Posted this in the Engine forum, but got no response...

My 383 is out of the '68 El Camino while it goes in for paint and body work. The rear main seal on this 5 year old motor appears to be leaking. What exactly will I have to do to replace it? Can I just pull the rear main cap and do it? Or, will I have to pull all caps and lift the crank out slightly to do it? Do I need to consider replacing the main bearings? I would rather not have to completely disassemble the motor and want to avoid any machine work. The motor has been used 75% at the track over the past 5 years with about 200 passes and maybe 1000-2000 street miles. Any advice would be a great help.

** UPDATE **
OK, so I pulled a few rod caps and main caps to do some inspection. Of course there is wear on the bearing after 5 years, but is this normal or excessive? The crank journals look excellent and feel perfectly smooth. Check the pics out...

Rod bearing:
http://www.nuibe.com/misc/rod6c.jpg

Main cap #3:
http://www.nuibe.com/misc/main3c.jpg

Rear main cap:
http://www.nuibe.com/misc/rearmainc.jpg

So, what do you think? Should I leave it alone? Just swap the rod and main bearings? Should I replace the rings? If so, will the block need machining? I want to do what is necessary, but I am on a budget and am not looking to make any expensive "improvements".

The motor was running perfectly when I pulled it and was turning about the same times it always had, no signs of lost power. I'm just trying to do maintenance while it's out. Any and all advice welcome.

Thanks guys!

Its easily done with the motor upside down and leaving the crank in place. Just be sure to "clock" the seal with a slight 'offset' and use a sealer on the ends only. This will prevent the classic "Chevy" leak. Almost all of the "building a chevy" books show how this is done. (this is assuming you don't have a ONE piece rear seal)

Greg, anytime I have the motor out and pan off I like to check the rod/mains to look for any problems. Also, remember to check crank end-play while you're at it.

Is your crank seal a 1 or 2 piece?

2 piece seal. So I can pull the rod and main caps. If they look good, I can put them back without doing anything special? Just reinstall and retorque? If I decide to replace bearings as a precaution, do I have to have any machine work done? Sorry, my experience with this is limited to building this motor when it was new parts, but I've never done any rebuilding or anything.

Hey Greg,

Unless you find something wrong, you can just lube the bearings and put them back. Be sure to put them in the same location. To replace them, no machine work is required unless the crank is damaged. Just check each to make sure the size is correct. The undersize is stamped on the back. Standard should have "STD".

What color are you going with?

Greg,if everything looks good (no copper showing, etc) just retorque them to the original specs. Be sure to keep the caps oriented correctly and use the same bolt lubricant as originally used. If the bearings look good I'd just keep them. If they look beat-up then you'll need to look at the journals closer and probably have the rod big ends checked for roundness.

Pat, I'm not 100% sure yet. I have another couple weeks to decide. The top choice for me right now is Arrival Blue, as found on the 2004 Chevy Silverado SS (and other GM products). It will be some sort of metallic blue, since I've never had a car that color before.

Thanks for the advice guys. I will post picks when I pull the caps and ask for advice again at that time if they don't look perfect.

That should look pretty nice. On the seal, be sure to put a thin layer of silicon on the rear main cap where it mates to the block.

Hey Greg long time no see. Glad to hear that the car is getting some new paint on it. These guys are heading you in the right direction. I would make sure to check all of the bearings and end play, its better to see something now if there is a problem rather than when something comes apart. If the bearings look good and are not showing signs of excess wear I would just clean them up really well and stuff them back in, just torque them down to where they belong. If the bearings are showing lots of wear and the crank has no major lines change them.

That blue should look really good. It is a little brighter than my velle but very nice none the less. Good luck

Thanks guys. I don't expect to see any unusual wear, but then who ever does :rolleyes: I'll keep you posted. The temptation to try to 'get a little more' out of the engine while it is on the stand is killing me!!! I just can't afford to since my funds are all directed to getting this thing to look presentable. My friend thinks I'm crazy for wanting the car to be faster than it is, but it's just never enough, is it?

Please see updates in original post at top smile.gif

Greg,
Don't forget you will have to set your thrust clearance when you install the rear cap.

Huh? :D Is that if I replace bearings, or no matter what? I don't seem to recall doing that when I originally assembled the motor, but maybe I've just forgotten since it was 5 year ago...

Now that I have thought about it more, I do remember doing this. An I will do it again this time :D

So, can anybody tell me if everything looks normal and fine? Do I have to replace these bearings, or should I just put it back together and call it good?

Greg,
Good to see you still around here. I see your car just keeps getting faster. I finally got my combo working pretty good and you old converter works great.
As for the bearings I will leave that to the guys with more motor experience.
The Arrival blue will look great I was looking at it for my wagon project. I ended up settling for Electron Blue. It is a color on 02-03 Z06 Vettes. I ended up liking it better than the Arrival.

Good luck with the project.

Thanks Richard. I'm glad to see the combo is working out for you. I actually changed my mind on the color slightly. I am doing the Daytona Blue Pearl that is on a 2004 Nissan 350Z, as pictured below. (Forgive me for posting a pic of an import on here :D )

http://www.nuibe.com/misc/350z.jpg

My buddy just had his car painted that 04 Nissan color. In some light it looks blue, in other light it looks purple. Just in case you didn't know.

Come on engine gurus, give me some advice... :D

Sorry Greg, i dont trust anything but a dial bore gauge, and a Micrometer.

I think it would be smarter now to have the engine freshed and have the crank polished or ground, then later.

And while the rotating assembly is out, you can have a machine shop check and touch up the rods and main housings.

Then you will Know they're right, rather then going by best guess estimate.

The look fine to me as far as i can tell. I would go ahead and put new ones in while you got it apart though.

I'd change bearings while it's apart, the grooves showing don't look all that bad though. If the crank is smooth just change the bearings, good piece of mind IMO. No copper showing is a good sign. Make sure you match the new bearings to what you're replacing. Also put some assembly grease on the crank where the seal rides so the seal doesn't burn on startup. Dry seals sometimes go bad on startup from friction/heat. Regular chassis grease or vasoline will work as well. Plastiguage during assembly just to be on the safe side if you don't measure the crank etc. for bearing clearance. Open the oil pump up and inspect the shafts, gears, and pump body also. Or just replace it, cheap. JMO, Bob