346 V8 Main Seal Leak? HELP?

[gary griffin]

My 1942 engine was running fine and I had it pulled to paint the engine compartment  and the engine. When hoisted at about a 30 degree angle oil came out of the center area  near the main seal at a fairly good stream. Is this a normal circumstance or what??

Also we broke a couple of head bolts trying to remove a bracket that was there for an after market oil filter I imagine.

Any help and or advice would be appreciated, I am in a real rush but want to do it right.

garygriffin@q.com    or 206 276 0398

[buicksplus]

The 42 engine should have a rope seal at the rear main.  If it is in good shape, I would not expect a steady stream of oil to pour through it with the engine at that angle.  I suggest you replace it.  I have replaced these seals without removing the crankshaft, but it is tricky. You need to remove the oil pan, flywheel, and the rear main bearing cap.  Loosen the other main bearings and you can move the crank enough to get into the rear bearing and R&R the old upper seal.

Broken head bolts are common with these engines.  You will need to remove the head to resolve this.  Sometimes broken bolts leave a bit of bolt above the block deck.  In that case, I have managed to carefuly remove the fragment with vice grips after days or weeks of soaking with penetrating oils.  I have heard of welding a nut onto the fragment with a wire feed welder.  Drilling them out can work if you're patient and start with a pilot hole near the center of the bolt.  Keep expanding the hole until you can peel the remnant into the center of the hole.  Avoid using easy-outs -- if they snap off (they often do), you will be stuck with hardened steel in the stud.

If you tear up the threads in the hole, you can usually save it with a heli-coil thread insert or drill and tap to a larger size.

Personally, if I had the engine out of the car like you do, I would consider tearing it down and having the bores, bearings, and crank checked out and remachined if necessary.  Most machine shops can fix the broken bolts while they are at it.  It will take more time, but unless you know the history of the engine, this is a great opportunity to get the engine checked an made up to spec.

Good luck!

[tozerco]

Gary,

A little advice if I can on the broken head bolts - I had 14 of them in my block.

If all other options fail (I had no luck at all with trying to weld nuts to the top of the broken bolt - the welds break long before the bolt will release), you will have to drill them out. I fully support Bill's advice on "Easyouts". Break one of those off in a bolt and you are in REAL trouble. Breaking one off is almost guaranteed because the ends of the bolts are generally what has rusted as they sit in the water jacket. When steel rusts it gets bigger and the end of the bolt ends up larger than the hole you are trying to pull it back through.

Grind what's left of the top of the bolt a bit flat and counter-punch the dead centre of the bolt. Drill a small diameter hole (no larger than about 3/16) right through the bolt being careful to remain vertical to the block surface. Drilling is easy as the old bolts are relatively soft.

Take your head and re-fix it to the block with a couple of the head bolts screwed back into other, cleared bolt threads - the head can then act as a drill guide for you.

I don't like helicoils for a number of reasons and used "Time Serts" and have been very happy with the result. Use the largest size drill that will fit snugly through the head bolt holes that is the size (diameter) of the old threads and drill out the rest of the old bolt - you can't help but have the new holes drilled perfectly perpendicular to the block using this "head as a drill guide" method. The kit for these inserts comes with a drill bit that will drill for a 7/16 coarse (I think - check this) insert but this drill will not fit through the head holes. Shouldn't matter by then though because you will already have drilled the larger holes and the Time Sert drill will track on that larger hole.

The kit also includes the 7/16 (I think) tap for the new thread to take the Time Sert insert but you will have to remove the head to start this cutting as it will not fit through the head bolt holes. You will need to be careful to ensure that the tap is vertical to the block - I actually made up a 2 inch thick timber "head"with larger head bolt holes drilled through it and bolted it to the block where the head would be.

Once the new thread is cut, screw in the Time Sert insert (I used some high temperature Loctite on the OUTSIDE thread of the insert. Don't get it on the inside!) with the special seating tool provided and you have a new, clean, clear proper sized thread for a new head bolt. I have also added some (I think it was called Permatex) sealer to the END of the bolt before I screwed them home to help ensure the bolt ends don't rust and cause the repeat problem the next time the heads have to come off. Someone else on this forum put me on to that trick so you might be able to search older posts for the correct description of this sealer.

Best of luck,

[gary griffin]

Do anybody have the bolt size, thread count, length, and bolt grade.

[TMoore - NTCLC]

Just give Terrill Machine Shop in DeLeon, TX a call, and let them know you need the bolts - they have the correct grade bolts and will ship them same day.  Be sure to specify whether they are the longer (water inlet/outlet) or regular length bolts.

I have never known a rear main to leak while the engine was tilted.  Are you sure it was coming from there?  I would think that if the sear was that loose, then you should have had oil dripping out while the engine was running.  Double check - make sure oil didn't just run down to that area (maybe the distributor was off while the engine was being hoisted, and oil drained out of that opening? )  Anyway, I would look for other culprits before I condemned the seal.

Good luck - and keep good notes, I will be just a few years behind you with my restoration!

[kkarrer]

Before you change that rear mainseal check to see if there's a new style neoprene one available.   The guys at Terrill Machine or Best Gasket will know.  Replacing it isn't too tough, but eitherway oil shouldn't be "pouring out" from there.  You'd have noticed it with the engine running almost certainly.  It sounds like the oil might have come from above that area so check it out by tilting it again and hold a rag against the block above the main as you do.  You didn't say whether or not your car is standard or hydra-matic, but I'm guessing that it's standard.  I mention it because pulling an engine with the standard tranny is a much easier deal than messing with resealing that hydra-matic etc.   Drilling those head bolts WITHOUT using the easy outs is the best way to go unless you remove the head.
Ken Karrer 41 6227D coupe

[harry s]

The best replacement rear main seal is the Mercedes mid 1980s diesel. The part number is 001 997 12 41. NAPA used to carry these seals although I think they had a different part number. Harry