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Serpentine Belt Length?

NoDak

NoDak

Next project - fuel mizer Suburban
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Location
Bismarck, ND
Does anyone know what belt length is required for the following 6.5L arrangements?

1. 1995, obd1, single alternator, a/c, vacuum pump deleted

2. 1996, obd2, dual alternator, a/c, vacuum pump deleted
 
These "should" be the belt sizes.

'95 - 101.5"
'96 - 99.5" or 100" (try 99.5" first)
 
I got the feeling for the 96 with dual alt, you probably need a longer belt?
Green gives you single alt. Just a warning, although he may be correct.

Whatever you are using now, substract 1" nominal.
 
I guess Green Machine could confirm that, but I agree that it looks funny in that the dual alt '96 is shorter than a single alt '95?

I have the Diesel Page Volume II, and the article states the factory dual alt with the vac pump belt length is 120.3". So, I expected something less than that for the vac delete. Note this article was for '96 to 2000 vintage.

In that same article, the guy had removed the vacumm pump. However, he also went to larger alternator pulley to "dial-in" the tachometer. Both alt pulleys were matched/upsized from 55mm to 66mm dia. to match alt speed and charging. Then he also tweeked the idler pulley size? At any rate, I don't believe he ever gave the actual belt length he ended up with. Doesn't really matter, as his was unique anyway.
 
That number around 120" is about right. I don't have dual alt 96 but in general the vac pump deletion reduce the length between 1" to 1.5" so you can try with 119" first may be 118.5".
 
NoDak said:
I guess Green Machine could confirm that, but I agree that it looks funny in that the dual alt '96 is shorter than a single alt '95?

I have the Diesel Page Volume II, and the article states the factory dual alt with the vac pump belt length is 120.3". So, I expected something less than that for the vac delete. Note this article was for '96 to 2000 vintage.

In that same article, the guy had removed the vacumm pump. However, he also went to larger alternator pulley to "dial-in" the tachometer. Both alt pulleys were matched/upsized from 55mm to 66mm dia. to match alt speed and charging. Then he also tweeked the idler pulley size? At any rate, I don't believe he ever gave the actual belt length he ended up with. Doesn't really matter, as his was unique anyway.
Click to expand...
Sorry, I posted right before I went to bed :mad2: and didn't read entire post lol. As JMJNet said, the rule of thumb is subtract about an inch from your stock belt size when you remove the vacuum pump. So if your stock belt size is 120.3" on the '96 I would venture to guess you should try a 119". A 96 with Dual alternators will be longer then a 95 with a single alternator because of the belt routing of the second alternator.

What I would do is see if your belt still has a part number and go from there. The part numbers normally say the belt size in them, but from what I can tell, you are right about the stock belt length being 120.3". Subtract an inch, buy one, remove vac pump, and try :).
 
Cool!! I'm in the ball park now. The '95 is a running rig, it's getting the ATT and some other tweeks this weekend. The '96 I speak of, is in many pieces, it is a Suburban project, long story, '96 Diesel donor, '99 1500 Suburban "patient". At any rate, the donor engine brackets did not include the dual alt's, I'm adding as part of the rebuild. Thanks much!!!!
 
As far as part no. It is like K06xxxx = 6 groove, xxxy is the length xxx.y in.

The K can be replaced by other number.

So 120 in length will be K061200, 101 in length will be K061010.
 
My truck came from the factory with Dual Alternators. Haven't seen anyone else on the forums that claims this option.

Here's the belt that I use:

Goodyear Gatorback

Part # Metric part # #Ribs Effective length Outside length

4061187 6PK3015 6 118.75 119.5

There weren't many choices for this length and 6 rib. I'm not really thrilled with it but the next shorter won't fit. Need to try the pulling an alt and putting the belt on trick.

After being on for about a month the tensioner shifts to the indicator being maxed out. No squeeling or erratic pumping.

I'm thinking about scrounging up a gasser alt pulley and put it on the alt that doesn't drive the tach. This might take up just enough slack to be perfect.
 
Have to take the calipers to the junkyard and see what gasser alt has a pulley that's larger. Never see any diesels at the you pull it yard.
 
packratt said:
4061187 6PK3015 6 118.75 119.5
Click to expand...

So, that means the length is 118.7 inches nominal (inside loop) or 119.5 in (outside loop). Goodyear is available at AZ. Gates number should be K061187, rockauto have them which should be in OReilly or Napa also. Napa is branded as Napa but turns out to be Gates.
 
Wow! I've done about as much digging as one could stand. I didn't know you could get a truck without a/c!

It appears that the '96-'00 rigs without a/c use an idler mount in place of the drivers side a/c compressor. This may be reason for some of the belt length discrepancy, a/c versus no a/c, as this idler pulley may differ in size compared to the a/c compressor pulley.

As for the '94-'95 rigs, it appears the vac pump moved from down low on the passenger side (with a/c) to up high on the passenger side without a/c. Hmm? How would you configure a '94-"95 rig with no a/c and with no vac pump?

I'm not sure all of these arrangements are even possible, but I've tried to collect all the input from this thread, other threads and my hard copy.

'94-'95 1 Alt No A/C Vac Pmp
'94-'95 1 Alt No A/C No Vac Pmp How?
'94-'95 1 Alt A/C Vac Pmp 102.5 (102 - 102.5)
'94-'95 1 Alt A/C No Vac Pmp 101.5 (101.18 - 101.63)
'94-'95 2 Alt No A/C Vac Pmp
'94-'95 2 Alt No A/C No Vac Pmp
'94-'95 2 Alt A/C Vac Pmp
'94-'95 2 Alt A/C No Vac Pmp

'96-'00 1 Alt No A/C Vac Pmp 100.5
'96-'00 1 Alt No A/C No Vac Pmp 99.5
'96-'00 1 Alt A/C Vac Pmp 101
'96-'00 1 Alt A/C No Vac Pmp 99.5
'96-'00 2 Alt No A/C Vac Pmp
'96-'00 2 Alt No A/C No Vac Pmp
'96-'00 2 Alt A/C Vac Pmp 120.3
'96-'00 2 Alt A/C No Vac Pmp 119.3 (119.5)
 
Just for the record... my '95 had a 102" and it took a 101" perfectly w/o the vacuum pump.
 
Removing the three capscrews mounting the vacuum pump was kindof a test. Luckily, I had my main mechanic on the job, he has a hoist. Two you could reach from the top, but one I think you would have to get from the bottom? I'd say he did it in less than 1/2 hour. I'm sure, if the customer (me) wasn't watching, he could have done it faster. LOL!!

As far as belt lengths go, I have not upgraded alternators (have replaced with same), but I'd have to figure out which one that is. Maybe we could build on that spreadsheet I started if there is interest in such a thing. I kindof gave up though, when packratt pointed out there were even more combinations to add.
 
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