Line boring and crankshaft seal

[1972ho]

Will line boring the mains cause a stock diameter crankshaft shaft main seal to leak if the seal sticks up higher than the main bores when the halves of a two piece seal are installed

[ClassAct]

Will line boring the mains cause a stock diameter crankshaft shaft main seal to leak if the seal sticks up higher than the main bores when the halves of a two piece seal are installed

Yes.

[SupStk]

Depends on the engine you are talking about and how much the caps were cut.

[swampbuggy]

So if the question at hand "does" create a possible oil leak, what does one do to resolve the problem ? This question is slanted towards experienced machinists / engine builders. Mark H.

[BILL-C]

We mount blocks in our CNC machine , probe rear bearing housing bore, and remachine rear seal area on crank centerline on all vintage engines that originally came with 2 pc or especially rope rear main seals. Factory alignment is usually terrible.

[1972ho]

Oh and it leaks bad even just running the pump with a drill motor a constant flow line and I’ve used two seals and I noticed the other day that seals halves stick up above the bearings housing.Now can I try a cut the seal even with the housing to try and make it work.

[PackardV8]

Will line boring the mains cause a stock diameter crankshaft shaft main seal to leak if the seal sticks up higher than the main bores when the halves of a two piece seal are installed

Insufficient info for useful advice.

1. What engine? Two piece seals are not a universal design.
2. Rope seal or neoprene? Yes, there are Pontiacs, Packards and many others still out there. Many have neoprene conversions.
3. How much was removed from the bottom cap? How many thou was the main bore centerline raised?
4. How will this be accounted for in the camshaft drive chain or gear?

[BillK]

If it is leaking while priming it then there must be something more wrong than the fact that the block was align honed. I have probably had at least a hundred blocks align honed over the years and have not had a leak issue due to that. The seals usually protrude a little from the block anyway, that is what hold them on place, just like a bearing.

Just curious, is this a Pontiac that originally had a rope seal ? One of my customers bought a "conversion" seal from one of the Pontiac specialty places about a month ago and was not happy at all in how it fit. He ended up using the Ford seal that is normally used for this purpose and had no issues.

[modok]

If it was line bored then the seal bore can be re-cut at the same time. Takes only an extra few minutes.

If it was line-honed only and the seal bore is too small, then the seal bore may have to be re-cut separately.


Chevy type seal where it sits on a ledge, the ledge is the only thing the seal is supposed to hit, sometimes the outside of the seal needs to be ground down if it hits.



Most seals will tolerate .006" runout no problem, or the housing being .004 too small, seals a4re nowhere near as critical as bearings.

Now if we are talking about rope seals or lip seals that are supposed to replace a rope seal.... probably I can't help you, but I share your pain.
Sometimes I find those things so far off.... all I can think is... I bet they always leaked, and it must have been good enough.

[Truckedup]

I messed with rope seals on Inline 6 GMC And Chevy 6 engines....the trick is using an original asbestos seal. Very hard to find and the next option is from Best Seals....and the seal must be carefull rolled into the groove with a mandrel, can be metal or wood....The drag on the crank with a new rope seal is alarming.....Do it right and it won't leak much more than a drop now and then...

[1972ho]

Actually I’ve never had this problem with ford 302 seals but for some reason the last 2 seals I’ve bought since the line hone leak.So I’ve both of the halves sit about .100 above the bearings halves wouldn’t that cause the seas to bow outward when the caps are torqued down and cause a massive leak and not seal at all.

[leahymtsps]

Do you have the means to measure how far the bore is out of round (or tight 90* from the parting line)? Better
to know than to guess.

Tom

[1972ho]

Not until I pull the engine out I would have thought the machine shop would have checked these things before returning the block.What is it these days with some of these machine shops an making sure things are squared away before sending stuff out.Does the end users now days have to tell a machine shop everything that they want to check.The other day I took 3 eagle rods to a shop that wanted them to check and they acted like I was giving them something that they were not set up to do.

[BILL-C]

Not until I pull the engine out I would have thought the machine shop would have checked these things before returning the block.What is it these days with some of these machine shops an making sure things are squared away before sending stuff out.Does the end users now days have to tell a machine shop everything that they want to check.The other day I took 3 eagle rods to a shop that wanted them to check and they acted like I was giving them something that they were not set up to do.

How much would you expect to pay a shop to "check out" the rear main seal area of an old block that originally came with a rope seal and assure you that you can install a seal yourself and not leak? What is the exact procedure you would expect them to use and what would you expect to pay to fix the block when found to not be perfect?

[1972ho]

What rope seal this is nineties ford Motorsports block.