Author Topic: Oil leak  (Read 225 times)

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Offline Dhall32720

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  • Location: Florida
Oil leak
« on: April 17, 2019, 07:32:49 PM »
I have an oil leak on my 76 400C. Seems to be coming from gear shift somewhere, can’t pin point it. I replaced gear shaft seal, counter shaft seal and collar, neutral switch and seal because it was cracked, push rod seal, tach gear seals and both blank seals on either side of the neutral switch. Still leaking. It’s coming from the left rear of the motor, hard to tell where it’s coming from. My question, is there s gasket between top and bottom of crank case. And if I replace gaskets and split the case does the top half come off and all the gears stay in place and not fall out?  I have to get leak fixed, driving me crazy.

Offline 5port

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Re: Oil leak
« Reply #1 on: April 17, 2019, 08:14:59 PM »
Hi!  There is no gasket as such between the two halves of the crankcase.  The joint should be sealed with a special semi-hardening rubber gasket cement, applied liquid before the two are assembled.  It is possible that this has not been applied correctly on a rebuild.  Also, apart from all the possible leaky seals, the gearbox overflow tube should discharge on the chain/sprocket area and, if you have a crankcase compression leak, overfilled gearbox or a 2T oil pump internal leak it could show there.  Also, the 2T oil feed tube goes past and could be split and the 2T tank overflow tube is in that area and may show overflow there if you fill to the filler neck.  Cheers

5port
5port

Offline Dhall32720

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Re: Oil leak
« Reply #2 on: April 17, 2019, 08:23:29 PM »
Appreciate the info 5 Port, that is where my leak is, I will check there out before I split the case for sure. Thanks again.

Offline Ozhammer

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Re: Oil leak
« Reply #3 on: April 17, 2019, 11:10:04 PM »
I had a leak in that area, which turned out to be the gearbox selector rod blanking plugs. These are located slightly above and to the rear of the neutral switch, so might be worth checking before you consider splitting the crankcases.

Just make sure you use the original parts if replacing them as the superseding parts are not as good a fit.

HTH

2 strokes are all I need!

'74 S3
'75 CB400-4
'78 RD250E
'78 RD400E
'79 RD400F
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Online Bluehaze

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Re: Oil leak
« Reply #4 on: April 17, 2019, 11:47:54 PM »
Method to find leak source:
Wash suspect area well, allow to dry, apply talcum powder.
When it begins to leak again, it will be evident from where it starts.

Offline Gr8uncleal

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Re: Oil leak
« Reply #5 on: April 18, 2019, 08:28:49 AM »
Method to find leak source:
Wash suspect area well, allow to dry, apply talcum powder.
When it begins to leak again, it will be evident from where it starts.

RD riders should google "talcum powder" to see what it is!