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Allan G
Total Likes: 3
Original Post (Thread Starter)
#844528 03/29/2021 9:59 PM
by Tracey Spear
Tracey Spear
Hello Forum

I took my '69 Thunderbolt out for a long ride this weekend. I hooked up with some AMCA members for a ride. Went with a 79 Guzzi, a 61 Panhead, a Knucklehead rat bike, and an awesome CBX. I rode about 120 Miles on Fri. Stayed with my son, Rode probably 100-120 miles on the ride, and another 120 Sunday to get home. Say 360 total miles.

I left the house with a full tank of oil. Toward the end of the ride I checked and oil was at the L mark. Hmmm. I bought a gallon, added a couple quarts, and strapped the rest to the bike. Upon returning Sunday checked and it was back on the L mark. So I lost about a gallon of oil. Where did it go?

I looked up a thread from Jan '14

Regarding the breather: On the second attempt at joining the cases the camshaft was in a bind. The third attempt I was careful to line up the cam and the breather disk and made sure the cam rotated freely. Still.

I don't think it is burning it. That much oil through the engine would be billowing clouds of smoke. And there are none. Plugs look pretty good, a bit sooty but it runs rich at idle. Exhaust tips are sooty but not greasy.

When I park there are no puddles, a drip or two, that's it. One would think it would be dripping everywhere, but it 's not.

Today I pulled the primary cover and there is definitely oil in the primary, but not much. So there is a crank oil seal issue there, at least.
I drained the sump. This is all the oil from both primary and sump.

[Linked Image from]

I don't know if this picture will show it, but there is evidence of oil on the right side muffler. Left much cleaner, but not spotless, there are a few streaks on the top.

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The only thing I have found so far, was the bolt that secures the oil return manifold to the case was a bit loose. I found that Sunday morning and tightened it. And still lost two quarts on the 120 mile ride home.

Where does a gallon of oil go, without leaving much trace?

Somewhere between running, and running well, I suppose.

I finally got around to better background than my junky garage. Here are a few pics.

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Liked Replies
#844530 Mar 29th a 10:23 PM
by koan58
“I left the house with a full tank of oil. Toward the end of the ride I checked and oil was at the L mark. Hmmm. I bought a gallon, added a couple quarts, and strapped the rest to the bike.”

So when the oil is at the L mark, you can still get another 4 pints in the tank?
Does that bring the level to H?

I wonder if you may be over-filling the tank?
1 member likes this
#844876 Apr 1st a 11:27 PM
by NickL
That doesn't look like an official/original bung in that oil gallery.
They were normally a hex head plug arrangement that sat flush.
I would think someone has wound a cut down allen bolt in there.
You'll need to jack the motor up to get at it.
1 member likes this
#844917 Apr 2nd a 10:12 AM
by gavin eisler
gavin eisler
Hi Tracy,
In the interest of research I looked through your previous posts. You have come a long way and stuck with it, well done.its been quite a ride.
I think you should forget about entering your bike in the show, there will be more shows in the future.
You appear to have two failed oil seals, the one behind the points and the one behind the engine sprocket, more importantly you need to properly seal the oil way drilling plugs. access to the plugs will mean removing exh pipes , motor mounts and jacking / lifting the motor to get access. The factory sealed these plugs with some sort of loctite originally, to get this to work the oil ways will need to be emptied and cleaned so the sealer goo has a chance of working. To replace the points seal the timing needs disturbed and the points AR mech, or EI rotor will have to be removed.To replace the crank drive side seal the whole primary side has to come off. At this point I would consider lifting the whole motor out so I could do the work on the bench.
All this is a fair bit of work, chin up , its only time and a little money. not something to be rushed because of a show.
if it was just the oil seals I would be happy leaving the motor in the frame, the oilway plugs are a different matter, Ive never attempted to fiddle with them with the motor in the frame, maybe jacking will be easier than complete removal. Certainly strip the primary with the motor in place, the rear brake and chain make removing the major nuts easier and anything you can do to lighten the lump will make life easier if you do decide to lift out the motor. hing in there.
PS Are you absolutely certain you have motor oil in the primary? ATF loses its red colour rapidly, is there definetly more oil in there than there should be?
1 member likes this
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