So, when I picked up my '98 GC Limited, it had a blown engine. Sounded like a metal coffee can full of rocks, so a test drive wasn't possible.

Before yanking it out, thought I'd drain the oil. SUPRISE, I got about 4 gallons of chocolate milkshake. Yup, its going to be toast. Once I got it out and dropped the pan, the ugliness was everywhere. Every piston had be broken to some degree, The lower block cracked, One rod completely obliterated and the piston jammed in the bore and the corresponding rod hammered on the throw with about 1/2" of play.



So, obviously not rebuildable. Snagged a 150k mileage used 5.2 unit from a local yard with 140 psi in all cylinders. Swapped them out over the course of several weekends, got it fired up, and Yea Baby, back in the game!

But not it has a weird quirk. It will idle fine all day long, Did an extended idle to bring up to temp after the swap, and drive forward like you would expect. However, once put into reverse, its like half the cylinders get turned off. It bucks and surges and is rough as hell until it dies. Throw it in neutral or drive and its fine.

Suggestions on things too look at?

 

Okay, the only thing I can think of off the top of my head is in reverse, the engine torques the other way in the mounts. If you have a loose or weak mount, it could be shorting a harness somewhere when in reverse. Just a wild card, but is the distributor cap hitting the firewall? This is common with Chevy small blocks in older cars, but usually on acceleration.

 

Good suggestions. Mounts were trashed, so new ones went in with the engine swap. Torque motion is now fairly limited. Plenty of room around the distributor cap. However, along that line of thinking, there is a massive harness back there as well as looms through out the engine bay and over the transmission. Maybe I'll start checking these for pinch points.

So is there an electric idle enhancement function somewhere in this system that is independent of the a/c system?

 

the problem is in the transmission, stuck servo or damaged drum....more than likely was like this for some time and the original owner just drove it til the engine died

 

DAMN, Russ! You just nailed it! My Chevy truck would always die when you shifted out of reverse and into drive unless you caught it with throttle, and then sometimes not. I had to rebuild the trans because of a blown turbine in the converter and never stalled after that! I always wondered why! Not only that, but it wouldn't start in neutral, only park! It got so I hated to have to back up!

 

I had a friend go through this, sold a nice Cherokee for scrap price, all that was wrong was the bell housing bolts were somehow loose and the CPS would kill the engine in reverse. Check your bolts everywhere and your crank position sensor.

 

Will definetely check mounting bolts and CPS since they were all R&R for the engine exchange.

So is the servo accessible from the pan like the old torqueflites or is it a rebuild accessible only item? Not too thrilled about the prospect of a trans overhaul.

 

would require a tear down