Correct Serpentine Belt and Tensioner Numbers?(56k warning)

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Correct Serpentine Belt and Tensioner Numbers?(56k warning)

October 02, 2022, 05:03:15 PM

What is the motorcraft part number(both numbers) for the serpentine belt and kidler/tensioner for my 83 3.8 v6 with a/c, "BUT" the a/c is driven by a seperate v-belt?
Is that considered dealer installed, factory or does that count as no a/c regardless?

I bought a new belt for it awhile ago that was advertised as correct but its too small, wont fit at all. I dont have a tape measure handy to measure the stretched old one but that would only give me the size not the number. Also, the belts seem to have their own part number system so thats throwing me off.

Re: Correct Serpentine Belt Number

Reply #1 – October 02, 2022, 07:34:34 PM

Rockauto is saying an 80.5/80.6" belt for an HR980 setup with a v belt.

The all in one FS6 setup is 96".

There is also a dealer AC option of 91.5"

No AC is 77.5"

The most common belt naming convention is"K". That is the section size. Then "6", that's the number of ribs, and "XXX" where is the length in inches or mm.
A K6805 is a K section, 6 ribbed, 80.5" long belt.
Other companies may call it a K060805, etc.

Re: Correct Serpentine Belt Number

Reply #2 – October 02, 2022, 10:34:09 PM

The belt i first bought was jk6-792 but that definately doesnt fit, so if the correct belt is only 1.5" larger the number would likely be jk6-805, correct?
I went thru some of my books and "seems" they list the hr980 ones as no a/c.
I forgot coolcats had a part number section for some things and E2SZ-8620-E is the number shown for v6 no a/c belt. Searching around leads me to jk6-782 for that one.
Now im confuse.

Another, seperate, thing throwing me off is the tensioner itself. Mine looks like this

Slightly different than the ones on my 86 and 84 v6 cars i had, do they have the same size pulley?

Re: Correct Serpentine Belt Number

Reply #3 – October 02, 2022, 11:34:02 PM

Wrap a rope around the pulleys, mark with a sharpy and measure.
I found a couple of belts from my old '84 V6 Tbird with the separate a/c v-belt.
They are labeled 805K6

Re: Correct Serpentine Belt Number

Reply #4 – October 03, 2022, 06:55:54 PM

Quote from: Ductape91 – on October 02, 2022, 10:34:09 PM

I forgot coolcats had a part number section for some things and E2SZ-8620-E is the number shown for v6 no a/c belt. Searching around leads me to jk6-782 for that one.
Now im confuse.

That Ford PN cross references to a K6772, which is basically 77.5" and is that you'd expect for a non AC V6.

Re: Correct Serpentine Belt Number

Reply #5 – October 03, 2022, 10:11:56 PM

Quote from: JeremyB – on October 03, 2022, 06:55:54 PM

Quote from: Ductape91 – on October 02, 2022, 10:34:09 PM

I forgot coolcats had a part number section for some things and E2SZ-8620-E is the number shown for v6 no a/c belt. Searching around leads me to jk6-782 for that one.
Now im confuse.
That Ford PN cross references to a K6772, which is basically 77.5" and is that you'd expect for a non AC V6.

I purchased a nos jk6-782 already, which had motorcraft part number e2sz-8620-e on the package so ill see when it comes in the mail.

Re: Correct Serpentine Belt Number

Reply #6 – October 05, 2022, 12:36:52 AM

I couldnt find the "correct" style belt tensioner i have with the bolt head facing toward the pulley instead so im going to try and make a later one work. Mine doent have the hole on top.
The bolt on the later one i picked up is a 3" long 3/8 bolt, 2 1/2" threaded area with a 5/16 hex head. Pulley wheel is basically 3"×1" not including the ridges.
The area between the pulley wheel and bolt hole is only 2 1/4" so no flipping it over unless i grind the bolt down. I have to take the old one out to see what those sizes and measurements are.

Re: Correct Serpentine Belt Number

Reply #7 – October 05, 2022, 01:15:48 PM

If the 792 from post reply #2 was too short, your 782 will be even shorter and won't work.

You need an 805.

Re: Correct Serpentine Belt Number

Reply #8 – October 05, 2022, 07:29:34 PM

Quote from: JeremyB – on October 05, 2022, 01:15:48 PM

If the 792 from post reply #2 was too short, your 782 will be even shorter and won't work.

You need an 805.

Thats what i was afraid of, but the belt was only 10 bucks so if its wrong it aint the end of the world. Like mentioned above somewhere im going to grab some rope and get a measurement when i go back this weekend.
My real question is why is it 805 instead of 782 or 792 when there isnt any difference in pulley sizes or placement that i can find.

Re: Correct Serpentine Belt Number

Reply #9 – October 06, 2022, 04:49:08 PM

I've never seen a non-AC 3.8. I can't think of why it's different either. I just know the HR980 3.8s use an 80.5" belt.

Re: Correct Serpentine Belt Number

Reply #10 – October 07, 2022, 12:47:25 AM

Quote from: JeremyB – on October 06, 2022, 04:49:08 PM

I've never seen a non-AC 3.8. I can't think of why it's different either. I just know the HR980 3.8s use an 80.5" belt.

Ill pick one up tomorrow so ill have every possible outcome in hand.
Im still trying to figure out the tensioners possible role in any of this, i dont know if non a/c but power steering pulley is any different in diameter to a/c and power steerings pulley. Ive seen some no power steering or a/c and it looks the same size but cant confirm it. Is the alternator pulley the same between 40 amp and 60 amp ones?
Smog pump and crank pulley isnt any different from what i could see.
So where is the extra 2 inch difference coming from?

Re: Correct Serpentine Belt Number

Reply #11 – October 07, 2022, 10:02:14 AM

I can tell you that the power steering pulley diameter changed with the two different A/C systems available on the 3.8L (HR980 vs. FS-6). Maybe that also happened with the non-A/C vs. A/C pulley, I can't say for certain. AFAIK all the other pulleys were the same.

If you need to double check a dimension on a pulley or anything else, I'd be more than happy to check my '84 3.8L setup for you. Right now I haven't torn anything apart for the A/C swap so it's still in stock configuration. I also have the upgrade A/C parts laying around and can check those sizes as well.

Re: Correct Serpentine Belt Number

Reply #12 – October 08, 2022, 10:33:10 PM

Ok, here goes. I went to the garage today to sort this whole mess out and fell into an even bigger one.
The stores didnt have 805 belt size in stock so no big deal i bought one online and just have to wait for it now. Since i was buying stuff i bought a new fan clutch and some gaskets for my new fuel pump ive had and wanted to put in and there will be no better time to do it than while im in there doing this belt stuff.

On to the belt stuff.
While i wait i decided to start pulling it all apart in preperation and take some measurements.

The measurements are across the pulleys, not including the outer ridges, and are as follows:

Waterpump pulley: 5" part # E3AE-8059-A79

Power Steering: 6 1/2" part # E3SC-BD673-AA(it was hard to make out the "BD" might be a different number or letter)

Smog Pump: 5 1/2"

Alternator: 2 1/4" part # E2AF-10A352-CA

Crankshaft Pulley: 7 1/2"

Idler/Tensioner Pulley: 3" part # E2BE-8B604-AA

I ran a wire around the pulleys and measured that but that was after i forgot and already took out the belt tensioner, the size without the idler was 79 1/2".

Ah, the belt tensioner.

Seems to be very different than the ones ive seen on these 3.8 v6s before, ive had a couple.
There is a piece of metal that goes over it for some reason, It is also flat without the bend on the side.
The spacing on the hold down bolts are 2" apart while the one i picked up to replace it are 1 1/2" apart.

I cant find this style tensioner anywhere i looked.
I cant use the new one (ys-118 #E3SE-8B604-AA) at all on it without changing the part it mounts to, if that doesnt include what that part mounts to.
Not a happy camper atm.

Re: Correct Serpentine Belt and Tensioner Numbers?(56k warning)

Reply #13 – October 09, 2022, 10:29:04 AM

Hmm. Looking at rockauto, I see the idler assembly is listed as "From 3/83". There's no idler available for a 1982 3.8. I'm guessing you have a 1982/ early 1983 idler and nobody makes it.

Maybe Eric can point you to a NOS source.

Will a later idler bracket bolt to your FEAD?
https://www.ebay.com/itm/125104244729?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=JBoMfjXEQx6&sssrc=2349624&ssuid=m0zxkZc3Sfi&var=&widget_ver=artemis&media=COPY

Re: Correct Serpentine Belt and Tensioner Numbers?(56k warning)

Reply #14 – October 09, 2022, 03:06:20 PM

Quote from: JeremyB – on October 09, 2022, 10:29:04 AM

Hmm. Looking at rockauto, I see the idler assembly is listed as "From 3/83". There's no idler available for a 1982 3.8. I'm guessing you have a 1982/ early 1983 idler and nobody makes it.

Maybe Eric can point you to a NOS source.

Will a later idler bracket bolt to your FEAD?
https://www.ebay.com/itm/125104244729?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=JBoMfjXEQx6&sssrc=2349624&ssuid=m0zxkZc3Sfi&var=&widget_ver=artemis&media=COPY

Its weird, if i had an f100 or an 82 continental ect. id likely be in the same boat. All i see is idler pulleys and i couldnt find anything about just replacing the pulley itself.
Ill have to take a measurement on the bolt spacing where it bolts onto the alternator bracket to be certain but i think its the same and would fit.
My idler brackets part number is E3AE-8A614-AA.