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2001 3.0 GR, 42" tires, ARB lockers, central tire inflation system, some other bits and bobs.
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Discussion Starter · #1 ·
Hey all,
I'm slowly digging into my engine to replace the injection pump and got the timing chain to align nicely (crankshaft at TDC marker, 6mm bolt in place in the idler gear, camshaft marks match blue chain links, injection pump match mark aligns with the yellow link) but the position of the crankshaft and injection pump marks are off.

The manual shows the cam sprocket marks at about 3:00 position, while in reality they seem to be 180° off at around 9:00 position ... but as far as I can tell, as long as I line up the new injection pump with the match marks I have all should be well, right? Am I missing something?

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nissan patrol 4x4
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The timing shoud have been dismantled with the timing in the correct position, you need to rotate everything back to the position shown on the diagram plus the IP and idler cog letter timing marks aligned, there's an old mechanics saying " when all else fails, read the instructions"
Reg
 

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2001 3.0 GR, 42" tires, ARB lockers, central tire inflation system, some other bits and bobs.
Joined
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14 Posts
Discussion Starter · #3 ·
The timing shoud have been dismantled with the timing in the correct position, you need to rotate everything back to the position shown on the diagram plus the IP and idler cog letter timing marks aligned, there's an old mechanics saying " when all else fails, read the instructions"
Reg
The timing is not dismantled at all. I know to stop when I'm not sure...

And yes, I did read the instructions. They actually say nothing at all about aligning match marks – only that the M6 bolt needs to be installed in the right position to lock the idler in place, which it is.

In fact, the instruction specify to make manual match marks and to ignore the TDC alignment procedure.

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2001 3.0 GR, 42" tires, ARB lockers, central tire inflation system, some other bits and bobs.
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14 Posts
Discussion Starter · #5 ·
You could be 180° out of timing, so at TDC on the exhaust stroke not compression stroke
Aaaaah of course, that makes perfect sense. Thanks.
 

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nissan patrol 4x4
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109 Posts
The timing is not dismantled at all. I know to stop when I'm not sure...

And yes, I did read the instructions. They actually say nothing at all about aligning match marks – only that the M6 bolt needs to be installed in the right position to lock the idler in place, which it is.

In fact, the instruction specify to make manual match marks and to ignore the TDC alignment procedure.

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From memory when you put the idler lock bolt in you make sure the all the required timing marks ,TDC , timing chain and cam lobes are aligned correctly , you can't turn the crank over once the locking bolt is in place, therefore the cam chain reassembly has to be done exactly as the instructions indicate or the timing will be wrong. I've done two IP replacements in the last year & believe me , even when it's done exactly as it should you can still have problems getting them started again.
Reg
 

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Registered
2001 3.0 GR, 42" tires, ARB lockers, central tire inflation system, some other bits and bobs.
Joined
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14 Posts
Discussion Starter · #7 ·
From memory when you put the idler lock bolt in you make sure the all the required timing marks ,TDC , timing chain and cam lobes are aligned correctly , you can't turn the crank over once the locking bolt is in place, therefore the cam chain reassembly has to be done exactly as the instructions indicate or the timing will be wrong. I've done two IP replacements in the last year & believe me , even when it's done exactly as it should you can still have problems getting them started again.
Reg
Yeah there'll be a huge sigh of relief once this is all done for sure.

To add more amusement to this adventure, the replacement IP showed up yesterday and despite what the seller told me, it's the wrong model (16700-VX101 instead of the 16700-VG100 I have). Oh joy...

I was planning to send the old one in for refurb anyway, I guess I'll just have to wait until that is done.
 

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2001 3.0 GR, 42" tires, ARB lockers, central tire inflation system, some other bits and bobs.
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14 Posts
Discussion Starter · #8 ·
Alright, just to close this up, everything is back together and runs like a charm! After some discussion with the local Patrol folks I learned that despite the different model numbers those pumps are indeed compatible and this exchange had been done many times before, so I decided to go ahead.

Reassembly was uneventful except I bodged putting the timing chain cover on neatly, had to clean the sealant off and start over again. Bit of a drama bleeding the air out of the entire system but eventually fired up and runs nice and smooth now.

Minor detail I learned about matching up the timing marks: the teeth counts are all coprime, so over time each tooth will make contact with all the others from the meshing gear, distributing wear evenly across all teeth. Same goes for the timing chain and its cogs. This explains why the timing marks don't line up perfectly on each revolution, and since it's not always the same prime number combination across all the gears and idlers, the number of revolutions you need to get all of them synchronized at the same time is much higher than for each individual pair of gears. And on the way you'll almost inevitably get combinations where some but not all of the timing marks line up.
 

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NISSAN PATROL Y61 3.0 Di (ZD30) 09/2000
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I guess this is the least common multiple across all gear/idler individual number of teeth. From the top of my head, it is a number between 1000 and 2000, but I might be wrong.
 
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