Author Topic: Oil leak  (Read 1423 times)

Offline adriangsmith

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Oil leak
« on: July 03, 2018, 07:32:35 PM »
I have an oil leak from the bolt above the sprocket in the picture below. It coming up the bolt stem.  Did i miss something when rebuilding the engine?

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Offline Nurse Julie

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Re: Oil leak
« Reply #1 on: July 03, 2018, 08:17:10 PM »
I have looked through all my old photos but, bloody typical, not 1 pic showing that area. But, I think it should be a blind hole, ie, goes nowhere, because a casing bolt goes in it. Has a too long bolt been put in there in the past and gone through too far maybe?
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Offline Nurse Julie

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Re: Oil leak
« Reply #2 on: July 03, 2018, 09:21:31 PM »
Just looking at your pic again Adrian, what bolt hole are you referring to?. If its the one at the top, its an external fixing point so no oil will come out of there, am I looking at the wrong hole?
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Offline adriangsmith

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Re: Oil leak
« Reply #3 on: July 03, 2018, 09:27:39 PM »
Hi Julie. Yes the bolt at the top. It goes through the casing you can see the bolt shaft going back into the casing in between the cast ribs. Quite a long bolt at 80mm or so.

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Offline adriangsmith

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Re: Oil leak
« Reply #4 on: July 03, 2018, 09:29:30 PM »
The vertical bolt just to the left upper of the sprocket

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Offline adriangsmith

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Re: Oil leak
« Reply #5 on: July 03, 2018, 09:33:41 PM »
No oil leaks from the casing joins at all. It is leaking out of the bolt stem between the 2 ribs.

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Offline Nurse Julie

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Re: Oil leak
« Reply #6 on: July 03, 2018, 09:41:37 PM »
Yes, i see which one you mean now. Not sure why you have oil coming up through there, unless you have put a too long casing bolt in and made a hole in the casing or as Oddjob says, maybe something not aligned properly. Is there much oil coming up?
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Offline adriangsmith

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Re: Oil leak
« Reply #7 on: July 03, 2018, 09:43:23 PM »
Quite a good seep once its revved up

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Offline Nurse Julie

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Re: Oil leak
« Reply #8 on: July 03, 2018, 09:49:26 PM »
I know i had real issues with those casing bolts on my engine, trying to fit the correct length bolt to each hole was difficult. I measured all my bolt holes with the vernier in the end to make sure i put the right size in the right place. really, it can only be a slight misalignment or the bolt has gone through the casing. No other way oil could come up the thread, the bolt / thread shouldn't be anywhere near oil.
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Offline Nurse Julie

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Re: Oil leak
« Reply #9 on: July 03, 2018, 10:04:52 PM »
Here is a pic with the sprocket off, I can see how if an over long stud had been put in, it could easily have caused a crack. The crack may not be visible as it could be internal not external [ Guests cannot view attachments ]
« Last Edit: July 03, 2018, 10:07:00 PM by Nurse Julie »
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Re: Oil leak
« Reply #10 on: July 03, 2018, 10:15:24 PM »
Also, if you say it weeps when you rev the bike, the oil is under pressure. The bottom of that bolt hole is very close to the oilway junction from the oil pump that feeds the gearbox. You could try removing the oil pump, put an airline up the oilway and see if anything comes up the bolt hole, if it does, there is a crack there somewhere.
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Offline adriangsmith

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Re: Oil leak
« Reply #11 on: July 03, 2018, 10:42:36 PM »
Cheers Julie,
I will check tomorrow.
I'll take the sprocket off as well so i have a clear view.
Triumph Thruxton 2004
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Honda CB400F   1976 (current project)

Offline Nurse Julie

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Re: Oil leak
« Reply #12 on: July 04, 2018, 09:14:20 AM »
I thought of that Ken but it may have been done by a previous owner. If the engine had been apart before and the wrong length bolt fitted, then Adrian has put the correct length bolt in which is now leaving a space under the bottom of the bolt for the oil to get out. The wrong long length bolt may have caused the damage but also hidden the damage by putting pressure on the crack.
LINK TO MY EBAY PAGE. As many of you know already, I give 10% discount and do post at cost to forum members if you PM me direct.
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Offline adriangsmith

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Re: Oil leak
« Reply #13 on: July 07, 2018, 08:04:29 AM »
Bolt measured the correct length.
Oil leak stopped with copious amounts of threebond liquid gasket on the threads and down the bolt shaft.

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Offline Bryanj

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Re: Oil leak
« Reply #14 on: July 07, 2018, 04:30:50 PM »
That would suggest to me that there is either damage or crap on the crankcase joit

 

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