#46
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Thanks so much 07Nissan. This was great information and the pics make the timing marks very clear. So good to know all of this before tearing into this thing.
Thanks again. |
#47
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Sorry, but I'm still just a little confused on the TDC and chain marks.
(see attached picture) If I take the cover off, and then rotate the engine until all 7 of the chain marks are aligned with the gear marks, couldnt I just lock the CS there and take off all three chains and put on the two new secondary chains and the original primary chain and just make sure that the marks are all still lined up? Where does the need for TDC come in? |
#48
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TDC and index marks
Again, another good question:
The purpose of aligning the No. 1 cylinder to TDC is so that you do not have to rotate the engine until the index marks on the chains and gears align themselves to their original points. What happens is that gear teeth are not in sync with the number of links on the chains. As the engine rotates, the index marks will be shifted so that if you align the secondary chain marks to the gears, you may find that the primary chain index mark may be off by several links. This has nothing to do with keeping in time. For example: if there were 10 gear teeth and there were 100 links on the chain, then everything would be in sync 10/100, but if there were 110 links, all of the marks would align up every 10th rotation of the engine, or if there were 101 links, the marks would line up every 100th rotation. In my case, I got lucky and had to only rotate the engine 3 times (in the wrong direction) by hand to make everything line up and I only did it because it gave me an additional point of reference. hope this helps |
#49
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Quote:
Last edited by 07Nissan; 12-28-2011 at 01:27 PM. |
#50
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I agree with 07 Nissan, the engine should be a TDC prior to removing the chains, but the timing chain index marks may not align to the marks on the gears. I have not been able to find out if this engine (VQ40) is a non-interference design. If it is not, then you could cause damage by having the pistons hit the valves.
Also, I have heard about a Borg Warner "fix" for this problem. Does anyone know anything about this (roller bearing v nylon slipper)? |
#51
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Quote:
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#52
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Hey guys. I did something stupid. I'm in the middle of this repair at my Dad's place (800 miles from home) We chose NOT to take off the valve covers initially, I had no chain wear so did not replace the chains. BUT, I did have to remove both primary and both secondary chains to get the tensioners out. We marked everything ahead of time. Pointed the crankshaft pulley at its mark knowing at worst we would be 180 off and since we had the flywheel locked we and all chains and gears marked we would just put them back as is either way.
Heres my issue. We had slippage because of the valve springs when we removed the secondary chains. We pulled the valve covers at this point. We lined all of our marks on all gears and chains back up perfectly. No problems. However when we line our timing mark on the crankshaft pulley up it is not on TDC at the #1 cylinder. Even 180 around and it is still not on. Is there a way to time the engine from scratch. The only problem I can even think of that may be wrong is one of the cams is off time from when it was detached from its gear. If so I would think it would have to be 180 off because the gears are all keyed with a pin. Any suggestions would be great. I'd hate to go back together and be off. Thanks ahead of time guys. |
#53
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The primary timing chain is not indexing corectly and at what points (camshafts/crank)? Can you thumbnail some photos of what it looks like now?
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#54
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Quote:
I know this doesn't help now but the easiest way to make sure you line everything back up correctly is to paint links on the chains and mating marks on the gears. With that done it doesn't matter what position the engine is at as long as you reassemble it the same way it came off.
__________________
Nissan Master certified Technician
Hybrid and GTR certified EV certified ASE Master Certified. |
#55
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Quote:
In my previous posts I mentioned *not* to use the TDC crankshaft pulley method to find TDC. Cylinder #1 is *not* at TDC using this method. Why? I don't know. Attached is a pic from the Nissan service manual that shows the proper position for the secondary/primary timing chains and camshaft sprockets when cylinder #1 is at TDC (thx to joeveebee for this pic). On my engine there were very dark, copper-colored links on the primary and secondary timing chains that I used to match up the various positions. There are also very distinct, round indents on each of the four camshaft sprockets that are used to match up to the various painted (and copper-colored) links on the secondary/primary timing chains. I wish I could be of more help, but each engine is marked differently. If you're not absolutely sure you've installed the chains in the correct position, I would suggest taking it to the dealer and, at the minimum, have them install the primary and secondary timing chains for you. Good luck! |
#56
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You can use the dowel pins on the cams and the keyway on the crankshaft to line everything up before you reassemble. The dowels on the cams should all face up so they are pointing level with the surface of the cylinder head. The keyway on the crankshaft should be at about 11 o'clock. There should be a mark on the engine to line it up with.
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#57
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Quote:
Last edited by 07Nissan; 12-28-2011 at 04:29 PM. |
#58
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For those p[lanning to do this: please read this
good obs 07 Nissan, did not catch the comment from hogballjim about recycling the secondary timing chains.
Again, for those who are planning to do this: please do not skimp or take short cuts. It will only cost you more, sooner than later. The NTB has the MINIMUM parts listed for the repair. Nissan will not add more parts than necessary so as to keep their costs down. Ask yourself, "What is your time worth?" and is it more or less than the money that you are trying to save? This is not meant to be a negative or condisending editoral. I, like others in this forum, will continue to help others with their timing chain repairs. |
#59
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Hey Guys. My timing chain tensioner repair is done. Took me longer than expected (about 3 ten hour days of work) but I attempted to do it with out removing the valve covers first. Dumb mistake. I had to go back and remove them later and my dad and I spent several hours trying to make sure we had not gotten anything out of time. Turns out we did not. However for those attempting this repair heres something to watch for.
We marked EVERYTHING in spite of all the manufacture's marks. Still when we removed the secondary timing chain sprockets the cams tried to turn slightly due to valve spring pressure. We got nervous that we had things possibly out of sync until we were able to look back at the cd repair manual pic shown above by (o7 Nissan). My Pathfinder now runs great. No more whine whatsoever and as stated before by one of you guys the replacement parts are made better than the original. Once again I can't thank you guys enough for all the help and pics posted along the way. This is the most helpful forum I've ever been on. Happy New Year you guys. |
#60
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Quote:
I certainly don't want to get into a debate as to whether you should or should not follow NTB09-128. However, for those that choose to follow NTB09-128, it is easy to replace the secondary cam chain tensioners without removing the intake plenum and valve covers. I followed NTB09-128 to the letter and the job went smoothly and, IMO, saves time and effort. As long as you do NOT try to find cylinder #1 TDC using the crankshaft pully method and, instead, use the large pictorial in the service manual that shows the correct position of the crankshaft keyway, secondary/primary chains, and camshaft sprockets PRIOR to removal of the chains, you'll be fine. As I've been saying all along--if you feel any significant tension on either secondary cam chain prior to removal, you are NOT at cylinder #1 TDC. Again, congratulations, Hogballjim! Happy New Year!! |
Tags |
chain, fyi or diy, repair, tensioner, timing, vq40, whine |
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