automatic belt tensioner

[16again2009]

Is there a way to adjust the automatic cam belt tensioner. Mine seems to be to tight. I can't turn the belt by hand at the water pump.

[OK-944]

Actually, yes - if you remove the belt tensioner, then hold the tensioner in a partially "collapsed" position while removing the lock screw...you can then release the tension completely...move the bottom of the spring off of its "keeper," and then rotate the adjustment ring at the other end of the spring. There are four cylindrical holes cut into the shoulder of this adjustment ring, and you can use these as a reference so you can adjust with some precision/repeatability. After this, replace the bottom of the spring on its keeper, and re-assemble. You may need a bit of trial-and-error to get it right. I also recommend a thorough cleaning first - then reinstall to see if this (cleaning) was all that was needed.

In my case...the tensioner ('87NA) was not applying quite enough pressure - so, after cleaning/retesting to verify that it was still too loose...I tightened the spring by three "holes" (3/4 of a turn), and now it sets perfectly.

Wish I could have chimed in earlier when it would have been easier to add photos - but its been reinstalled and the covers are on. Sorry!

edit: just remembered that there is a lock nut on the adjustment ring - just sayin!

[RedCarGuy]

checking the timing belt tension is a very particular evaluation. you have to make sure you have turned the crank to put the slack in the appropriate spot to measure.

from your very short description, there's not enough information to confirm or deny if it is improperly tensioned.

[OK-944]

Yes...before you follow my recipe above - do what RedCarGuy says to verify that your belt is actually too tight. As I've mentioned above, my tensioner ('87NA) set too loose - which, to me, made more sense in light of the age of the spring...so something to think about.

[16again2009]

This was done when I replaced the belts. The flywheel lock was still on and after releasing the tensioner I could not turn the water pump by hand.

[OK-944]

Question: did you polish the pump rotor surface (area of belt contact area) prior to doing your test? Even a very small bit of residue on this surface can make it almost impossible to turn this rotor by hand.

And even with a perfectly smooth surface...I'd highly recommend that you don't rely on any one test for such a critical function. You might want to consider purchasing a tension measuring tool (like the Arnnworx)...or at least get someone who has one (and knows how to use it!) to measure for you - so you can then become intimately familiar with how much the belt should deflect by twisting ("twist" method) and how the belt should respond by plucking it (like a guitar-string). Van Svenson, in his belt-change video, goes over this pretty well.

Ultimately...if you decide to go with a measuring tool - I'd still advise you to become familiar with how a correctly adjusted t-belt should feel by the "twist and pluck" method.

[16again2009]

I want to thank all of you for your responses. When I get a chance I will delve into it and try your suggestions. I will report back what I learn although it will be awhile.

[RedCarGuy]

I second what OK said. If you are unfamiliar with this procedure (we all are at one time!) learn as much as you can before starting the engine up. I have heard about trying to turn the water pump by hand but to me, that's way too subjective and could easily give you false information.

Again to echo OK, even if you use a measurement tool, try the twist method to get some perspective and feel for it. Van's videos are fantastic and there is a lot of information on this subject in these forums as well as on the Clark's Garage page. I have the Arnnworx tool and found it very difficult to get repeatable measurements that aligned with what they said it should be. After a lot of second-guessing, I felt much more confident with using the twist method.

Good luck, don't be shy to use this forum to ask questions, include as much info as possible, the folks on here are very knowledgeable and helpful!

[16again2009]

Thanks guys for all the info. I will check it soon and let you know what I find out.