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Topic: Belt Tension on '87 3.8? (Read 1943 times) previous topic - next topic

Belt Tension on '87 3.8?

Anybody know the proper belt tension on an '87 3.8L? It's a manual tensioner for a serpentine belt. My Hayes and Chilton manual don't have anything about it. My Helm manual is packed up for our upcoming move.

Going to pick up a Dayco #93866 to get it set right instead of just guessing.

http://www.daycoproducts.com/dayco%C2%AE-belt-tension-gauges

Belt Tension on '87 3.8?

Reply #1 –
The 84 shop manual says for a 6 rib serpentine belt on the 3.8L:
New belt installation: 160-190
Used belt reset:  130-160
Allowable limits: 90-180

The 84 belt doesn't include the A/C compressor. It has a separate V belt. Don't know if that makes any difference.
I have never owned a belt tension gauge.

I ran into a new one for me 3 months ago when I helped my grandson replace the alternator in his 2003 Mitsubishi Montero Sport.
You get out your MUT-III scan tool and thump the belt with your finger. Then measure the vibration frequency of the belt.
But if you don't have the tool they also have a deflection measurement if you push on the belt with a 22lb force.

Belt Tension on '87 3.8?

Reply #2 –
Thanks!

Looks like there is sort of a standard for 6-rib serpentine belts and the specs line you posted line up with it. AC shouldn't make a difference. My '85 and '87 came with a v-belt to run the AC compressor, but I've converted them over to an '86 configuration that puts everything on one serpentine belt.

Belt Tension on '87 3.8?

Reply #3 –
Measured out at 80 lbs, although that's guessing as the scale only goes down to 100. Measured 3 different spans a few times. Output is very repeatable.

Belt Tension on '87 3.8?

Reply #4 –
Measured out at 80 lbs, although that's guessing as the scale only goes down to 100. Measured 3 different spans a few times. Output is very repeatable.

Needs a water pump before I can really fix it.

Belt Tension on '87 3.8?

Reply #5 –
Quote from: JeremyB;466420
Measured out at 80 lbs, although that's guessing as the scale only goes down to 100. Measured 3 different spans a few times. Output is very repeatable.

Needs a water pump before I can really fix it.




actually there is a method,, in the haynes manual i saw an illustration where goes like this.......
the picture shows a straight edge is laid over top a belt of two pullys,
the center of the free air span of the belt is located.
a force gauge pushes down on the belt and at a specified amount of mechanical effort, the distance the belt has downward deflected form the straight edge is measured in inches.

Belt Tension on '87 3.8?

Reply #6 –
did you also integrate the 5.0L tensioner?
i really dislike the 3.8L tensioner, i find it to be very inconvenient.

Belt Tension on '87 3.8?

Reply #7 –
I took another look in my Hayes manual but it doesn't have the method you mention. It says to push firmly and measure deflection, giving a spec for under 12" and over 12" span. However, this is only applicable for  v-belts, not to mention it isn't very accurate. My Hayes manual specifies using a nice tensioning meter (>$120).

The Chilton manual assumes all serpentine belts have automatic tensioners.

The tool I bought does the same thing as a a force gauge where you measure deflection over distance, but only requires you to push down on the belt until the tool clicks. It's a cheap version of the $120 tool. A direct tension force is given rather than a deflction over distance measurement.

Haven't put in the 5.0 tensioner. Have you verified it keeps the belt at the correct tension?

Belt Tension on '87 3.8?

Reply #8 –
it was a suggestion, and you could be first.

since im very familiar with your tenshioner and the mount,, it seems very reasonable the 5.0 version would be able to fit.

the 5.0 tensioner needs a small index hole to reference the angle which it mounts.

to be honest,,, i dont have to imagine this too much to know it *will* work.  it has to.

on your car you have two vertical slotted holes which your tensioner mounts.  one of these would be where the 5.0L 1/2'' carrage bolt passes through.  then on the 5.0 there is a small tit that would index to your cars physical mount you'd have to drill.

the ford bronco tensioners are better though,,  the pully is plastic but its interior bearings are better than on our cars and plus,, on the bronco you can find that pully is the same on a lot of riding lawn mower decks.