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jlaird

jlaird

Great Pumpkin
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Pulled the flywheel and the back plate, Miss Agatha is not leaking from the oil pump cover, dry as a bone.

Best I can tell at the moment it is not leaking from the scroll seal either. That area seems dry as is the back of the crank flange, the quarter inch of crank that I can see, flywheel, etc.

It looks, more to follow tomorrow, that it is leaking from below that, like at the rear of the oil pan. Sealed with form a gasket though. I will also try to take a pic or two but is kind of tight in there.

The run is down the rear of the oil pan from below the crank as best as I can see tonite.

Will have more tomorrow when I can see more, may have to put the engine up on the work bench even so I can really see good and determin if as it seems that it is not the bottom of the scroll seal.

It is not fun to have old eyes.

Comments and ideas welcome as always.
 
Used a mirror and a flash light, looks like the oil is from the scroll seal after all, from the bottom part. That cover plate, or lip or what ever, is as I remember part of the rear bearing cap.

Don't think I know how to make that snugger, will use a feeler guage on it tomorow. I did check the upper when I assembled the engine and it was .003 but as the bottom is not adjustable I did not check it.

Now just how the heck do I fix that.
 
You might have to use Paul A. method that involves JBWeld and a dremel tool. Never done it, but when it was explained to me I could clearly see how it would work.
 
Jack, if the 948 is just like the 1275, change that stupid freakin' gasket b/w the plate and the engine. I pulled a buddies out THREE FREAKIN' TIMES tryin' to figure out where the leak was comming from. I even sealed the main cap to block cause I thought it might be from there. Turned out to be the stupid plate gskt.
 
It was not comming from between the plate and the engine, that was sealed up tight as a tick. It had a new gasket along with form a gasket and was dry between when pulled.

It is comming from the bottome of the crankshaft at the scroll seal then drips down the rear of the pan. The top of the scroll seal looks dry as a bone.
 
Jack, the 1275 Payen bottom end kit comes with very nice rubber oil pan rail for the front and rear half circles of the oil pan, they have not always been available, Payen reintroduced them again in their gasket sets about 7-8 years ago, we used to be stuck just using the cork pieces. Ok the 1275 and 948 are not the same here they take different pices, so using the 1275 pieces is not a option, and while the rubber pan pieces at one time dd exist for the 948 as upgrade from cork, good luck finding some. Here's the deal cork is a lousy oil gasket, it's like a spounge, it will eventually fill with oil then pass it on, so here's what I did with the 948 I'm rebuilding right now, I use Permatex Ulitimate Black RTV, forget Haylomar in this type of application, you need something that keep this area sealed under pressure, haylomar sucks at that. use the cork pieces but use some of the Ultimate Black RTV in the area, I use it to the seal the cork to tha main cap and then again on outside area of the pan where cork and pan join. hope this helps, this is a much more common leak on these little engines that most folks realize. As for the gasket brand , nothing but Payen, ever.
 
Hey Jack,
If it turns out to be the scroll area of the crank, I did the Paul A. jb weld repair and found it to work fantastically. There's a recent thread here on BCF about Paul closing up shop, but I still have the instructions on how to perform the repair if you're interested.
regards
Mark
 
Mark, thanks, I have that.

I am presently looking for the clearance for the oil seal top part.
 
Ok, here is what I did. Removed top cap from the rear of the engine, scroll bearing cover.

Cleaned all very well. sanded the ends a bit on a peice of glass with sand paper.

Fited with new gasket and a very think coating of form a gasket.

Used a large c clamp to hold it down as I tightened the bolts to make sure is was a close to the crank as possible.

I found another one of those parts in my stash and did note that it did have marks on the surface next to the seal that indicated it actually touched when it was installed. Hmmmm.

This one I just put on is tight beleive me, I could not get the point of a dental pick under it.

Oh yes, Hap, it is not leaking from the pan it was/is the seal thatd does not exhist on the rear of the crank.
 
I'm not aware of a published clearance. A lot depends upon the bearing housing bore and the crank. Don't let the machine shop polish the scroll area of the crank. They like to get everything nice and shiny slick, but all it is doing is opening up the area where the scroll has to work. The bearing bore is the same all across the rear main bearing tunnel. The little triangular piece was originally bored at the factory at the same time the block was align bored.

The little triangular piece has the semi-circular bore in it for the top half of the scroll seal. It has 180 degrees of clearance. It is free, but limited by the bolt holes, to move in all directions except past the parting line with the bearing cap. So, clearance is something you have to worry about for the 180 degrees of the circle. Side to side clearance is just as important as top clearance. This triangular piece needs to be aligned with the rear main bearing cap at the parting line too. Otherwise you will get leaks out one side where the cap is shifted away from the crank and potentially interference on the other side. If you remove the triangular piece, which you did, then you are going to have to take your best guess at where to align it side to side.

Sorry to rain on your situation, but I've seen too many engines with over-heated scroll seal areas. Also badly worn ones to the point that the counter screw grooves were worn into the bearing cap and triangular piece. Bluing (using Dykem machinist layout fluid) and indexing can help figure out where to put the cap side to side.

HTH,
Mike Miller
 
This is not the first time the cap has been off, was off when engine was rebuilt. In fact as I remember it was off when I got the engine.

The crank is Old Old Old but never used before, it is standard both mains and journals. However, it was polished lightly. My machinest grew up and learned his trade in England and even knows what an A 40 is. LOL

The second cap I have does indeed have screw groves marked on it by the old oil over the years.

In any case, great comment, it is on now and I guess I can do no better, so will live with the outcome what ever it is. Can not leak more oil than it was.
 
Yea, let me get one tomorrow.
 
To add to what Mike said, if it's too tight against the crank I seen them lock down the crank on the engine stand. To add to what Mike said you like the same amount of clearnece as you have here as you have with main cap side, about .002" is perfect, you can sneak in the with feeler gauge, and measure, not easy, but can be done.

Even if everything is perfect with a A series engine, you'll still get a drop on two on the garage floor, it's the nature of the reverse scroll, when the engine is turned off, there will be some oil there and it will probably end up dribbling out. The old joke about a A series is if there not leaking a drop here and there, then it's because there is no oil in the engine :smile:
 
:lol: All too true.

"Scroll" and "seal" were an unfortunate pairing of terms, IMO.
 
Hey Jack,
If the engine is already out and sitting on a bench, why not do the "Paul A". repair? It'll solve all the questions brought up in this thread. You have to be careful of course, and once you start there's no turning back, but I think it's the best way to fix the problem on a street use engine(I guess it doesn't do much good on an engine that is regularly run at extremely high RPMs, due to the large amount of crank flexing that is going on). I used a super cheap($8.00 I think), low power, "Dremel type" tool kit from Harbor Freight (you could just about stop the bit from turning with your fingers)to do the job. It worked perfectly! Super small and light with no torque to speak of, so it reduced the possibility of accidently gouging the repair area. One of those magnifying glasses that is mounted on a work stand would be a great help also. give 'er a try man! I'll even mail you that "dremel" tool if you want.
regards
Mark
 
DrEntropy said:
:lol: All too true.

"Scroll" and "seal" were an unfortunate pairing of terms, IMO.
Click to expand...

Dude you're crackin me up! If you don't mind, I'm going to send all my posts to you first for editing!
 
Thanks for the offer Mark but I have several of my own.

I am surely glad the clown that designed the scroll is dead. He can not longer engineer this kind of dumb stuff.
 
It’s almost like it was designed to leak wading for the front seal, no rear seal still makes me grin when people say there rear seal leaks ... and the draft tube. My guess it was suppose to leak oil to keep the dust down on the road to keep the dust from getting in the car. Maybe they had a major share of Duckhams and Castrol? Jack I have the rivergate seal on my car I know everybody says they don’t work but mine seems to hold just fine I polished the crank surface with crocus cloth and when I installed I was very careful to make sure it was aligned perfectly with the crank. Hope it all works out.
Scroll Seal is an Oxymoron.
 
Installed flywheel today, now on to a few other project while it is out like paint for the generator, Proper timeing chain seal, thank you Mark, and the tranny.

More to follow. Oh also vacumned the house and got the underground sprinkler system working as well. Enough for today.
 
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