Author Topic: Oil Drip from Points Cover (Read 4411 times)

Bob Wessner · « **on:** October 31, 2005, 07:13:33 PM »

We've had some nice riding days here abouts recently, but I know they are going to come to an end soon. When they do, I'm planning to tackle some minor oil leaks, the usual along the left side (shifter seal, alt. cover, etc.) but have noticed a minor drip of oil occasionally at the bottom of the points cover.

In looking at the parts diagram (attached below) I see an o-ring (red arrow) at the rear of thin shaft (blue arrow) and I'm assuming this is the source of the leak. Has anyone had occasion to make such a fix? How is the shaft/seal fitted? Seems like a very thin shaft is running the whole points/advance assembly. Anything I should pay particular attention to? I've never had occasion to remove the entire points assembly and advance unit before.

Jonesy · « **Reply #1 on:** October 31, 2005, 07:21:44 PM »

The seal I'm familiar with is on the actual crankshaft (the part the thin shaft srews into) and is held in place between the 2 halves of the crankcase. This is the actual shaft seal. I've had the advance unit off of mine before, but I've never removed the small retainer shaft. There is a seal removal tool that will pull out the whole seal and allow you to drive a new one in- without dismantling the motor! (and it just so happens I have one, in case you'd like to borrow it...)

See #7 in the diagram:

Bob Wessner · « **Reply #2 on:** October 31, 2005, 07:41:31 PM »

Quote

without dismantling the motor!

Dan,

That was my real fear as I was writing the post, that someone would com back saying it requires removing/tearing down the engine

.. in which case I would probably, unhappily live with it a while. I hate oil leaks. If it can be done from the outside, yea! I would definately like to borrow the tool some time, thanks.

Clyde · « **Reply #3 on:** October 31, 2005, 09:55:48 PM »

I had a leak on my F1 from behind the points plate, but it turned out to be the O-ring which seals the post in the crank shaft. The shaft/post is screwed into the crank shaft and I just used two nuts tightened together to remove it (8mm thread from memory in the shaft and 6mm on the post)
I would be interested in a picture of the tool that allows you to insert the seal. They have a lip to locate them, but if there is a tool I would like to make one up
Regds Clyde

Bob Wessner · « **Reply #4 on:** November 01, 2005, 02:20:03 AM »

I was going to add both the o-ring and the seal to my next parts shopping list just to be safe. Thanks, Clyde.

CB750F2 · « **Reply #5 on:** November 01, 2005, 03:33:34 AM »

G/Day Bob. I have had a similar experience to Clyde. I suggest that you change this small seal and see if the leak stops. If you do go ahead with this I would be interested to know if you find any play in the locating spigot on the advance mechanism and its mating hole in the end of the crankshaft. The diameter of the spigot on my F2 is 4mm and the hole in the crankshaft is 4.25mm. Th result is a sloppy fit and probably incorrect timing. Pat from Aust.

Bob Wessner · « **Reply #6 on:** November 01, 2005, 04:09:01 AM »

Quote

If you do go ahead with this I would be interested to know if you find any play in the locating spigot on the advance mechanism and its mating hole in the end of the crankshaft.

Will do. I just thought of one other question. Re: the shaft, I am assuming it is a standard right-hand thread (i.e., loosen it by turning counter-clockwise)?

Jonesy · « **Reply #7 on:** November 01, 2005, 05:22:16 AM »

Here's the puller. When used carefully, the seal can be removed while the engine is still assembled. I was able to replace the sprocket driveshaft seal on my 750 this way.

bryanj · « **Reply #8 on:** November 01, 2005, 05:48:44 AM »

The sprocket/driveshaft seal is NOT lipped as i remember it but the crank ones are so you have to pull the bottom half crankcase to do it. If it is the actual crank seal prosnally i would wait till it leaks more and then with the engine out change the cam chain and maybe primary chains as the most work is humping it out

Robert · « **Reply #9 on:** November 01, 2005, 06:27:58 AM »

Quote from: Bob Wessner on October 31, 2005, 07:13:33 PM

We've had some nice riding days here abouts recently, but I know they are going to come to an end soon. When they do, I'm planning to tackle some minor oil leaks, the usual along the left side (shifter seal, alt. cover, etc.) but have noticed a minor drip of oil occasionally at the bottom of the points cover.

Same here

(nice riding days recently plus dripping from the same place.
It gets progressively worse and starts to have some influence to the ignition too
I have a dead spare engine left that I'm going to use to practice before tackling the good & running engine, but would be interested in all information I can get to change the crankshaft seal without splitting the case. On noticing the tool pictured above I'd be especially interested what's the proper way to use it.

Jonesy · « **Reply #10 on:** November 01, 2005, 06:50:47 AM »

Well, if the seal is lipped as Bryan said, then the cases would have to be split in order to make the change. I didn't know this... sorry if I got anyone's hopes up!

Bob Wessner · « **Reply #11 on:** November 01, 2005, 07:44:14 AM »

Quote

I have a dead spare engine left that I'm going to use to practice before tackling the good & running engine

Likewise, I too have a "training engine." As of now, I would consider disassembling an engine to be beyond my current skill level.

I have my fingers crossed the o-ring replacement will help, and the tool almost looks lethal, probably would not get past airport security.

dusterdude · « **Reply #12 on:** November 01, 2005, 07:59:26 AM »

bob,you can buy that seal puller at almost any auto parts store in your area,there are not too expensive either

Clyde · « **Reply #13 on:** November 01, 2005, 03:10:07 PM »

Bob,
The thread of the post/shaft is normallly threaded, ie undo by turning counterclockwise.
The seals are definitely lipped for the reason that there is oil pressure behind them. I have changed an engine sprocket seal without splitting the cases, by similar devious means, but I am not sure I would tackle the crank shaft seal.
I agree with above i.e. I would wait for it to get a lot worse before pulling the engine.
Regds Clyde

Bob Wessner · « **Reply #14 on:** November 01, 2005, 03:13:15 PM »

Thanks. So I take it that changing the o-ring alone will not likely help?

Clyde · « **Reply #15 on:** November 01, 2005, 04:14:34 PM »

It did in my case
Regds Clyde

Bob Wessner · « **Reply #16 on:** November 01, 2005, 04:49:16 PM »

Thanks Clyde, will go forward with that much anyway.

mhurcomb · « **Reply #17 on:** November 02, 2005, 01:21:52 AM »

I replaced my crank oil seal very easily.Pryed out the old one,ground the lip down on the new seal,smeared three bond sealer round the outside and tapped it into place.Could'nt face pulling the motor apart that I had only recently rebuilt.The reason it leaked was I discovered I had been supplied the wrong seal.The new one hasn't leaked yet.Got to be worth a crack.

CB750F2 · « **Reply #18 on:** November 02, 2005, 02:55:28 AM »

G/Day again Bob. Sorry for the slow response but I see that Clyde has answered your question about the type of thread on the advancer post. During my recent restoration of my F2 I left out the crankcase seal assuming that the seal could be fitted after the crankcases were assembled - trap for the inexperienced. I machined an insertion tool which allowed me to successfully fit the seal without splitting the crankcases. In your case I would do what others have said - change the "o" ring fitted to the advancer post and see what happens. Pat

Bob Wessner · « **Reply #19 on:** November 02, 2005, 04:28:06 AM »

Quote

I machined an insertion tool which allowed me to successfully fit the seal without splitting the crankcases.

Pat, sounds like there could be a market among SOHC/4 owners for your tool.

I will give the o-ring a try for sure, thanks.

Gin Rickey · « **Reply #20 on:** August 17, 2007, 10:54:16 AM »

Bob, I know it's been a while, but do you remember how things turned out? I'm new with motorcycles alltogether, and am trying to start up a '73 cb350f for the first time in a long while...not geting enough spark...but as my battery tired out, I saw the same leak--coming directly from the points shaft. I stopped, of course. Now, what? The leak is only a drip, but the motor only cranked for 5 minutes worth of revolutions, hardly a ride's worth of spinning. (I'm guessing the amount would be significant if I were running it longer). Any advice would be great. Thanks.

Bob Wessner · « **Reply #21 on:** August 17, 2007, 12:47:17 PM »

Sadly, still have the drip, very little, just an annoyance really because.... I haven't attempted any fixes yet.

But, I am getting a lot of riding in.

jtb · « **Reply #22 on:** August 17, 2007, 04:04:26 PM »

Quote from: CB750F2 on November 02, 2005, 02:55:28 AM

G/Day again Bob. Sorry for the slow response but I see that Clyde has answered your question about the type of thread on the advancer post. During my recent restoration of my F2 I left out the crankcase seal assuming that the seal could be fitted after the crankcases were assembled - trap for the inexperienced. I machined an insertion tool which allowed me to successfully fit the seal without splitting the crankcases. In your case I would do what others have said - change the "o" ring fitted to the advancer post and see what happens. Pat

Thanks for that, Pat. It makes me feel better.

CB750F2 · « **Reply #23 on:** August 17, 2007, 10:29:13 PM »

G'Day Jtb. It's been almost 2 years since I installed that seal without splitting the crankcases and there is no sign of a leak. In my case I couldn't put it off because there was no seal installed at all!! Pat

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Author Topic: Oil Drip from Points Cover (Read 4411 times)

mhurcomb