Rod Bearings
It is pretty common knowledge that the turbo charged 944s like to spin the #2 rod bearing when it reaches at or around 150,000 miles. Many people who frequently track their 944s (both normally aspirated or turbo charged) are worried about oil starvation to their rod bearings, and will change them frequently. Since my 951 has around 160,000 miles on it, and I plan to track the car some I decided I needed to change my rod bearings before I ever head to the race track.
To further help with the oil starvation issue, and since I was already down there,I also installed a Lindsey Racing oil pan baffle as well as a Ishihara-Johnson crank scraper. I also installed a Lindsey Racing two piece turbo crossover pipe and a three piece removable cross member. That way, if I ever need to drop the pan again, it will only take roughly three hours instead of sixteen. I also have write ups regarding those as well.
Changing the rod bearings is not a difficult task once you have gone through the agony of removing the oil pan, but it will require some patience.
Also, I removed all of my rod bearings at one time when I changed mine. I didn't have the rod bearings yet because I wanted to make sure that all the bearings were standard size before ordering. The rod bearings will be stamped STD for standard, or if they are oversized will have a decimal amount stamped on them. If you are absolutely certain you have STD rod bearings, and your crank isn't worn out enough to be cut, then you could replace the rod bearings one at a time. It goes for a much faster process.
First you must remove the oil pan and all the steps associated with it. Here you can see the engine rotating assembly with the oil pan removed. You will need to remove the two rod nuts from each connecting rod. Visible connecting rod nuts are pointed out in this photo. You will need to be able to rotate the engine by hand to get access to all the connecting rods. Attach a 15/16" to a ratchet on the end of the crank to spin the rotating assembly by hand. If your valve train is still together, you do not need to worry about getting your timing off or anything.
Before you try rotating it over by hand, remove the spark plugs. It will make rotating by hand MUCH easier. This will also be needed whenever you are moving the piston and rod up and down when removing/installing the rod bearing.
Here is a detailed picture showing the two rod bolts. Use a 14mm 12 point socket to remove the rod bolts. To pull the bearing cap off, hit one side of it with a hammer and brass punch towards the other side. You will see it move a little bit, then change sides and do the same thing. It'll move down again. Keep going back and forth while pulling down on the cap. Eventually you'll be able to pull it straight down and off. Now that the bearing cap is removed, you need to get the top rod bearing out. So, push the piston up by hand, or use a brass push if you can't get your hands in there. Pull the top rod bearing out by rotating it. Push on the driver side towards the passenger side, eventually it'll pop out and fall out. Here's the bearing cap with the old bottom rod bearing in place. Note the little divots on one side. Do the same thing as before. Rotate it against the divot, and it'll free up and come loose. As you take the bearings caps off, lay them out in the order they are in the engine. The rods and caps are specific to each other and must be installed as you took them out! If you forget to do this or knock them over or something, don't worry. The caps and rods have numbers stamped in them that match, this will just speed things up because the numbers on the rod can be pretty hard to read if you're doing this on your back in the garage. It's still a good idea to double check the matching numbers though. After you have confirmed what size rod bearings to use. Make sure you also get some new rod nuts and some engine assembly lube. Engine assembly lube is thick, almost grease, like lubricant that lubricates things until the oil gets in there. Take a plain bearing and liberally coat it with assembly lube. Note where the divot is, it is on the passenger side of the engine. Install this top rod bearing by rotating it up inside the connecting rod aligning the divot in the rod with the divot in the rod bearing. Pull the piston down to where it is sitting against the crank. If you have a hard time pulling the piston down you can thread on an old rod nut, and use some pliers to pull down on the piston. Look up inside the cylinder and make sure that the divots are lined up, and that the bearing ends match the ends of the rod. Now coat the other rod bearing in assembly lube and the bearing cap in assembly lube. Install the rod bearing on the cap, once again making sure the divots line up. Hold the rod against the crank while pushing the bearing cap through the two studs. Coat the rod studs in lubricant, and thread the new nuts on. Tighten each side a little bit at a time, switching sides, before you finally torque them down to 50 ft/lbs +-3 ft/lbs. Do this for each of the four rods and you're done.
