SanDiegoXJ
NAXJA Forum User
- Location
- San Diego, CA
So here's the long story:
1994 Jeep Cherokee Country 4.0L AW4 had about 178,000 miles, was leaking oil and burning coolant. A local member offered to do a complete rebuild and install for $1,700, which I thought was a great deal. And since I was burning coolant, I figured I probably had a bad head gasket. so I drop the Jeep off.
They completely rebuild the block with a new "hotter" cam. (not really sure what that is, but I'm guessing it just has a slightly longer stroke). The head also gets a valve job, resurfaced, and reinstalled. All of the old components, get reinstalled including the old flex plate and harmonic balancer.
When I get it back, it has new poly mounts, and a bit of a vibration, but that I attributed to the stiffness of the poly mounts. About a week later the vibe has gotten really bad, and when I drop the throttle, I can hear a BAM, BAM, BAM....so I pull off and check around, and the driver's side engine mount is missing one nut, and the other is about half way up the stud.
so I put a new nut on, tighten down both sides and fire it up. MUCH better...but still a vibe. Still thinking it might be the poly mounts, but just to be sure, I run down and buy some napa rubber mounts and put them in. Start it up, start revving it up in neutral, and it's better, but still getting a vibration at about 1750 RPM that seems to die out around 2500 RPM.
I search around and the only thing I can find is that maybe the harmonic balancer is going out. So I get a new Precision balancer and install it...no change. Again, at idle, the thing sounds beautiful...under WOT, it pulls like a champ and sounds great...at mild throttle, like cruising at 35 mph, it shakes like I'm on washboard.
So I keep searching, and the only thing I can find is that the torque converter needs to be indexed on the flexplate and they didn't do that when they pulled the tranny. But I see several other posts, that say it really doesn't matter. The flex plate can only be installed one way, and that's all that matters.
The only other possible cause I can think of, that seems very far fetched, is that the bolt that holds the idler pulley on is in a stripped bracket so it wobbles a little bit...but I find it hard to believe it could shake the engine that bad without throwing the belt.
Any suggestions at all?
TIA
1994 Jeep Cherokee Country 4.0L AW4 had about 178,000 miles, was leaking oil and burning coolant. A local member offered to do a complete rebuild and install for $1,700, which I thought was a great deal. And since I was burning coolant, I figured I probably had a bad head gasket. so I drop the Jeep off.
They completely rebuild the block with a new "hotter" cam. (not really sure what that is, but I'm guessing it just has a slightly longer stroke). The head also gets a valve job, resurfaced, and reinstalled. All of the old components, get reinstalled including the old flex plate and harmonic balancer.
When I get it back, it has new poly mounts, and a bit of a vibration, but that I attributed to the stiffness of the poly mounts. About a week later the vibe has gotten really bad, and when I drop the throttle, I can hear a BAM, BAM, BAM....so I pull off and check around, and the driver's side engine mount is missing one nut, and the other is about half way up the stud.
so I put a new nut on, tighten down both sides and fire it up. MUCH better...but still a vibe. Still thinking it might be the poly mounts, but just to be sure, I run down and buy some napa rubber mounts and put them in. Start it up, start revving it up in neutral, and it's better, but still getting a vibration at about 1750 RPM that seems to die out around 2500 RPM.
I search around and the only thing I can find is that maybe the harmonic balancer is going out. So I get a new Precision balancer and install it...no change. Again, at idle, the thing sounds beautiful...under WOT, it pulls like a champ and sounds great...at mild throttle, like cruising at 35 mph, it shakes like I'm on washboard.
So I keep searching, and the only thing I can find is that the torque converter needs to be indexed on the flexplate and they didn't do that when they pulled the tranny. But I see several other posts, that say it really doesn't matter. The flex plate can only be installed one way, and that's all that matters.
The only other possible cause I can think of, that seems very far fetched, is that the bolt that holds the idler pulley on is in a stripped bracket so it wobbles a little bit...but I find it hard to believe it could shake the engine that bad without throwing the belt.
Any suggestions at all?
TIA