Help camshaft timing

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grumpy too

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Just started pulling the head off my 2008 25 YD (jap) and found the mark on the LH camshaft is one link out from the mark on the chain and if the RH camshaft had a mark it would appear to be in the correct position ie the camshafts are out of sync with each other when the blue/green marks on the chains are in the correct positions the yellow mark at bottom is bottom centre of bottom cog but LH cam is one link out.

Any ideas why as this motor was running really sweet but it has gas bubbles in the radiator and an oil leak at rear RH side of head gasket which is why I am pulling the head off (note chain looks perfect and no wear on top guide)?????

Thanks Bob
 

Old.Tony

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You'd already be aware that gas bubbles in the radiator indicate a cracked head. The crack may have developed near the oil leak (and may be the root cause of the leak). A minor crack wouldn't impair performance hugely.

I can't explain the timing mark issue. You'd think that being one tooth out would have an impact on performance, opening the exhaust valves early (say) would rob the vehicle of power and cause black smoke (unburnt fuel), and opening them late could lead to the valve still being out when the piston reached TDC.

Good luck with the rebuild!
 

grumpy too

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Sorry found out with proper examination all links are one out which means it is ok but the right hand cam looks to be different to LH but if punch marks are right it can't be hey.
Top chain looks good to almost new, any idea how to check?
 

Old.Tony

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Small mistake in my post - one camshaft isn't exclusively used for exhaust or intake, both shafts operate both valves, the YD25 in the D40 runs the ports across the motor (intake to the right, exhaust to the left) with the intake valves in front of the exhaust in each cylinder. This means it's likely to have some impact (no pun intended) with valve timing regardless of which camshaft is correctly aligned.

In terms of inspection, the automatic tensioner takes up the slack, so it would need to have some room left to move - the chain should be tight against the tensioner and the tensioner should not have fully come out. The chain itself should not have visible signs of wear or any cracks in the links/pins.
 

grumpy too

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Thanks Tony
Yeah have about 16 thou between plates on chain, think any closer and they would touch on the bends which they seem to do but will consult the manual definitely no apparent sign of wear and the guides seem to be unmarked but will see when it comes out.
Was hoping the bubbles/gas was the gasket not the head but will see when it comes off, do have a head here on another motor but no idea what it will be like as in the words of the bloke I bought the car from "it just stopped" it had a really bad injector by the look of the engine bay and under the car so probably melted a piston, do know where there is another one but it had a turbo problem and locked up so probably u/s too.
Have to try and find the tools to fit the head bolts now, not available locally, any ideas? didn't think that would be a problem.
 

Old.Tony

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It's like a reverse Torx bolt, if memory serves. I'd leave Nissan alone, they'll want $1K for the tool. I don't know how large the bit has to be, sorry. Not a job I've had to do, but when you get it (eBay?), make sure you can fit it to a torque wrench.
 

grumpy too

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Thanks Tony
Got some from trade tools and got a set of torx wrench at the same time as it was free freight if over $75 but $34 for freight if bought separately ??? really didn't need the torx wrench bits except the T70 for the fuel pump but really don't think I need to do timing chain.
Bob
 

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