Oil laek from dynamo gasket

Singles, twins and fours.
Keithwainwright
Posts: 4
Joined: Tue Feb 12, 2019 8:58 pm
Contact:

Oil laek from dynamo gasket

Postby Keithwainwright » Mon Jun 03, 2019 5:25 pm

I have had my 650 huntmaster a while now and have just finished rebuilding the engine and it runs spot on ,starts first kick ticks over nice and revs freely with no smoke or burning oil . I left it to stand for about six weeks and drained the oil from the crank before starting as the oil had disappeared from the oil tank ,it wasn't on the floor so must be in the sump. It still runs good but now I have a leak from the dynamo cork gasket. How can this be ? .If it got in this space where the chain is how can it drain back. I cant see how it can get in or out . Can I drill the bottom of this cavity to let it drain on to the pump area . Any info is usefull thanks

Mick D
Holder of a Nylon Anorak
Holder of a Nylon Anorak
Posts: 196
Joined: Tue Nov 27, 2018 2:49 pm
Contact:

Re: Oil laek from dynamo gasket

Postby Mick D » Mon Jun 03, 2019 5:59 pm

Hi
It might be just coincidence - reseal the dynamo cork and see what happens.
Regards Mick

Keithwainwright
Posts: 4
Joined: Tue Feb 12, 2019 8:58 pm
Contact:

Re: Oil laek from dynamo gasket

Postby Keithwainwright » Mon Jun 03, 2019 7:25 pm

I don't see how oil is supposed to be in this cavity at all .If I look at the gasket the part of the outer and inner cover creates a cavity for the chain and two sprockets to run and this appears to be separated from the other cavity's. Thanks for the input

Mick D
Holder of a Nylon Anorak
Holder of a Nylon Anorak
Posts: 196
Joined: Tue Nov 27, 2018 2:49 pm
Contact:

Re: Oil laek from dynamo gasket

Postby Mick D » Mon Jun 03, 2019 7:34 pm

Hi
Hot grease, the recommended chain lubrication, can manifest as oil.
Regards Mick

Simon.Gardiner
Holder of a Silver Anorak
Holder of a Silver Anorak
Posts: 812
Joined: Tue Aug 02, 2011 11:37 pm
Location: South West (Bristol-ish)
Contact:

Re: Oil laek from dynamo gasket

Postby Simon.Gardiner » Mon Jun 03, 2019 9:41 pm

Keithwainwright wrote:I don't see how oil is supposed to be in this cavity at all .....

Apparently it can come through the idler pinion bush. The 'proper' idler bush for the timing cover is different to the other idler/camshaft bushes as it has a 'return thread' cut into the end of it to work oil back into the timing chest. Maybe it's not 100% effective.
Also I've seen a few covers where the 'ordinary' bush (without the thread) has been used instead, so maybe it's not actually that necessary!
And as Mick says, your 'oil' may be more to do with what's been happening to the grease.....

SG
'55 Huntmaster, '56 VH, ' 51 VH, '80 R100RT, '00 Sprint ST (but all those Ariel parts can only make one running bike...)

malcolm.johnson
Posts: 80
Joined: Fri Aug 19, 2011 12:09 pm
Contact:

Re: Oil laek from dynamo gasket

Postby malcolm.johnson » Tue Jun 04, 2019 8:05 pm

I do not know about Huntmaster engines, but the BSA pre unit twins use a cork washer which is slightly compressed under the dynamo drive sprocket for the dynamo chain, to seal the only source of oil. Very similar engines. None of any of my BSA twins ever had that chamber fill with oil.

Keithwainwright
Posts: 4
Joined: Tue Feb 12, 2019 8:58 pm
Contact:

Re: Oil laek from dynamo gasket

Postby Keithwainwright » Mon Jun 24, 2019 8:00 pm

Took the timing cover off and there was oil up to the bush . So I put a small hole in the cavity about 20 mm up the side so that a little splashes about . The problem went away

User avatar
alan.moore
Holder of a Golden Anorak
Holder of a Golden Anorak
Posts: 1141
Joined: Sat Jul 19, 2014 1:29 pm
Location: Leicestershire UK
Contact:

Re: Oil laek from dynamo gasket

Postby alan.moore » Tue Jun 25, 2019 2:46 pm

Keith,
Is it possible that when it wet sumped, whilst standing for 6 weeks, the oil level reached the idler pinion bush and over time worked its way into the chain cavity?

Cheers
Alan
1939 VH Redhunter;1942 RN WNG;1951 Triumph 6T Thunderbird;1970 BSA B175 Bantam;1986 Yamaha SRX600 single
http://cloggymoore.wix.com/triumph-pre-unit-6t


Return to “Four stroke”

Who is online

Users browsing this forum: No registered users and 5 guests