Model 31 Oil Problem

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JEAN-NOEL
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Re: Model 31 Oil Problem

Post by JEAN-NOEL »

Just a thought : check the vent pipe to see if it is not blocked. In the return pipe you have not only oïl, but air bubbles, générating air pressure in the oïl tank if is not correctly vented.
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Rob Harknett
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Re: Model 31 Oil Problem

Post by Rob Harknett »

Sorry I did overlook you checked the oil level etc.
In the past when this topic has cropped up. It has been said not to trust the one way valve type devises that could fail, also said they reduce the oil flow dia. I use a tap on one of my bikes, at least I am in control of that, I will have to forget to turn it on also forget to check return. I also seem to recall a long vent pipe, intended to allow any dips to go on the rear chain, getting blocked by oil pooling. Not enough pressure to drive it out the pipe. I am sure you will find, one or both the faults mentioned to check, will find why your oil stopped returning etc.. hope its not anything more serious, good luck.
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Expat
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Re: Model 31 Oil Problem

Post by Expat »

Hello teebee. Is oil definitely leaking from the cap and not a pinhole or tiny split in the neck of the tank or welded area there?

Regards

Steve
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These are my principles, if you don’t like them, I have others. (Groucho Marx)
teebee67
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Re: Model 31 Oil Problem

Post by teebee67 »

Thanks,I will check the breather pipe. Ran the bike (on the stand) again today - good oil return even after 10 mins or so. What I did notice was, when I revved the engine and the oil return increased, some of it sprayed right at the filler cap hole. I'm wondering if the cork washer is not sealing and that is where the oil is coming from. It looks OK to me but I don't really know how it should look good.
I'm only old on the outside.
Mick D
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Re: Model 31 Oil Problem

Post by Mick D »

Hi

A blocked breather coupled with spray hitting the cap would give you the problem you have - try to eliminate both

Regards Mick
teebee67
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Re: Model 31 Oil Problem

Post by teebee67 »

Thanks Rob, I am going to look at the tap type valve with an ignition cut out (I know I would forget to turn it on otherwise). Steve, I am pretty sure it is leaking from the cap - just found that when the cap reaches it's "closed" position it can be tightened a little more though it is very hard to turn further, I am going to give it a ride with the cap tightened really hard and see what happens. Burrage it hasn't got anything fitted to the vent outlet (hadn't when I bought it) but I will check it isn't obstructed. Jean-Noel the returning oil does seem to be a little "frothy". Mick, I'm not sure why the oil sprays towards the filler, not sure if I can change it's direction but I'll give it a go.

Thanks all, some good info here. I've been fitting a key type ignition switch today but I will double check all the advice tomorrow.
I'm only old on the outside.
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Duncan
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Re: Model 31 Oil Problem

Post by Duncan »

Hi Tony, what year is your bike and what type of oil tank and filler cap do you have?
teebee67
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Re: Model 31 Oil Problem

Post by teebee67 »

Hi Duncan, it's a bit of a mongrel. It's a 1961 AJS rolling chassis fitted with a 1959 Matchless G12 engine. It's the standard oil tank fitted with a standard "press and twist" type cap which is vented and has a cork washer a gasket.
I'm only old on the outside.
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Duncan
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Re: Model 31 Oil Problem

Post by Duncan »

Hi Tony, these are usually quire oil tight unless the gasket is damaged, I am still trying to understand why the return feed is spraying on the cap, is it possible that there is something in the return pipe partially obscuring the return hole making it spray?
teebee67
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Re: Model 31 Oil Problem

Post by teebee67 »

Hi Duncan, I'm going to give it a good dose of looking at tomorrow. I'm thinking it might be out of position or bent.
I'm only old on the outside.
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