC.

I have also had this argument.......And got paid to pull the heads and replace the valves when it turned out I was right...over and over again


Most of the broken timing chains I have seen are on cars between 120 and 250k miles

Scoobie

iTrader: (8)

Thank you for the replys fellows. I am in Afghanistan for 7 more months so sadly I'll have locate someone back stateside in the Orlando area to have a look for me. We were going to ship my wifes Altima back from Germany to Florida for her to drive but seemed persistent she could drive the SS which was being stored to save us money. I feel bad that it happened while she was driving it for the first time.

If the heads have to come off and the timing cover, looks like AI or LE will be getting a phone call from me.

96lt1m6

iTrader: (31)

Timing chain

SS RRR

iTrader: (2)

Intake/exhaust valves that are not actuating and open may have something to do with that as well.

Scoobie

iTrader: (8)

Assuming the chain is broken, then the heads have to come off. Assuming the heads have to come off to replace valves, what at minimum (the necessary items) should be replaced on a 70K mile LT1. Basically, I want to try to figure out what this is going to cost me. Add labor, as I am in Asscrackistan. I just dropped 3100 on this car last month. I would like to fix her and maintain at minimum a moderately happy wife.

SS RRR

iTrader: (2)

Worst case you may be looking at a rebuild of both top and bottom ends if the pistons and valves took damage. Just depends on what the innards look like.

Scoobie

iTrader: (8)

Ok, so my brothers friend is a mechanic, I do not know his qualifications. He looked at the car and called my wife. He said it was the chain. Said he could repair it for 400.00 including parts. Not bad, but he told my wife the car is a "Non Interferance" engine and so the valves should be good. (I told her to tell him I was worried about valve impact on the piston) I am going to ask him to pull the push rods and inspect for bends. That would be an indicator, right? Valvetrain is all stock. Anything else I should ask him to look for? I am about to call him.

quik95lt1

iTrader: (7)

^do this.......if it did break something in the valvetrain you stand a very good chance of breaking alot more by spinning it......check to make sure no springs are broken, bent pushrods, or bent valves.......if all is ok THEN check spark

Scoobie

iTrader: (8)

Ok, just talked to the mechanic. He knows Engines and I feel confident he knows what he's doing. He works primarily on Rigs and trucks though. He said he'll pull the valve covers and inspect for damage, to include pulling the pushrods. He said he can "scope the cylinders as well" I'll post up what I find out tomorrow. It is Midnight here and off to bed. Thanks again everyone.

speed_demon24

iTrader: (6)

Not sure if serious.