Hydraulic seal easy fix ?

simonfraser

simonfraser

Well-Known Member
Joined
13 Mar 2004
Messages
7,609
Location
Outboards 4 mobo’s, unless you do a lot of miles
Visit site
I have a leaky seal, only drips once a week been going on for a year, so no hurry .....
But the component is stuck, so exploring WD40 / Kroil etc.

Some threads suggest long term contact of the seal with the freeing oil causes swelling.
Tested it on an old seal, yep it sure swells up after a 48 hr soak.

Being a bit slow here, after a few days, why not just cause the seal to swell a bit, leak gone, simple fix ?
 
Last edited:
To get back to the OP's question, I was told by an experienced motorcycle mechanic that a 150cc shot of Shell Advanced motorcycle fork oil injected directly into the carburettor with with a pump oil can while the engine was running would tighten up leaky crankcase seals on two stroke engines.

I was incredibly sceptical.

However, at an oldtimer Moto Cross in the Czech Republic where a British rider that I knew quite well was hoping to take the Championship, I found him heartbroken because his bike would start, but it stopped and would not restart when hot.

Classic crankcase seal failure.

I related my info to him-there were no spare parts or time to fit any-so he whizzed off and came back with some german motorcycle fork oil that translated as having an additive to enhance front fork oil seal performance under arduous conditions-IE, Moto Cross racing.

We made ourselves very unpopular by injecting the oil into a running engine. This enveloped anything downwind in a dense cloud of evil smelling smoke. It cleared the paddock near his pit pretty quick!

It did, however, allow him and his 400 Yamaha to make the start, finish on the rostrum and take the championship.

An old wives tale I believed, but it appeared to have a foundation in truth.

So, solvents WILL soften leaky seals enough for them to stop leaking.
 
Last edited:
simonfraser said:
.......................................

Being a bit slow here, after a few days, why not just cause the seal to swell a bit, leak gone, simple fix ?
Click to expand...
That is how all the "leak fix" snake oils work :-). And they do... The problem is, at the same time the seal gets soft and in most cases disintegrates entirely after a comparably short period of time. A good fix to limp home, I wouldn't call it a long term solution.
 
rotrax said:
T

However, at an oldtimer Moto Cross in the Czech Republic where a British rider that I knew quite well was hoping to take the Championship, I found him heartbroken because his bike would start, but it stopped and would not restart when hot.
Click to expand...

That story reminds me of a smallish Pommy (Englishman) I met on a wartime airstrip (Caversham) which had been converted into a motor racing circuit.

He had a grin from ear-to-ear as he pushed his BSA Bantam towards me so I had a chat with him. He said it was the first time since before the war that he had traveled over 100 mph. (He was laying prone on the bike as he did it to reduce the wind drag) He said he wasn't sure why the bike had extra power but he had turned the engine head around 180° and he thought that had done the trick!

Clive Cooper
 
Last edited:
jiris said:
That is how all the "leak fix" snake oils work :-). And they do... The problem is, at the same time the seal gets soft and in most cases disintegrates entirely after a comparably short period of time. A good fix to limp home, I wouldn't call it a long term solution.
Click to expand...

Agreed. If the seal material swells, that's because it's being degraded by the wrong type of oil.
 
You must log in or register to reply here.

Share this page

Top