45 oil tank

Oil running out of vent

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rocket ron
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45 oil tank

#1

Post by rocket ron »

Happy New Year.
I have a problem with my repop oil tank (now there’s a surprise). The tank empties through the vent pipe into the engine. There is obviously a manufacturing fault but without cutting it open I can’t see what it is.
Is it feasible to seal off the vent pipe and use a vented tank cap instead?
Thank you
Ron
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Re: 45 oil tank

#2

Post by Pascal »

:cry: Are you sure it is the ventpipe causing your oilproblems, not the thick return line?
If it was mine, I'd cut the tank open..fix it and weld it shut.
A good welder shouldn't have trouble doing so.
Just cut it open half an inch or so from the weld.
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Re: 45 oil tank

#3

Post by RooDog »

Just a question, and I am not a 45 person, but, there should only be three oil fittings on that tank; feed, return, and a balance tube, not really a vent, but a pipe that balances the internal pressure between the tank and the engine's cam chest. Correct?

There should be no opening to the atmosphere, no?

So it should be easy enough to check if the fittings and internal piping are correct, and clear.

Also: Do not overfill the oil tank above the FULL mark on the dip stick.....

If I am wrong about any of this, please let me know.....
....RooDog....
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Re: 45 oil tank

#4

Post by Pascal »

RooDog wrote: Fri Jan 07, 2022 2:57 pm Also: Do not overfill the oil tank above the FULL mark on the dip stick.....
Naahh...just leave enough room, say an inch or so, between cap and oillevel..
It will help cooling on hot days.
In winter, I ride with as little oil as possible..just to keep the temp up.
45's are not that difficult to satisfy...they're easy and forgiving..
rocket ron
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Re: 45 oil tank

#5

Post by rocket ron »

It’s definitely the vent pipe, Pascal. Had already checked the return. When I removed the cam cover to check pump bush I could see the oil flowing until the tank was empty. Had another think about vented cap; even if it did work there would be oil vapour issuing from the cap, not a good idea.
I guess your solution is the only one. ☹️
Thanks
Ron
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Re: 45 oil tank

#6

Post by flatboy1950 »

I had this exact problem & after disconnecting each pipe one by one , I found the oil was draining back through the return pipe from the scavenge pump. This pipe is routed differently from the original set up , but the solution is simple : I drilled a small 1/8 " hole in the return pipe just to the rear of the filler cap. Centre punch it carefully & then drill. I had a thin plastic pipe connected to the vacuum cleaner right next to the drill point to such up any swarf.
Certainly worked for me !!!
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flatboy1950
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Re: 45 oil tank

#7

Post by flatboy1950 »

I forgot to mention that this return pipe dips deep into the tank & was siphoning back into the engine. The small hole stops the siphoning !!
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Re: 45 oil tank

#8

Post by Pascal »

That's strange Flatboy, cos the return pipe already has a small hole just in front of the dipstick.
This hole allows dripping; THE sign your scavanger is working and oil is being pumped thru the engine and back..

But again, here the problem lays in the ventpipe; the thin pipe from the chest to the tank, mounted with a bolt to a stud.
The stud has a pipe soldered to it inside the tank, and here's the culprit probably...; either the soldering wasn't done properly...or the pipe itself is cracked.
You'll need to open the tank to check unfortunately..

Is it an original or repop tank?
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Re: 45 oil tank

#9

Post by flatboy1950 »

My siphoning tank was a Repro for sure !!
Never yet had a problem with an original tank.
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rocket ron
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Re: 45 oil tank

#10

Post by rocket ron »

UPDATE.
The pressed in fitting for the vent pipe had an extra hole in it that allowed oil to flow into the engine.
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My friend put a blob of weld on it.
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closed the access hole and the job was done.
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Moral of story: check everything on an aftermarket tank.
Ron
rocket ron
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Re: 45 oil tank

#11

Post by rocket ron »

FIY
Inside an oil tank (not mine)
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