Resolved 1G 6-bolt Timing belt tension. Am I being too OCD?

[Drewpy Dawg]

I know questions about timing belt replacement have been beat to death on this forum, but the installation I'm working on is bugging me and I've not found an answer.

This is on a 6 bolt motor with new OEM tensioner, new tensioner pulley, perfectly good used tensioner arm, new EVO 9 belt, and Fidanza cam gears. The block was decked a little but the head has never been cut. All timing marks line up perfectly.

I'm trying to set the tension of the belt and get the gap between the tensioner body and tensioner arm to meet the .15 - .18 inch spec. I've done it exactly according to the factory manual, I've done it using the alternate method on the VFAQ, and I've done the 'set the tension so the pin spins freely' method. I've used a beam type torque wrench to put exact pressure on the pulley when torquing the bolt and I've used a small breaker bar to just apply a little pressure by feel. It all seems to go fine until I let it sit for 15 minutes and re-check the gap. I'm consistently ending up with a gap of about .12 - .13. I go through all the steps again and even when I get the gap correct initially it then settles in to .12 - .13. The only other result I've had is when I over-correct and the gap ends up WAY too big. Nothing I do seems to adjust the gap in small increments. It's either a little too small or way too big. Maybe I'm being too much of a perfectionist, but I'm really not satisfied with the measurement being out of spec. If it didn't matter there wouldn't be a spec, right?

I can't see where any of my components are faulty. The plunger of the tensioner extends fine, it can be compressed all the way, and it's definitely putting some pressure on the arm. The pulley moves freely. All the bolts are brand new OEM. There is no wear that I can see on the tensioner arm where the plunger contacts it. I don't see or feel anything strange when I turn the motor over by hand. Everything seems to be perfect except that .020-.030 of an inch. At this gap the pin spins/slides freely in the hydraulic tensioner, so by that method it's good, but the measurement isn't quite right. Am I over-reacting to this?

 

[92AWDHX40]

http://www.vfaq.com/mods/timingbelt-1G.html follow this

 

[danl]

How are you measuring the gap after waiting 15 minutes?

If you can install/remove the grenade pin after 15 minutes, you are good. At least that is what I’ve done the past 20 years and all my timing belts have been fine.

 

[Drewpy Dawg]

How are you measuring the gap after waiting 15 minutes?

I'm using wire gauge drill bits as gauge pins to measure the gap. The .152 bit won't fit. The next one that does is .128.

If you can install/remove the grenade pin after 15 minutes, you are good. At least that is what I’ve done the past 20 years and all my timing belts have been fine.

That's what I'm thinking. The pin slides in and out easily even though the measurement of the gap is a little tight. While I'm not a total newb I am not nearly as experienced with timing belts as many people here, so I was looking for some confirmation that I'm not flirting with disaster.

Thanks.

 

[1990TSIAWDTALON]

The grenade pin method is tried and true. A tensioner won't get any tighter, only looser and yeah I think your over thinking it. Good to go with the grenade pin if it's a new tensioner.

 

[danl]

I'm using wire gauge drill bits as gauge pins to measure the gap. The .152 bit won't fit. The next one that does is .128.



That's what I'm thinking. The pin slides in and out easily even though the measurement of the gap is a little tight. While I'm not a total newb I am not nearly as experienced with timing belts as many people here, so I was looking for some confirmation that I'm not flirting with disaster.

Thanks.

Measuring with a drill bit has some variance depending on the angle you have it at, how perfect the surface is on the tensioner body, and how perfect the timing tensioner arm surface is. I’ve had the same exact problem you are experiencing due to surface irregularities. If you can slide the grenade pin in and out after 15 minutes, your tension is correct. The pin hole in the body is a precision hole and the same is true of the pin hole in the tensioner piston. You are good.