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Discussion Starter · #1 ·
I recently did a rebuild for a guy on his '86 200SX. New rings, valve job, and a cylinder hone. Simple stuff. But before I started out the rebuild I had an issue with a knock coming from right hand side of the block. And with the cam chain being there I thought of it to be the cam chain tensioner not working. I ordered a used one off of eBay and put it in with the rebuild. The quad ran great other then being a little rich. And tonight as I went to work on it and make it a little leaner it started knocking on me again in the same area. I had run this engine for about 45 minutes total since dropping it back in. I took the bolt off of the tensioner and adjusted it. But as the engine runs it pushes the tensioner loose in about 20 seconds. And I'm looking for help and knowledge on how the tensioner is supposed to be adjusted and how it's also supposed to work. Thanks in advance
 

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Hello,

Are you using the stock automatic tensioner like this one, or a manual adjust replacement?




If you need a copy of the service manual you can get one HERE.

Welcome to the forums!
 

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I took the bolt off of the tensioner and adjusted it. But as the engine runs it pushes the tensioner loose in about 20 seconds.
Is it a stock OEM tensioner? It gets pushed loose as the motor runs? What did you mean by "I took the bolt off of the tensioner and adjusted it."...?

Thanks,
 

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Discussion Starter · #6 ·
I took the bolt off of the tensioner and adjusted it. But as the engine runs it pushes the tensioner loose in about 20 seconds.
Is it a stock OEM tensioner? It gets pushed loose as the motor runs? What did you mean by "I took the bolt off of the tensioner and adjusted it."...?

Thanks,
Yes, it's the stock one. Bought it on eBay from a quad that was parted out. And I took the center bolt out with its washer to adjust the tensioner using a small flat head screw driver. I'll tighten it and when I start the engine up and run it for about 20 seconds the knock comes back. I take the bolt out to adjust it again and it is loose again.
 

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Would it be better to use a manual tensioner like this one?
I doubt it unless you have good reason to. On a stock motor the OEM tensioner is more than sufficient, generally pretty reliable too.

I don't fully understand your situation. Is the cam chain worn out? Or was is replaced? Has the tensioner failed?

Thanks,
 

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Discussion Starter · #8 ·
I replaced the tensioner with a used one believing the original had failed. I never replaced the cam chain. The tensioner is backing itself out and becomes loose in very short run time of the engine.
 

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I took the bolt off of the tensioner and adjusted it. But as the engine runs it pushes the tensioner loose in about 20 seconds.
Is it a stock OEM tensioner? It gets pushed loose as the motor runs? What did you mean by "I took the bolt off of the tensioner and adjusted it."...?

Thanks,
Yes, it's the stock one. Bought it on eBay from a quad that was parted out. And I took the center bolt out with its washer to adjust the tensioner using a small flat head screw driver. I'll tighten it and when I start the engine up and run it for about 20 seconds the knock comes back. I take the bolt out to adjust it again and it is loose again.
You don't tighten an automatic tensioner, the spring inside of it pushes all the slack out of the chain and maintains itself automatically as the chain wears.

It sounds like your cam chain may be worn out. When they do, they get too long for the guides and tensioner to control them... then they slap and make a lot of noise... then they jump time and the motor quits... if you are lucky.

You can use the OEM tensioner to check the condition of the chain. Have you done that yet?
 

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Discussion Starter · #10 ·
Is it a stock OEM tensioner? It gets pushed loose as the motor runs? What did you mean by "I took the bolt off of the tensioner and adjusted it."...?

Thanks,
Yes, it's the stock one. Bought it on eBay from a quad that was parted out. And I took the center bolt out with its washer to adjust the tensioner using a small flat head screw driver. I'll tighten it and when I start the engine up and run it for about 20 seconds the knock comes back. I take the bolt out to adjust it again and it is loose again.
You don't tighten an automatic tensioner, the spring inside of it pushes all the slack out of the chain and maintains itself automatically as the chain wears.

It sounds like your cam chain may be worn out. When they do, they get too long for the guides and tensioner to control them... then they slap and make a lot of noise... then they jump time and the motor quits... if you are lucky.

You can use the OEM tensioner to check the condition of the chain. Have you done that yet?
Alright, I was wondering how they worked. But no I have not used it to check. Could you explain how to?
 

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Yeah sure. First thing you do is crank the motor over by hand (in the normal direction of rotation only) by pulling the two plugs out of the left side cover & use a socket on the flywheel bolt and bring it to TDC on the compression stroke. You should see a "T" mark on the flywheel match up with the index mark in the small hole in the left side cover when the motor is at TDC. Make SURE you are on the compression stroke, not the exhaust stroke! Do NOT back up the crank while doing this... if the "T" mark slips past the window while you are cranking, continue turning the crank two full revolutions (so you will be on the compression stroke) and try to stop on the "T" mark again. For this test you don't have to be perfectly lined up... just close.

Then take the chain tensioner off from the motor. It will extend automatically on its own... Then push the tensioner back into the motor against the chain guide... just like you were going to install it. The tensioner will be held out away from the motor a small amount.

Make a note about how far the tensioner is sticking out. Measure the gap if you aren't good at guessing.

Then come back and tell us how far that tensioner stuck out.

Then loosen the tensioner with a screwdriver and reinstall it, before finally releasing the screwdriver.
 
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