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Hey everyone! 

 

I just bought my 1988 Jeep Comanche about a week ago. It has 98,000km on it (60,895 miles). The truck is in great condition - no rust on it at all which is very rare for any vehicle in Alberta. It has the 2.5L v4 with a standard 5 speed transmission and 2 wheel drive. It sat under a tarp for a few years before I got it. I tossed in some photos too, mostly because I am still at the "holy s*** I love this thing so much" stage of ownership.

 

I'm noticing a squeal from the engine at higher RPMs (no tach, just a super large fuel gauge, so I can't tell you exactly what RPM). I also notice that in 5th gear at around 85-95km (not outside this range) the truck rumbles quite a lot. By rumbles I mean vibration that shakes my mirrors, shifter and the seat.

 

I think the squeal is belt related based on experience with other older cars, but I have also read about a harmonic something or other in the Comanche being a squeaky source as well that relates to the belt. I'm wondering if that could be the source of the vibration tok, or if I should just go get my alignment checked/tires balanced. 

 

Any input is welcome!

 

- Noah

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welcome to the addiction.  :waving:  be sure to add your baby to the registry so you get a build sheet and birthday.  :L: 

 

how tight is your s-belt?  how old is it?  have you pulled it off and spun the individual bearings yet?

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Just now, Pete M said:

welcome to the addiction.  :waving:  be sure to add your baby to the registry so you get a build sheet and birthday.  :L: 

 

how tight is your s-belt?  how old is it?  have you pulled it off and spun the individual bearings yet?

Thanks! I'm loving it so far. I'll get on that registry right away 👌

 

No idea on the age of the belt, but the tension seems alright. I haven't taken it off yet - will get on that tonight hopefully. 

 

How is it to find parts for the old Comanches? Truthfully, I just bought the thing on a whim 😅

 

- Noah

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where you can find parts depends a lot on exactly which part you need.  the auto store will have the majority of things you'll generally need. :L:  body parts are harder to come by, especially the MJ-specific ones out back

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15 minutes ago, MulzetN said:

2.5L v4

150 CID AMC 2.5L I4. Pet peeve of mine. Anyways 

 

16 minutes ago, MulzetN said:

I'm noticing a squeal from the engine at higher RPMs (no tach, just a super large fuel gauge, so I can't tell you exactly what RPM). I also notice that in 5th gear at around 85-95km (not outside this range) the truck rumbles quite a lot. By rumbles I mean vibration that shakes my mirrors, shifter and the seat.

 

So I would check your belt tension, it can be adjusted via the Power Steering bracket or the alt bracket if you have AC. Only 84- early 86 2.5L has the V-belt set up and that set up is obnoxious and slightly nerve-racking when you watch the belt flop up and down with the AC on. 

 

As for those pesky vibes. Is it just in 5th around 50-60 mph(80-95kph) or is it specifically 5th gear? I have some pesky vibes still at 45+ and I've changed damn near everything suspension related except the front coils and the passenger leaf spring. Honestly, I think those vibes are just the age of the vehicle and the balance that is the 2.5L. I recommend replacing everything that is rubber, so engine mounts, trans mount, bushings, coil to body bushing. If its rubber, replace it. No urethane. Wouldnt hurt to have the drive shaft balanced and your tires checked too. 

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  • 5 months later...
On 10/8/2020 at 8:39 PM, eaglescout526 said:

150 CID AMC 2.5L I4. Pet peeve of mine. Anyways 

 

 

So I would check your belt tension, it can be adjusted via the Power Steering bracket or the alt bracket if you have AC. Only 84- early 86 2.5L has the V-belt set up and that set up is obnoxious and slightly nerve-racking when you watch the belt flop up and down with the AC on. 

 

As for those pesky vibes. Is it just in 5th around 50-60 mph(80-95kph) or is it specifically 5th gear? I have some pesky vibes still at 45+ and I've changed damn near everything suspension related except the front coils and the passenger leaf spring. Honestly, I think those vibes are just the age of the vehicle and the balance that is the 2.5L. I recommend replacing everything that is rubber, so engine mounts, trans mount, bushings, coil to body bushing. If its rubber, replace it. No urethane. Wouldnt hurt to have the drive shaft balanced and your tires checked too. 

Delayed response here. I had the driveshaft balanced and that helped with the vibration (which was speed related, not rev). Once I get new tires I will do an alignment on it. I suspect that will fix the rest of the vibration problem.

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On 10/8/2020 at 8:30 PM, Pete M said:

where you can find parts depends a lot on exactly which part you need.  the auto store will have the majority of things you'll generally need. :L:  body parts are harder to come by, especially the MJ-specific ones out back

Rockauto has been a wonderful thing.

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Check the harmonic balancer. They do go bad. I'd replace in anyways. Its a $50 part, new. If it is bad, then it can take out engine bearings. Yes, I learned the hard way.

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On 10/8/2020 at 7:39 PM, eaglescout526 said:

150 CID AMC 2.5L I4. Pet peeve of mine. Anyways 

 

 

So I would check your belt tension, it can be adjusted via the Power Steering bracket or the alt bracket if you have AC. Only 84- early 86 2.5L has the V-belt set up and that set up is obnoxious and slightly nerve-racking when you watch the belt flop up and down with the AC on. 

 

As for those pesky vibes. Is it just in 5th around 50-60 mph(80-95kph) or is it specifically 5th gear? I have some pesky vibes still at 45+ and I've changed damn near everything suspension related except the front coils and the passenger leaf spring. Honestly, I think those vibes are just the age of the vehicle and the balance that is the 2.5L. I recommend replacing everything that is rubber, so engine mounts, trans mount, bushings, coil to body bushing. If its rubber, replace it. No urethane. Wouldnt hurt to have the drive shaft balanced and your tires checked too. 

Actually a 2.46 liter.......

 

How old are the tires? It sat for a long time? 

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75sv1 - noted. I've tightened the belt a few times and the squeal usually goes away for about a week then comes back. Not sure if it is just loosening off. Next time I am in there I might try the harmonic balancer. It's pretty simple?

 

Cruiser54 - pretty old with uneven wear. I had brand new winters on it with the same problem though. I'm replacing the rubber soon and will get the alignment done. I've noticed that since having the driveshaft balanced I only notice the rumble through the seat which makes me think it is tire related.

 

 

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Harmonic balancers are fairly simple, if you have the right tools. I'd also see about replacing the front cover seal while I'm there. I think you can drill some holes in the front of the seal, and then screw in a couple of screws. Then pull on them. If not, then just replace the harmonic balancer. I'd also question what brand of belt you are using? I'd get the Gates HD. I think NAPA is starting to sell them. They are green. I haven't installed the ones I have though. Also, go through any Idler pulley. See if the bearings are OK. Also, the AC clutch bearing. Although if that is out, I think you'd be frying your belt. 

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Get a picture of the front of your harmonic balancer.  When I looked at mine closely, it was pretty apparent that the rubber insulator was done with life and wanted to end it all.  

 

I don't recall this job being anything extraordinarily difficult.  In fact, I'm trying to remember for sure but I don't even think I removed the radiator, but it's been a while.

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Radiator can stay in. 

 

Here's a pic of a bad balancer. 

 

Before doing anything else, I'd squirt some silicone spray on the belt with the engine running and see what happens. Could just be a cheap belt. 

Harmonic balancer failure.jpg

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You will need a harmonic balancer puller, about $15 or so. Also, an installer. I think kits are about $100. Might see about tool rentals at the parts store. If you could find  a bolt with the correct threads and a bit longer than the stock bolt, it should work as on installer. Should be able to do with Radiator in, as mentioned.

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