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PCV installation

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Often with the A-Series engines, I find that the sealing area on the rear main bearing cap and the triangular seal flange on the block are worn from the crankshaft flexing. This flexing is usually caused by a bad bearing somewhere in the engine or a badly worn pilot bushing leting the clutch disk and input shaft woble. Machine shops often will "Polish" the scroll area of the crankshaft so it looks nice to the customer. This further increases the "sealing" clearance to the crankshaft. I always write on the tag going with the crank, not to polish the scroll seal area. If you find the rear main cap and the block flange grooved, it will be necessary to line-bore the block. Good machine shops should be entrusted with this task as this operation loosens the timing chain just a bit. Cutting the cap too much will loosen the chain even more. Also, there is a gasket that goes under the block flange.

T-J is on track. I think your issue with the leak is in the rear main area. One can also increase the drain holes size by a 16th of an inch. And, machining with a ball mill inside the groove in the main cap can increase the area for oil to pool and then drain out the holes. Machine about a 3/4" slot to the edge of the main bearing and the length of the two holes.

If you need a replacement triangle plate or just the plate gasket, please advise. I have plenty of these from broken race engines and 30+ years of accumulation.

HTH,
Mike Miller
 
Thanks for the information! I have no idea what level of work was performed by the machine shop and since I'm pulling the engine, how would I tell? Is this something I can measure and report back?
Thanks, Rut
 
It will be very visual. And, you will be able to easily feel it with your fingertips. There will be grooves or burn marks on the seal area. The very worst ones I've ever seen actually had enough of a groove cut that it would not clean up with a normal line-boring. Had to replace cap and flange and then line bore.

Mike
 
Some other thoughts to consider and look for:
1) Oil Pan integrity. Is the rear main cap gasket strip, the grooved part of the pan, leaking? I've seen the solder joints open and leak. Also the junction join between the formed pan rail and the formed strip holder crack.
2) Did the rebuilder mix up small bore gasket strips or channels with the large bore ones and not get enough "crush" on the gasket strip?
3) Was the oil pan rail gasket used, a "cheapy" cut pasteboard stuff, and not a good quality Payen type with small bolt holes and a good fit. This might have left a leak path near the bearing cap to block flange.
4) Could the crank oil slinger ring be broken? The oil as it drains out of the bearing is blocked from direct impingement on the scroll seal area by this ring.

Just some extra thoughts. Trying to think of all possible issues with a very bad leak at the rear of the engine. Also, leaks in the bell housing from the trany drain forward toward the engine. These can appear in the same location as an engine leak. Put some of the green Brad Penn or the purple RP in the trany and see if you get that color of oil puddling as well.

More HTH,
Mike
 
Think some did and some don't.
 
Stopping the Scroll Seal from Leaking
The upper scroll seal clearance needs to be within a few thousandths, hot, to preclude oil from leaking past it. To get it this close is a little tricky. If you remember, this is a piece of cast iron shaped like a "U". Using a piece of flat glass and a very fine piece of sandpaper, sand the legs of the U until they are clear bright. This should take maybe a dozen or so strokes, maybe as much as two dozen.

Now for the interesting part: the holes, three of them for the bolts holding the seal to the block, are just a bit larger than the bolts. Using a large clamp made for woodworking, after the bolts are in snugly but not tight, pull the seal down to the crank shaft, tighten bolts, and install safety wire. Hopefully you have not gotten it too tight, but if it is a real leaker, this should not be too much.

The bearing blocks, including the upper scroll seal, were line bored when the engine was manufactured. Over the years, with rebuilds and wear, the crank diameter changed a bit, as did the seal. It also may have been polished by the rebuilder, destroying the scroll seal tolerance. You know darn well it did not leak as it came from the factory.

Don't forget that a new gasket is cheap insurance. Make one from a heavy paper bag. Use a sealer of some sort, not much, just a bit on your finger.

I am afraid this is with the engine out, sorry.
 
Jack, I'm trying to wrap my head around this, but I don't fully understand. I've read a lot in the manuals, but I'm a very visual person and I'll eventually find a way. Is there a video on this subject somewhere? I hate to drop the engine and take it somewhere, but I will if I have to.
Thanks, Rut
 
Thanks, good info...
Rut
 
yep, I can buy all the info in that link as well.

However, I would expect that a proper line bore is the only real way to mostly solve this problem.

The info I posted was just my solution to the problem. Does Miss Agatha still leak. Very darn little and only after a hard run. My garage floors are epoxy so easy to wipe right up. I usually do it after every 3 or 4 months and it only takes 30 sec.
 
I found the original work order from the machine shop in Mobile, AL that did the work on this 1275. I'm not bashing anyone, but I thought I'd share the prices as well. Remember, this was 2003. Some of this I'm still figuring out.
Labor:
Clean & install C/B $65.00
Hone block $50.00
Rework camshaft $50.00
Polish crank $20.00
Valve job $65.00
Resurface $55.00
Check conn. rods NC
Clean piston and ring grooves NC

parts:
Cam brys $22.96
Exp. plugs $4.40

Grand total of $348.22 with tax and freight!

Considering my problem the thing that most concerns me is the polish crank and I hope it was not to remove the 'scroll seal'.
Rut
 
I hope you find a smoking gun when you pull the engine and look for all the problems mentioned regarding the rear scroll. I had none of those problems and mine would have a constant drip at idle when hot. After I would shut it down it would briefly become a small stream and leave about a 8 inch puddle on the floor. I suspect that the groove under the scroll was full at idle and the small holes could not handle it all. Bottom line was, there should not have been that much oil being forced through the scroll. With the PCV installed - no drip and if I pull in the garage and shut it off, the next day there are 2 or 3 drops on the floor. Thats's been over 2 years ago and it has not changed. My MGB has a real rear seal and it too only drips a couple of drops unless it sits for a long time. It is worse when just sitting, but that's a topic for another forum.

I'm just saying that even if you do everything else you still should install a PCV. Why not at least try it first and then proceed with the rest if needed? JMHO-that may not be worth much.
 
Rut said:
Labor:
Clean & install C/B $65.00
Hone block $50.00
Rework camshaft $50.00
Polish crank $20.00
Valve job $65.00
Resurface $55.00
Check conn. rods NC
Clean piston and ring grooves NC

parts:
Cam brys $22.96
Exp. plugs $4.40

Grand total of $348.22 with tax and freight!

Considering my problem the thing that most concerns me is the polish crank and I hope it was not to remove the 'scroll seal'.
Rut
Click to expand...

Clearly,if this is all, many things were skipped. This isn't even close a "rebuilt engine".. just a little reconditioning. I doubt that the scroll seal was removed. A polish is just that, no metal is actually removed. It's well outside the journal and can't imagine it could be mistaken for one.
 
That was just the basic machine shop checklist. Whoever assembled it had to verify that everything was right and had the right clearances. Since they only honed the cylinders there is no indication of the piston size. Also you would think they would specify how much was taken off the cam journals which is what I assume they mean by "rework cam". Surely they did not mess with the lobes. Valve job probably included guides and seals but not new springs. No mention of the rocker assembly. Definitely just a basic freshen up. Which may have been all that was needed.
 
Exactly, but that's what the machine shop did. The po said that a very well respected local restorer did the rest...bearings, assembly, etc. From the look of the oil leak and some of the other things I've found, nothing will surprise me at this point. I bought this car with a minor rolling restoration in mind to get her running for a few months of enjoyment. The next step is to dismantle her and do the body work and paint as time permits. I'll tackle all of the mechanicals at that time and I'm making notes of what needs to be done vs what I can get by with. Once I catalog everything I'll know where I stand. This ain't no one night stand!
Thanks, Rut
 
But we right here for ya guy.

Answers a pleanty.
 
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