Epic: Grand - First motor tear down

The Chrysler Magnum 5.2L motor is a very good motor. It is loosely based on the Chrysler LA engine family, more directly the 318. This motor has been used is more vehicles that you can shake a stick at (and I'm pretty good at shaking a stick at things). The motor may not be very fuel efficient when compared to it's rivals but the power and durability makes up for it; a modest 230hp and 300 ft lbs of torque.One of the distinct advantages of these motors is the factory installed roller lifters. This is where we thought my problem laid. The motor had 206,000 miles on it and I had only put 3000 of them on. I had zero maintenance history to work from.

I decided to replace all the lifters, the oil pump and every bit of tune up components I could. Ended up purchasing an AEM dry flow cleanable air filter, Jeg's brand performance cap and rotor, Jeg's brand 50k volt coil, Taylor 8.8mm spark plug wires and E3 Sparkplugs. I had the same wires and plugs on my 5.9L in a 98 Dodge Ram I use to had great luck with them.

As a rule of thumb, I like to take pictures of an engine prior to tearing it down. Especially on one I haven't worked on before. I have done enough 4.0L motor work now that I feel completely comfortable just tearing into it but I hadn't worked too deep on a 5.2L before so I went ahead and took multiple shots. This allows me to go back and reference where wires may have been routed, lines plugged in, etc. I took about a dozen pictures.

Reference picture of the 5.2L

Luckily I didn't end up needing them for reassembly. It's nice to have a catalog of pictures to look back on.

The tear down begins...

The new replacement roller lifters

Pretty grody....

After a lot of scrubbing and oil bathing...

Scrubbing and oil bathing

When I was gearing up for this project, I did a lot of research on simple and inexpensive ways to get a little more efficiency and power out of the the motor. I found out that trimming some of the internals on the "kegger" intake manifold would allow for better airflow. I found a lot of debate on this and determined that minor clearancing would benefit a stock motor, if the motor were being built up, you can safely take more material out and not drastically change anything. Taking too much out runs the risk of losing bottom end power while gaining top end. For a 4wd vehicle, bottom end is important. I decided to remove a little and smooth off some edges. I went through and drew the cut to lines through out and went to town.

In process of opening up the chambers.

All done with the cutting, just needs to be cleaned up.

I ended up taking about 0.25" out of the chambers and the middle web. I'd heard that I could completely remove the web in the center and not hurt anything, only gain but I was skeptical and didn't want to risk it.

Cleaning and reassembly begins after priming all the lifters.

Cleaning and reassembly

Top end all reassembled

Now that the top end was just about finished up, I started on the bottom. Put the Jeep up on stands and stretch the front suspension out. Drop the Y pipe and oil pan.

The bottom end is naked

Pulled the oil pump off, dropped the rear main cap off and replaced the rear main seal. Reinstalled the cap, torqued to spec and put the new oil pump on. Now, I'm a proud American and would love to buy everything made in the USA. Sometimes though, the budget just doesn't allow for it. It's sad to think that something that gets shipped in from across the globe ends up cheaper than something that comes from at most a few thousand miles. That being said, I was pleasantly surprised when I opened my oil pump box and found this...

Installation went smoothly, I pre-primed the pump in a bucket of oil. Doesn't get all the air bubbles out but got the oil in there to aid in the process.

When Chrysler decided to put this motor into the Grand Cherokee, they must have had a really big shoe horn. The fire wall overlaps the top of the distributor making the cap and rotor a PIA to mess with but worse is when dealing with the exhaust manifolds. More specifically the passenger side exhaust manifold. It seems there is a slight oversight by the Jeep Engineers. One of the two bolts from the Y pipe to maniold connection is a gigantic cluster #@!*. The nuts are supposed to be on the manifold side, the problem is, when you slide the Y-Pipe up onto the manifold, you can no longer get to where this nut needs to be, from the underside of the Jeep OR the top side. Talk about infuriating. After lots of failed attempts and grumbling, I end up using some 3M adhesive (I call it gorilla snot) to get the nut to stick onto the manifold, just long enough to get the threads of the bolt started. Luckily the nut has a "flag" on it that catches the manifold so you don't need a wrench on it. At least Jeep did 1 thing right. Luck held out just long enough for the threads to start and then the gorilla snot let go. What should have been a 5 minute reinstall of the Y-pipe took an hour. Bleh.

Finally everything is back together. With the coil wire disconnected, I crank the engine over several times to build up oil pressure and the gauge appeared to be showing good pressure. Put the coil wire on and start the engine.

To be Continued....