Timing adjusted itself.....??... MYSTERY..

Ok, so I've just finished working on my patrol again........ This is what happened earlier..

The trol was going well no sign of problems. 4.5 dual fuel. I went to start the trol it made a grinding bang sound... wtf?? ... It did the same thing after a few times. Quite loud. After a few more goes it cranked over then went bang and stopped cranking.... Seemed like compression lock up..... At this stage I was rather concerned as I never ever had or heard this before.
I walked away and pondered for a while on the problem and how to get it going. After 10 or so min I thought Id give it one more go before i crack it..... Cranked it and it started....it was running like crap.
I thought I'd check the timing. The dizzy wasn't loose but the timing changed from my original setting. I always set the timing to about 7.5 deg before tdc and it was on about 13 or 14 btdc. I don't get it. How does the timing change by itself. I have an ecutalk all set to normal but surely this can't be the cause.
So if the timing was out this much the engine was locking up and not firing. It seem to kick backwards. Does this sound right???

How can the timing change itself from original setting on the harmonic balancer??? How do I stop this from happening again as I'm rather concerned.... .???

I'm not familiar with the timing marks on those engines, is it possible for the timing mark to move?
Holden red motors have a two-piece balancer and the outer is prone to slipping...

Yeah I remember something about that with the red motors bear..... Showin my age he he.
Haven't heard that being a problem with these motors. Perhaps someone else knows different and can shed some light on it.

So to be sure I'm going it right. To adjust the timing I unplug the throttle position sensor plugs, adjusts the timing using a light with a warm engine by moving the distributor and reconnect the tps plugs. Correct?
So there are no pins to short out on the ecu etc??

faulty tps maybe ?.
you should be able to multi metre test tps, 1 would think.
dizzy jamming advanced
I personally had that happen in a nissan of all cars.
shame, shame.
bearings between advance plates had made there own little holes to jamb in.

when I was a lad lol, harmonic balancer were exchange units it was that common

What did you find ?.

Hey Robo, I have an ecutalk reads the tps to be correct. I did a manual check (multimeter) as per book and seemed to be correct. I readjusted the timing and it seems to run ok. Just concerned it might happen again and leave me stranded.

When you mention advance plates had made holes where would this be located? Part of the dizzy? (sorry, my mechanical knowledge isn't 100%)

Yes, inside dizzy there is a sandwich-plate set up that allows the timing to move.
I have not pulled your dizzy apart , but if you remove cap, rotor and cover plate if it has a plate also, you should be able to see, even move the plates a bit by hand.
It may not even be the traditional plate design setup, but a setup none the less that will allow some rotation.
It should be a smooth rotation, both ways.
If not then there's your problem.
Off the top of my head, I don't know the exact set up of your dizzy , there could also be something else sticking.
but not sure of design.

On my/wife's 4.2 its a fair design to keep dirt out and guess your's will be the same good design.
but this does not stop mechanical wear and tear.
the heat can even cause lube to dry out .
and gravity to allow lube to drain away also.
When/before I put pertronic in my dizzy, I used a good spray of, lithium spray grease, ( with the extension tube ) to re-lube it as a maint measure.
touchwood all good so far, that was over 2 yrs now.
Hope this helps.

Quote:

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Originally Posted by 4by

Hey Robo, I have an ecutalk reads the tps to be correct. I did a manual check (multimeter) as per book and seemed to be correct. I readjusted the timing and it seems to run ok. Just concerned it might happen again and leave me stranded.

When you mention advance plates had made holes where would this be located? Part of the dizzy? (sorry, my mechanical knowledge isn't 100%)

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when you did this check did you try and find any dead spots while moving the acl peddel?.

Quote:

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Originally Posted by Robo

Yes, inside dizzy there is a sandwich-plate set up that allows the timing to move.
I have not pulled your dizzy apart , but if you remove cap, rotor and cover plate if it has a plate also, you should be able to see, even move the plates a bit by hand.
It may not even be the traditional plate design setup, but a setup none the less that will allow some rotation.
It should be a smooth rotation, both ways.
If not then there's your problem.
Off the top of my head, I don't know the exact set up of your dizzy , there could also be something else sticking.
but not sure of design.

On my/wife's 4.2 its a fair design to keep dirt out and guess your's will be the same good design.
but this does not stop mechanical wear and tear.
the heat can even cause lube to dry out .
and gravity to allow lube to drain away also.
When/before I put pertronic in my dizzy, I used a good spray of, lithium spray grease, ( with the extension tube ) to re-lube it as a maint measure.
touchwood all good so far, that was over 2 yrs now.
Hope this helps.

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Yes, I remember when I removed the dizzy cover to check for cracks there was a black plate below the rotor button. 2 screws I think held it on, but I didn't remove it. I thought there would be nothing under there significant to check. I'll pull it apart again and have another look and give it a spray.

Didn't seem to be any dead / flat spots. It accelerates smoothly. I do have an engine miss due to a cracked or bad injector seal around no 6. (another problem I have to fix) If I push on injector 6 the engine runs smooth, if I push the other way it shakes. I've removed the rail and injectors to replace the O rings, but now I find the injector filters are damaged and need replacing. Can't seem to buy these filters so Ill have to buy second hand injectors or perhaps order new injectors from China. What a pain...... (Sorry for the long story, I only just bought the car and it's spent more time getting repaired than being driven.... all great fun.. :)