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Discussion Starter #1
Hey everyone. New to the forum. Picked up a non running 93 2x4 this summer and got it running a few weeks back. There’s a decent amount of noise coming from the engine. Almost like a loose bolt vibrating. I adjusted the valves but no change in the sound. It sounds eerily similar to the timing chain that went out on my old Honda dirt bike. No sound at idle but when the rpms are up it’s pretty loud.

Could it be as simple as the timing chain tensioner? Seems like a fairly easy fix. Digging into the chain itself looks like a PITA. Thanks for the help!
 

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I would start by removing the tensioner and making sure that it isn't sticking in one place or that the internal spring isn't broken in the tensioner. Is it a slapping noise or a knocking? There are also 2 guides I believe that are used which could possibly be severely worn out, (although it's pretty rare that those go bad on these engines). Does the sound seem to be coming from the chain side of the engine? I believe the chain runs on the RH side of the engine.
 

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Also, if its like my 87 250 quadrunner, you would need to start by removing the rocker box cover on the engine first. That should give you a top view of the cam gear/chain. There you should be able to at least see enough of the chain to see if it's loose or if there is a possible guide issue. However I would start by taking the tensioner out and inspecting that. If it's setup like my 87 is, there should be a 2 bolt mount to the cylinder, with a middle bolt that houses the tension spring. When you put it back together you will need to "reset" the tensioner by removing that middle bolt to take the spring out, then theres a little arm on the end of the tensioner that acts like a 1 way ratchet so the plunger can't be pushed back in. (It's usually easier to break the center bolt lose before you remove the tensioner). You need to move that so that you can push the plunger all the back back in once the spring is removed. Then bolt the tensioner back into place, once you do that put the spring back into place and then put the center bolt back in and it should ratchet and lock once it tensions the chain. I have seen the little arm on the tensioner break, as well as the internal spring, which causes it not to tension the chain correctly.
 

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Discussion Starter #4
Thanks Koslaw. I’ll pull the tensioner out today and give it a look.

As far as the noise goes, it’s more of a rattling/clicking sound. It’s barely noticeable at idle but when I throttle up it gets louder. It’s difficult to tell exactly where it’s coming from.
 

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I would also make sure that it isn't something loose on the outside, such as a fender or body piece thats vibrating when the engine speeds up.
 

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Discussion Starter #6
I would also make sure that it isn't something loose on the outside, such as a fender or body piece thats vibrating when the engine speeds up.
Hey. Yeah I’ve tightened just about every bolt I could find. I still haven’t found any time to dig into the tensioner. Thanks again for the help.
 

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Wonder if it is the one-way gear that the starter engages.
 
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