Crankcase oil seal leaks

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Hi All.
The cranckase oil seal leaks trough the cranckshaft.
I have changed with a new one, but it leaks too.
Someone supply a tighter oil seal?.
Other sugestions will be apreciated.
Thanks.
Piero
 
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My seal on the DS leaks. Ive tried three seals. They were installed with great care but to no avail. Having a dry belt drive it is just not what
one would want. If you have a stock setup you would never know it is leaking.
I run the Jim Comstock breather valve which should really eliminate leaking.
I dont know, a multi lip seal of some kind? You tell me!
 

lazyeye6

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After installing the Comstock breather and a new DS oil seal I still had leakage. Then I found that the leakage was from the lower mounting bolt of the inner primary case. I re-installed those bolts using a gasket sealing compound on the threads and, voila, no more leakage at all..
 
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Hi.
Mine leaks from oil seal!
Piero
After installing the Comstock breather and a new DS oil seal I still had leakage. Then I found that the leakage was from the lower mounting bolt of the inner primary case. I re-installed those bolts using a gasket sealing compound on the threads and, voila, no more leakage at all..
 

texasSlick

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Leakage with a new seal is usually caused by a rough, scored, or out of round crankshaft seal journal.

Excessive play in the main bearings, either due to a worn crankshaft journal, excessive clearance in the main bearing outer race to case, or simply a worn out main bearing can also be a factor.

Slick
 

Time Warp

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The best one is folk who drag the bearings or inners off the journal without heat expanding them (and that is only a hot air gun) and put gall scores in the seal surface which is minimal as is, scored and you are all but stuck with seepage under the seal lip.
 
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Hi.
I understand, but this is not the my case.
The engine is on the stand without primary transmission cases with oil seal in view.
I have drained the old oil and fit the new one.
After five days, without started the bike or turned the cranckshaft, the oil seal has began to leak.
I understand that after the first days the oil was gone from tank in the sump.
So, if the oil seal leaks with the bike on the stand i can understand that the crankshaft journal is worn and i need a tighter oil seal.
Piero


Leakage with a new seal is usually caused by a rough, scored, or out of round crankshaft seal journal.

Excessive play in the main bearings, either due to a worn crankshaft journal, excessive clearance in the main bearing outer race to case, or simply a worn out main bearing can also be a factor.

Slick
d
 
Last edited:

Chris

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Hi.
I understand, but this is not the my case.
The engine is on the stand without primary transmission cases with oil seal in view.
I have drained the old oil and fit the new one.
After five days, without started the bike or turned the cranckshaft, the oil seal has began to leak.
I understand that after the first days the oil was gone from tank in the sump.
So, if the oil seal leaks with the bike on the stand i can understand that the crankshaft journal is worn and i need a tighter oil seal.
Piero



d
Hi Pierodn
My crankshaft oil seal leak turned out to be porous cases. Had them coated.
Chris
 
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Seals with a steel OD can leak on the OD, rubber on the OD has a better chance of sealing but a sealent on the OD is even better, steel or rubber will benefit.
 

Time Warp

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Is it that obvious ?
Time to wipe it down and a application of talcum powder to see the path for sure ?

Even rubber bodied oil seals I use Wellseal applied to both surfaces and left the suggested 5 minutes (at least) before installation.

No doubt the seals used are the same item which came from where ?

If it leaks that badly between the lip and seal and the seal is the right one there would have to be a defect of some sort surely (Is there a X ring or labyrinth seal available I do not know)

Worse case (Not that I have given it any thought and it is the early morning) if the journal was compromised in some way that was not reversible, maybe a Speedi-Sleeve could be used for a repair somehow.
 
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How many people/mechanics that change a main bearing on the DS...afterwords polish off the hundreds of microscopic or bigger scratches made on the sealing surface of the crank?
+ Yes, wicking loctite on metal bodied seals.
 
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Hi Piero,

i am once bitten, twice shy on this problem/thread......

do you have inspected your timings side or did you a general service on the parts in the timing side on your bike lately/last years?


my bike had a blown crankshaft oilseal on the timing side and i didn`t know about that kind of problem....

drove me almost crazy!!!!

i tried and tried and tried to fix the problem on different ways from checking the piston rings, making new breathing routes with pcv-valves and so and so on.......

My crankcase was pumbed up with oil and the oil went through the driveside oilseal [as through the tachometer drive].
As you describe your problem.


Do an oil pressure test.

when the pressure isn`t right:


don`t hesitate to service your timing side:

service the oilpump....put in a new oilpump sealing [NMT272] ....put in a new crankshaft oilseal [#048023......#21 for 1972 Commandos] and a new points oilseal.....check your timing chain adjustment [you MUST use the intermediate shaft support plate tool]
and check the slipper .... this is done in a few hours and you get peace of mind for several years!


if this isn`t the problem:

put in a pcv-valve [i get me one from NYC Norton...this is top of the notch!!!]

and

get an oversize oilseal for the drive side [there is for sure a company near your place who can make an oversize oilseal for your dimensions]

hope it helps and you get your problem solved!

chris
 

DogT

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I've had the bolts of the primary side mounting studs leak into the primary also. I replaced the bolts with studs and nuts. The lower nut I had to grind down so the chain wouldn't hit it. I also used red or blue locktite on the studs into the crank. It also makes for easier assembly. You can get the proper studs at the auto store. I think they were 1" 1/4-20 UNF on one side and 1/4-20 UNC on the other. I had one bolt that was stripped out when I got the bike, I just went up another size with that one. This was a hint from hobot a long time ago. I also use a smear of RTV on the primary to crank gasket. My leak is in the crank flange. I didn't do a good job with the Hylomar but I'd have to split the whole engine down to fix it. I wish there were a fix for that. The proper breather would help, bit it leaks just sitting, not too bad, a flower base takes care of it. I also don't let it wet sump with a dreaded manual oil ball valve.
 
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