crankshaft/timing belt problems?

[scottscott1990]

So I just got done taking off the timing belt cover to inspect the timing belt because of a recent failure to start i had a while back. I went to go start my vehicle that ran the night before (got me home a least), but when I tried to start it in the morning it wouldn't even get close.

 

So when I checked for spark I found out my rotor wasn't spinning so I decided to check the timing belt. As i was taking off the crankshaft pulley I noticed that the belt and crankshaft sprocket wasn't moving at all even though I was spinning the pulley so I'm guessing its a major problem.

 

I checked out another thread and there where a lot of different answers overwhelming me so I'm not to sure what the F just happened to my engine its was running kinda rough before (lack of power) but otherwise was driving fine.

 

I'm at a loss of what to do so any help would be great. If you need more info on any details let me know. I have never dug into an engine like this and have no idea what to do.

[ahardb0dy]

You need to remove the crank pulley and the timing gear to check the keyway. On my old 87 hardbody the dampener/crank pulley and timing gear shared half of one key, and it stripped, had to replace the key and install a new timing gear and dampener. It lasted a while but a few months later it did the same thing and I ended up replacing the engine with a JDM engine. My mechanic at the time was saying if we pulled the engine apart to replace the crank we would not know what else bad we may find so I decided to just replace the engine.

 

Later models Nissan switched to one key for the gear and one for the dampener, not sure what year they did that.

[scottscott1990]

I'll give it a shot thanks

[scottscott1990]

so that is the problem and not just that but the shaft has a nice chunk of it missing to i'll load a picture here soon and im guessing thats really bad

[ahardb0dy]

Well you can have someone weld the area where the chunk came out, I'm guessing it is in the area where the key goes? If welded than the area would need to be grinded down smooth. Or replace the crankshaft, or do as I did and replace the engine with a JDM one. The JDM engine I bought for my 87 and also the one I bought for my 94 pathfinder I have now both run/an like new.

[scottscott1990]

ya if i had time and money i would love a new engine but the welding part i think is possiable that was the only thing i could think of thanks for all the help

[ahardb0dy]

where do you live?

[scottscott1990]

where did u get a new key for the gear tho?

[scottscott1990]

butte Montana

[ahardb0dy]

When that happened to my old hardbody I bought everything new (key, timing gear, dampener) from the dealer, wasn't messing around with it. And as I said even with everything new, and my keyway wasn't damaged like your is, and everything was torqued to spec, it did it again a few months later.

[scottscott1990]

and you never found a reason why it keep doing that?

[ahardb0dy]

No, just a poor design I guess, as I said the timing gear and dampener shared 1/2 of a small key. The newer ones use one key for each part. I guess if the crank bolt becomes loose it could cause the dampener to move and shear the key, but when I had mine re-done the first time everything was tight.

[scottscott1990]

ya i have a key for both and i cant tell if it was just a bad key and it failed or if there is a bigger problem inside causing resistance while it spins or something along those lines but i really don't know.

 

but one more question when i looked at my timing marks on the belt and cams and noticed that they where off alignement and because i couldn't move my belt i couldn't tell by how much but when i go to put the belt on again how do i line up the marks what im getting at is the belt is already off and the marks on the cams are not in a spot where i can make sure the line up with the belts marks

[ahardb0dy]

Not exactly sure, but you need to have the #1 piston at TDC, than make sure each cam gear is lined up with the timing marks. Someone with more knowledge will reply I'm sure.

 

Is the belt still on (old belt)

 

So you said the crank pulley will spin but the timing gear and belt don't, so is the key missing where the dampener/crank pulley sits on the shaft of the crankshaft? Is that where the chunk of metal is missing? If the belt does not turn the timing may still be set, if the belt was broke I can see the timing being off as the timing gear on the crankshaft could turn independently of the upper timing gears.

 

Pics yet?

Edited October 15, 2012 by ahardb0dy