The Stovebolt Site Forums The Shop Area Engine Shop Dropping the crank

With the transmission still attached to my '54 235, is it reasonable to expect the crankshaft to drop enough to get the upper rear main rope seal installed correctly, per Oly's tech tip, or should I plan on removing the transmission first? Even after loosening the bearing cap(s), I don't see how the crank would drop enough (or any) to get the job done with the tranny still attached.

I've got all the parts and stuff I need to do this and a few other things, so this is the last piece of my planning before I get to it. Thanks for your help.

I've never tried that with the tranny still attached. Don't think you'll get the crank to drop enough until you remove the tranny. Maybe someone else will chime in.

I agree with waldo53. That seal is hard enough to install under good conditions. I have done it, and have seen it done by others, without removing the transmission, but after all the struggle, I don't think anyone saved any time- and you end up scuffing the seal quite a bit in the process. I haven't read the tech tip you refered to, but I assume you are talking about loosening the remaining three main caps quite a bit, then using the woven-wire "finger puller" type of installer and turning the crankshaft while you remove the old seal and install the new one. Loosening all the main caps lets the crankshaft come down quite a bit, even with the transmission still attached, but I never measured the amount of movement you can get that way.

If you take the transmission out, I don't know if you can lower the crankshaft enough to disengage the timing gears on the front. The front cover seal may keep the crankshaft from moving enough to disengage the timimg gears, but that is a test you don't want to fail. If you disengage the timing gears and turn the crankshaft, not realizing what happened, you will cause yourself a great deal of unexpected grief when you next start the engine- or try to start it. To avoid the timing gear issue, I would leave the front main cap in place, with the bolts loosened a couple of turns so the front of the shaft won't move vertically very far. I personally haven't experienced this misfortune, but if it can happen, it surely will happen (Murphey's laws- but I don't remember which one).

Harvester

Don't attempt the repairs w/o first getting a service manual. You can get a Motors manual or a GMC manual on e-Bay or probably an online bookstore.

I am continually amazed by the number of owners who tear into an engine or major chassis component and who have no idea where they are headed. The best navigators in the world still use maps so why would anyone go this way without a manual?

It isn't necessary to completely remove the trans. Support the trans with a jack and remove the bolts.then slide the trans back far enough to clear the front bearing retainer from the housing, only around 3/8". Now the back of the crank and trans can be lowered along with the crank. doesn't take much, just a very little to allow the old seal to be pulled out and the new one in. I have pulled the new ones in with the old 'chinese handcuff' tool and by using copper wire 'sewed' through the end of the seal and tightly wrapped around the seal and itself. the wire works just as good as the tool. Just be sure to lube everything up good. I use lubriplate, just 'cause I always have some handy and it works for me.

I've changed lots of upper rope seals with the transmission still insttalled. It only takes a few thousandths of movement to free up the seal so it can be rolled out of the block. The tool kit with the long-handled puller with the screw end makes a huge difference, as it gives you enough room to get a good pull on the seal. Once the puller is screwed into the seal, a thin-bladed screwdriver inserted between the seal and the block makes a handy pry bar to help get the seal moving. If you need a little extra movement, loosening the transmission-to-bellhousing bolts might help, but I've never needed to do that.
Jerry

I do have the service manual and I've looked over it quite a bit. All it says about the top part of the main seal is "it will be necessary to remove the engine from the chassis and remove the shaft". I'd just like to know from experience what has to be done to get the upper part installed correctly without pulling the engine. You guys are the only "map" I have for things that aren't spelled out in the manual.

It sounds like you can roll in the new top seal with the transmission is still attached or loosened. I'm not sure I like this idea because I wonder if the rolling process distorts or damages the seal. I was hoping that removing the transmission might let me drop everything far enough to put it in there without pulling it through the groove. Maybe I should just pull the engine...

Rope seals can be pulled into place with zero damage, if it's done right. Soak the seal in oil, and roll it out until it's thinner and longer than original, then pack it into place with a mallet and punch after it's pulled over the crankshaft. It's very flexible, and a careful pull into the upper groove does no harm. The seal is intentionally made about an inch over-length, so it can be packed into the groove and trimmed to length after it's installed. Any slight damage done to the end of the seal by a pulling wire or the Chinese handcuff tool gets cut off before the rear main cap is installed.
Jerry

No, you don't need to take the engine out and remove the crankshaft to change the upper half of the seal. And, yes, you can change it using the various methods described, with or without removing the transmission. The oil/lubriplate/grease suggestions are good ones that will help the process, and packing it as described by Hotrod Lincoln was common practice. Lowering the crankshaft a little is the critical part of the exercise. The reason Chevrolet manuals show removing crankshaft is that the required 'seal installation tool' is a driver that looks rather like a hammer that you use to seat the seal in the groove. I don't recall ever seeing anyone use that tool, even if the crankshaft was out of the block. The installer tool was part of the 'Essential Tools' kit for Chevrolet shops, and probably also for GMC shops. Chevrolet shop manuals show using installer tool. If I can find a picture of one, I'll see if I can post it- just for amusement.

Harvester