Nissan Repair: Navara D21 - 1988 model adjust timing chain, cotter pin, hash marks

Question
QUESTION: Hi. Am hoping you can assist. I am installing a reconditioned head on a 1988 Navara D21, 2.4 litre petrol z24.

I had read that I could just take old one off, take cam sprocket off, put new head on, then put cam sprocket and chain back on.  

I cannot get chain back onto cam sprocket now though. I did not do anything to maintian chain on sprocket as I was not aware I needed to.

My question is wewhether there is a simple way to release tension on timing chain without having to pulling the whole front cover and pullys off.

I was told there may be an external nut on the side somewhere? I will have a look. If not what are my options. I don't want to replace timing chain. I simply want to put cam sprocket and chain back into position. Or am I kidding myself.

The other problem is I dropped a washer down the timing chain shaft, (not on purpose) will this just fall through to the bottom of the pan.

Your help would be greatly appreciated.

John G

ANSWER: Hi John -

First of all in order to manipulate the chain, you will have to remove the tensioner. This is a ratcheting type device, so once the chain is loosened, you will have to lock it in the fully cocked position in order to fit the timing chain on the sprockets. Once you get the tensioner off, then you will see the 2 holes that need to be lined up to place the tensioner in the cocked position. Use a cotter pin or nail to keep it in place. I know you want to only replace the chain, but a good idea is to replace the tensioner and the guide while you are there. I know this is what you did not want to do, as the timing cover will have to come off to get to the tensioner.

Once you have replaced the cocked tensioner, then you must line up the timing marks. Turn the engine to TDC, and then line up the sprocket hash marks to the head. The best way to do this is to get a diagram on line to see what I mean. While you put the chain on, the cam sprocket and damper MUST not move. One click off, and the car will not start, or run very bad.

As for your washer. If it did indeed fall down to the pan, then it should be OK, but it could be stuck before that. However since you have to remove the timing cover now, then get a telescoping magnet and you should be able to recapture the washer.

Hope this helps -
aloha
calvin

---------- FOLLOW-UP ----------

QUESTION: so  first point is that I have to take cover off which means all pullys on front of motor. and that there is no way of adjusting tensioner externally?

Answer
Hi John -

Unfortunately no. The tensioner is ractheted so that you have to remove it to reset it.

The other way to do it (of course it is too late now but for next time) is to wedge an angular piece of wood securely between the timing chain (and tensioner) and guide before removal of the sprocket so that the tensioner does not extend when the chain is loosened. This way nothing moves, and the head an sprocket could be replaced same way as removed without disturbing the tensioner.

Hope this helps -
aloha
calvin