I don't know if I've done something daft, so I'm hoping someone will tell me.

I recently changed the barrels and pistons on my 602cc, 1989 engine, and put everything back together with new gaskets and seals. Since then, I've had a bit of an oil leak from the nearside pushrod tubes.

When I investigated, I noticed that the cutouts in the seal cups were facing downwards (i.e. towards the ground). I thought they were meant to be facing upwards (towards the cylinder). Both sides are the same, so if I've cocked it up, I'm at least being consistent about it.

Would somebody be kind enough to tell me whether or not I've got them wrong, please.

Thanks.

beerbunny,
that's correct, the 'flats' on the goggle seals should be at the top on 602 engines.
Check in Haynes, Chapter 1, Fig 1.18. )

Stripping it down and refitting them the right way up should do the trick, but if you've used the type with little 'eyebrows' on them, check that those haven't caught on the edge of the tappet bore and been damaged.

I find that it's much easier, with less chance of things going wrong, if cylinder heads are fitted without the rocker gear and pushrods.
It's distressing how many cylinder heads end up with damaged pushrod tubes, mostly by folk attempting to rebuild an engine for their first time, although some can be repeat offenders...
Also worth replacing those daft peg bolts on the lower end of the rocker shafts with Allen bolts, M8 x 1.25 thread.

ken.

( Was this the engine that the vendor stated had new barrels & pistons fitted, or may not? )

Another way is to put the side you are working on to TDC (top dead center). This way both valves are closed and push rods have free play.
Also stick some grease on the seals allowing them to slide when doing up the heads. Remember to do the manifold before the heads securing proper sealing between manifold and heads, in particular exhausts. They have a bad habbit of burning gaskets if not flat against each other.

Oh good, I've got it wrong again. I can't believe it; I thought I was being really careful.

Thanks, guys, for the info.


Yes, it's the same one. And I don't believe this engine had ever been apart, so somebody was telling me porkies. As I suspected.

Turns out the seals were fitted correctly; I'd failed to notice another cut out on the seal cup diametrically opposite the one that has to face the cylinder and that was what I was seeing. Oh well, something else learned.

I think I've found out why one of the seals was leaking; there's a circular lip set in from the edge of the seal and this was damaged, so I've fitted what appears to be a good old seal. Here's hoping.

Possibly I'm being paranoid, but there is damage to all the pushrod tube seals that I have in my possession. And in all cases, it's on the side of the seal nearest the cylinder (the upper side). I'm referring to the damage to the circular lip inboard of the edge of the seal that I mentioned in my last post, btw.

I'm guessing that this is caused by the sharp edge of the cam follower hole while the head is being refitted. Is there anything I should be doing to try to avoid this? Or am I attaching too much importance to this damage?

Thanks,

John

John,
have you followed my suggestion about removing the rocker gear and pushrods, then installing those items once the head is safely in position?

Fwiw, I never put a spanner near a cylinder head nut until the head has been offered into place, pressed inwards against the light resistance of the pushrod seal springs and the lower nut wound in finger tight.
As Viking has recommended, grease will help the seals slip into place easier.

It might also help to do a trial fit of the heads without the seals, springs and cups fitted, so that you can see just how the pushrod tubes sit relative to the tappet bores...

ken

John,
possibly caused by the cups pressing the lip into the edge of the machining.
I always assemble with grease and make sure that the cups and the seals are free to slide up the tubes with the only resistance being the spring

If you havn't yet stripped the heads back off sometimes you can poke the cups and seals about with a screwdriver so they make better contact

When you assemble the heads on finger tight take some time fiddling about centralising the heads so the tubes are in the middle of the holes not either canted forward or back to its fullest extent, then wiggle the barrel so the head studs are central in thir cutouts in the fins.

finally at this point I fit the manifold so that all the mating surfaces for the manifolds line up and seal. Once happy, first torque head nuts, torque manifold studs and bolts , final head torque.

if you follow haynes sometimes the head wont pull round to the heads and the bolts are a pain and the gaskets cant seal the misaligned flange.

Sean

and if you follow mine and Kens practice of using Allen head bolts in place of the peg bolts you can torque them accurately.
http://cgi.ebay.co.uk/M8-x-30-12-9-HIGH-TENSILE-Allen-Cap-Head-BOLTS-10-/180572250222?pt=UK_DIY_Material_Nails_Fixing_MJ&hash=item2a0af1e06e

By the time you sent me that advice, I'd already fitted the heads, etc. But I've got them off again and I've ordered new 'spectacles' (including a couple of spares), and I will do as you suggested. Btw, fwiw, I didn't damage the old seals, I just spotted it when I was checking them for the damage I'd seen on the ones I did fit. So presumably, it's pretty easy to do.


I'll do this tomorrow; I'll try anything that might help.

Thanks for the advice, Ken.


Thanks for that, Sean, I'll add all that to the procedure.


And I'll do that, too. Thanks, Viking.

Thanks to you all.

Cheers,

John

Okay, I've broken my 6mm open-ended spanner trying to undo the two rocker spindle screws. I'm just off to Berwick to buy a couple more.

Would heating the head make it easier to remove these screws? Is there a better tool than a 6mm open-ender?

I'm beginning to wish I'd left well alone.