What happens if the timing chain breaks ?

[DierDesire824]

was wondering what happens when the timing chain breaks if it does break would it cause a ticking before breaking and then after snapping would it make a loud boom shoot some grey smoke

also would it do any damage if snapped while driving on the freeway

[MN6WS6]

Timing chains breaking on a small block is not something that happens all that often, assuming you are talking about an f-body. My 98 Astro with 277,000 miles on the clock is on it's stock one, as was my 91 Caprice with 180,000 on the clock, and my dad's old Astro which is still going with over 350,000 on the clock. But, if it did break, you're talking about a massive rebuild. Bent valves, torn up pistons (from hitting the valves), distinct possibility of bent pushrods, might even have torn up the valve seats. You're looking at pulling the heads, sending them out to be pressure tested, resurfaced, and determine how much damage was done to anything in the head. Might as well put pushrods in it since they'll be out anyway. Inspect the pistons, and if they're torn up, now you're talking about pulling the engine and having a total rebuild.

Suggestion? I'd probably start by borrowing a bore scope or finding a buddy who has one. Pull a plug and start looking around inside the cylinder. If the top of the piston is banged up, you know you're talking about either replacing the motor or a complete rebuild. I wouldn't do a compression test without first inspecting each cylinder, because if you did break a chain, then all that's going to do is tear up the engine even more.

[Joe 1320]

Things like pistons hitting valves, pushrods bending, all kinds of neat stuff. In non-interferance engines, the whole thing just stops running.

[oramac5891]

I appologize if I'm wrong but it's been a few years since I sold my 93 Z28. If you're thinking the timing chain is a possibility, I'm pretty sure you can remove the oil cap and look through the opening in the valve cover with a flashlight. This should allow you to see one or more rocker arms. Have an assistant slowly turn the crank with a socket and ratchet while you look through the oil fill hole. If you can see the rocker arm moving up and down you know that the timing chain is connecting the crank and cam.