Broken timing chain

[bryanworks]

Pretty sure my timing chain broke, if so do the valves and pistons interfere? Trying to decide if I want to install a new chain or have a mechanic replace the valves and guides. Any help is greatly appreciated, thanks in advance.
Bryan

[maxnix]

Originally Posted by bryanworks

Pretty sure my timing chain broke, if so do the valves and pistons interfere? Trying to decide if I want to install a new chain or have a mechanic replace the valves and guides. Any help is greatly appreciated, thanks in advance. Bryan

If your Q45 is between 1990-1993 and you don't have the updated timing chain guides installed, the engine is probably toast. Some heads can have valves replaced if bent, but beware if anything is broken. Timing chains very rarely break, but the early guides do allowing the chain to jump, and the guide pieces can foul the oil pump chain and score the oil pump body.

Go to www.nissaninfiniticlub.net to read extensively on the subject of timing chain guides.

[flyinlouis]

Hi, I also think my timing chain is broken. Yesterday, I cranked the engine, it started for about 0.25 second and stopped. After that, the engine cranks with a whining noise but does not start...

I have a 1994 Q45 and wonder if the engine is toasted in the case of a timing chain broken?? The car has 107000 miles (not so much...) Do the piston intefere with the valves in that case or is it just a matter of replacing the timing chain?

Thanks!

[maxnix]

Originally Posted by flyinlouis

Hi, I also think my timing chain is broken. Yesterday, I cranked the engine, it started for about 0.25 second and stopped. After that, the engine cranks with a whining noise but does not start...

I have a 1994 Q45 and wonder if the engine is toasted in the case of a timing chain broken?? The car has 107000 miles (not so much...) Do the piston intefere with the valves in that case or is it just a matter of replacing the timing chain?

The 1994 and later VH45DE had the new guides installed at the factory. Chain does not break at that early a mileage unless seriously abused by too few oil changes. Yes it is an interference engine. Might check your Bosch plugs to see if they dropped any of their electrodes yet.

What is the condition of your fuel filter and fuel pump?

[flyinlouis]

Originally Posted by maxnix

The 1994 and later VH45DE had the new guides installed at the factory. Chain does not break at that early a mileage unless seriously abused by too few oil changes. Yes it is an interference engine. Might check your Bosch plugs to see if they dropped any of their electrodes yet.

What is the condition of your fuel filter and fuel pump?

Ok Guys, false alarm. As you sais, those chain do not break. Anyway replacement of the timing chain involves removing the engine with the transmission for the service. It's a major work and you can see that the timing chain was not designed to be replaceable. Now, my problem was a flooded car.

I troubleshooted by elimination. I chedked fuel supply by disconnecting the fuel hose between the fuel injector busses. Fuel was flowing big time as soon as the ignition key was turned to the "on" position. ==> no problem.

Then I pulled the fuel pump fuse & checked with a digital oscilloscope the signal going to a spark splug primary coil. I could see beatiful pulses there so ==> no problem.

Then I checked signal going to a fuel injector. I could also see beautiful pulses so ==> no problem.
Then I was wandering how come the engine would not start: fuel supply is good, ignition coil were triggered by the ECU so were the fuel injectors??? I then put back the fuel pump fuse & cranked the starter... vrrroom! the beast started...it was flooded.

I still don't understand why it flooded thought but it's running smoothly now.

[maxnix]

Originally Posted by flyinlouis

I still don't understand why it flooded thought but it's running smoothly now.

If you start the car cold and move it a very short distance immediately and shut it off, it will flood easily.

Why it is important to warm car up to operating temperature before driving.

There are some interesting posts at NICO about voltages required for pump operation and waveforms for proper injector operation you might want to peruse. Lots of other very useful for the technically inclined, also. You may want to do a search on Bosch.

[wgreene63]

Those are the exact symptoms I am having. I moved my 1990 Q45 20 feet to wash it and the next day it started for about 2 seconds and quit. I have tried to start it several times and the engine seems like it has no compression. It turns, I can see the fan turning but doesn't start. I was thinking timing belt/chain but if it is just flooded that would answer my prayers. If it is flooded, how do I fix that? I know with a carburated car you simply turn it over with the accelerator floored until it clears. Not sure what to do with the Q45. Any help would be appreciated.

Car has about 92k miles on it.

[maxnix]

If it is flooded, all injectors firing at once has washed your cylinder wall free of lubrication so you have no compression.

After it has set a day, pull fuel pump fuse and spin for about 15-30 seconds. Re-install fuse and start as normal (should not require any throttle unless seriously out of tune).

In the future, don't shut off engine before it has reached operating temperature.

[wgreene63]

I cranked it over for about 1 minute and it started. Did not know about the flooding issue. I know now. Thanks for the reply.

[infinman]

During cranking, the Q45 injectors are "fired"simultaniously{all at once}untill closed loop{warmup} is achieved.Then they go to "sequential" firing.If you start your Q then shut it off right away,then restart again,you will most likely "flood "the engine.Each attempt to start will only worsen the condition.Pulling the injector fuse to clear flood is the best remedy.Good luck