Did my timing chain jump? (Photos)

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cesanneo2

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Hi all.

I opened the top cover and I started turning the engine to align the marks. Chain marks and cam marks do not line up...
There is no paint left on the 3rd mark of the chain. I marked marks on sprockets red for better visibility.
Do I need to turn it until they do, or at this point we know it jumped? Would it be saveable? I was able to manually turn the crank with a 50cm bar and 19mm socket.
I drove it probably 5 minutes before a full stop (low revs under 2k) after I heard the noise.
PS: what I found interesting, in every timing photo the coloured links are on top of the marks. In my case, the marks are pointing in between the links, not to the moddle of a link. Pic from repair manual for comparison.
thank you! :)
 

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Last edited:
The bottom sprocket for the primary chain - and it might just be my eyes not seeing it properly - looks like it's stuffed. The teeth that are visible look like the tops are worn off.

It can take several revolutions of the engine before the marks all line up. If you've turned the engine over completely, the timing can't be out too much or there'd be pistons wearing valves as little hats!
 
The bottom sprocket for the primary chain - and it might just be my eyes not seeing it properly - looks like it's stuffed. The teeth that are visible look like the tops are worn off.
Thank you. As long I have the marks on cog wheels OK I do not need to worry about what is on the old chain right?
I will be replacing the chains with sprockets, but I will take a close look at the teeth. In my R50 I removed the crankshaft pulley / harmonic balancer bolt with 18V battery operated rattle gun... that did not work here. R50 had 32 size bold so I was sure there will be no issues with the 19mm size in R51 YD25. There was... It is automatic so no sticking in gear and breaks method. I will try to lock it with an old accessory belt and give it a go this way. Fallback scenario finding a compressor and air gun. That may become an expensive bolt to remove.
 
So... the "block cheater bar against the frame and use starter motor" method did not work either... Getting a 400 Nm impact wrench on Wednesday. If that fails I will go for option 1) replace only top chain and get air gun 700Nm at some point in the future. Option 2) get 700 Nm air gun.
Top chain snap is catastrophic. How about the bottom bottom?
Bottom drives fuel pump and what else? thanks! :)
 
The bottom chain drives the top chain, so it's also catastrophic!

Amazed that a breaker bar had trouble, but then I couldn't undo the alternator with a long handle on the socket and gave the task to the local mechanic, who said they used a 1m breaker bar with a 1m pipe to extend it!
 
The bottom chain drives the top chain, so it's also catastrophic!

Amazed that a breaker bar had trouble, but then I couldn't undo the alternator with a long handle on the socket and gave the task to the local mechanic, who said they used a 1m breaker bar with a 1m pipe to extend it!
Thanks. Based on your information, I decided to look at the bottom chain too. Tensioner is out by around 10mm so quite stretched too.
That means I got the balancer out! :)
My 1/2 inch bar with a pipe on it was bending by about 15 degrees. It would snap before it goes. Btw the only way to lock the balancer was using old accessory belt. Load fastening straps were slipping.

Anyways - what worked was 850 Nm AEG 18V 1/2" impact wrench. It took about 15-20 seconds on the highest setting. (AEG says 6Ah battery is needed for 850 Nm but I got it off with 4Ah battery). The bolt was clean - no locktite, nothing.
 
Thanks. Based on your information, I decided to look at the bottom chain too. Tensioner is out by around 10mm so quite stretched too.
That means I got the balancer out! :)
My 1/2 inch bar with a pipe on it was bending by about 15 degrees. It would snap before it goes. Btw the only way to lock the balancer was using old accessory belt. Load fastening straps were slipping.

Anyways - what worked was 850 Nm AEG 18V 1/2" impact wrench. It took about 15-20 seconds on the highest setting. (AEG says 6Ah battery is needed for 850 Nm but I got it off with 4Ah battery). The bolt was clean - no locktite, nothing.

Who was your previous mechanic? Arnold Schwarzenegger?
 

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