Hello,

I have the engine out of the car, and I am replacing all gaskets and seals. I am trying to find out how to change the rear main seal. I have a couple of questions concerns.

Looks like the only way to properly change the rear main seal is to remove the main caps and lift the crankshaft.

I have never done this before and it makes me a bit nervous. Has anyone done this before and do I also need to diconnect the rod caps or is it possible to lift the cranckshaft enough without disconnecting the rods?

If I do have to remove the rod caps, are the rod bolts reusable or not - i keep hearing something about getting the correct strech on the bolt when installing rod caps

Thanks,
Fernando

 

The proper way to replace is to remove the crankshaft for the rope seal replacement which was stock. The seal has to be rolled and pressed into the groove above the crank. There was a tool to assist with this. Then the ends have to be trimmed properly so they dont interfear with the bearing cap install. There was someone selling the 2 piece neoprene seal for these engines but I do not know the source. This type of seal can be installed without removing the crank. The rod bolts are re-useable just torque them to proper specs.

 

Thanks for your help, I appreciate it

 

If the engine is already out you should inspect all the bearings and check the clearances with plastigauge, install a new seal during that process.

 

You will have to remove the crank to replace a rope type seal. The tool Oldsmaniac was refering to is called a Sneaky Pete. It was designed to grab the rope seal with small fingers like a Chineese finger torture toy and help to pull the seal in with the crank in place while turning the crank also. Supposedly this could be used while the engine is in the car with the oil pan off. I have this tool and could never get it to work right. If you can find the two piece neoprene style rear seal you might be able to push one in and around the crank with it still installed. You may have to loosen the main caps and pry the crank up a bit. Try turning the crank while your pushing the seal in. The two piece seal is supposed to be installed not flush with the block but slightly offset with a little dab of RTV between the halves. You may want to tear the engine completely down and remove the pistons to check for any broken rings. That's real common on the 394's. If you are going to tear it all the way down, you might want to take it to a machine shop to have them boil it out and check for any cracks. I have a 394 on a stand in my garage right now. Man is that thing a pig. I think with the heads on, it weighs almost 800 pounds. Make sure your engine stand is up to the task. I always support the front with a piece of steel cut to length, when I'm not rotating it.

Fernando the rod bolts should be reusable for you. Of course ARP makes a better bolt that could be used, however, sometimes they have to be fitted to the rods. The other meathod of torquing the rod bolts that you reffered to was measuring the stretch on the bolt itself while your torquing. This requires special tools and you would need to know how much stretch is required for the specific fastener. The more common meathod is simply to torque to spec. Please keep us posted on your progress and let's see some photos.
114-1485_IMG.jpg

 

Hi 67 Cutlass Freak,

I really appreciate your advice, I will post some picture soon and keep you all posted on the progress.

Thanks