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Discussion Starter #1 (Edited)
Inspecting and testing 164 24v TB Tensioner 60584475

Ok, John Harrill sent me his old tensioner that let his timing belt slip and bend some valves.

He could not get the tensioner piston to hold 1/8" air gap and keep belt correctly tensioned.

I found that I could push tensioner piston in about 1/4" by just placing end of piston against my work bench and pushing on bottom of housing with my hand.

On a good tensioner with proper internal preload the piston will not move at all unless you compress piston with leverage on engine with special tools or in a work bench vise.

I recommend that anyone replacing a 24v timing belt remove tensioner from engine and try to compress piston as I did and if you can move it by hand replace tensioner piston assembly.

I always use a vise to compress piston enough to insert 1/16" rig pin through holes in housing and pin to hold piston then install it back on engine and set up belt tension with rig pin in place and then set pulley eccentric to get the 1/8" air gap between pulley eccentric face and body of tensioner with end of piston tight against eccentric face. Belt is correctly tensioned when you have 1/8" air gap and 1/16" rig pin can be removed and inserted freely in holes in body and piston of tensioner.
 

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Kudos, Steve.

In its' last days, my tensioner would not hold the 1/8" air gap, indicating that the piston was too compressible. The borrowed one is now in place and adjusts perfectly: 1/8" air gap and 1/16" rig pin inserts all the way through.

This was measured repeatedly after turning the engine by hand. Once satisfied with this, compression tests followed using the starter. I checked the belt tension after the readings and it is spot on.

Now, maybe we can get you to cut open the bad one. I still think there are tiny squirells inside, making it all work. :D
 

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There are no dumb questions, just uninformed questioners...how do you measure an 1/8" air gap? What does this translate to with feeler guages? Do you have a picture that shows the proper clearance?
 

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Yes, the 24V tensioner requires quite a bit of force (such as using a vise) to get it compressed.

There is TSB on how to set the clearance. From what I remember, it says use a 1/8" drill bit to check the clearance between pivot arm and the top of the tensioner. Use the rig pin that come with a new tensioner or a "welding rod" (which should be about 1/16") through the tensioner hole to check (and to hold the piston during installation).
 

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Bob, thank you for the advice. I seem to recall now that you mention it about the 1/8" drill bit for checking the clearance. I will dig down through my TSB's and find that bulletin. :)
 

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Discussion Starter #6
TSB 01.94.05 and 01.94.06 air gap check

Bob, thank you for the advice. I seem to recall now that you mention it about the 1/8" drill bit for checking the clearance. I will dig down through my TSB's and find that bulletin. :)
Both step 7 in 01.94.05 and step 20 in 01.94.06 show air gap test for proper belt tension using 1/8" drill bit. also you must have 1/16" drill rod,welding rod inserted in tensioner body and hole in piston.
 

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Here's what it looks like, using 1/8" and 1/16" drill bits:
 

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