HELP!! REBUILD LEAK!!

[mellow]

So, i finished putting my engine together, fitted leak kit and guess what, It Bloody Leaks!!!

It has a small leak from the case join just behind the left seal ( arrowed in picture)



Any advice men? Do I have to completely strip it again wasting all those gaskets/seals? Can I undo the lower case nuts to remove lower case and re apply sealer? I put plenty of three bond on I thought. Guess I must have missed a bit to the side of where the seal sits

[kostas]

It does seem that you have pinched the seal right on the split line.
It may cause the cases not to sit completely flush...

Is it a genuine Yama seal?

[mellow]

Yes it is mate

[midlifecrisisrd]

Turn the engine upside down, fit some bolts into the lower side case screws to take cable ties holding the 2 gear shafts in the lower case (after the clutch basket and retainer half moon are removed of course)

You can then split the engine without removing the crank or top end

Steve

[headcoats]

Does look like something going on with the seal ?

Are they matching top and bottom cases as in same scribed number ?

[Yogi]

If you zoom in,it does look like you’ve pinched the seal between the cases
as Kostas said

[mellow]

Yes matching cases number scribed in.
Will go take a better look at the seal but I'm sure its ok🤔
Is it not an option to undo lower nuts and top bolts then lift top end off in one go with barrels attached? If not will try the cable tie thing thanks👍🙂

[mellow]

Just looked at the picture. See what you mean about seal.
Should I try slackenimg upper/lower bolts and see if I can shift seal out of case join?🤔

[Yogi]

It’s a tough one but could be worth a try
I wouldn’t got prodding the seal with knives or such like though

[kostas]

Flip over- cable tie as Steve suggests and completely remove the bottom half.
Rotate the seal 90 degrees before refitting and make sure the seal grooves are clean

Pain it is but has to be done

Kostas

[mellow]

Ok thanks guys. That's my weekend taken up. Was hoping to get it fitted this weekend 😞👍

[midlifecrisisrd]

Did the seal have the lip in the middle around the outer edge?

I had bought all the seals months before my last build and when I got round to fitting them the seal was wrong

Looked the right dimensions but no outer lip

Never used it and ordered another which arrived correct

Steve

[mellow]

Yes mate has the lip👍

[mellow]

Been back down the shed for a look. The seal seems the same both sides of the crank.
Starting to wonder if there just wasn't enough threebond in that one place

Side it leaks from



other side

[midlifecrisisrd]

That first picture looks way wrong

There should be no gap between the seal and the case for sealant

Looks like a gap at the edge of the seal

Steve

[mellow]

I have no idea🤔🙄.
I will take the bottom off again saturday😞

[4l04ever]

I would not reuse those seals as that may cause an air leak. Just get a new pair and make sure you seat them well in the casing including tapping the bearing down into the casing with the pins correctly aligned.

[mellow]

The primary drive seal is fine. No leak. Have ordered new seal for dodgy side👍

[mellow]

Evening men.

I have split the cases. There was a small area just next to seal that didn't have any threebond Guessing that's why it leaked there.

Next question................I have cleaned the old threebond off most of the lower case, I will remove the gear clusters to get into the awkward areas then re tie them with the cable ties, but how do i change the left crank seal and get to the crank area to clean old sealer off that? Pull the crank up a bit just enough to do this then push back down?

Thanks for the advice so far

[Yogi]

I’d do just that
Pull the crank out enough to replace seal and clean
then put plenty of threebond on the bottom case(I always use a small throw away brush to spread it everywhere once applied)
Then refit carefully

Good luck Matt

[mellow]

Evening men.
I have now cleaned the three bond off both case surfaces, now it's stupid question time

Bearing in mind the engine is upside down in the pictures, so you are looking at the bottom of the top case, should I turn the pegs up a few mm to locate in the lower case cut outs or will they sit in ok as they are?





Also, does threebond have to be brushed out or can you just put a nice bead along center of joining face and let the tightening "squidge" it out?

Finally, how long should i leave it to sit before pressure testing again?

Thanks

[Yogi]

If it was me I’d dry fit it first to check it fits snuggly together
then apply threebond generously,making sure it’s all over the mating surfaces
Bolt back together checking it’s pulls down evenly
Then take indoors overnight before pressure testing tomorrow

Matt

[mellow]

Can you give me a lift with it then please. Bit heavy😁👍💪
Will the pins be fine where they are?

[Yogi]

Lol,leave it where it is if it’s warmish

Pins should be fine where they are just make sure the case surfaces are touching
before tightening any bolts

[mellow]

Give up😞think it's still f**king leaking 😡🤬

[Yogi]

Do them crank pins fit in the lower case ok?

[midlifecrisisrd]

Apr 13, 2019 16:13:35 GMT 1 Yogi said:

Do them crank pins fit in the lower case ok?

Good point Matt

I've had to dremel cases before

Steve

[Yogi]

Apr 13, 2019 16:46:54 GMT 1 midlifecrisisrd said:

Apr 13, 2019 16:13:35 GMT 1 Yogi said:

Do them crank pins fit in the lower case ok?

Good point Matt

I've had to dremel cases before

Steve

They look big pins to me

[oldbritguy]

This is worrying me a bit as I am about to put my motor together this weekend.
Watching in anticipation
J

[stusco]

I’ve had to enlarge the notch before I used a sharp wood chisel it worked perfectly (before dremmel)