Checking belt tension, are you kidding me!!!

[CatTwentyTwo]

I'm in the process of performing the recommended 5 year/60,000 mile maintenance on my wife's PT Cruiser and one of the items is to check the alternator belt tension. I looked it up in the service manual and was kind of surprised to see how the factory says to check it. What you are supposed to do is get special tool 8371, which is basically a microphone and connect it to the special DRBIII scan tool. Then to check tension, you hold the microphone 1" from the belt and pluck it a minimum of 3 times with your finger. The frequency of the belt in hertz will be displayed on the DRBIII screen and the tension is correct when the frequency is between 207 and 217 hertz. Oh, and there is a big warning not to check the belt tension with the engine running.:facepalm: So is this what modern automotive technology has come to, you can't even check a belt anymore without special tools? Needless to say, I will be checking it the same way that I've been checking belts since the 60's, if it feels good it is good.

 

[bruceb58]

Re: Checking belt tension, are you kidding me!!!

I am surprised it isn't a serpentine belt with an automatic tensioner.

 

[ajgraz]

Re: Checking belt tension, are you kidding me!!!

As far as making it easily and quickly checkable by a dealer's service dept., that's actually quite cool.

For the home mech, not so much.

 

[CatTwentyTwo]

Re: Checking belt tension, are you kidding me!!!

I am surprised it isn't a serpentine belt with an automatic tensioner.

It has one of those to Bruce, but for some reason it only drives the power steering and A/C. It would have been nice if they had been able to use it for the alternator also.

 

[j_martin]

Re: Checking belt tension, are you kidding me!!!

Don't have an 8371. Just use your piano. That's g# below middle C.

When I'm setting up to pull over a tree with the 4X4, I set the tension of the shock line by ear.

 

[JB]

Re: Checking belt tension, are you kidding me!!!

Procedures for setting belt tension have been tech writers' and wrenchs' nightmare for years.

V-belts are not too bad because they can stretch a little or slip a little and do no harm and usually break before they harm driving or driven implements.

Gilmer belts are a different matter. They do not stretch, cannot be allowed to slip and will break the ends off of cams if too tight. The Suzi DF70 had a lot of broken cam ends before they got a correct procedure for adjusting the cam belt tensioner.

I once got a set of notes from an engineer that said to adjust a Gilmer (toothed) belt, "just tight enough, but not too tight." :facepalm: Needless to say there were some changes before that Manual went out. We ended up inventing a "deflection at ounces" tool.

The "twang" technique sounds excellent. Not only will it measure tension in a good belt, but it will also detect failing reenforcing strands in a belt that needs replacement.

 

[bruceb58]

Re: Checking belt tension, are you kidding me!!!

Don't blame the tech writer. They normally don't have not enough practical expereince to know how to properly do it and don't have enough law experience to know where they can get into trouble liability wise.

I have a lot of experience with tech writers in my business doing patents. The best were those that were actual retired engineers that had practical experience in their past. The last one I dealt with actually came up with a better description of what I designed that what I had in my design notes.

 

[snake77]

Re: Checking belt tension, are you kidding me!!!

Vehicle now have eliminated the belt tensioner all together and are running stretch belts that require special tools to more or less install
the serpentine belt on like you did on your bicycle chains.

 

[bruceb58]

Re: Checking belt tension, are you kidding me!!!

Vehicle now have eliminated the belt tensioner all together and are running stretch belts that require special tools to more or less install
the serpentine belt on like you did on your bicycle chains.

Stretch belt? Please give an example of a stretch belt.

 

[snake77]

Re: Checking belt tension, are you kidding me!!!

Stretch belt? Please give an example of a stretch belt.

Here you go.
http://www.youtube.com/watch?v=Hbzb_37QUTo

 

[bruceb58]

Re: Checking belt tension, are you kidding me!!!

Interesting. Was not aware of these.

 

[JB]

Re: Checking belt tension, are you kidding me!!!

New to me, too. Cool.

Bruce, I was not blaming Tech Writers, I was a Tech Writer. I was blaming the engineer for providing such useless instruction.

My engineering background saved many an engineer from serious embarrassment.

 

[bruceb58]

Re: Checking belt tension, are you kidding me!!!

I was blaming the engineer for providing such useless instruction.

Many an engineer also has no practical sense to them!

 

[BlkY2k]

Re: Checking belt tension, are you kidding me!!!

Many an engineer also has no practical sense to them!

Amen, I`ve always said that the engineers that design some of these new vehicles should have to wrench on them for awhile before they go into production.

 

[dockwrecker]

Re: Checking belt tension, are you kidding me!!!

Many an engineer also has no practical sense to them!

I say the same thing about architects in my business!