2.5 v belt style harmonic balancer obsolete?

[JMO413]

The picture shows a serp balancer but I'm pretty sure it's a generic picture. 

[Eagle]

1 hour ago, Jeep Driver said:

XJ/MJ did use the GM V6 which the Dorman pulley I linked to does cross to. 

 

Since the V6 and early 2.5 used GM alts and PS pumps.........I suspect they used the same balancers. 

 

90% chance that balancer will fit.

 

It may fit, physically, but it almost certainly won't balance. The GM 2.8L V6 version that GM sold to AMC/Jeep was externally balanced. There's no way an externally balanced V6 would use the same damper as an in-line 4 cylinder.

[Shortbusdriver]

You guys are AWSOME!, it would have taken me weeks to compile this amount of information, I'm not so great with computer use-still hunt and peck with the keyboard. 

The 80's have always proven to be a challenge with auto manufacturers for me, mixed sae and metric fasteners, random  part changes at any point during production, even different part numbers depending on trim color! (A late 80's maxima) I still love to repair, restore and to improve these machines! 

The Crown automotive #3242886 is a serpentine style crank pulley listed as both 2.5 and 4.2 motors,81 to 93 which led me to think the balancer is interchangeable, but if the factory part numbers are different how can that be? It may just be the diameter is different which could lead to overdrive/underdrive options for the accessories? I just don't know.

Thanks for the mention of the water pump, in my studies I did find that the v belt type spins in the opposite direction of the serpentine type. I wonder how many people have had cooling issues because of this.

Thanks again to all who have chimed in on this subject! I would still be running in circles if not for you!

 

[Jeep Driver]

1 hour ago, Eagle said:

 

It may fit, physically, but it almost certainly won't balance. The GM 2.8L V6 version that GM sold to AMC/Jeep was externally balanced. There's no way an externally balanced V6 would use the same damper as an in-line 4 cylinder.

Assuming it did fit.............

 

Hop on down to the machine shop and have the HB neutrally balanced. 

[JMO413]

You welcome. I find this stuff fun. I have been a parts guy for 20 years. I believe the Dorman 594-137 should be correct. 

[RGniady81]

Quick question pertaining to this. Has anyone successfully converted a v-belt driven 4 cyl to a serpentine driven system?

[Shortbusdriver]

I have not done this myself but in my searches I found that the crankshaft snout is different, people mentioned needing to add a shim to get the crank pully to align with the rest of the components. Otherwise everything else can just be bolted on from the serpentine motor. IIRC there is a 3/8" difference between the serp and v groove crank pully.

hope that helps!

 

[Jeep Driver]

27 minutes ago, Shortbusdriver said:

I have not done this myself but in my searches I found that the crankshaft snout is different, people mentioned needing to add a shim to get the crank pully to align with the rest of the components. Otherwise everything else can just be bolted on from the serpentine motor. IIRC there is a 3/8" difference between the serp and v groove crank pully.

hope that helps!

 

The snout change came later, around '97 IIRC.

 

You can install an early serpentine balancer on a later snout but not a later balancer on an early snout...........no shim.

 

If your MJ has AC, the later AC compressor will not mate to your existing lines AND the later balancer will not go on the snout..........so.........for all practical purposes the later TJ/XJ MPI accessories are out of the question. 

 

You'll need a complete accessory package/assembly from a '87-'90 XJ or MJ. 

[Lycaon1349]

Sorry to revive a 3 year old post but did anyone end up getting anywhere with this? I'm going the other direction with a conversion, using a 2.5 in a Willys CJ build and ive started converting over to a 3 point v belt setup but I'm stuck trying to find a balancer. Did anyone find out for sure if the GM balancer will fit dimensionally on the 2.5 snout? I'd gladly have one neutral balanced if it were that easy. Also would a V belt balancer from a 4.2 fit? Hesco sells one that doubles as a crank position sensor and that would be perfect for the MicroSquirt fueling setup ill be running for it. Thanks all 

[saveevryjp1998]

On 4/13/2022 at 9:48 PM, Lycaon1349 said:

Sorry to revive a 3 year old post but did anyone end up getting anywhere with this? I'm going the other direction with a conversion, using a 2.5 in a Willys CJ build and ive started converting over to a 3 point v belt setup but I'm stuck trying to find a balancer. Did anyone find out for sure if the GM balancer will fit dimensionally on the 2.5 snout? I'd gladly have one neutral balanced if it were that easy. Also would a V belt balancer from a 4.2 fit? Hesco sells one that doubles as a crank position sensor and that would be perfect for the MicroSquirt fueling setup ill be running for it. Thanks all 

Just to be clear the original post was about the 86 mj 2.5. I'm not sure what year you have but be careful which. If you read the entire thread start to finish, you'll understand what I mean. Funny you mention doing this because my neighbor bought one and I mentioned to him about tossing one in his a few weeks ago. I'm sure he'd love to follow a build thread if you have one especially since he is new in the Jeep diy world.