My car suddenly died on me and i took it to the mechanic and even though it was showing no spark(i checked icm and coil) he said my opti was fine, i may have a blown chain. He wants to tear apart the front of the engine. The car cranks but will not start. Whats a blown chain? Thats what his secretary told me he said, can anyone help me on this one, how major is this?

 

hes talking about the timing chain....


He "Thinks"?!?!?! thats about the easiest thing to test for in 20 seconds.

Take of the oil filler cap and crank it, see if you can see the rockers moving, if they dont move its the chain, if they move its not the chain.

 

If it did break the timing chain that could be pretty major, especially if you are paying someone to fix it. It's a lot of labor to get in there to just get to the timing chain to replace it, let alone if any valves got bent when it went or possibly cracked a piston. Hopefully thats not it. I can't beleive a mechanic would say he needs to tear apart the front of the engine to see if the chain went, as mentioned it's pretty easy to tell without ripping into the motor first. How many miles on your motor? The stock chain will stretch a good bit with age but they are pretty strong for a stock motor, I don't hear of them breaking very often.

 

I broke my timingchain so if you did also don't feel too bad. Like the previous post says, crank the engine and have someone watch the rockers to see if they move and let us know. Remove oil cap and use flashlight to look in....

Brad

 

If the timing chain is broken, the engine will crank abnormally fast, since some of the valves will be left open and therefore no compression in some cylinders.

 

Now that you mention it, the engine did seem to crank pretty fast. I really appriciate the reply's guys. I have 86,000 miles and no big mods, just whats in the sig. Couple more questions, whats the labor hours on a timing chain and is there a good aftermarket chain that you guys would reccomend? Also i need to get rid of my ac pump, is that any easier accesable while at the timing chain?? Thanks

 

check it yourself! take the oil filler stand/cap off and crank the motor.. see if the rockers are moving.. if not, the timing chain is toast.

You are looking at probably around $1000+ in labor, because the heads will neeed to be pulled, as I can almost gaurantee a bent valve!

 

The car was sitting at idle when it died, it was running fine right before it died. How could a valve be bent? If he had to go that deep into the engine, i may as well get all new hp stuff.

 

the pistons will still crank at least a couple more revolutions, just because of built up inertia. It wouldn't all stop at once. since the pistons will still reach TDC at least once more after the chain broke, and the valves were open, the piston and valve will connect and bend a valve. since it was idling i'm betting it wouldn't of cracked the piston. yes the a/c compressor will be slightly more accessible. and yes, you should do all your mods now b/c if you doni't you'll just be having to pay to take it all back apart. might as well do it while its apart.

 

Thanks for all the advise guys.

 

This is accurate.
$1000 for parts and labor for the timing chain repair alone is possible. Plus, your heads are probably going to need new valves.
My timing chain broke at 100k, and I had the whole motor rebuilt...

 

Let us know what you find. Like others said, it'll take about 30 seconds to determine if it's your chain. Just pull the oil cap off, or just remove the cap and neck (it just comes out), and see if anything moves when cranking. If nothings moving, then it's the crank.

I had the same symptoms with my car, and it was the Opti. How does he know it's not the Opti? Don't trust the mechanic, he wants to get paid. Do the quick check yourself, and let us know the results.

 

My timing chain broke at the track during 1-2 shift at near 5500 rpm,chain/very bent valves/way crooked pushrods.
Heads were not damaged ,,,,,,lucky!!!!

Took advantage of the fact engine was out of the car,did LT4 HotCam/PP heads?headers at the same time[very cost effective]

Thank you ZEKE's ,,great job !!!!

 

All these stories of busted timing chains makes mw want to remind folks of the value of getting a good timing set at the first opportunity. The oem timing chain is mediocre at best. Step up to the GMPP Extreme Duty timing set for LT1s/LT4s. The set isn't cheap at a retail price of $300, but sure seems like a wise investment after hearing about the costly horror stories of busted chains. Yes, you might say all chains can break, but when you compare the oem Lt1 chain to the GMPP ED chain, there is no argument which is stronger and more durable.

 

I definitely agree. Since I just installed my Opti, I'm going to try and hold out until I install a different cam. I hope it doesn't bite my in the @ss later!