Packard Forum Index » Post-War (1946-54)

Fitting the 'rope' rear oil seal on my 1951 288 has become problematic . . . . .

The seal is from a Kanter engine gasket kit I bought a couple of years ago. Brand is 'GraphTite' and is graphite-impregneted, the Real McCoy I'd say.

I obeyed instructions and worked the seal as far into the grooves on the block and bearing cap as I could first by hand, then rolling and tapping the seal halves into place with round mandrels / steel bar etc. Ultimately it was still sitting quite a way out above the groove.

So the problem is it's so tight that when I barely nip up the bolts on the rear main cap you cannot turn the crank at all even when I torque bolts to only 70ft pounds. (Spec is 90 - 95 ft pounds). The cap is sitting about 1/16inch above the block edge . Seems like the seal is too big/bulky and I am worried that a binding seal will burn the journal or lock and spin in its groove.

Advice I've had differs. Some reckon tighten the cap fully and the seal should compress into place when left a while. Then an engine rebuilder reckoned the seal shouldn't be that tight and it should have some resistance but not excessive.

I'm hoping someone can advise me about this please.

Main bearing cap. Rope seal goes into furthest groove



Seal coaxed into the groove as far as possible



Crank in place and ends of rope seal trimmed



A small piece of the seal



Instructions

Dear Larry:

Given you have the motor out of the car, why not pull the bearings out of the caps and see if it turns then. I'd also put a little silicone grease on it. Then try seating the thing using a bar on the crankshaft.

Packard specified a wooden dowel of same diameter as crankshaft.

Hope this helps.

Thanks for your reply Tim. I guess what you're saying is that I should apply much more pressure and flatten the seal so it doesn't bear on the journal so much -? Then turn the crank to seat the seal in?

At the moment the rear main bearings aren't even in contact with the crank because the seal is holding them away. The crank turns easily by hand when the seal isn't in place.

If the seal is the correct one (and Kanter hasn't sent me a 'too big' seal) then it must somehow eventually seat properly. But I just don't like putting too much brute force on everything by tightening the cap down really hard. I suppose I'll give it 90ft pounds and see what happens . . .

I'll try what you recommend. Will have to hit the wooden dowel hard to get it to flatten the seal more . . . . hope I don't shred the seal doing that!!

Dear Larry:

What removing the bearings from the caps does is prevent the crankshaft from being bent.

This way the rear main cap can be cranked down without any intereference. You can just leave the others off and remove the bearing from the rear main cap. Then keep working at it until it turns.

Then check to see if there is any interference from the main bearings.

Thanks Tim - now I get the picture! Glad I didn't tighten the cap down yet. I'm still wondering why the seal is so large. I wouldn't have thought for a moment that it would be necessary to exert so much pressure just to get it into place.

HOW would someone be able to do a seal replacement (using this size of seal) with engine in situ when the seal takes so much effort to 'squash' into shape! Reading other posts it seems it would be 'hit and miss'.

Ok . . . an update on fitting the seal. Took your advice Tim and removed all main bearings (except #1, which I left in with cap loose for the crank to spin on). Placed crank in position and tightened rear cap evenly on each of its four bolt to 30 then 50, 70 and eventually 90 ft lbs, giving the crank 4 or 5 rotations between tightenings to 'burnish' the seal as suggested in the WM.

It was tight (and the crank is a tad heavy to get in/out on my own), so my arms are aching as a result, but it did turn ok and freed up a little more each time. Now spins with moderate resistance at 90 ft lbs.

Took the rear cap off and the seal has flattened out wide right to the edges of the cap and slightly beyond. Looks ok so I'm pleased with the outcome. I had underestimated the nature of the rope seal. It has compressed dramatically despite my early doubts that it would. I will post a photo of the installed seal if I remember to.

Thanks again for the useful advice. Pistons and rods in next!

Thanks for the great compliment Larry.

The genuine Packard stuff was a lot better, but those days are long gone. I actually don't understand why they would leak given there is a slinger, but I have dealt with diesel oil leaks that were even more obscure.

My experience with rope seals are that they are extremely snug even to the point of not being able to turn the crank with a crank shaft socket and a breaker bar. If you have the seal installed properly as it seems that you do it is kind of the nature of the beast as weird as that may seem. I have messed around with a few rope seal engines and they do tend to drip a bit of oil nothing major just a very slow drip. I have never used the new style graphite impregnated style but I have heard good things about them.

It's good to know that the seal should be quite tight initially . . . removes my concern about 'burning' the crank or having some other sinister outcome. The instructions said 'no grease' but mentioned using a little assembly lube so I used some molybdenum assembly lube on it and it does spin a bit easier, as now I can wrestle the crank around by hand. I'm happy with the result! Thanks for your comment Anthony.

Hi Larry,
I am an old a certified automotive machinist from the late 60's and early 70's and have installed many rear main rope seals with and without impregnated graphite. If you're still not sure, do this. Regardless of what the instructions say, rope seals require lubrication. I've seen dry seal installations that wore the knurl completely off of a crankshaft resulting in a continuous and problematic rear seal leak. I've also seen them get so hot that the heat hardened the seal and turned the crankshaft sealing journal blue. The trick to a successful installation is to oil soak the seal which is a dual benefit in that it adds pliability (softens) and allows the seal to easily form to the groove. In addition, it also lubricates the seal during the break-in period. Do this and you won't have to worry about friction burning the crankshaft and it will spin much easier by hand. Just lay the seal down on a clean surface and use an oil squirt can to apply the oil and then work it into the seal with your fingers. Saturate it enough that its thorougly soaked but not dripping, hand form it to the groove as you described above, install the crank and see how much difference it makes in the rotation.