I was driving my 1987 cheverolet 2.5L 4 cyl down the highway and it started making a rattleing noise and then just shut off and it wont start back up what do you think it could be? the timing chain? or something else?

A stripped timing gear is a strong possibility, especially if the engine had a constant buzzing or rattling noise from the worn gears for some time before it quit. A too-easy turnover on a start attempt is practically a definitive diagnosis. Changing the gear takes several hours in a well-equipped professional garage; figure at least a weekend if you do it yourself.
Another possibility is that the crankshaft sensor disintegrated, and you heard the pieces clattering down into the oil pan. This would set an engine error code (probably 42) and keep the engine from starting (the sensor is used for spark timing).
The sensor is mounted on the ignition module and goes into a hole in the block where the module is mounted. The hardest part about changing it is getting at it; it's a blind reach on the firewall side of the engine. If it's really dirty back there, I strongly recommend a thorough cleaning before removing the module so you don't drop dirt into the inside of the engine.

Could be many things, but that motor is known for the camshaft gear losing a tooth which will certainly cause a no start condition. If this is what happened, that noise you heard could be that tooth rattling around inside the timing cover. Just a guess, so good luck.

Has to be something else. That engine has neither a chain nor a belt for timing.The camshaft is located near the crankshaft. It has a gear on the end that meshes with a larger gear on the crankshaft.
When you try starting it, what kind of noise does it make? Any more rattling? But the sound of the starter-does it make the same noise turning as it used to? Or do you hear a distinctly different note, like a higher pitched (freer running ) whine? I'm wondering about the valve train. Maybe something came apart. I guess I would take off the valve cover and watch the valves and rocker arms as someone cranks it over. You may see a rocker arm that is off or not aligned proper.
If all looks good under the valve cover, and no more rattles of death, you are back to checking for spark and gas in a no-start condition. Good luck, Adam.
I hope you keep it running-I owned an 87 celebrity 'bout 10 years ago. That car made it to over 400,000 miles, honest. It took 2 engines to make it, but what a great car.

Paul, Monte and Danny are pointing you in the right direction, do not pay any mind to the other posts as these guys are definitely not professionals in the automotive field. I can tell these three guys definitely know whats going on. Get a manual on the car and have at it. I would check compression first, just so you don't take something apart you have no need to... Should have at least 90 lbs to get it running. Start there and see what you come up with. You can ask me more after you find out compression readings, I do this to keep my brain in the game as I am a shop owner now and don't get to get my hands dirty enough anymore.

I would say its the timing, your engine is like a big air pump, running off of gas air spark and timing. You need to listen for the fuel pump to come on first when you turn the key if the car is fuel injected, then take fuel line off of throttle body let a friend turn key on while you hold line into a storage container to catch the fuel this will answer the fuel problem, if there is fuel replace the line. Next lets check the timing marks on the timing gears, You need to remove the cover most of these setups have a timing mark on the gears and on the block check to see that the marks are aligned, you do this by rotating the engine by hand to line up the marks, If they do not line up, theres the problem also look for any broken teeth that may have cause the engine to untime. Ususally it is a good idea to purchase a manual on your year car to have a quick reference or when you buy the new timing gear set it will have instructions on how to align the gears back properly. If the timing is not the problem the next step will be to check the crank shaft position sensor at which time I would recommend letting someone run a scan with a scan tool to get the fault codes to identify the problem sensor. I believe the rattling you heard is from the valves opening and closing at the wrong time leaving me to believe its in the timing gears bad throwing your timing off. The key to working on your car is planning and doing your research on how to best ready yourself for the job. If you get frustrated take a break and come back to it, if you cant manage this type of attitude, take it to a qualified mechanic , you dont want to be a parts replacer take it slow and easy the experience and knowledge you gain will be priceless. Hope this helps

Confirm fuel flow by disconnecting the fuel line at the throttle body...these motors and 87 designs are known for fuel pressure regulator failure...symptoms are the same, and this is a repair you may do yourself. Hope this helps.

It seems to have been answered, but instead of playing guessing games with it to get peace of mind take it to your local garage and have it fixed profesionaly,good luck with it

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