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Old 10-02-2013, 02:14 AM   #1
tgb3040
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Default Question about oil through the crank vent on a 72 Triumph?

Hello,
I just bought a 72 Triumph Bonneville 650 engine. It has an open crank ventilation; open into the transmission that is. I am not used to this since I only wrenched 69 and earlier before. I mounted a new alternator stator. I wanted to make sure everything was alright so I ran the engine without the transmission cover for about 5 minutes. During this, almost a pint of engine oil came through and out on the ground. This seems a little excessive to me, but I don’t know what to expect. Do I need to tear the motor apart in search of a fault, or might this be considered normal?

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Old 10-02-2013, 02:57 AM   #2
'59
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Default Re: Question about oil through the crank vent on a 72 Triumph?

'open into the transmission' ? , do you mean primary chain side.
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Old 10-02-2013, 03:08 AM   #3
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Default Re: Question about oil through the crank vent on a 72 Triumph?

Quote:
Originally Posted by '59 View Post
'open into the transmission' ? , do you mean primary chain side.
Yes, into the primary chain side, sorry.
And I ran it without the chain case cover...

Last edited by tgb3040; 10-02-2013 at 03:13 AM.
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Old 10-02-2013, 03:44 AM   #4
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Default Re: Question about oil through the crank vent on a 72 Triumph?

It's normal. There's no seal on the crank on the later models, there are also a few small breather/oil return holes (I believe).

The primary and engine share the same oil.
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Old 10-02-2013, 03:48 AM   #5
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Default Re: Question about oil through the crank vent on a 72 Triumph?

Those motorsrun without a drive side oil seal to share engine oil with the primary. tere are three small drillings to allow the oil to drain back to the sum at a certain level. Run with the primary open &it's going to end up on the floor.
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Old 10-02-2013, 04:07 AM   #6
'59
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Default Re: Question about oil through the crank vent on a 72 Triumph?

a pint sounds like a heck of a lot but then a little oil does appear to go a long way. Not saying that there is a problem but i'd just look to make sure there was a good oil return in the tank.
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Old 10-02-2013, 07:06 AM   #7
tgb3040
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Default Re: Question about oil through the crank vent on a 72 Triumph?

Yes, I am starting to think: oil pump.
Now I can't get the motor started to check the return flow. I have a spark and I have fuel, so this indicates to me oil in the crank case.
I have good oil pressure, but the non return valve in the return piston might be leaking... That would give me these symptoms.
Hmmm, now, of to work.
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Old 10-02-2013, 08:03 PM   #8
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Default Re: Question about oil through the crank vent on a 72 Triumph?

Emptied the crank case, got the motor started, good return flow, no problem there. Not nearly as much drainage this time as the last. So things are good. Thanks everybody.
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