The Stovebolt Site Forums The Shop Area Engine Shop Sorry, Rear Main Seal question

So I have been having a persistent oil leak from the Rear Main Seal in my 58-62 235. I now have both Rubber and Rope style rear main seals. I'm positive I should be able to install a Rubber style seal in my year engine, but the last one did not work, did I miss something?

I'm reading the instructions on the back of the Rubber Style seal and am a little confused by some of the terminology used. And I quote
" Apply a thin coat of anaerobic sealant to the bearing cap chamfer and to the bearing cap mating surface adjacent to the seal but not on the seal end "

1- What is Anaerobic Sealant?
2- What is the Bearing Cap Chamfer? ( Is it the channel the Rubber Seal sits in ? )
3- Do I really apply sealant between the block and bearing cap?

Sorry for yet another Rear Main Seal question, but I did do a search and it did not turn up anything. Thanks for your time

#1 A sealer that will setup without air #2 On the main cap outer edge where it contacts the block surface,they put a "chamfer" so its not a sharp edge,#3 yes put a thin coat of sealer on the block surface where the main caps goes,you do this because the oil can leak through the "chamfer" if you don't. I would really check out you main clearance,It sounds like you have the wrong size main bearings in there, If you have resealed the rear main with both types of seals and still leaking? sure its the rear main seal? Do you know that the crank bolts go through into the oil? did you seal them, maybe you had a bad bolt and the oil is leaking through the bolt threads.

Thanks for the reply. Do you have a suggestion for a sealer on #1? I did put sealant on both the rear main cap bolts and all the bolts that hold the flywheel to the crank. Won't the sealant between the rear cap and block surface create extra bearing clearance?
I have not tried the rope style seal yet, which brings up another question. In the instructions of the rope seal, it says to apply a small amount of RTV sealant to the back side of the rope seal. Shouldn't I be doing the same with the rubber style as well?

I would use the gray silicone on the main caps, Don't put thick coat of it, Just a very thin coat, It will come out and not change the clearance. Rope will seal most anything, Its wider on the contact to the crank. If there was some ware on the crank area where the seal rides on the the crank the rope will fix that,Rope seal needs to be fitted tight and to do it on your back will be not easy but can be done. Trimming the ends of the rope is the key,Sharp razor blade a must, Your engine will turn over harder but once the crank spins it will get better. Getting the seal in the block side is tricky,you can get a tool for this at parts houses,the next best thing to do is loosen all the mains caps so that the crank "drops" a little and slid the rope in and once it's in tighten up the mains before you cut the ends of the rope seal.Take the cap and put it in your vise and install the rope and use a round tool to roll it into the groove and then cut the ends on that,RTV thin coat on the cap and install.

I hate to ask this but you do know which way the rubber seal goes in?

Hi, yes I followed the directions on the back of the rubber seals package. I am going to try and installed the rope style seal this weekend. I have one of those chinese handcuff style pullers for the upper seal, hopefully that will make it easier. How would you go about applying the RTV for the " Cap to Block " if I have shims installed on the rear cap?

Yes that's the tool, And apply the RTV in the corners of the cap,If you use a thin coat of RTV it will not hurt anything and will not change you clearances.All your trying to do is seal where oil can slip by in the corners.

Sorry to be soo inquisitive. In all the corners or just the backside of the cap, like is the pic below, RTV shown in Orange. I know it's not the correct cap, just using it for reference. Thanks

http://i1236.photobucket.com/albums/ff441/AZ59apacheguy/rtv-area-lg.jpg

So I have also spent the better part of an hour trying to get the rope seal into my Chinese Handcuff style puller with NO success. Any tips on how to get the rope seal into the puller?

In your pic (a small block cap) the sealer is running from the crank seal out to the rear pan gasket seal. You will do the same on a 235 except the sealer will go at a slight angle.

Thanks for the reply Pre '68 Dave, that's sort of what I came up with. I got tired of trying to deal with the Handcuff and Rope Seal method and decided to install the new Rubber Seal. My block is a '58 to '62, there should be no reason why I couldn't use that style in this engine anyway. Going to finish buttoning her up this weekend and see how it goes. Thanks

I personally prefer the Neoprene seal in 1956-62 engines. There are two times I have run into that they will not work.
#1, If the seal surface has been turned down during a crank grind.
#2, If the seal groove is not concentric with the crank, and I have seen this.

I assume this is the 235 that was the subject of other posts with photos of the bearings. Those mains with dowels and shims would not be part of a 58 to 62 235, I would think.

Dowel mains stopped mid 55 in 235's, not sure about 261's. 261's seen to have a time line of there own.

I'm not following you guys with the hole Dowel Mains subject. What do you mean?
I'm getting real tired of dealing with this engine. So my thoughts are this: I'm going to install the pan tomorrow and fire her up either later in the day or Monday afternoon. If she leaks, I'm tapping out and the engine will come out as well, I've got another 235 I can throw in there. I also was able to trade a 350 I got on a completely rebuilt 283 from a REPUTABLE engine builder. I got a three year warranty and papers on this one ;-) It will also be a period correct engine for my truck. I'll let you know how it goes either way.

Packing the rope seal into the bearing caps is key here. Taking time and packing it will pay dividends later. There have been discussions of dropping the crank if the engine is still in the truck to really pack the rope seal in the block.

What's the problem with getting the rope seal into the Chinese handcuff tool? The weave will open up to a dimension bigger than your thumb- - - -all you need to do is push on the weave. Just be sure not to put more than 1/2" or so of the seal into the weave, as it must be pulled through the block far enough to release it after the seal is installed. The seal is at least an inch longer than necessary so it can be trimmed flush after it's packed into place.

I cannot understand why people have so much trouble making rope seals work. It's basic shade tree mechanic work that untold thousands of do-it-yourself farmers and tinkerers did for decades. I've installed dozens of them, and made money doing it! Maybe we're just too spoiled by precision-fit parts to dig in and get the job done these days!
Jerry

One other thing, RTV will not stick to a oily surface. You must use a brake clean type cleaner to really dry out the mating surfaces or oil will leach out under the RTV.

Main bearing caps that use dowel pins to locate them were used up to 1955 on 235's, after that, 1956 and later, they used some other method to locate the main caps with the crank. So if your engine has dowel pins locating the main caps, it can not be a '58-'62 235. A 261 is different so you could be dealing with one of those.

RTV on the back side of the rubber seal helps hold the steady in the block. Getting sealer on the back side only while the crank is in place is going to be very difficult.
If you can get a rear main rope seal from Best Gasket Company, you won't have any leaks and you will not have to pack the seal. They use a very good rope material thats pretty easy to install and could be done with crank in the block, but lowered (all the main caps off). I would not try it with only the rear cap off.

Joe

To respond to the question about not following us, the engines with the dowels and shims were made to use the rope seal, not the neoprene one.

Then the handcuff I bought was broke, because I tried every which way and it would not grab onto the rope seal. I would have installed the rope seal if I could get the handcuff puller to work. I'm not spoiled, and I have " Dug in " plenty with this headache of an engine. Please don't insult my intelligence, I'm not an idiot. I have received a lot of useful advice from you and have appreciated it, no need to get all condescending on me. I don't just ask questions from you guys, I try to do my research first. Thanks for the reply's

I wasn't able to make one of those tools work either. I tied a piece of picture hanging wire on the end and used that. I wouldn't suggest doing it without pulling the transmission back and dropping the crank some.

The new rope that is out is nothing like the old seals. I gave up any rope other then from BEST GASKET. They came up with a really good replacement that requires no packing.
For a rope to seal, it must be bigger then the area its going to seal, then get compressed into place. The old stuff could handle being pulled into the seal groove then packed in with a special tool. This new stuff just falls apart. I slightly packed a seal from Best and locked the engine up solid after a break-in. Once cooled down, it ran till it heated up again. I had to replace the seal and follow directions to the letter.

Have you checked your bearing clearance since you have it apart? No seal will work if the crank is bouncing around.

Good luck, and keep us posted.
Joe

I'm not trying to be condescending to anyone- - - -it's just that a simple, routine job that every mechanic worthy of the name used to do as a matter of making a living every few days is suddenly getting impossible to do, and I don't understand why. Either the tools, the seals, or something has changed. The Lisle "sneaky Pete" tool made the job simpler for us, because it had several special-purpose accessories that made the job go about twice as fast as using a piece of copper wire to pull the seal through the groove, but thousands of seals got changed the old-fashioned way.

Somebody help me understand what is different now, 40 years after these seal changes were a matter of routine!
Jerry

Yeah like I stated earlier, my " Sneeky Pete " tool didn't work, that's why I did not install it. I have plenty of background working on cars and I also repair complicated $40K Dialysis Machines.
I have built this truck up from a gutted body mounted on a chassis, I'm not a begginer. Maybe the tools made today aren't what they were all those years ago when you were using them.

I can tell you one thing is the seal material.
I find it almost imposable to cut the ends, even with a new razor blade, without fraying the ends.
The old asbestos seal was easy to cut.

Hi. Yes I have checked the clearance and it's around .0015 to .002. I sealed up the engine yesterday, going to try and fire her up today or tomorrow. We'll see how it goes. Thanks

The K-D Tools #492 kit that's on eBay today is identical to the setup I bought in the late 1960's and used for the next 30 years. The difference must be the seal material. With a seal rope soaked in oil and rolled out to a diameter of 1/4" or so, the chinese handcuff tool would slip it right through the slot and come out the other side far enough to remove the tool, pack the rope into place, and trim it off with no problems. The kit even included a piece of stainless steel shim stock to put between the seal and the crankshaft to avoid scarring the crankshaft with the razor blade. Two funnel-shaped guides were included to help squeeze the seal down as it went into the slot in the block.

The only real difference I can see with the tool set is the fact that the price has more than tripled!
Jerry

So I fired up the engine today. Ran her for a good 15-20min, varied the RPM's up and down, so far NO LEAKS. I'll be keeping an eye on 'er though.

Great to hear! Keep us informed!

Jerry, its the seal material that has changed. The stuff that comes in kits is garbage! It won't hold together or hold its shape like the old asbestos stuff. You can't cut or pack it with out it falling apart. The stuff Best Gasket sells is like the old material with out asbestos added. I worked on a Stanley steamer for a couple years repacking and sealing valves. The material I used was form England and I suspect the Best material is to. It cuts clean with a new knife and requires no packing. If fact if you do pack it any at all, the engine will lock up, I did it! I have a dozen of them out running the streets and not one is even seeping!

Joe

So a little update. Drove the truck for 6-10 miles today and not a single drop of oil from anywhere!!!!!! Man am I glad that's over with.

That's awesome to hear AZ59apacheguy! OK.. please tell us what you did different from the first time you changed it.Just so we can have the same results as you did. That is great news!

This time around I brushed in a very thin layer of Permatex Gasket seal where the lower seal sits. I used a VERY thin layer of high temp RTV between the shims, rear main bearing cap and block assembly. I also put a very small dab of RTV between the seal halves. That's the only things I did differently

Glad it worked out for you! No more drips!