Front and rear main seal questions

[NAM VET]

OK, so now test fitting some components of my 230 ci motor. I had bought a Best Gasket set, which did not include a rear main seal, so in my exuberance and haste to have everything ready for my motor, inadvertently bought TWO inside half circle main rear rubber seals. But today, when I was attempting to insert them, they just don't fit. The two halves are just too wide and don't appear to have the correct profile anyway. I think the rear inner seals should just easily slip into their groove, but there is not way these are going to fit. Maybe if I boiled them in water to soften them perhaps. Even with lube, they are a no-go.

So called M37' Garage, and spoke with one of CT's mechanics, and stated my situation and he believes I have an early motor and hence need the two part external rubber seal, attached to the two plate halves. I have three holes in the rear cap, and three in the rear block. So I have ordered a rear outer plate two part seal. But I recollect when I was by my machine shop I pulled out part of a inner rear rubber seal. And besides, he has returned every part of my motor to me, and there is no two part rear seal in the discard box. Here are two pictures of what I am dealing with.

The Best Gasket rear main seal is part #3675, "Dodge/Ply 6 218-230 '51-' 59, and Chrysler/DeSoto 6 '48-54.

here: [URL=http://s663.photobucket.com/user/h ... .jpg[/img][/url

and: [URL=http://s663.photobucket.com/user/h ... .jpg[/img][/url]

next post is about the front main seal..

thanks,
\
NV

[NAM VET]

And now for the front seal. I test fit the half circle plate that attaches with two screws and arches over the front main cap, and then test fit the cover, which is located with two pegs, then the timing cover goes over that. But reading my TM"s, it mentions ".... placing the front oil seal, then mounting the plate..."

I have the big gasket that fits between the front of the block and the back side of the plate, but am wondering if there is also some sort of seal I should use. My machine ship did insert a gasket after pressing out the old timing cover seal and pressing in a new one. In this picture of the two plate gaskets, mine is the larger one on the left, but should I also be using either the cork or thin gasket in addition to the big gasket?

The blue seal is for the sprocket, not the crank front seal. See "timing cover set.."

http://bestgasket.com/engine_catalog_ye ... ......[510]

[ashyers]

NV,
The rear seal looks like the two we've installed. Here's a photo:

rear seal.JPG (87.54 KiB) Viewed 2021 times

FYI, the seal in the photo you included is in backwards. Note the direction of the lip.

I will say that the seals we've used were not terribly consistent dimensionally. When you mock things up check the rotation of your crankshaft frequently as you go. Once we hit the final torque with the seal installed the seal bound up the crank! It took a bit of massaging to get it sorted. Seems the mold is a bit sloppy and left enough flash to effect the fit in the bore and pressure on the crank's sealing surface.

I don't follow what you're trying to say in regard to the front seal. Our engine had a slinger/seal/gasket arrangement to seal the crank's snoot. The "hoop" was sealed to the block w/ two pieces of O-ring stock. The engine plate had a gasket and so did the timing cover. Hope that helps.

Andy

[just me]

The front seal is a not quite standard lip seal. The order of assembly is front cover, paper gasket, seal. The factory books do not show a slinger in the drawings or the parts break out, but both engines I've worked on had them. I will be putting it back in mine. I made two tools for the front seal. One to install the seal into the cover because of that protruding ring on the backside. The other to center the seal on the crank during front cover assembly. (That one is shown in the manual)
My block uses the expensive and not leaky rubber rear main. (53 block) The holes for the plate seal are not drilled or tapped in my block or main bearing cap. The machined are of the block and cap are much larger than my civilian engine and a rope seal just sort of disappears in it like a snake in the Grand Canyon.

[NAM VET]

well, I think I am getting this seal thing sorted out. I reviewed the pictures of my motor I took when I had it out, before I took it to the machine shop, and two of them show the two part flange seal on the outside of the block. Then too, this AM i boiled my rubber inside two part seal, and still it just won't fit without crushing it. So I will install the two part flange seal when I get it in a couple of days.

I put the crank in, with small beads of Hylomar under both front and rear caps, and was greatly relieved when I could keep turning the crank as I tightened the caps down to 80 pounds. I put the ARP bolt lube on the big half inch cap bolts, with new Grade 8 lock washers.

Now, as for the "front oil seal", after studying the exploded parts diagrams, and understanding which seal the manual refers to, the "front seal" is the one in the timing cover. I had a new one put in with a gasket first by the machine shop. And besides, why would the crank's front need another seal anyway, as the area where the cam and crank sprockets are is oil bathed anyway, and there are several oil drain holes under the half moon aluminum front seal plate. I don't have any sort of Oil Slinger up front. As soon as my piston ring adjustable taper ring gets here, I'll file my rings to fit, and put the pistons in.

NV

[Kaegi]

I would find the front oil slinger. everyone I have rebuilt has had them. if the front seal fails and you have an oil slinger it will barely leak at all. without the slinger it will pour oil out.

[NAM VET]

K, good advice, but do you have a picture of this "slinger" and where it goes, how, and who may have it?

NV

[NAM VET]

Well, in reading old threads on the front seal/slinger, it appears that whether or not the "slinger" fits depends on which front cover seal is installed. I went out and checked the blue one that came with my Best Gasket set, and was not installed by my builder. CT mentions this seal in the Best set, says is junk. Mine is labeled ASA. I had ordered one from VPW, and the machine shop installed it an older one, a National seal with a part number of 8532580 on the rim. A search for this National # does not come up with any such seal number. Maybe it was specific to military motors? My "new" seal has the rear protruding ring on the seal metal rim.

I kept the old removed timing cover seal, and it is a National number ?50303. And does not have the rear "lip." And my motor did not appear to have any sort of "slinger" either. I suspect the old removed timing cover seal is quite old. And I cannot find it with a search either. There are recommendations for seal 6636s, which supposedly does not have room for the slinger. I wouldn't mind having the latter installed, but I just also had the gasket replaced that goes between the cover recess and the just replaced seal, and it would surely be damaged.

I would only like to do this once, and have to think what I want to do. More reading, I guess.

NV

[Kaegi]

maybe I have been working on too many polys these last years and am imagining the oil slingers on flatheads. do any of them have oil slingers? now you have me wondering.....

[just me]

I had one in my engine, but the new seal won't fit it. So, it is left out. It isn't in ANY of my flat 6 manuals for this vintage.

[NAM VET]

Well, I am up to about $220 for my rear main seal odyssey, and still don't have one that works for my motor. The one I got today, the two piece six hole outside rear seal/plate came in a military package dated 1952. The dealer told me it would come in a military package. But this one is over a half century old. The only thing I remember about 1952 is getting spanked by my dad for breaking a milk bottle in the garage. I cleaned the cosmoline off the two parts, and the rubber seal is hard as iron. It would wear a groove in my crank.

So called another distant dealer and he said he has one, much newer, not the Best Gasket model, and has it on the way to me. So much for trying to have all my parts ready ahead of time for my rebuild.

the saga continues......

NV

[Kaegi]

I had one in my engine, but the new seal won't fit it. So, it is left out. It isn't in ANY of my flat 6 manuals for this vintage.

ok thanks so I wasn't falsely remembering them.

[Cal_Gary]

Have you tried John Bizal at Midwest Military? His stuff is fresh and he'll ensure you get the right seal.
Gary

[Elwood]

Well, I am up to about $220 for my rear main seal odyssey, and still don't have one that works for my motor. The one I got today, the two piece six hole outside rear seal/plate came in a military package dated 1952. The dealer told me it would come in a military package. But this one is over a half century old. The only thing I remember about 1952 is getting spanked by my dad for breaking a milk bottle in the garage. I cleaned the cosmoline off the two parts, and the rubber seal is hard as iron. It would wear a groove in my crank.

So called another distant dealer and he said he has one, much newer, not the Best Gasket model, and has it on the way to me. So much for trying to have all my parts ready ahead of time for my rebuild.

the saga continues......

NV

Nam Vet, what is the serial number on your engine block? I'm surprised that your engine has the old style external rear main seal.

I've had so much bad luck buying NOS soft parts that I won't buy them any more. Doesn't matter if the package is still sealed, this stuff is at least 50 years old, and much of it (like leather seals) wasn't that good even when it was new.

I had to chuckle when I read your comment about trying to have all of the parts ready ahead of time. As much as I try to do the same, things never work out that way. I've lost track of how many unexpected problems have come up while working on this truck, everything from new production parts from major military parts vendors that are clearly not made to the correct dimensions, to damage in places that one has to wonder about the intelligence (or lack thereof) of a previous owner, driver, or mechanic.

[NAM VET]

one would think something fairly simple, like a main seal, would be an easy thing to resolve. But apparently not. I just finished reading an 11 page forum post on a military jeep forum about their problems with rubber or rope seals. They have the same problems, rope seals vs rubber. Sounds like Victor made thousands of defective seals which are included in many and various sets, and are not distinguishable from good rubber seals until you try to install one. The jeep people's RMS problems just go on and on....

My truck is a Dec '52 build, but i doubt the motor is original to the vehicle. My motor had at least one Depot rebuild, because I can see where a military rebuild specification tag was at one time attached to the block, and later removed at a subsequent rebuild. Knowing how depot rebuilds were done, the army would typically pull a bad motor, and get a replacement from depot, and the removed motor would go back to depot, get rebuilt, and sit on the shelf to be sent out to replace the next engine coming in.

The Army does not want to deadline a vehicle waiting for a motor to come back, but wants it up and operational as soon as possible. My truck was last a Missouri NG truck. And sometime after going to the civilian market, had a casual rebuild, with poor standards. One rod was non standard, and much heavier, so I replaced it with one matching the other five to make balancing it much easier. The owner I bought it from had owned it and used and garaged it for 26 years, and mentioned that the motor had been rebuilt, but I suspect by someone before he acquired it.

I think many of these trucks very likely have replacement motors from Depot maintenance that are an earlier or later version.

My block number is US 24 882. My block is drilled for the six hole rear main seal plate. Happened upon the FelPro version of a six hole RMS, BS6300, so will drop by my local auto supply house, and have one or more ordered. I just assumed that Best Gasket was the only source of a RMs. Perhaps there is only one company making the imperfect differing RMS's anyway. And they are in assorted seal kits for these trucks.

I am picking up the better National front timing cover seal today, my machine shop said he will remove the just installed older National seal, and put this allegedly better one in it. He took hundreds of pictures of my motor as he tore it down, and has them on a flash drive for me.

And to further muddy the issue, I just compared the two oil pressure relief plungers I got from VPW, and they differ from the one that was in my motor. The one in my motor is the same as the one in the TM, so it is going back in, correctly placed. Some one on this site recently posted as the reason for their motor's failure a backwards oil pressure plunger. I am not going to assume that the different plungers all work fine in our Military partial bypass systems.

Back in '68, when I was at Ft. Riley KS, for my ROTC 6 week summer camp, our final formation had a speaker, some old crusty battle hardened General, and I very clearly remember his brief admonition that we were never to assume anything. That the ammo would show up, the radios would work, the enemy would do the expected thing, the tanks would show up, the maps were accurate, and so forth. His words have stayed with me ever since. Sometimes to the amusement of my family. "We are all going to the mall, if we get separated, our rally point is .... " My kids would respond, but we all have phones, and I would reply, yes, but what if your phones fail, don't assume anything.

Had fun shooting at our usual Tuesday late evening IDPA practice at our local gun shop's indoor range. I like to vary my handguns. Took my Browning High Power, the very one Bill Laughridge at Cylinder & Slide made up for me for my deployment to Desert Storm back in '89. I bought my truck from him last summer. He has done all my pistols ever since.

Now, out to the garage before it gets too hot for me.

NV