How Can I Know If My Timing Chain Is Broke

rjwright · Aug 9, 2004

I don't get spark, but the distributor still spins. Although I've noticed that the engine turns over faster. Is it normal for the rotor to still spin when the timing chain is broke? My engine is a 2.8 and my vehicle is a 85 Bronco II. [-o<

STLKIKN · Aug 9, 2004

If the timing chain is broken, the rotor won't spin.
If the timing chain has jumped a tooth or two, the rotor will still turn.

You will still get spark with a jumped timing chain, but the engine probably won't run.

rjwright · Aug 9, 2004

that's good to know about the chain. I still can't get spark to the plugs. I've changed the dist cap, rotor, selenoid,coil,module on the dist,and just yesterday the computer. No spark. Any other ideas? oh, also I changed the plug wires.

Broncoholics · Aug 9, 2004

Do you have power to the coil?

Blue_coyote · Aug 10, 2004

If you have a 2.8 with a bad timing chain, then the problem is WAY more severe....the 2.8 is gear-driven timing (there IS NO timing chain!) Try pulling a valve cover and see if the valves are moving when it cranks (if they don't, then the problem would be the timing gears)

First thing I'd check is the TFI module on the distributor, followed by the coil.

rjwright · Aug 10, 2004

i put a module and new coil and no spark to the coil. there is no power to the coil.
Also replaced the computer and still nothing. It broke down while I was driving down the road. Just cut out cold and never sputtered since no spark at all @-)

STLKIKN · Aug 10, 2004

Well, as blue coyote pointed out, I know little about the 2.8 2.9 V-6 engines... (thanks for the correction B.C. I learned something new today...)

But if the distributor is cam driven, the theory still works the same whether the cam is gear, belt or chain driven.
So onto the no power at the coil... has a plug come apart, have you checked the wires for breaks/ shorts?
Does the 2.8 have a crank sensor? If it does and it has failed, you will not get spark. (oil pressure senders on some makes have the same effect, is your oil pressure tied into the computer on a 2.8?)
Have you checked the ignition fuses? (check under dash AND under hood if you have them.
Have you checked fusible links at the battery for any burned out ones?

BigNasty · Aug 29, 2004

I had a similar issue in a 5.0 chevy in my old T/A..
It just up and died one day.. no spark etc.. all the voltages to the throttle body injectors were perfect, power to the ECM was fine and I just couldn't find a reason for it to not start up after a day of testing voltages parts etc..

All the signs were there for it to start and run just fine until I actually turned the motor over, then nothing would happen.. test everything.. rechecked parts etc.. nothin..

I gave up after two days of testing everything I could and had it towed to a dealer for them to have a go at it.
The service guys were at a loss as everything they did showed that it should have been running perfectly, but for them, it would not start at all, not even an attempt to start.

THEN a tech did something pretty much like anyone else that is giving up would do.. threw up his hands then leaned on the car.. it started right up!
He jumped up and it died...
Prognosis - positive battery cable ECM lead.
It had a break in it that showed full voltage as it should while not being used, but as soon as you turned the motor over, it heated just enough, instantly, to kill the power to the ECM, when letting off the starter, it cooled enough to make the connection again and allowed reading full voltage through the cable. When he leaned on the car, his hand touched the cable, moving it just enough to keep the connection, allowing it to start.

Not sure if that will help as tracking down things like that can be a pita going it alone, but may give some food for thought on tracking the problem.

billybroncojr · Sep 1, 2004

I had a similar problem on my 88 Ranger. At one point the radiator had developed a pinhole and was spraying hot liquid on the wiring harness that runs between the coil and the block. The problem this caused was corrosion in the wires, I pulled the plastic loom away from the wires and they basically fell apart. I fixed the problem and everything was ok in the world again.

My suggestion: trace the wires from the coil to the dist. and look for corrosion, at this point what can it hurt!

Later,
Jeff