Grey motor rear crank seal

[Fraze]

Advice needed please. I' m a having trouble with the rear crank seal on a newly rebuilt engine. The "rope" seal provided in the gasket kit , in my opinion, is not adequate. It is very soft which means it can't be packed in, and when cut frays badly, and threads can get between the engine block and bearing cap which would not be a good thing! Can anyone suggest a packing more like what was originally fitted to these engines?  Thanks Frazer

[ardiesse]

Fraze,

Unfortunately, the rope seal is all you have to work with.  This is what was originally fitted.  Correction: I think the original rope-type seals had asbestos in them, but asbestos is viewed with great suspicion these days.

I recently did a rings-and-bearings job on a grey motor, and installed the rear main bearing oil seal wrongly.  It spun in the groove, got chewed out, and the engine leaked oil at a great rate, after maybe 50 miles.  And you can imagine what fun it is removing and stripping down a newly rebuilt motor, just to cure an oil leak . . .

This is what wiser minds told me:

Soak the new seal in engine oil for at least 24 hours prior to installation.
Install the seal halves in the block and the rear main bearing cap.
With your thumbs, press the ends of the "u" down well in both the block and the rear main bearing cap.  Do not push down on the sealing surface of the seal - you want the crankshaft to do that when it's installed.
With a good pair of flush-cutting side-cutters, cut the excess away, but leave maybe 1/2 mm protruding from each mating face.
Put the rear main bearing cap in place (without bearings, without crankshaft), and tighten the bolts down just past finger-tight.
Remove the cap, and with a scalpel or sharp craft knife, trim away the bits of the seal that have got between the mating faces.  Or push them down into the groove with the knife blade.
Repeat the above two steps as often as needed.  Ensure that there is no gap where the two halves of the seal bear against each other.
When you're satisfied that there are no more threads between the mating faces of block and rear main bearing cap, wipe the oily ooze away from the mating faces, install the bearings, lay the crank in place (gently!), put a thin bead of sealant on the mating faces of the rear main bearing cap (but stay away from the seal), install and torque up the main bearing caps, and continue the engine assembly.

Please tell me the newly rebuilt motor is not complete and in the car . . .

Rob

[fcwrangler]

Great info Rob, this will come in handy when I pull my engine down and check that all is good and get the head done.
Jim

[Fraze]

Thanks for this info Rob, good stuff. My engine has done about 1500 miles since rebuild and I pulled it out yesterday because I got fed up with the oil leak. I have been asking around and a guy I know who works for an engine builder with lots of grey motor experience and he told me that they wont use the rope supplied in the gasket sets, but use a Ford packing, he is getting specific detail for me and I will post it when I get it. My engine is ex an FB and had never been pulled down before. The rear seal was a much more solid packing, like a pump packing which didn, t fray when cut. It was white in colour and felt very waxy.Obviously time and use had changed it but you can tell it is far superior. (PS I said solid - DENSE is a better description) Frazer

[ardiesse]

Fraze,

I think you're on to something.  I rebuilt a grey motor in 1984, then another in 2006 and the last in 2012.  In the 22 years, I noticed that something had definitely changed in the composition of the rear main bearing oil seal.  Dense is a good way of putting it.  I have a rope-type seal left over from a blue 3.3 I rebuilt in 2000, and it is preformed to shape, and feels a lot stiffer than the newer grey motor rear main bearing seals.  I was thinking of using it, but the red/blue motor rear main bearing oil seal groove is wider and less deep than the one on a grey motor.

Most industrial bearing/pump/seal supply houses sell pump packing by the length, and it looks awfully like the material for rear main bearing seals.

Let us know what you discover.

Rob

[Fraze]

SUCCESS!!!!! It was a pain pulling down a 1500mi engine but the oil leak from the rear main is cured. I had a long talk to the engine builder guys I know and the Ford packing turned out to be a false trail, it was a nice dense packing but too narrow for the grey groove. They have prepared a number of competition Greys and they machine the block and bearing cap to suit a more modern seal. I did not go into that because I wasn't going to head down that track
Instead I took on board Rob's (Ardiesse) advice of "fit and try"! With the crank out I fitted the "rope" seal as supplied in the gasket set. I left it about 1 mm proud at each end but tapered each side (like a cone shape at the ends). I had lots of trouble cutting the strands of seal with hobby knife and razor blade so I used a pair of very sharp (surgical) scissors.I then fitted the bearing cap and snugged down the bolts, then took it off again to inspect for wayward strands of seal. I repeated this exercise 3 - 4 times then fitted the crank and did it all over again until I was absolutely satisfied that the cap would go on without strands of seal getting between the cap and block. 
I took the FC on a run yesterday and when I checked this morning there is not a single drip of oil on the garage floor - much to my relief. Cheers, Frazer   (and yes I did put oil in the sump!)

[hsv-001]

I do remember something about a large socket we used to use when trial fitting and trimming this seal if that's any help ? Haydn

[lonestar395]

Some useful advice there ardiesse, I will remember that when I am assembling my off topic engine in the near future...Stuart

Sent from my SM-G900I using Tapatalk